@article{Aakre2018, abstract = {Although addressing climate change will ultimately require global cooperation, substantial progress may be achieved through small clubs of countries, where it is easier to forge and implement deals needed for policy coordination. Here we quantify the gains from cooperation in the Arctic region and find that nearly 90{\%} of the potential for abating black carbon can be reached by countries acting in self-interest alone because soot, the main source of black carbon, causes severe harm to human health along with warming. Abating methane, by contrast, requires more cooperation because impacts are more diffused geographically. Well-designed clubs with as few as four members can realize more than 80{\%} of the full group cooperation potential for reducing these pollutants. The pivotal player in every effective club is Russia - most other members of the Arctic Council, the institution most focused on advancing the collective interests of the region, offer little leverage on the problems at hand.}, author = {Aakre, Stine and Kallbekken, Steffen and {Van Dingenen}, Rita and Victor, David G.}, doi = {10.1038/s41558-017-0030-8}, issn = {1758-678X}, journal = {Nature Climate Change}, month = {jan}, number = {1}, pages = {85--90}, title = {{Incentives for small clubs of Arctic countries to limit black carbon and methane emissions}}, url = {http://www.nature.com/articles/s41558-017-0030-8}, volume = {8}, year = {2018} } @article{Aamaas2016a, abstract = {{\textless}p{\textgreater}For short-lived climate forcers (SLCFs), the impact of emissions depends on where and when the emissions take place. Comprehensive new calculations of various emission metrics for SLCFs are presented based on radiative forcing (RF) values calculated in four different (chemical-transport or coupled chemistry–climate) models. We distinguish between emissions during summer (May–October) and winter (November–April) for emissions in Europe and East Asia, as well as from the global shipping sector and global emissions. The species included in this study are aerosols and aerosol precursors (BC, OC, SO{\textless}sub{\textgreater}2{\textless}/sub{\textgreater}, NH{\textless}sub{\textgreater}3{\textless}/sub{\textgreater}), as well as ozone precursors (NO{\textless}sub{\textgreater}{\textless}i{\textgreater}x{\textless}/i{\textgreater}{\textless}/sub{\textgreater}, CO, VOCs), which also influence aerosols to a lesser degree. Emission metrics for global climate responses of these emissions, as well as for CH{\textless}sub{\textgreater}4{\textless}/sub{\textgreater}, have been calculated using global warming potential (GWP) and global temperature change potential (GTP), based on dedicated RF simulations by four global models. The emission metrics include indirect cloud effects of aerosols and the semi-direct forcing for BC. In addition to the standard emission metrics for pulse and sustained emissions, we have also calculated a new emission metric designed for an emission profile consisting of a ramping period of 15 years followed by sustained emissions, which is more appropriate for a gradual implementation of mitigation policies.{\textless}br{\textgreater}{\textless}br{\textgreater}For the aerosols, the emission metric values are larger in magnitude for emissions in Europe than East Asia and for summer than winter. A variation is also observed for the ozone precursors, with largest values for emissions in East Asia and winter for CO and in Europe and summer for VOCs. In general, the variations between the emission metrics derived from different models are larger than the variations between regions and seasons, but the regional and seasonal variations for the best estimate also hold for most of the models individually. Further, the estimated climate impact of an illustrative mitigation policy package is robust even when accounting for the fact that the magnitude of emission metrics for different species in a given model is correlated. For the ramping emission metrics, the values are generally larger than for pulse or sustained emissions, which holds for all SLCFs. For SLCFs mitigation policies, the dependency of metric values on the region and season of emission should be considered.{\textless}/p{\textgreater}}, annote = {From Duplicate 1 (Regional emission metrics for short-lived climate forcers from multiple models - Aamaas, Borgar; Berntsen, Terje K.; Fuglestvedt, Jan S.; Shine, Keith P.; Bellouin, Nicolas) Times Cited: 8 Shine, Keith/D-9093-2012 Shine, Keith/0000-0003-2672-9978 0 8 1680-7324}, author = {Aamaas, Borgar and Berntsen, Terje K. and Fuglestvedt, Jan S. and Shine, Keith P. and Bellouin, Nicolas}, doi = {10.5194/acp-16-7451-2016}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {jun}, number = {11}, pages = {7451--7468}, title = {{Regional emission metrics for short-lived climate forcers from multiple models}}, url = {https://www.atmos-chem-phys.net/16/7451/2016/ http://www.atmos-chem-phys.net/16/7451/2016/}, volume = {16}, year = {2016} } @article{Aamaas2017c, abstract = {{\textless}p{\textgreater}We calculate the absolute regional temperature change potential (ARTP) of various short-lived climate forcers (SLCFs) based on detailed radiative forcing (RF) calculations from four different models. The temperature response has been estimated for four latitude bands (90–28° S, 28° S–28° N, 28–60° N, and 60–90° N). The regional pattern in climate response not only depends on the relationship between RF and surface temperature, but also on where and when emissions occurred and atmospheric transport, chemistry, interaction with clouds, and deposition. We present four emissions cases covering Europe, East Asia, the global shipping sector, and the entire globe. Our study is the first to estimate ARTP values for emissions during Northern Hemisphere summer (May–October) and winter season (November–April). The species studied are aerosols and aerosol precursors (black carbon, organic carbon, SO{\textless}sub{\textgreater}2{\textless}/sub{\textgreater}, NH{\textless}sub{\textgreater}3{\textless}/sub{\textgreater}), ozone precursors (NO{\textless}sub{\textgreater}{\textless}i{\textgreater}x{\textless}/i{\textgreater}{\textless}/sub{\textgreater}, CO, volatile organic compound), and methane (CH{\textless}sub{\textgreater}4{\textless}/sub{\textgreater}). For the response to BC in the Arctic, we take into account the vertical structure of the RF in the atmosphere, and an enhanced climate efficacy for BC deposition on snow. Of all SLCFs, BC is the most sensitive to where and when the emissions occur, as well as giving the largest difference in response between the latitude bands. The temperature response in the Arctic per unit BC emission is almost four times larger and more than two times larger than the global average for Northern Hemisphere winter emissions for Europe and East Asia, respectively. The latitudinal breakdown likely gives a better estimate of the global temperature response as it accounts for varying efficacies with latitude. An annual pulse of non-methane SLCF emissions globally (representative of 2008) lead to a global cooling. In contrast, winter emissions in Europe and East Asia give a net warming in the Arctic due to significant warming from BC deposition on snow.{\textless}/p{\textgreater}}, annote = {Times Cited: 0 Shine, Keith/D-9093-2012; Collins, William/A-5895-2010 Shine, Keith/0000-0003-2672-9978; Collins, William/0000-0002-7419-0850 0 1680-7324}, author = {Aamaas, Borgar and Berntsen, Terje K. and Fuglestvedt, Jan S. and Shine, Keith P. and Collins, William J.}, doi = {10.5194/acp-17-10795-2017}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {17}, pages = {10795--10809}, title = {{Regional temperature change potentials for short-lived climate forcers based on radiative forcing from multiple models}}, url = {https://www.atmos-chem-phys.net/17/10795/2017/acp-17-10795-2017.pdf}, volume = {17}, year = {2017} } @article{Aas2019, abstract = {The profound changes in global SO2 emissions over the last decades have affected atmospheric composition on a regional and global scale with large impact on air quality, atmospheric deposition and the radiative forcing of sulfate aerosols. Reproduction of historical atmospheric pollution levels based on global aerosol models and emission changes is crucial to prove that such models are able to predict future scenarios. Here, we analyze consistency of trends in observations of sulfur components in air and precipitation from major regional networks and estimates from six different global aerosol models from 1990 until 2015. There are large interregional differences in the sulfur trends consistently captured by the models and observations, especially for North America and Europe. Europe had the largest reductions in sulfur emissions in the first part of the period while the highest reduction came later in North America and East Asia. The uncertainties in both the emissions and the representativity of the observations are larger in Asia. However, emissions from East Asia clearly increased from 2000 to 2005 followed by a decrease, while in India a steady increase over the whole period has been observed and modelled. The agreement between a bottom-up approach, which uses emissions and process-based chemical transport models, with independent observations gives an improved confidence in the understanding of the atmospheric sulfur budget.}, author = {Aas, Wenche and Mortier, Augustin and Bowersox, Van and Cherian, Ribu and Faluvegi, Greg and Fagerli, Hilde and Hand, Jenny and Klimont, Zbigniew and Galy-Lacaux, Corinne and Lehmann, Christopher M.B. and Myhre, Cathrine Lund and Myhre, Gunnar and Olivi{\'{e}}, Dirk and Sato, Keiichi and Quaas, Johannes and Rao, P. S.P. and Schulz, Michael and Shindell, Drew and Skeie, Ragnhild B. and Stein, Ariel and Takemura, Toshihiko and Tsyro, Svetlana and Vet, Robert and Xu, Xiaobin}, doi = {10.1038/s41598-018-37304-0}, issn = {20452322}, journal = {Scientific Reports}, number = {1}, pages = {953}, title = {{Global and regional trends of atmospheric sulfur}}, volume = {9}, year = {2019} } @article{Achakulwisut2015, abstract = {Current understanding of the factors controlling biogenic isoprene emissions and of the fate of isoprene oxidation products in the atmosphere has been evolving rapidly. We use a climate-biosphere-chemistry modeling framework to evaluate the sensitivity of estimates of the tropospheric oxidative capacity to uncertainties in isoprene emissions and photochemistry. Our work focuses on trends across two time horizons: from the Last Glacial Maximum (LGM, 21 000 years BP) to the preindustrial (1770s); and from the preindustrial to the present day (1990s). We find that different oxidants have different sensitivities to the uncertainties tested in this study, with OH being the most sensitive: changes in the global mean OH levels for the LGM-to-preindustrial transition range between −29 and +7{\%}, and those for the preindustrial-to-present day transition range between −8 and +17{\%}, across our simulations. Our results suggest that the observed glacial-interglacial variability in atmospheric methane concentrations is predominantly driven by changes in methane sources as opposed to changes in OH, the primary methane sink. However, the magnitudes of change are subject to uncertainties in the past isoprene global burdens, as are estimates of the change in the global burden of secondary organic aerosol (SOA) relative to the preindustrial. We show that the linear relationship between tropospheric mean OH and tropospheric mean ozone photolysis rates, water vapor, and total emissions of NO{\textless}sub{\textgreater}x{\textless}/sub{\textgreater} and reactive carbon – first reported in Murray et al. (2014) – does not hold across all periods with the new isoprene photochemistry mechanism. Our results demonstrate that inadequacies in our understanding of present-day OH and its controlling factors must be addressed in order to improve model estimates of the oxidative capacity of past and present atmospheres.}, annote = {ACP}, author = {Achakulwisut, P. and Mickley, L. J. and Murray, L. T. and Tai, A. P.K. and Kaplan, J. O. and Alexander, B.}, doi = {10.5194/acp-15-7977-2015}, isbn = {1680-7324}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {14}, pages = {7977--7998}, publisher = {Copernicus Publications}, title = {{Uncertainties in isoprene photochemistry and emissions: Implications for the oxidative capacity of past and present atmospheres and for climate forcing agents}}, url = {https://www.atmos-chem-phys.net/15/7977/2015/}, volume = {15}, year = {2015} } @article{AcostaNavarro2014, author = {{Acosta Navarro}, J. C. and Smolander, S. and Struthers, H. and Zorita, E. and Ekman, A. M. L. and Kaplan, J. O. and Guenther, A. and Arneth, A. and Riipinen, I.}, doi = {10.1002/2013JD021238}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {jun}, number = {11}, pages = {6867--6885}, title = {{Global emissions of terpenoid VOCs from terrestrial vegetation in the last millennium}}, volume = {119}, year = {2014} } @article{Adebiyi2020, abstract = {Coarse mineral dust (diameter, ≥5 $\mu$m) is an important component of the Earth system that affects clouds, ocean ecosystems, and climate. Despite their significance, climate models consistently underestimate the amount of coarse dust in the atmosphere when compared to measurements. Here, we estimate the global load of coarse dust using a framework that leverages dozens of measurements of atmospheric dust size distributions. We find that the atmosphere contains 17 Tg of coarse dust, which is four times more than current climate models simulate. Our findings indicate that models deposit coarse dust out of the atmosphere too quickly. Accounting for this missing coarse dust adds a warming effect of 0.15 W{\textperiodcentered}m−2 and increases the likelihood that dust net warms the climate system. We conclude that to properly represent the impact of dust on the Earth system, climate models must include an accurate treatment of coarse dust in the atmosphere.}, author = {Adebiyi, Adeyemi A and Kok, Jasper F}, doi = {10.1126/sciadv.aaz9507}, journal = {Science Advances}, month = {apr}, number = {15}, pages = {eaaz9507}, title = {{Climate models miss most of the coarse dust in the atmosphere}}, volume = {6}, year = {2020} } @article{AGGARWAL20092532, abstract = {To better understand the influence of sources and atmospheric processing on aerosol chemical composition, we collected atmospheric particles in Sapporo, northern Japan during spring and early summer 2005 under the air mass transport conditions from Siberia, China and surrounding seas. The aerosols were analyzed for inorganic ions, organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and the major water-soluble organic compound classes (i.e., dicarboxylic acids and sugars). SO42− is the most abundant inorganic constituent (average 44{\%} of the identified inorganic ion mass) followed by NH4+ (21{\%}) and NO3− (13{\%}). Concentrations of OC, EC, and WSOC ranged from 2.0–16, 0.24–2.9, and 0.80–7.9$\mu$gm−3 with a mean of 7.4, 1.0, and 3.1$\mu$gm−3, respectively. High OC/EC ratios (range: 3.6–19, mean: 8.7) were obtained, however WSOC/OC ratios (0.23–0.69, 0.44) do not show any significant diurnal changes. These results suggest that the Sapporo aerosols were already aged, but were not seriously affected by local photochemical processes. Identified water-soluble organic compounds (diacids+sugars) account for {\textless}10{\%} of WSOC. Based on some marker species and air mass back trajectory analyses, and using stable carbon isotopic compositions of shorter-chain diacids (i.e., C2–C4) as photochemical aging factor of organic aerosols, the present study suggests that a fraction of WSOC in OC is most likely influenced by aerosol aging, although the OC loading in aerosols may be more influenced by their sources and source regions.}, author = {Aggarwal, Shankar Gopala and Kawamura, Kimitaka}, doi = {https://doi.org/10.1016/j.atmosenv.2009.02.032}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Atmospheric aerosols,Diacids,Major ions,Organic carbon,Photochemical aging,Sugars,Water-soluble organic carbon}, number = {16}, pages = {2532--2540}, title = {{Carbonaceous and inorganic composition in long-range transported aerosols over northern Japan: Implication for aging of water-soluble organic fraction}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231009001605}, volume = {43}, year = {2009} } @article{Ahlm2017, abstract = {Abstract. Marine cloud brightening through sea spray injection has been proposed as a climate engineering method for avoiding the most severe consequences of global warming. A limitation of most of the previous modelling studies on marine cloud brightening is that they have either considered individual models or only investigated the effects of a specific increase in the number of cloud droplets. Here we present results from coordinated simulations with three Earth system models (ESMs) participating in the Geoengineering Model Intercomparison Project (GeoMIP) G4sea-salt experiment. Injection rates of accumulation-mode sea spray aerosol particles over ocean between 30° N and 30° S are set in each model to generate a global-mean effective radiative forcing (ERF) of −2.0 W m−2 at the top of the atmosphere. We find that the injection increases the cloud droplet number concentration in lower layers, reduces the cloud-top effective droplet radius, and increases the cloud optical depth over the injection area. We also find, however, that the global-mean clear-sky ERF by the injected particles is as large as the corresponding total ERF in all three ESMs, indicating a large potential of the aerosol direct effect in regions of low cloudiness. The largest enhancement in ERF due to the presence of clouds occur as expected in the subtropical stratocumulus regions off the west coasts of the American and African continents. However, outside these regions, the ERF is in general equally large in cloudy and clear-sky conditions. These findings suggest a more important role of the aerosol direct effect in sea spray climate engineering than previously thought.}, author = {Ahlm, Lars and Jones, Andy and Stjern, Camilla W. and Muri, Helene and Kravitz, Ben and Kristj{\'{a}}nsson, J{\'{o}}n Egill}, doi = {10.5194/acp-17-13071-2017}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {nov}, number = {21}, pages = {13071--13087}, title = {{Marine cloud brightening – as effective without clouds}}, url = {https://acp.copernicus.org/articles/17/13071/2017/}, volume = {17}, year = {2017} } @article{Ainsworth2012, abstract = {Tropospheric ozone (O3) is a global air pollutant that causes billions of dollars in lost plant productivity annually. It is an important anthropogenic greenhouse gas, and as a secondary air pollutant, it is present at high concentrations in rural areas far from industrial sources. It also reduces plant productivity by entering leaves through the stomata, generating other reactive oxygen species and causing oxidative stress, which in turn decreases photosynthesis, plant growth, and biomass accumulation. The deposition of O 3 into vegetation through stomata is an important sink for tropospheric O3, but this sink is modified by other aspects of environmental change, including rising atmospheric carbon dioxide concentrations, rising temperature, altered precipitation, and nitrogen availability. We review the atmospheric chemistry governing tropospheric O 3 mass balance, the effects of O3 on stomatal conductance and net primary productivity, and implications for agriculture, carbon sequestration, and climate change. {\textcopyright} 2012 by Annual Reviews. All rights reserved.}, author = {Ainsworth, Elizabeth A. and Yendrek, Craig R. and Sitch, Stephen and Collins, William J. and Emberson, Lisa D.}, doi = {10.1146/annurev-arplant-042110-103829}, issn = {1543-5008}, journal = {Annual Review of Plant Biology}, month = {jun}, number = {1}, pages = {637--661}, title = {{The Effects of Tropospheric Ozone on Net Primary Productivity and Implications for Climate Change}}, url = {http://www.annualreviews.org/doi/10.1146/annurev-arplant-042110-103829}, volume = {63}, year = {2012} } @article{Akagi2011, abstract = {Biomass burning (BB) is the second largest source of trace gases and the largest source of primary fine carbonaceous particles in the global troposphere. Many recent BB studies have provided new emission factor (EF) measurements. This is especially true for non-methane organic compounds (NMOC), which influence secondary organic aerosol (SOA) and ozone formation. New EF should improve regional to global BB emissions estimates and therefore, the input for atmospheric models. In this work we present an up-to-date, comprehensive tabulation of EF for known pyrogenic species based on measurements made in smoke that has cooled to ambient temperature, but not yet undergone significant photochemical processing. All EFs are converted to one standard form (g compound emitted per kg dry biomass burned) using the carbon mass balance method and they are categorized into 14 fuel or vegetation types. Biomass burning terminology is defined to promote consistency. We compile a large number of measurements of biomass consumption per unit area for important fire types and summarize several recent estimates of global biomass consumption by the major types of biomass burning. Post emission processes are discussed to provide a context for the emission factor concept within overall atmospheric chemistry and also highlight the potential for rapid changes relative to the scale of some models or remote sensing products. Recent work shows that individual biomass fires emit significantly more gas-phase NMOC than previously thought and that including additional NMOC can improve photochemical model performance. A detailed global estimate suggests that BB emits at least 400 Tg yr-1 of gas-phase NMOC, which is almost 3 times larger than most previous estimates. Selected recent results (e.g. measurements of HONO and the BB tracers HCN and CH3CN) are highlighted and key areas requiring future research are briefly discussed. {\textcopyright} 2011 Author(s).}, author = {Akagi, S. K. and Yokelson, R. J. and Wiedinmyer, C. and Alvarado, M. J. and Reid, J. S. and Karl, T. and Crounse, J. D. and Wennberg, P. O.}, doi = {10.5194/acp-11-4039-2011}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {9}, pages = {4039--4072}, title = {{Emission factors for open and domestic biomass burning for use in atmospheric models}}, url = {https://www.atmos-chem-phys.net/11/4039/2011/}, volume = {11}, year = {2011} } @article{Akimoto2015a, abstract = {The emissions of NOxand CO2in East Asia (Northeast and Southeast Asia) contribute more than 30{\%} of the global total since 2008, and consequently the control of air pollutants and CO2alleviating regional air pollution and global climate change is of great concern of not only in this region but also worldwide. In order to arrive at a rational view of the short-lived climate pollutants (SLCPs) co-control approach in East Asia, the effectiveness of the reduction of NOx/NMVOC and CH4emissions for the reduction of tropospheric O3has been evaluated by individual and simultaneous 50{\%}-reduction of the emissions in Northeast Asia (NEA) using both a global chemical climate model (CHASER/SPRINTARS-MIROC), and a regional chemical transport model (WRF-CMAQ). The simultaneous reduction of NOx/NMVOC and CH4emissions was found to reduce the regional concentration of surface O3in NEA, and globally averaged net radiative forcing most effectively.Global mean RF and regional air quality change were also evaluated for the climate stabilization scenario ("450-ppm"), and climate stabilization with additional air pollution mitigation strengthened scenario ("450-ppm-cntr") developed in IIASA with the aid of GAINS model. In the 450 ppm-cntr scenario, emissions of NOxNMVOC, BC and OC were further reduced respectively, for East Asia from the emissions in 450 ppm. The improvement of air quality as well as the mitigation of climate change would grant to the basis of the SLCP co-control approach in East Asia.}, annote = {From Duplicate 1 (SLCP co-control approach in East Asia: Tropospheric ozone reduction strategy by simultaneous reduction of NOx/NMVOC and methane - Akimoto, Hajime; Kurokawa, Jun'ichi; Sudo, Kengo; Nagashima, Tatsuya; Takemura, Toshihiko; Klimont, Zbigniew; Amann, Markus; Suzuki, Katsunori) From Duplicate 1 (SLCP co-control approach in East Asia: Tropospheric ozone reduction strategy by simultaneous reduction of NOx/NMVOC and methane - Akimoto, Hajime; Kurokawa, Jun'ichi Jun‘ichi; Sudo, Kengo; Nagashima, Tatsuya; Takemura, Toshihiko; Klimont, Zbigniew; Amann, Markus; Suzuki, Katsunori) From Duplicate 1 (SLCP co-control approach in East Asia: Tropospheric ozone reduction strategy by simultaneous reduction of NOx/NMVOC and methane - Akimoto, Hajime; Kurokawa, Jun'ichi; Sudo, Kengo; Nagashima, Tatsuya; Takemura, Toshihiko; Klimont, Zbigniew; Amann, Markus; Suzuki, Katsunori) Times Cited: 5 Takemura, Toshihiko/C-2822-2009; Kyushu, RIAM/F-4018-2015; U-ID, Kyushu/C-5291-2016; Klimont, Zbigniew/ Takemura, Toshihiko/0000-0002-2859-6067; Kyushu, RIAM/0000-0002-3518-444X; Klimont, Zbigniew/0000-0003-2630-198X 0 5 1873-2844 From Duplicate 2 (SLCP co-control approach in East Asia: Tropospheric ozone reduction strategy by simultaneous reduction of NOx/NMVOC and methane - Akimoto, Hajime; Kurokawa, Jun'ichi; Sudo, Kengo; Nagashima, Tatsuya; Takemura, Toshihiko; Klimont, Zbigniew; Amann, Markus; Suzuki, Katsunori) Times Cited: 5 Takemura, Toshihiko/C-2822-2009; Kyushu, RIAM/F-4018-2015; U-ID, Kyushu/C-5291-2016; Klimont, Zbigniew/ Takemura, Toshihiko/0000-0002-2859-6067; Kyushu, RIAM/0000-0002-3518-444X; Klimont, Zbigniew/0000-0003-2630-198X 0 5 1873-2844 From Duplicate 2 (SLCP co-control approach in East Asia: Tropospheric ozone reduction strategy by simultaneous reduction of NOx/NMVOC and methane - Akimoto, Hajime; Kurokawa, Jun'ichi; Sudo, Kengo; Nagashima, Tatsuya; Takemura, Toshihiko; Klimont, Zbigniew; Amann, Markus; Suzuki, Katsunori) Times Cited: 5 Takemura, Toshihiko/C-2822-2009; Kyushu, RIAM/F-4018-2015; U-ID, Kyushu/C-5291-2016; Klimont, Zbigniew/ Takemura, Toshihiko/0000-0002-2859-6067; Kyushu, RIAM/0000-0002-3518-444X; Klimont, Zbigniew/0000-0003-2630-198X 0 5 1873-2844}, author = {Akimoto, Hajime and Kurokawa, Jun'ichi and Sudo, Kengo and Nagashima, Tatsuya and Takemura, Toshihiko and Klimont, Zbigniew and Amann, Markus and Suzuki, Katsunori}, doi = {10.1016/j.atmosenv.2015.10.003}, isbn = {1352-2310}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {CH4,NMVOC,NOx,PM2.5,Radiative forcing,SLCPs,Tropospheric ozone}, month = {dec}, pages = {588--595}, title = {{SLCP co-control approach in East Asia: Tropospheric ozone reduction strategy by simultaneous reduction of NOx/NMVOC and methane}}, url = {https://www.sciencedirect.com/science/article/pii/S1352231015304222?via{\%}3Dihub http://linkinghub.elsevier.com/retrieve/pii/S1352231015304222}, volume = {122}, year = {2015} } @article{Akritidis2019a, author = {Akritidis, Dimitris and Pozzer, Andrea and Zanis, Prodromos}, doi = {10.5194/acp-19-14387-2019}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {nov}, number = {22}, pages = {14387--14401}, publisher = {Copernicus Publications}, title = {{On the impact of future climate change on tropopause folds and tropospheric ozone}}, url = {https://acp.copernicus.org/articles/19/14387/2019/}, volume = {19}, year = {2019} } @article{Alexander2015, abstract = {The oxidizing capacity of the atmosphere, defined as the global mean tropospheric abundance of the hydroxyl radical (OH center dot), strongly influences air pollution by controlling the lifetimes of gaseous pollutants and the production of particulate matter. Predicting future changes in OH center dot due to anthropogenic emissions and climate change is of interest to air quality managers, but it is difficult because of multiple competing effects. Models of atmospheric chemistry suggest that these competing effects buffer significant change in OH center dot in the past and in the near future. However, proxy-based observations for past changes in OH center dot and other oxidants over the preindustrial-industrial and glacial-interglacial time scales suggest much larger changes than models estimate. Model sensitivity studies show that variability in past and future OH center dot is highly sensitive to relative emissions of reactive nitrogen and carbon, water vapor, lightning, and stratospheric ozone, implying that one or more of these variables is highly sensitive to climate.}, annote = {Times Cited: 7 Alexander, Becky/0000-0001-9915-4621 0 7}, author = {Alexander, Becky and Mickley, Loretta J}, doi = {10.1007/s40726-015-0006-0}, isbn = {2198-6592}, journal = {Current Pollution Reports}, number = {2}, pages = {57--69}, title = {{Paleo-Perspectives on Potential Future Changes in the Oxidative Capacity of the Atmosphere Due to Climate Change and Anthropogenic Emissions}}, volume = {1}, year = {2015} } @incollection{IPCC2018, author = {Allen, M.R. and Dube, O.P. and Solecki, W. and Arag{\'{o}}n-Durand, F. and Cramer, W. and Humphreys, S. and Kainuma, M. and Kala, J. and Mahowald, N. and Mulugetta, Y. and Perez, R. and Wairiu, M. and {K. Zickfeld}}, booktitle = {Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change,}, chapter = {1}, doi = {https://www.ipcc.ch/sr15/chapter/chapter-1}, editor = {Masson-Delmotte, V. and Zhai, P. and P{\"{o}}rtner, H.-O. and Roberts, D. and Skea, J. and Shukla, P.R. and Pirani, A. and Moufouma-Okia, W. and P{\'{e}}an, C. and Pidcock, R. and Connors, S. and Matthews, J.B.R. and Chen, Y. and Zhou, X. and Gomis, M.I. and Lonnoy, E. and Maycock, T. and Tignor, M. and Waterfield, T.}, pages = {49--92}, publisher = {In Press}, title = {{Framing and Context}}, url = {https://www.ipcc.ch/sr15/chapter/chapter-1}, year = {2018} } @article{Allen9999a, abstract = {Near-term climate forcers (NTCFs), including aerosols and chemically reactive gases such as tropospheric ozone and methane, offer a potential way to mitigate climate change and improve air quality−so called “win-win” mitigation policies. Prior studies support improved air quality under NTCF mitigation, but with conflicting climate impacts that range from a significant reduction in the rate of global warming to only a modest impact. Here, we use state-of-the-art chemistry-climate model simulations conducted as part of the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP) to quantify the 21st-century impact of NTCF reductions, using a realistic future emission scenario with a consistent air quality policy. Non-methane NTCF (NMNTCF; aerosols and ozone precursors) mitigation improves air quality, but leads to significant increases in global mean precipitation of 1.3{\%} by mid-century and 1.4{\%} by end-of-the-century, and corresponding surface warming of 0.23 and 0.21 K. NTCF (all-NTCF; including methane) mitigation further improves air quality, with larger reductions of up to 45{\%} for ozone pollution, while offsetting half of the wetting by mid-century (0.7{\%} increase) and all the wetting by end-of-the-century (non-significant 0.1{\%} increase) and leading to surface cooling of −0.15 K by mid-century and −0.50 K by end-of-the-century. This suggests that methane mitigation offsets warming induced from reductions in NMNTCFs, while also leading to net improvements in air quality.}, author = {Allen, Robert J. and Horowitz, Larry W. and Naik, Vaishali and Oshima, Naga and O'Connor, Fiona M. and Turnock, Steven and Shim, Sungbo and {Le Sager}, Philippe and van Noije, Twan and Tsigaridis, Kostas and Bauer, Susanne E and Sentman, Lori T. and John, Jasmin G. and Broderick, Conor and Deushi, Makoto and Folberth, Gerd A. and Fujimori, Shinichiro and Collins, William J.}, doi = {10.1088/1748-9326/abe06b}, journal = {Environmental Research Letters}, number = {3}, pages = {034010}, title = {{Significant climate benefits from near-term climate forcer mitigation in spite of aerosol reductions}}, url = {https://iopscience.iop.org/article/10.1088/1748-9326/abe06b}, volume = {16}, year = {2021} } @article{Allen2016a, abstract = {Parties to the United Nations Framework Convention on Climate Change (UNFCCC) have requested guidance on common greenhouse gas metrics in accounting for Nationally determined contributions (NDCs) to emission reductions. Metric choice can affect the relative emphasis placed on reductions of ‘cumulative climate pollutants' such as carbon dioxide versus ‘short-lived climate pollutants' (SLCPs), including methane and black carbon. Here we show that the widely used 100-year global warming potential (GWP100) effectively measures the relative impact of both cumulative pollutants and SLCPs on realized warming 20–40 years after the time of emission. If the overall goal of climate policy is to limit peak warming, GWP100 therefore overstates the importance of current SLCP emissions unless stringent and immediate reductions of all climate pollutants result in temperatures nearing their peak soon after mid-century, which may be necessary to limit warming to “well below 2 °C” (ref. 1). The GWP100 can be used to approximately equate a one-off pulse emission of a cumulative pollutant and an indefinitely sustained change in the rate of emission of an SLCP. The climate implications of traditional CO2-equivalent targets are ambiguous unless contributions from cumulative pollutants and SLCPs are specified separately.}, annote = {Times Cited: 24 Shine, Keith/D-9093-2012; Forster, Piers/F-9829-2010; Pierrehumbert, Raymond/ Shine, Keith/0000-0003-2672-9978; Forster, Piers/0000-0002-6078-0171; Pierrehumbert, Raymond/0000-0002-5887-1197 0 24 1758-6798}, author = {Allen, Myles R. and Fuglestvedt, Jan S. and Shine, Keith P. and Reisinger, Andy and Pierrehumbert, Raymond T. and Forster, Piers M.}, doi = {10.1038/nclimate2998}, isbn = {1758-678X}, issn = {17586798}, journal = {Nature Climate Change}, month = {aug}, number = {8}, pages = {773--776}, title = {{New use of global warming potentials to compare cumulative and short-lived climate pollutants}}, url = {http://www.nature.com/articles/nclimate2998}, volume = {6}, year = {2016} } @article{Allen2002, abstract = {Model simulations of tropospheric O3 require an accurate specification of the reactive odd nitrogen (NOx) source from lightning that is consistent in time and space with convective transport of O3 precursors. Lightning NOx production in global models is often parameterized in terms of convective cloud top heights (CLDHT). However, a closer relationship may exist between flash rate and other measures of convective intensity. In this study, flash rates are parameterized in terms of CLDHT, convective precipitation (PRECON), and upward convective mass flux (MFLUX) from the Goddard Earth Observing System Data Assimilation System (GEOS DAS). GEOS-based flash rates are compared to flash rates from the National Lightning Detection Network (NLDN) and Long Range Flash (LRF) network and the Optical Transient Detector (OTD). Overall, MFLUX-based flash rates are most realistic. PRECON- and CLDHT-based flash rates are too large in the tropics. The MFLUX- and PRECON-based flash rates are a factor of 3 too high (low) over the equatorial western Pacific (central and southern Africa), while CLDHT-based flash rates are much too low at nearly all marine locations. In many cases, biases in the flash rate distributions can be traced to biases in the GEOS DAS convective fields. Improvements in flash rate parameterizations will be tied closely to improvements in model physics as well as to increases in the amount of tropical data that are available for assimilation. Flash rates calculated from the 6-hour averaged CLDHTs are much less variable than observed, and O3 production rates calculated using the NOx produced from these flash rates are likely to be larger than observed.}, author = {Allen, Dale J and Pickering, Kenneth E}, doi = {10.1029/2002JD002066}, issn = {01480227}, journal = {Journal of Geophysical Research: Atmospheres}, month = {dec}, number = {D23}, pages = {ACH 15--1--ACH 15--21}, title = {{Evaluation of lightning flash rate parameterizations for use in a global chemical transport model}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2002JD002066 http://doi.wiley.com/10.1029/2002JD002066}, volume = {107}, year = {2002} } @article{Allen2016b, abstract = {Atmospheric aerosols are of significant environmental importance, due to their effects on air quality, as well as their ability to alter the planet's radiative balance. Recent studies characterizing the effects of climate change on air quality and the broader distribution of aerosols in the atmosphere show significant, but inconsistent results, including the sign of the effect1–3 . Using a suite of state-of-the-art climate models, we show that climate change is associated with a negative aerosol–climate feedback of −0.02 to −0.09Wm−2 K−1 for direct radiative effects, with much larger values likely for indirect radiative effects. This is related to an increase in most aerosol species, particularly over the tropics and Northern Hemisphere midlatitudes, largely due to a decrease in wet deposition associated with less large-scale precipitation over land. Although simulation of aerosol processes in global climate models possesses uncertainty, we conclude that climate change may increase aerosol burden and surface concentration, which may have implications for future air quality.}, author = {Allen, Robert J. and Landuyt, William and Rumbold, Steven T.}, doi = {10.1038/nclimate2827}, isbn = {1758-678X}, issn = {17586798}, journal = {Nature Climate Change}, number = {3}, pages = {269--274}, title = {{An increase in aerosol burden and radiative effects in a warmer world}}, volume = {6}, year = {2016} } @article{AllenShineFug2018, abstract = {While cumulative carbon dioxide (CO2) emissions dominate anthropogenic warming over centuries, temperatures over the coming decades are also strongly affected by short-lived climate pollutants (SLCPs), complicating the estimation of cumulative emission budgets for ambitious mitigation goals. Using conventional Global Warming Potentials (GWPs) to convert SLCPs to ``CO2-equivalent''emissions misrepresents their impact on global temperature. Here we show that peak warming under a range of mitigation scenarios is determined by a linear combination of cumulative CO2 emissions to the time of peak warming and non-CO2 radiative forcing immediately prior to that time. This may be understood by expressing aggregate non-CO2 forcing as cumulative CO2 forcing-equivalent (CO2-fe) emissions. We show further that contributions to CO2-fe emissions are well approximated by a new usage of GWP, denoted GWP*, which relates cumulative CO2 emissions to date with the current rate of emission of SLCPs. GWP* accurately indicates the impact of emissions of both long-lived and short-lived pollutants on radiative forcing and temperatures over a wide range of timescales, including under ambitious mitigation when conventional GWPs fail. Measured by GWP*, implementing the Paris Agreement would reduce the expected rate of warming in 2030 by 28{\%} relative to a No Policy scenario. Expressing mitigation efforts in terms of their impact on future cumulative emissions aggregated using GWP* would relate them directly to contributions to future warming, better informing both burden-sharing discussions and long-term policies and measures in pursuit of ambitious global temperature goals.}, author = {Allen, Myles R and Shine, Keith P and Fuglestvedt, Jan S and Millar, Richard J and Cain, Michelle and Frame, David J and Macey, Adrian H}, doi = {10.1038/s41612-018-0026-8}, isbn = {2397-3722}, journal = {npj Climate and Atmospheric Science}, number = {1}, pages = {16}, title = {{A solution to the misrepresentations of CO2-equivalent emissions of short-lived climate pollutants under ambitious mitigation}}, url = {https://doi.org/10.1038/s41612-018-0026-8}, volume = {1}, year = {2018} } @article{Allen2019, abstract = {Many climate models simulate an increase in anthropogenic aerosol species in response to warming1, particularly over the Northern Hemisphere mid-latitudes during June, July and August. Recently, it has been argued that this increase in anthropogenic aerosols can be linked to a decrease in wet removal associated with reduced precipitation2, but the mechanisms remain uncertain. Here, using a state-of-the-art climate model (the Community Atmosphere Model version 5), we expand on this notion to demonstrate that the enhanced aerosol burden and hydrological changes are related to a robust climate change phenomenon—the land–sea warming contrast3,4. Enhanced land warming is associated with continental reductions in lower-tropospheric humidity that drive decreases in low clouds—particularly large scale (stratus) clouds—which, in turn, lead to reduced large-scale precipitation and aerosol wet removal. Idealized model simulations further show that muting the land–sea warming contrast weakens these hydrological changes, thereby suppressing the aerosol increase. Moreover, idealized simulations that only feature land warming yield enhanced continental aridity and an increase in aerosol burden. Thus, unless anthropogenic emission reductions occur, our results add confidence that a warmer world will be associated with enhanced aerosol pollution.}, author = {Allen, Robert J and Hassan, Taufiq and Randles, Cynthia A and Su, Hui}, doi = {10.1038/s41558-019-0401-4}, issn = {1758-678X}, journal = {Nature Climate Change}, month = {apr}, number = {4}, pages = {300--305}, title = {{Enhanced land–sea warming contrast elevates aerosol pollution in a warmer world}}, url = {http://www.nature.com/articles/s41558-019-0401-4}, volume = {9}, year = {2019} } @article{Allen2020, abstract = {{\textless}p{\textgreater}Abstract. It is important to understand how future environmental policies will impact both climate change and air pollution. Although targeting near-term climate forcers (NTCFs), defined here as aerosols, tropospheric ozone, and precursor gases, should improve air quality, NTCF reductions will also impact climate. Prior assessments of the impact of NTCF mitigation on air quality and climate have been limited. This is related to the idealized nature of some prior studies, simplified treatment of aerosols and chemically reactive gases, as well as a lack of a sufficiently large number of models to quantify model diversity and robust responses. Here, we quantify the 2015–2055 climate and air quality effects of non-methane NTCFs using nine state-of-the-art chemistry–climate model simulations conducted for the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP). Simulations are driven by two future scenarios featuring similar increases in greenhouse gases (GHGs) but with “weak” (SSP3-7.0) versus “strong” (SSP3-7.0-lowNTCF) levels of air quality control measures. As SSP3-7.0 lacks climate policy and has the highest levels of NTCFs, our results (e.g., surface warming) represent an upper bound. Unsurprisingly, we find significant improvements in air quality under NTCF mitigation (strong versus weak air quality controls). Surface fine particulate matter (PM2.5) and ozone (O3) decrease by -2.2±0.32 µg m−3 and -4.6±0.88 ppb, respectively (changes quoted here are for the entire 2015–2055 time period; uncertainty represents the 95 {\%} confidence interval), over global land surfaces, with larger reductions in some regions including south and southeast Asia. Non-methane NTCF mitigation, however, leads to additional climate change due to the removal of aerosol which causes a net warming effect, including global mean surface temperature and precipitation increases of 0.25±0.12 K and 0.03±0.012 mm d−1, respectively. Similarly, increases in extreme weather indices, including the hottest and wettest days, also occur. Regionally, the largest warming and wetting occurs over Asia, including central and north Asia (0.66±0.20 K and 0.03±0.02 mm d−1), south Asia (0.47±0.16 K and 0.17±0.09 mm d−1), and east Asia (0.46±0.20 K and 0.15±0.06 mm d−1). Relatively large warming and wetting of the Arctic also occur at 0.59±0.36 K and 0.04±0.02 mm d−1, respectively. Similar surface warming occurs in model simulations with aerosol-only mitigation, implying weak cooling due to ozone reductions. Our findings suggest that future policies that aggressively target non-methane NTCF reductions will improve air quality but will lead to additional surface warming, particularly in Asia and the Arctic. Policies that address other NTCFs including methane, as well as carbon dioxide emissions, must also be adopted to meet climate mitigation goals.{\textless}/p{\textgreater}}, author = {Allen, Robert J. and Turnock, Steven and Nabat, Pierre and Neubauer, David and Lohmann, Ulrike and Olivi{\'{e}}, Dirk and Oshima, Naga and Michou, Martine and Wu, Tongwen and Zhang, Jie and Takemura, Toshihiko and Schulz, Michael and Tsigaridis, Kostas and Bauer, Susanne E. and Emmons, Louisa and Horowitz, Larry and Naik, Vaishali and van Noije, Twan and Bergman, Tommi and Lamarque, Jean-Francois and Zanis, Prodromos and Tegen, Ina and Westervelt, Daniel M. and {Le Sager}, Philippe and Good, Peter and Shim, Sungbo and O'Connor, Fiona and Akritidis, Dimitris and Georgoulias, Aristeidis K. and Deushi, Makoto and Sentman, Lori T. and John, Jasmin G. and Fujimori, Shinichiro and Collins, William J.}, doi = {10.5194/acp-20-9641-2020}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {aug}, number = {16}, pages = {9641--9663}, title = {{Climate and air quality impacts due to mitigation of non-methane near-term climate forcers}}, url = {https://acp.copernicus.org/articles/20/9641/2020/}, volume = {20}, year = {2020} } @article{Allen2019a, abstract = {Nitrogen oxide (NOx) production by lightning in the tropics is estimated using tropospheric NOx amounts (LNOx*) over deep convective grid boxes derived from Ozone Monitoring Instrument (OMI) nitrogen dioxide (NO2) slant columns and detection-efficiency–adjusted World Wide Lightning Location Network (WWLLN) flashes. The lightning NOx production efficiency (LNOx PE) in the tropics is determined for the austral and boreal summers of 2007 to 2011 by regressing regional mean daily values of LNOx* for individual seasons against daily flash totals during flash windows prior to the OMI overpass. LNOx PE is determined to be approximately two times larger over marine locations than over continental locations possibly because marine flashes are more energetic. Overall, the mean LNOx PE for the tropics is calculated to be 170 ± 100 mol per flash with values over the tropical Pacific (low flash rate region) being largest. The main contributors to uncertainties in PE are uncertainties in WWLLN flash detection efficiency, upper tropospheric NOx lifetime in the near field of convection, and air mass factor biases.}, annote = {doi: 10.1029/2018JD029824}, author = {Allen, Dale J. and Pickering, Kenneth E. and Bucsela, Eric and Krotkov, Nickolay and Holzworth, Robert}, doi = {10.1029/2018JD029824}, issn = {21698996}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {Lightning nitrogen oxide,NASA Aura,NOx production per flash,OMI,Tropics,WWLLN}, month = {dec}, number = {23}, pages = {13498--13518}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Lightning NOx Production in the Tropics as Determined Using OMI NO2 Retrievals and WWLLN Stroke Data}}, url = {https://doi.org/10.1029/2018JD029824}, volume = {124}, year = {2019} } @article{Alterskjær2013a, abstract = {Marine cloud brightening (MCB) is a proposed technique to limit global warming through injections of sea spray into the marine boundary layer. Using the Norwegian Earth System Model, the sensitivity of MCB to sea salt amount and particle size was studied by running a set of simulations in which Aitken (re = 0.04 $\mu$m), accumulation (re = 0.22 $\mu$m), or coarse (re = 2.46 $\mu$m) mode sea salt emissions were increased uniformly by 10-11 to 10-8 kg m-2 s -1. As desired, accumulation mode particles had a negative radiative effect of down to -3.3W m-2. Conversely, for Aitken mode particles, injections of 10-10 kg m-2 s-1 or greater led to a positive forcing of up to 8.4W m-2, caused by a strong competition effect combined with the high critical supersaturation of Aitken mode sea salt. The coarse mode particles gave a positive forcing of up to 1.2W m-2 because of a decrease in activation of background aerosols. Sensitivity experiments show that the competition effect dominated our results. MCB may have a cooling effect, but if the wrong size or injection amount is used, our simulations show a warming effect on the climate system. {\textcopyright} 2013. American Geophysical Union. All Rights Reserved.}, author = {Alterskjaer, K. and Kristj{\'{a}}nsson, J. E.}, doi = {10.1029/2012GL054286}, issn = {00948276}, journal = {Geophysical Research Letters}, month = {jan}, number = {1}, pages = {210--215}, title = {{The sign of the radiative forcing from marine cloud brightening depends on both particle size and injection amount}}, url = {http://doi.wiley.com/10.1029/2012GL054286}, volume = {40}, year = {2013} } @article{Alvarez2018, abstract = {Considerable amounts of the greenhouse gas methane leak from the U.S. oil and natural gas supply chain. Alvarez et al. reassessed the magnitude of this leakage and found that in 2015, supply chain emissions were ∼60{\%} higher than the U.S. Environmental Protection Agency inventory estimate. They suggest that this discrepancy exists because current inventory methods miss emissions that occur during abnormal operating conditions. These data, and the methodology used to obtain them, could improve and verify international inventories of greenhouse gases and provide a better understanding of mitigation efforts outlined by the Paris Agreement.Science, this issue p. 186Methane emissions from the U.S. oil and natural gas supply chain were estimated by using ground-based, facility-scale measurements and validated with aircraft observations in areas accounting for {\~{}}30{\%} of U.S. gas production. When scaled up nationally, our facility-based estimate of 2015 supply chain emissions is 13 ± 2 teragrams per year, equivalent to 2.3{\%} of gross U.S. gas production. This value is {\~{}}60{\%} higher than the U.S. Environmental Protection Agency inventory estimate, likely because existing inventory methods miss emissions released during abnormal operating conditions. Methane emissions of this magnitude, per unit of natural gas consumed, produce radiative forcing over a 20-year time horizon comparable to the CO2 from natural gas combustion. Substantial emission reductions are feasible through rapid detection of the root causes of high emissions and deployment of less failure-prone systems.}, author = {Alvarez, Ram{\'{o}}n A and Zavala-Araiza, Daniel and Lyon, David R and Allen, David T and Barkley, Zachary R and Brandt, Adam R and Davis, Kenneth J and Herndon, Scott C and Jacob, Daniel J and Karion, Anna and Kort, Eric A and Lamb, Brian K and Lauvaux, Thomas and Maasakkers, Joannes D and Marchese, Anthony J and Omara, Mark and Pacala, Stephen W and Peischl, Jeff and Robinson, Allen L and Shepson, Paul B and Sweeney, Colm and Townsend-Small, Amy and Wofsy, Steven C and Hamburg, Steven P}, doi = {10.1126/science.aar7204}, journal = {Science}, month = {jul}, number = {6398}, pages = {186--188}, title = {{Assessment of methane emissions from the U.S. oil and gas supply chain}}, url = {http://science.sciencemag.org/content/361/6398/186.abstract}, volume = {361}, year = {2018} } @article{Amador-Jimenez2020a, abstract = {The covid-19 pandemic led to rapid and large-scale government intervention in economies and societies. A common policy response to covid-19 outbreaks has been the lockdown or quarantine. Designed to slow the spread of the disease, lockdowns have unintended consequences for the environment. This article examines the impact of Colombia's lockdown on forest fires, motivated by satellite data showing a particularly large upsurge of fires at around the time of lockdown implementation. We find that Colombia's lockdown is associated with an increase in forest fires compared to three different counterfactuals, constructed to simulate the expected number of fires in the absence of the lockdown. To varying degrees across Colombia's regions, the presence of armed groups is correlated with this fire upsurge. Mechanisms through which the lockdown might influence fire rates are discussed, including the mobilisation of armed groups and the reduction in the monitoring capacity of state and conservation organisations during the covid-19 outbreak. Given the fast-developing situation in Colombia, we conclude with some ideas for further research.}, author = {Amador-Jim{\'{e}}nez, M{\'{o}}nica and Millner, Naomi and Palmer, Charles and Pennington, R. Toby and Sileci, Lorenzo}, doi = {10.1007/s10640-020-00501-5}, issn = {0924-6460}, journal = {Environmental and Resource Economics}, month = {aug}, number = {4}, pages = {1081--1105}, title = {{The Unintended Impact of Colombia's Covid-19 Lockdown on Forest Fires}}, url = {https://link.springer.com/10.1007/s10640-020-00501-5}, volume = {76}, year = {2020} } @book{Amann2013, abstract = {New scientific understanding could increase the cost-effectiveness of local and regional air quality management policies, enhance the acceptance of mitigation measures for long-lived greenhouse gas (GHG) emissions, and reveal win-win portfolios of controls for short-lived substances that yield immediate health and crop benefits while limiting temperature increase in the near term. However, although substantial efforts have been devoted to global analyses of the emissions of carbon dioxide (CO) and other long-lived GHGs, air pollutant emissions have received only limited attention in the global context. Past and likely future trends in air pollutant emissions evolve rather differently from those of long-lived GHGs, so that superficial extrapolations of GHG trends would lead to misleading conclusions. In many world regions, the evolution of air pollutant emissions has effectively decoupled from economic growth. Since 1990, air pollutant emissions declined (sulfur dioxide, SO), stabilized (nitrogen oxides, NO), or increased slightly (black carbon, BC; organic carbon, OC; and ammonia, NH). This review discusses to what extent structural changes, technological improvements, and dedicated environmental legislation have contributed to these changes. The scenarios of future emissions in the literature span a wide range, mainly owing to different assumptions about future environmental policies. Although the more recent scenarios agree on declining air pollutants up to 2030, avoiding potential rebounds of emissions after 2030 will require additional policy interventions.}, author = {Amann, Markus and Klimont, Zbigniew and Wagner, Fabian}, booktitle = {Annual Review of Environment and Resources}, doi = {10.1146/annurev-environ-052912-173303}, issn = {1543-5938}, keywords = {drivers of emissions,emission inventories,emission projections,global air pollution}, number = {1}, pages = {31--55}, title = {{Regional and Global Emissions of Air Pollutants: Recent Trends and Future Scenarios}}, volume = {38}, year = {2013} } @article{AMANN201799, abstract = {Megacities in Asia rank high in air pollution at the global scale. In many cities, ambient concentrations of fine particulate matter (PM2.5) have been exceeding both the WHO interim targets as well as respective national air quality standards. This paper presents a systems analytical perspective on management options that could efficiently improve air quality at the urban scale, having Delhi as a case study. We employ the newly developed GAINS-City policy analysis framework, consisting of a bottom up emission calculation combined with atmospheric chemistry-transport calculation, to derive innovative insights into the current sources of pollution and their impacts on ambient PM2.5, both from emissions of primary PM as well as precursors of secondary inorganic and organic aerosols. We outline the likely future development of these sources, quantify the related ambient PM2.5 concentrations and health impacts, and explore potential policy interventions that could effectively reduce environmental pollution and resulting health impacts in the coming years. The analysis demonstrates that effective improvement of Delhi's air quality requires collaboration with neighboring States and must involve sources that are less relevant in industrialized countries. At the same time, many of the policy interventions will have multiple co-benefits on development targets in Delhi and its neighboring States. Outcomes of this study, as well as the modelling tools used herein, are applicable to other urban areas and fast growing metropolitan zones in the emerging Asian regions.}, author = {Amann, Markus and Purohit, Pallav and Bhanarkar, Anil D and Bertok, Imrich and Borken-Kleefeld, Jens and Cofala, Janusz and Heyes, Chris and Kiesewetter, Gregor and Klimont, Zbigniew and Liu, Jun and Majumdar, Dipanjali and Nguyen, Binh and Rafaj, Peter and Rao, Padma S and Sander, Robert and Sch{\"{o}}pp, Wolfgang and Srivastava, Anjali and Vardhan, B Harsh}, doi = {10.1016/j.atmosenv.2017.04.041}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Air pollution,Co-benefits,Health impacts,PM,Policy analysis,Population exposure}, pages = {99--111}, title = {{Managing future air quality in megacities: A case study for Delhi}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231017302856}, volume = {161}, year = {2017} } @article{Amann2020, annote = {doi: 10.1098/rsta.2019.0331}, author = {Amann, Markus and Kiesewetter, Gregor and Sch{\"{o}}pp, Wolfgang and Klimont, Zbigniew and Winiwarter, Wilfried and Cofala, Janusz and Rafaj, Peter and H{\"{o}}glund-Isaksson, Lena and Gomez-Sabriana, Adriana and Heyes, Chris and Purohit, Pallav and Borken-Kleefeld, Jens and Wagner, Fabian and Sander, Robert and Fagerli, Hilde and Nyiri, Agnes and Cozzi, Laura and Pavarini, Claudia}, doi = {10.1098/rsta.2019.0331}, journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences}, month = {oct}, number = {2183}, pages = {20190331}, publisher = {Royal Society}, title = {{Reducing global air pollution: the scope for further policy interventions}}, url = {https://doi.org/10.1098/rsta.2019.0331}, volume = {378}, year = {2020} } @article{Amann2011, abstract = {Environmental policies in Europe have successfully eliminated the most visible and immediate harmful effects of air pollution in the last decades. However, there is ample and robust scientific evidence that even at present rates Europe's emissions to the atmosphere pose a significant threat to human health, ecosystems and the global climate, though in a less visible and immediate way. As many of the 'low hanging fruits' have been harvested by now, further action will place higher demands on economic resources, especially at a time when resources are strained by an economic crisis. In addition, interactions and interdependencies of the various measures could even lead to counter-productive outcomes of strategies if they are ignored.Integrated assessment models, such as the GAINS (Greenhouse gas - Air pollution Interactions and Synergies) model, have been developed to identify portfolios of measures that improve air quality and reduce greenhouse gas emissions at least cost. Such models bring together scientific knowledge and quality-controlled data on future socio-economic driving forces of emissions, on the technical and economic features of the available emission control options, on the chemical transformation and dispersion of pollutants in the atmosphere, and the resulting impacts on human health and the environment. The GAINS model and its predecessor have been used to inform the key negotiations on air pollution control agreements in Europe during the last two decades.This paper describes the methodological approach of the GAINS model and its components. It presents a recent policy analysis that explores the likely future development of emissions and air quality in Europe in the absence of further policy measures, and assesses the potential and costs for further environmental improvements. To inform the forthcoming negotiations on the revision of the Gothenburg Protocol of the Convention on Long-range Transboundary Air Pollution, the paper discusses the implications of alternative formulations of environmental policy targets on a cost-effective allocation of further mitigation measures. {\textcopyright} 2011 Elsevier Ltd.}, author = {Amann, M. and Bertok, I. and Borken-Kleefeld, J. and Cofala, J. and Heyes, C. and H{\"{o}}glund-Isaksson, L. and Klimont, Z. and Nguyen, B. and Posch, M. and Rafaj, P. and Sandler, R. and Sch{\"{o}}pp, W. and Wagner, F. and Winiwarter, W.}, doi = {10.1016/j.envsoft.2011.07.012}, file = {::}, issn = {13648152}, journal = {Environmental Modelling and Software}, keywords = {Air pollution,Convention on Long-range transboundary air polluti,Cost-effectiveness,Decision support,GAINS model,Integrated assessment,Science-policy interface}, number = {12}, pages = {1489--1501}, title = {{Cost-effective control of air quality and greenhouse gases in Europe: Modeling and policy applications}}, volume = {26}, year = {2011} } @techreport{AMAP2015a, address = {Oslo, Norway}, author = {AMAP}, doi = {https://www.amap.no/documents/doc/amap-assessment-2015-methane-as-an-arctic-climate-forcer/1285}, isbn = {978-82-7971-091-2}, pages = {139}, publisher = {Arctic Monitoring and Assessment Programme (AMAP)}, title = {{AMAP Assessment 2015: Methane as an Arctic climate forcer}}, url = {https://www.amap.no/documents/doc/amap-assessment-2015-methane-as-an-arctic-climate-forcer/1285}, year = {2015} } @techreport{AMAP2015a, address = {Oslo, Norway}, author = {AMAP}, doi = {http://www.amap.no/documents/doc/amap-assessment-2015-black-carbon-and-ozone-as-arctic-climate-forcers/1299}, isbn = {978-82-7971-092-9}, pages = {116}, publisher = {Arctic Monitoring and Assessment Programme (AMAP)}, title = {{AMAP Assessment 2015: Black carbon and ozone as Arctic climate forcers}}, url = {http://www.amap.no/documents/doc/amap-assessment-2015-black-carbon-and-ozone-as-arctic-climate-forcers/1299}, year = {2015} } @article{Andrade2017, abstract = {We present a comprehensive review of published results from the last 30 years regarding the sources and atmospheric characteristics of particles and ozone in the Metropolitan Area of S{\~{a}}o Paulo (MASP). During the last 30 years, many efforts have been made to describe the emissions sources and to analyse the primary and secondary formation of pollutants under a process of increasing urbanisation in the metropolitan area. From the occurrence of frequent violations of air quality standards in the 1970s and 1980s (due to the uncontrolled air pollution sources) to a substantial decrease in the concentrations of the primary pollutants, many regulations have been imposed and enforced, although those concentrations do not yet conform to the World Health Organization guidelines. The greatest challenge currently faced by the S{\~{a}}o Paulo State Environmental Protection Agency and the local community is controlling secondary pollutants such as ozone and fine particles. Understanding the formation of these secondary pollutants, by experimental or modelling approaches, requires the description of the atmospheric chemical processes driven by biofuel, ethanol and biodiesel emissions. Exposure to air pollution is the cause of many injuries to human health, according to many studies performed not only in the region but also worldwide, and affects susceptible populations such as children and the elderly. The MASP is the biggest megacity in the Southern Hemisphere, and its specifics are important for other urban areas that are facing the challenge of intensive growth that puts pressure on natural resources and worsens the living conditions in urban areas. This text discusses how imposing regulations on air quality and emission sources, mainly related to the transportation sector, has affected the evolution of pollutant concentrations in the MASP.}, author = {Andrade, Maria de Fatima and Kumar, Prashant and de Freitas, Edmilson Dias and Ynoue, Rita Yuri and Martins, Jorge and Martins, Leila D and Nogueira, Thiago and Perez-Martinez, Pedro and de Miranda, Regina Maura and Albuquerque, Taciana and Gon{\c{c}}alves, Fabio Luiz Teixeira and Oyama, Beatriz and Zhang, Yang}, doi = {10.1016/j.atmosenv.2017.03.051}, issn = {13522310}, journal = {Atmospheric Environment}, keywords = {Air pollution,Climate change,Emissions,Exposure,Fuel and energy,Megacity of S{\~{a}}o Paulo}, month = {jun}, pages = {66--82}, title = {{Air quality in the megacity of S{\~{a}}o Paulo: Evolution over the last 30 years and future perspectives}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231017302212 https://linkinghub.elsevier.com/retrieve/pii/S1352231017302212}, volume = {159}, year = {2017} } @article{Andreae2019, abstract = {Since the publication of the compilation of biomass burning emission factors by Andreae and Merlet (2001), a large number of studies have greatly expanded the amount of available data on emissions from various types of biomass burning. Using essentially the same methodology as Andreae and Merlet (2001), this paper presents an updated compilation of emission factors. The data from over 370 published studies were critically evaluated and integrated into a consistent format. Several new categories of biomass burning were added, and the number of species for which emission data are presented was increased from 93 to 121. Where field data are still insufficient, estimates based on appropriate extrapolation techniques are proposed. For key species, the updated emission factors are compared with previously published values. Based on these emission factors and published global activity estimates, I have derived estimates of pyrogenic emissions for important species released by the various types of biomass burning.}, author = {Andreae, Meinrat O.}, doi = {10.5194/acp-19-8523-2019}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {jul}, number = {13}, pages = {8523--8546}, title = {{Emission of trace gases and aerosols from biomass burning – An updated assessment}}, url = {https://doi.org/10.5194/acp-19-8523-2019 https://www.atmos-chem-phys.net/19/8523/2019/}, volume = {19}, year = {2019} } @article{Andreae2015, abstract = {Abstract. The Amazon Basin plays key roles in the carbon and water cycles, climate change, atmospheric chemistry, and biodiversity. It has already been changed significantly by human activities, and more pervasive change is expected to occur in the coming decades. It is therefore essential to establish long-term measurement sites that provide a baseline record of present-day climatic, biogeochemical, and atmospheric conditions and that will be operated over coming decades to monitor change in the Amazon region, as human perturbations increase in the future. The Amazon Tall Tower Observatory (ATTO) has been set up in a pristine rain forest region in the central Amazon Basin, about 150 km northeast of the city of Manaus. Two 80 m towers have been operated at the site since 2012, and a 325 m tower is nearing completion in mid-2015. An ecological survey including a biodiversity assessment has been conducted in the forest region surrounding the site. Measurements of micrometeorological and atmospheric chemical variables were initiated in 2012, and their range has continued to broaden over the last few years. The meteorological and micrometeorological measurements include temperature and wind profiles, precipitation, water and energy fluxes, turbulence components, soil temperature profiles and soil heat fluxes, radiation fluxes, and visibility. A tree has been instrumented to measure stem profiles of temperature, light intensity, and water content in cryptogamic covers. The trace gas measurements comprise continuous monitoring of carbon dioxide, carbon monoxide, methane, and ozone at five to eight different heights, complemented by a variety of additional species measured during intensive campaigns (e.g., VOC, NO, NO2, and OH reactivity). Aerosol optical, microphysical, and chemical measurements are being made above the canopy as well as in the canopy space. They include aerosol light scattering and absorption, fluorescence, number and volume size distributions, chemical composition, cloud condensation nuclei (CCN) concentrations, and hygroscopicity. In this paper, we discuss the scientific context of the ATTO observatory and present an overview of results from ecological, meteorological, and chemical pilot studies at the ATTO site.}, author = {Andreae, M. O. and Acevedo, O. C. and Ara{\`{u}}jo, A. and Artaxo, P. and Barbosa, C. G. G. and Barbosa, H. M. J. and Brito, J. and Carbone, S. and Chi, X. and Cintra, B. B. L. and da Silva, N. F. and Dias, N. L. and Dias-J{\'{u}}nior, C. Q. and Ditas, F. and Ditz, R. and Godoi, A. F. L. and Godoi, R. H. M. and Heimann, M. and Hoffmann, T. and Kesselmeier, J. and K{\"{o}}nemann, T. and Kr{\"{u}}ger, M. L. and Lavric, J. V. and Manzi, A. O. and Lopes, A. P. and Martins, D. L. and Mikhailov, E. F. and Moran-Zuloaga, D. and Nelson, B. W. and N{\"{o}}lscher, A. C. and {Santos Nogueira}, D. and Piedade, M. T. F. and P{\"{o}}hlker, C. and P{\"{o}}schl, U. and Quesada, C. A. and Rizzo, L. V. and Ro, C.-U. and Ruckteschler, N. and S{\'{a}}, L. D. A. and {de Oliveira S{\'{a}}}, M. and Sales, C. B. and dos Santos, R. M. N. and Saturno, J. and Sch{\"{o}}ngart, J. and S{\"{o}}rgel, M. and de Souza, C. M. and de Souza, R. A. F. and Su, H. and Targhetta, N. and T{\'{o}}ta, J. and Trebs, I. and Trumbore, S. and van Eijck, A. and Walter, D. and Wang, Z. and Weber, B. and Williams, J. and Winderlich, J. and Wittmann, F. and Wolff, S. and Y{\'{a}}{\~{n}}ez-Serrano, A. M.}, doi = {10.5194/acp-15-10723-2015}, isbn = {1680-7316}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {sep}, number = {18}, pages = {10723--10776}, title = {{The Amazon Tall Tower Observatory (ATTO): overview of pilot measurements on ecosystem ecology, meteorology, trace gases, and aerosols}}, url = {http://www.atmos-chem-phys.net/15/10723/2015/ https://www.atmos-chem-phys.net/15/10723/2015/ https://acp.copernicus.org/articles/15/10723/2015/}, volume = {15}, year = {2015} } @article{Andrews2014, abstract = {Abstract. A reliable and precise in situ CO2 and CO analysis system has been developed and deployed at eight sites in the NOAA Earth System Research Laboratory's (ESRL) Global Greenhouse Gas Reference Network. The network uses very tall ({\textgreater} 300 m) television and radio transmitter towers that provide a convenient platform for mid-boundary-layer trace-gas sampling. Each analyzer has three sample inlets for profile sampling, and a complete vertical profile is obtained every 15 min. The instrument suite at one site has been augmented with a cavity ring-down spectrometer for measuring CO2 and CH4. The long-term stability of the systems in the field is typically better than 0.1 ppm for CO2, 6 ppb for CO, and 0.5 ppb for CH4, as determined from repeated standard gas measurements. The instrumentation is fully automated and includes sensors for measuring a variety of status parameters, such as temperatures, pressures, and flow rates, that are inputs for automated alerts and quality control algorithms. Detailed and time-dependent uncertainty estimates have been constructed for all of the gases, and the uncertainty framework could be readily adapted to other species or analysis systems. The design emphasizes use of off-the-shelf parts and modularity to facilitate network operations and ease of maintenance. The systems report high-quality data with {\textgreater} 93{\%} uptime. Recurrent problems and limitations of the current system are discussed along with general recommendations for high-accuracy trace-gas monitoring. The network is a key component of the North American Carbon Program and a useful model for future research-grade operational greenhouse gas monitoring efforts.}, author = {Andrews, A. E. and Kofler, J. D. and Trudeau, M. E. and Williams, J. C. and Neff, D. H. and Masarie, K. A. and Chao, D. Y. and Kitzis, D. R. and Novelli, P. C. and Zhao, C. L. and Dlugokencky, E. J. and Lang, P. M. and Crotwell, M. J. and Fischer, M. L. and Parker, M. J. and Lee, J. T. and Baumann, D. D. and Desai, A. R. and Stanier, C. O. and {De Wekker}, S. F. J. and Wolfe, D. E. and Munger, J. W. and Tans, P. P.}, doi = {10.5194/amt-7-647-2014}, issn = {1867-8548}, journal = {Atmospheric Measurement Techniques}, month = {feb}, number = {2}, pages = {647--687}, title = {{CO2, CO, and CH4 measurements from tall towers in the NOAA Earth System Research Laboratory's Global Greenhouse Gas Reference Network: instrumentation, uncertainty analysis, and recommendations for future high-accuracy greenhouse gas monitoring efforts}}, url = {https://amt.copernicus.org/articles/7/647/2014/}, volume = {7}, year = {2014} } @techreport{Anenberg2019, abstract = {Exhaust from vehicles is a major source of outdoor air pollution worldwide. This study links state-of-the-art vehicle emissions, air pollution, and epidemiological models to estimate the impacts of transportation sector emissions on ambient PM2.5 and ozone and associated health impacts in 2010 and 2015. It provides a detailed picture of the global, regional, and local health impacts attributable to emissions from four transportation subsectors: on-road diesel vehicles, other on-road vehicles, shipping, and non-road mobile engines such as agricultural and construction equipment. The study links vehicle tailpipe emissions to {\~{}}361,000 premature deaths from ambient PM2.5 and ozone worldwide in 2010 and {\~{}}385,000 in 2015, equivalent to 11.7{\%} of global ambient PM2.5 and ozone premature deaths in 2010 and 11.4{\%} in 2015. An estimated 84{\%} of global transportation-attributable deaths occurred in G20 countries, and 70{\%} occurred in the four largest vehicle markets in 2015: China, India, the European Union, and the United States. Exhaust from on-road diesel vehicles was responsible for nearly half of the impacts ({\~{}}181,000 premature deaths) worldwide, and fully two-thirds in India, France, Germany, and Italy. Together, PM2.5 and ozone concentrations from transportation emissions resulted in 7.8 million years of life lost and approximately {\$}1 trillion (2015 US{\$}) in health damages globally in 2015. The urban areas with the highest number of transportation-attributable air pollution in 2015 were Guangzhou, Tokyo, Shanghai, Mexico City, Cairo, New Delhi, Moscow, Beijing, London, and Los Angeles. By contrast, when normalized by population, the urban areas with the highest number of transportation-attributable air pollution deaths per 100,000 people were Milan, Turin, Stuttgart, Kiev, Cologne, Haarlem, Berlin, Rotterdam, London, and Leeds. Despite recent adoption of more stringent vehicle emission regulations in some major vehicle markets, the transportation sector remains a major contributor to the air pollution disease burden globally. This points to the need for reducing emissions from the transportation sector to be a central element of national and local management plans aimed at reducing ambient air pollution and its burden on public health. Wherever world-class vehicle emissions standards have not yet been adopted, countries and trade blocs should avoid continuation of the considerable public health damages highlighted in this report by accelerating their adoption. The experiences of the top vehicle markets underscore the substantial time lag between implementation of new vehicle standards and the realization of their full benefits for the in-use vehicle fleet that results from the long lifetimes of vehicles and equipment. Countries and trade blocs that already have adopted world-class vehicle emission standards should consider accelerating the expected public health benefits with strategies to reduce emissions from in-use vehicles, such as low emission zones, retrofit/replacement/scrappage programs, and targeted fleet renewal. Urban areas and subnational jurisdictions can justify more ambitious actions because of their disproportionate exposure to transportation emissions.}, address = {Washington, DC, USA}, author = {Anenberg, Susan C. and Miller, Joshua and Henze, Daven and Minjares, Ray}, doi = {https://www.theicct.org/sites/default/files/publications/Global_health_impacts_transport_emissions_2010-2015_20190226.pdf}, keywords = {diesel,exhaust,non-road vehicles,on-road vehicles,ozone,particulate matter,pollution,shipping}, pages = {55}, publisher = {International Council on Clean Transportation (ICCT)}, title = {{A global snapshot of the air pollution-related health impacts of transportation sector emissions in 2010 and 2015}}, url = {https://www.theicct.org/sites/default/files/publications/Global{\_}health{\_}impacts{\_}transport{\_}emissions{\_}2010-2015{\_}20190226.pdf}, year = {2019} } @article{Anenberg2012, abstract = {BACKGROUND: Tropospheric ozone and black carbon (BC), a component of fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter; PM(2.5)), are associated with premature mortality and they disrupt global and regional climate. OBJECTIVES: We examined the air quality and health benefits of 14 specific emission control measures targeting BC and methane, an ozone precursor, that were selected because of their potential to reduce the rate of climate change over the next 20-40 years. METHODS: We simulated the impacts of mitigation measures on outdoor concentrations of PM(2.5) and ozone using two composition-climate models, and calculated associated changes in premature PM(2.5)- and ozone-related deaths using epidemiologically derived concentration-response functions. RESULTS: We estimated that, for PM(2.5) and ozone, respectively, fully implementing these measures could reduce global population-weighted average surface concentrations by 23-34{\%} and 7-17{\%} and avoid 0.6-4.4 and 0.04-0.52 million annual premature deaths globally in 2030. More than 80{\%} of the health benefits are estimated to occur in Asia. We estimated that BC mitigation measures would achieve approximately 98{\%} of the deaths that would be avoided if all BC and methane mitigation measures were implemented, due to reduced BC and associated reductions of nonmethane ozone precursor and organic carbon emissions as well as stronger mortality relationships for PM(2.5) relative to ozone. Although subject to large uncertainty, these estimates and conclusions are not strongly dependent on assumptions for the concentration-response function. CONCLUSIONS: In addition to climate benefits, our findings indicate that the methane and BC emission control measures would have substantial co-benefits for air quality and public health worldwide, potentially reversing trends of increasing air pollution concentrations and mortality in Africa and South, West, and Central Asia. These projected benefits are independent of carbon dioxide mitigation measures. Benefits of BC measures are underestimated because we did not account for benefits from reduced indoor exposures and because outdoor exposure estimates were limited by model spatial resolution.}, author = {Anenberg, Susan C. and Schwartz, Joel and Shindell, Drew and Amann, Markus and Faluvegi, Greg and Klimont, Zbigniew and Janssens-Maenhout, Greet and Pozzoli, Luca and van Dingenen, Rita and Vignati, Elisabetta and Emberson, Lisa and Muller, Nicholas Z. and {Jason West}, J. and Williams, Martin and Demkine, Volodymyr and {Kevin Hicks}, W. and Kuylenstierna, Johan and Raes, Frank and Ramanathan, Veerabhadran}, doi = {10.1289/ehp.1104301}, isbn = {0091-6765}, issn = {00916765}, journal = {Environmental Health Perspectives}, keywords = {Air quality,Climate change,Health impact analysis,Outdoor air,Particulate matter}, month = {mar}, number = {6}, pages = {831--839}, pmid = {22418651}, title = {{Global air quality and health co-benefits of mitigating near-term climate change through methane and black carbon emission controls}}, volume = {120}, year = {2012} } @article{Anenberg2017a, abstract = {Across markets accounting for 80 per cent of global diesel vehicle sales, more than a third of diesel nitrogen oxide emissions are in excess of certification limits, causing many deaths.}, author = {Anenberg, Susan C. and Miller, Joshua and Minjares, Ray and Du, Li and Henze, Daven K. and Lacey, Forrest and Malley, Christopher S. and Emberson, Lisa and Franco, Vicente and Klimont, Zbigniew and Heyes, Chris}, doi = {10.1038/nature22086}, issn = {0028-0836}, journal = {Nature}, keywords = {Environmental impact,Risk factors}, month = {may}, number = {7655}, pages = {467--471}, publisher = {Nature Publishing Group}, title = {{Impacts and mitigation of excess diesel-related NOx emissions in 11 major vehicle markets}}, url = {http://www.nature.com/doifinder/10.1038/nature22086}, volume = {545}, year = {2017} } @article{acp-11-9253-2011, abstract = {Trends in the CO andC2H6 partial columns ∼0-15 km) have been estimated from four European ground-based solar FTIR (Fourier Transform InfraRed) stations for the 1996-2006 time period. The CO trends from the four stations Jungfraujoch, Zugspitze, Harestua and Kiruna have been estimated to -0.45 ± 0.16{\%} yrg-1, -1.00 ± 0.24{\%} yrg-1, -0.62 ± 0.19 {\%} yrg-1 and -0.61 ± 0.16{\%} yrg-1, respectively. The corresponding trends for C 2H6 are -1.51 ± 0.23{\%} yrg-1, -2.11 ± 0.30{\%} yrg-1, -1.09 ± 0.25{\%} yrg-1 and -1.14 ± 0.18{\%} yrg-1. All trends are presented with their 2-$\sigma$ confidence intervals. To find possible reasons for the CO trends, the global-scale EMEP MSC-W chemical transport model has been used in a series of sensitivity scenarios. It is shown that the trends are consistent with the combination of a 20{\%} decrease in the anthropogenic CO emissions seen in Europe and North America during the 1996-2006 period and a 20{\%} increase in the anthropogenic CO emissions in East Asia, during the same time period. The possible impacts of CH4 and biogenic volatile organic compounds (BVOCs) are also considered. The European and global-scale EMEP models have been evaluated against the measured CO and C2H6 partial columns from Jungfraujoch, Zugspitze, Bremen, Harestua, Kiruna and Ny-{\AA}lesund. The European model reproduces, on average the measurements at the different sites fairly well and within 10-22{\%} deviation for CO and 14-31{\%} deviation for C2H6. Their seasonal amplitude is captured within 6-35{\%} and 9-124{\%} for CO and C2H6, respectively. However, 61-98{\%} of the CO and C2H6 partial columns in the European model are shown to arise from the boundary conditions, making the global-scale model a more suitable alternative when modeling these two species. In the evaluation of the global model the average partial columns for 2006 are shown to be within 1-9{\%} and 37-50{\%} of the measurements for CO and C 2H6, respectively. The global model sensitivity for assumptions made in this paper is also analyzed. {\textcopyright} Author(s) 2011.}, author = {Angelbratt, J. and Mellqvist, J. and Simpson, D. and Jonson, J. E. and Blumenstock, T. and Borsdorff, T. and Duchatelet, P. and Forster, F. and Hase, F. and Mahieu, E. and {De Mazi{\`{e}}re}, M. and Notholt, J. and Petersen, A. K. and Raffalski, U. and Servais, C. and Sussmann, R. and Warneke, T. and Vigouroux, C.}, doi = {10.5194/acp-11-9253-2011}, isbn = {16807367 (ISSN)}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, number = {17}, pages = {9253--9269}, title = {{Carbon monoxide (CO) and ethane (C2H6) trends from ground-based solar FTIR measurements at six European stations, comparison and sensitivity analysis with the EMEP model}}, url = {https://www.atmos-chem-phys.net/11/9253/2011/}, volume = {11}, year = {2011} } @article{Archibald2020, abstract = {Our understanding of the processes that control the burden and budget of tropospheric ozone has changed dramatically over the last 60 years. Models are the key tools used to understand these changes, and these underscore that there are many processes important in controlling the tropospheric ozone budget. In this critical review, we assess our evolving understanding of these processes, both physical and chemical. We review model simulations from the International Global Atmospheric Chemistry Atmospheric Chemistry and Climate Model Intercomparison Project and Chemistry Climate Modelling Initiative to assess the changes in the tropospheric ozone burden and its budget from 1850 to 2010. Analysis of these data indicates that there has been significant growth in the ozone burden from 1850 to 2000 (approximately 43 ± 9{\%}) but smaller growth between 1960 and 2000 (approximately 16 ± 10{\%}) and that the models simulate burdens of ozone well within recent satellite estimates. The Chemistry Climate Modelling Initiative model ozone budgets indicate that the net chemical production of ozone in the troposphere plateaued in the 1990s and has not changed since then inspite of increases in the burden. There has been a shift in net ozone production in the troposphere being greatest in the northern mid and high latitudes to the northern tropics, driven by the regional evolution of precursor emissions. An analysis of the evolution of tropospheric ozone through the 21st century, as simulated by Climate Model Intercomparison Project Phase 5 models, reveals a large source of uncertainty associated with models themselves (i.e., in the way that they simulate the chemical and physical processes that control tropospheric ozone). This structural uncertainty is greatest in the near term (two to three decades), but emissions scenarios dominate uncertainty in the longer term (2050–2100) evolution of tropospheric ozone. This intrinsic model uncertainty prevents robust predictions of near-term changes in the tropospheric ozone burden, and we review how progress can be made to reduce this limitation.}, author = {Archibald, A. T. and Neu, J. L. and Elshorbany, Y. F. and Cooper, O. R. and Young, P. J. and Akiyoshi, H. and Cox, R. A. and Coyle, M. and Derwent, R. G. and Deushi, M. and Finco, A. and Frost, G. J. and Galbally, I. E. and Gerosa, G. and Granier, C. and Griffiths, P. T. and Hossaini, R. and Hu, L. and J{\"{o}}ckel, P. and Josse, B. and Lin, M. Y. and Mertens, M. and Morgenstern, O. and Naja, M. and Naik, V. and Oltmans, S. and Plummer, D. A. and Revell, L. E. and Saiz-Lopez, A. and Saxena, P. and Shin, Y. M. and Shahid, I. and Shallcross, D. and Tilmes, S. and Trickl, T. and Wallington, T. J. and Wang, T. and Worden, H. M. and Zeng, G.}, doi = {10.1525/elementa.2020.034}, issn = {2325-1026}, journal = {Elementa: Science of the Anthropocene}, month = {dec}, number = {1}, title = {{Tropospheric Ozone Assessment Report: A critical review of changes in the tropospheric ozone burden and budget from 1850 to 2100}}, url = {https://online.ucpress.edu/elementa/article/8/1/034/115205/Tropospheric-Ozone-Assessment-ReportA-critical}, volume = {8}, year = {2020} } @article{bg-7-121-2010, author = {Arneth, A and Sitch, S and Bondeau, A and Butterbach-Bahl, K and Foster, P and Gedney, N and de Noblet-Ducoudr{\'{e}}, N and Prentice, I C and Sanderson, M and Thonicke, K and Wania, R and Zaehle, S}, doi = {10.5194/bg-7-121-2010}, journal = {Biogeosciences}, number = {1}, pages = {121--149}, title = {{From biota to chemistry and climate: towards a comprehensive description of trace gas exchange between the biosphere and atmosphere}}, url = {https://www.biogeosciences.net/7/121/2010/}, volume = {7}, year = {2010} } @article{Arneth2010, abstract = {The terrestrial biosphere is a key regulator of atmospheric chemistry and climate. During past periods of climate change, vegetation cover and interactions between the terrestrial biosphere and atmosphere changed within decades. Modern observations show a similar responsiveness of terrestrial biogeochemistry to anthropogenically forced climate change and air pollution. Although interactions between the carbon cycle and climate have been a central focus, other biogeochemical feedbacks could be as important in modulating future climate change. Total positive radiative forcings resulting from feedbacks between the terrestrial biosphere and the atmosphere are estimated to reach up to 0.9 or 1.5 W m-2 K-1 towards the end of the twenty-first century, depending on the extent to which interactions with the nitrogen cycle stimulate or limit carbon sequestration. This substantially reduces and potentially even eliminates the cooling effect owing to carbon dioxide fertilization of the terrestrial biota. The overall magnitude of the biogeochemical feedbacks could potentially be similar to that of feedbacks in the physical climate system, but there are large uncertainties in the magnitude of individual estimates and in accounting for synergies between these effects. {\textcopyright} 2010 Macmillan Publishers Limited. All rights reserved.}, author = {Arneth, A. and Harrison, S. P. and Zaehle, S. and Tsigaridis, K. and Menon, S. and Bartlein, P. J. and Feichter, J. and Korhola, A. and Kulmala, M. and O'Donnell, D. and Schurgers, G. and Sorvari, S. and Vesala, T.}, doi = {10.1038/ngeo905}, issn = {17520894}, journal = {Nature Geoscience}, number = {8}, pages = {525--532}, publisher = {Nature Publishing Group}, title = {{Terrestrial biogeochemical feedbacks in the climate system}}, volume = {3}, year = {2010} } @article{acp-8-4605-2008, abstract = {Emissions of biogenic volatile organic compounds (BVOC) are a chief uncertainty in calculating the burdens of important atmospheric compounds like tropospheric ozone or secondary organic aerosol, reflecting either imperfect chemical oxidation mechanisms or unreliable emission estimates, or both. To provide a starting point for a more systematic discussion we review here global isoprene and monoterpene emission estimates to-date. We note a surprisingly small variation in the predictions of global isoprene emission rate that is in stark contrast with our lack of process understanding and the small number of observations for model parameterisation and evaluation. Most of the models are based on similar emission algorithms, using fixed values for the emission capacity of various plant functional types. In some cases, these values are very similar but differ substantially in other models. The similarities with regard to the global isoprene emission rate would suggest that the dominant parameters driving the ultimate global estimate, and thus the dominant determinant of model sensitivity, are the specific emission algorithm and isoprene emission capacity. But the models also differ broadly with regard to their representation of net primary productivity, method of biome coverage determination and climate data. Contrary to isoprene, monoterpene estimates show significantly larger model-to-model variation although variation in terms of leaf algorithm, emission capacities, the way of model upscaling, vegetation cover or climatology used in terpene models are comparable to those used for isoprene. From our summary of published studies there appears to be no evidence that the terrestrial modelling community has been any more successful in "resolving unknowns" in the mechanisms that control global isoprene emissions, compared to global monoterpene emissions. Rather, the proliferation of common parameterization schemes within a large variety of model platforms lends the illusion of convergence towards a common estimate of global isoprene emissions. This convergence might be used to provide optimism that the community has reached the "relief phase", the phase when sufficient process understanding and data for evaluation allows models' projections to converge, when applying a recently proposed concept. We argue that there is no basis for this apparent relief phase. Rather, we urge modellers to be bolder in their analysis, and to draw attention to the fact that terrestrial emissions, particularly in the area of biome-specific emission capacities, are unknown rather than uncertain.}, author = {Arneth, A and Monson, R K and Schurgers, G and Niinemets, {\"{U}} and Palmer, P I}, doi = {10.5194/acp-8-4605-2008}, journal = {Atmospheric Chemistry and Physics}, number = {16}, pages = {4605--4620}, title = {{Why are estimates of global terrestrial isoprene emissions so similar (and why is this not so for monoterpenes)?}}, url = {https://acp.copernicus.org/articles/8/4605/2008/}, volume = {8}, year = {2008} } @article{doi:10.1029/2018GL079938, abstract = {Abstract Tropospheric ozone (O3) pollution is known to damage vegetation, reducing photosynthesis and stomatal conductance, resulting in modified plant transpiration to the atmosphere. We use an Earth system model to show that global transpiration response to near-present-day surface tropospheric ozone results in large-scale global perturbations to net outgoing long-wave and incoming shortwave radiation. Our results suggest that the radiative effect is dominated by a reduction in shortwave cloud forcing in polluted regions, in response to ozone-induced reduction in land-atmosphere moisture flux and atmospheric humidity. We simulate a statistically significant response of annual surface air temperature of up to {\~{}} +1.5 K due to this ozone effect in vegetated regions subjected to ozone pollution. This mechanism is expected to further increase the net warming resulting from historic and future increases in tropospheric ozone.}, author = {Arnold, S R and Lombardozzi, D and Lamarque, J.-F. and Richardson, T and Emmons, L K and Tilmes, S and Sitch, S A and Folberth, G and Hollaway, M J and {Val Martin}, M}, doi = {10.1029/2018GL079938}, journal = {Geophysical Research Letters}, keywords = {air quality,climate,transpiration,tropospheric ozone,vegetation model}, number = {23}, pages = {13,13--70,79}, title = {{Simulated Global Climate Response to Tropospheric Ozone-Induced Changes in Plant Transpiration}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL079938}, volume = {45}, year = {2018} } @misc{Aschmann2014a, abstract = {{\textless}p{\textgreater}Chemistry–climate models predict an acceleration of the upwelling branch of the Brewer–Dobson circulation as a consequence of increasing global surface temperatures, resulting from elevated levels of atmospheric greenhouse gases. The observed decrease of ozone in the tropical lower stratosphere during the last decades of the 20th century is consistent with the anticipated acceleration of upwelling. However, more recent satellite observations of ozone reveal that this decrease has unexpectedly stopped in the first decade of the 21st century, challenging the implicit assumption of a continuous acceleration of tropical upwelling. In this study we use three decades of chemistry-transport-model simulations (1980–2013) to investigate this phenomenon and resolve this apparent contradiction. Our model reproduces the observed tropical lower stratosphere ozone record, showing a significant decrease in the early period followed by a statistically robust trend-change after 2002. We demonstrate that this trend-change is correlated with corresponding changes in the vertical transport and conclude that a hiatus in the acceleration of tropical upwelling occurred during the last decade.{\textless}/p{\textgreater}}, author = {Aschmann, J. and Burrows, J. P. and Gebhardt, C. and Rozanov, A. and Hommel, R. and Weber, M. and Thompson, A. M.}, booktitle = {Atmospheric Chemistry and Physics}, doi = {10.5194/acp-14-12803-2014}, issn = {16807324}, number = {23}, pages = {12803--12814}, title = {{On the hiatus in the acceleration of tropical upwelling since the beginning of the 21st century}}, volume = {14}, year = {2014} } @article{Athanasopoulou2017, abstract = {Abstract. For the past 8 years, Greece has been experiencing a major financial crisis which, among other side effects, has led to a shift in the fuel used for residential heating from fossil fuel towards biofuels, primarily wood. This study simulates the fate of the residential wood burning aerosol plume (RWB smog) and the implications on atmospheric chemistry and radiation, with the support of detailed aerosol characterization from measurements during the winter of 2013–2014 in Athens. The applied model system (TNO-MACC{\_}II emissions and COSMO-ART model) and configuration used reproduces the measured frequent nighttime aerosol spikes (hourly PM10 {\textgreater} 75 µg m−3) and their chemical profile (carbonaceous components and ratios). Updated temporal and chemical RWB emission profiles, derived from measurements, were used, while the level of the model performance was tested for different heating demand (HD) conditions, resulting in better agreement with measurements for Tmin}, author = {Athanasopoulou, Eleni and Speyer, Orestis and Brunner, Dominik and Vogel, Heike and Vogel, Bernhard and Mihalopoulos, Nikolaos and Gerasopoulos, Evangelos}, doi = {10.5194/acp-17-10597-2017}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {sep}, number = {17}, pages = {10597--10618}, title = {{Changes in domestic heating fuel use in Greece: effects on atmospheric chemistry and radiation}}, url = {https://acp.copernicus.org/articles/17/10597/2017/}, volume = {17}, year = {2017} } @article{Baker2015a, abstract = {{\textless}p{\textgreater}Policies to control air quality focus on mitigating emissions of aerosols and their precursors, and other short-lived climate pollutants (SLCPs). On a local scale, these policies will have beneficial impacts on health and crop yields, by reducing particulate matter (PM) and surface ozone concentrations; however, the climate impacts of reducing emissions of SLCPs are less straightforward to predict. In this paper we consider a set of idealised, extreme mitigation strategies, in which the total anthropogenic emissions of individual SLCP emissions species are removed. This provides an upper bound on the potential climate impacts of such air quality strategies. {\textless}br{\textgreater}{\textless}br{\textgreater} We focus on evaluating the climate responses to changes in anthropogenic emissions of aerosol precursor species: black carbon (BC), organic carbon (OC) and sulphur dioxide (SO{\textless}sub{\textgreater}2{\textless}/sub{\textgreater}). We perform climate integrations with four fully coupled atmosphere-ocean global climate models (AOGCMs), and examine the effects on global and regional climate of removing the total land-based anthropogenic emissions of each of the three aerosol precursor species. {\textless}br{\textgreater}{\textless}br{\textgreater} We find that the SO{\textless}sub{\textgreater}2{\textless}/sub{\textgreater} emissions reductions lead to the strongest response, with all three models showing an increase in surface temperature focussed in the northern hemisphere high latitudes, and a corresponding increase in global mean precipitation and run-off. Changes in precipitation and run-off patterns are driven mostly by a northward shift in the ITCZ, consistent with the hemispherically asymmetric warming pattern driven by the emissions changes. The BC and OC emissions reductions give a much weaker forcing signal, and there is some disagreement between models in the sign of the climate responses to these perturbations. These differences between models are due largely to natural variability in sea-ice extent, circulation patterns and cloud changes. This large natural variability component to the signal when the ocean circulation and sea-ice are free-running means that the BC and OC mitigation measures do not necessarily lead to a discernible climate response.{\textless}/p{\textgreater}}, author = {Baker, L. H. and Collins, W. J. and Olivi{\'{e}}, D. J.L. and Cherian, R. and Hodnebrog and Myhre, G. and Quaas, J.}, doi = {10.5194/acp-15-8201-2015}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {jul}, number = {14}, pages = {8201--8216}, title = {{Climate responses to anthropogenic emissions of short-lived climate pollutants}}, url = {http://www.atmos-chem-phys.net/15/8201/2015/}, volume = {15}, year = {2015} } @article{Balkanski2010, abstract = {Abstract. Aerosols and their precursors are emitted abundantly by transport activities. Transportation constitutes one of the fastest growing activities and its growth is predicted to increase significantly in the future. Previous studies have estimated the aerosol direct radiative forcing from one transport sub-sector, but only one study to our knowledge estimated the range of radiative forcing from the main aerosol components (sulphate, black carbon (BC) and organic carbon) for the whole transportation sector. In this study, we compare results from two different chemical transport models and three radiation codes under different hypothesis of mixing: internal and external mixing using emission inventories for the year 2000. The main results from this study consist of a positive direct radiative forcing for aerosols emitted by road traffic of +20±11 mW m−2 for an externally mixed aerosol, and of +32±13 mW m−2 when BC is internally mixed. These direct radiative forcings are much higher than the previously published estimate of +3±11 mW m−2. For transport activities from shipping, the net direct aerosol radiative forcing is negative. This forcing is dominated by the contribution of the sulphate. For both an external and an internal mixture, the radiative forcing from shipping is estimated at −26±4 mW m−2. These estimates are in very good agreement with the range of a previously published one (from −46 to −13 mW m−2) but with a much narrower range. By contrast, the direct aerosol forcing from aviation is estimated to be small, and in the range −0.9 to +0.3 mW m−2.}, author = {Balkanski, Y. and Myhre, G. and Gauss, M. and R{\"{a}}del, G. and Highwood, E. J. and Shine, K. P.}, doi = {10.5194/acp-10-4477-2010}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {10}, pages = {4477--4489}, title = {{Direct radiative effect of aerosols emitted by transport: from road, shipping and aviation}}, url = {https://acp.copernicus.org/articles/10/4477/2010/}, volume = {10}, year = {2010} } @article{Banerjee2016, abstract = {Abstract. A stratosphere-resolving configuration of the Met Office's Unified Model (UM) with the United Kingdom Chemistry and Aerosols (UKCA) scheme is used to investigate the atmospheric response to changes in (a) greenhouse gases and climate, (b) ozone-depleting substances (ODSs) and (c) non-methane ozone precursor emissions. A suite of time-slice experiments show the separate, as well as pairwise, impacts of these perturbations between the years 2000 and 2100. Sensitivity to uncertainties in future greenhouse gases and aerosols is explored through the use of the Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. The results highlight an important role for the stratosphere in determining the annual mean tropospheric ozone response, primarily through stratosphere–troposphere exchange (STE) of ozone. Under both climate change and reductions in ODSs, increases in STE offset decreases in net chemical production and act to increase the tropospheric ozone burden. This opposes the effects of projected decreases in ozone precursors through measures to improve air quality, which act to reduce the ozone burden. The global tropospheric lifetime of ozone ($\tau$O3) does not change significantly under climate change at RCP4.5, but it decreases at RCP8.5. This opposes the increases in $\tau$O3 simulated under reductions in ODSs and ozone precursor emissions. The additivity of the changes in ozone is examined by comparing the sum of the responses in the single-forcing experiments to those from equivalent combined-forcing experiments. Whilst the ozone responses to most forcing combinations are found to be approximately additive, non-additive changes are found in both the stratosphere and troposphere when a large climate forcing (RCP8.5) is combined with the effects of ODSs.}, author = {Banerjee, Antara and Maycock, Amanda C. and Archibald, Alexander T. and Abraham, N. Luke and Telford, Paul and Braesicke, Peter and Pyle, John A.}, doi = {10.5194/acp-16-2727-2016}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {5}, pages = {2727--2746}, title = {{Drivers of changes in stratospheric and tropospheric ozone between year 2000 and 2100}}, url = {https://acp.copernicus.org/articles/16/2727/2016/}, volume = {16}, year = {2016} } @article{Banzhaf2015, abstract = {In this study we present a dynamic model evaluation of chemistry transport model LOTOS-EUROS (LOng Term Ozone Simulation - EURopean Operational Smog) to analyse the ability of the model to reproduce observed non-linear responses to emission changes and interannual variability of secondary inorganic aerosol (SIA) and its precursors over Europe from 1990 to 2009. The 20 year simulation was performed using a consistent set of meteorological data provided by RACMO2 (Regional Atmospheric Climate MOdel). Observations at European rural background sites have been used as a reference for the model evaluation. To ensure the consistency of the used observational data, stringent selection criteria were applied, including a comprehensive visual screening to remove suspicious data from the analysis. The LOTOS-EUROS model was able to capture a large part of the seasonal and interannual variability of SIA and its precursors' concentrations. The dynamic evaluation has shown that the model is able to simulate the declining trends observed for all considered sulfur and nitrogen components following the implementation of emission abatement strategies for SIA precursors over Europe. Both the observations and the model show the largest part of the decline in the 1990s, while smaller concentration changes and an increasing number of non-significant trends are observed and modelled between 2000 and 2009. Furthermore, the results confirm former studies showing that the observed trends in sulfate and total nitrate concentrations from 1990 to 2009 are lower than the trends in precursor emissions and precursor concentrations. The model captured well these non-linear responses to the emission changes. Using the LOTOS-EUROS source apportionment module, trends in the formation efficiency of SIA have been quantified for four European regions. The exercise has revealed a 20-50{\%} more efficient sulfate formation in 2009 compared to 1990 and an up to 20{\%} more efficient nitrate formation per unit nitrogen oxide emission, which added to the explanation of the non-linear responses. However, we have also identified some weaknesses in the model and the input data. LOTOS-EUROS underestimates the observed nitrogen dioxide concentrations throughout the whole time period, while it overestimates the observed nitrogen dioxide concentration trends. Moreover, model results suggest that the emission information of the early 1990s used in this study needs to be improved concerning magnitude and spatial distribution.}, author = {Banzhaf, S. and Schaap, M. and Kranenburg, R. and Manders, A. M.M. and Segers, A. J. and Visschedijk, A. J.H. and {Van Der Gon}, H. A.C.Denier and Kuenen, J. J.P. and {Van Meijgaard}, E. and {Van Ulft}, L. H. and Cofala, J. and Builtjes, P. J.H.}, doi = {10.5194/gmd-8-1047-2015}, issn = {19919603}, journal = {Geoscientific Model Development}, month = {apr}, number = {4}, pages = {1047--1070}, title = {{Dynamic model evaluation for secondary inorganic aerosol and its precursors over Europe between 1990 and 2009}}, volume = {8}, year = {2015} } @article{Barkley2013, author = {Barkley, Michael P. and Smedt, Isabelle De and {Van Roozendael}, Michel and Kurosu, Thomas P. and Chance, Kelly and Arneth, Almut and Hagberg, Daniel and Guenther, Alex and Paulot, Fabien and Marais, Eloise and Mao, Jingqiu}, doi = {10.1002/jgrd.50552}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {jun}, number = {12}, pages = {6849--6868}, title = {{Top-down isoprene emissions over tropical South America inferred from SCIAMACHY and OMI formaldehyde columns}}, volume = {118}, year = {2013} } @article{Barnes2016, abstract = {Abstract Trends in trace atmospheric constituents can be driven not also by trends in their (precursor) emissions but also by trends in meteorology. Here we use ground-level ozone as an example to highlight the extent to which unforced, low-frequency climate variability can drive multidecadal trends. Using output from six experiments of the Geophysical Fluid Dynamics Laboratory chemistry-climate model (CM3), we demonstrate that 20 year trends in surface ozone driven by climate variability alone can be as large as those forced by changes in ozone precursor emissions or by anthropogenic climate change. We highlight regions and seasons where surface ozone is strongly influenced by climate variability and thus where a given forced trend may be more difficult to detect. A corollary is that this approach identifies regions and seasons of low variability, where measurement sites may be most effectively deployed to detect a particular trend driven by changing precursor emissions. We find that the representative concentration pathways 4.5 (RCP4.5) and RCP8.5 forced surface ozone trends in most locations emerge over background variability during the first half of the 21st century. Ozone trends are found to respond mostly to changes in emissions of ozone precursors and unforced climate variability, with a comparatively small impact from anthropogenic climate change. Thus, attempts to attribute observed trends to regional emissions changes require consideration of internal climate variability, particularly for short record lengths and small forced trends.}, annote = {doi: 10.1002/2015JD024397}, author = {Barnes, Elizabeth A and Fiore, Arlene M and Horowitz, Larry W}, doi = {10.1002/2015JD024397}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {chemistry climate models,climate variability,ozone trends,time of emergence}, month = {mar}, number = {10}, pages = {6112--6129}, publisher = {Wiley-Blackwell}, title = {{Detection of trends in surface ozone in the presence of climate variability}}, url = {https://doi.org/10.1002/2015JD024397}, volume = {121}, year = {2016} } @article{Barthel2019, abstract = {Sea spray aerosol particle is a dominating part of the global aerosol mass load of natural origin. Thus, it strongly influences the atmospheric radiation balance and cloud properties especially over the oceans. Uncertainties of the estimated climate impacts by this aerosol type are partly caused by the uncertainties in the particle size dependent emission fluxes of sea spray aerosol particle. We present simulations with a regional aerosol transport model system in two domains, for three months and compared the model results to measurements at four stations using various sea spray aerosol particle source source functions. Despite these limitations we found the results using different source functions are within the range of most model uncertainties. Especially the model's ability to produce realistic wind speeds is crucial. Furthermore, the model results are more affected by a function correcting the emission flux for the effect of the sea surface temperature than by the use of different source functions.}, author = {Barthel, Stefan and Tegen, Ina and Wolke, Ralf}, doi = {10.1016/j.atmosenv.2018.10.016}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Model uncertainties,Primary marine aerosol,Regional aerosol modelling,Sea spray aerosol particle,Sea surface temperature}, pages = {265--278}, title = {{Do new sea spray aerosol source functions improve the results of a regional aerosol model?}}, volume = {198}, year = {2019} } @article{doi:10.1080/10473289.2011.609761, abstract = { ABSTRACT In order to better understand the characteristics of atmospheric carbonaceous aerosol at a background site in Northeast Asia, semicontinuous organic carbon (OC) and elemental carbon (EC), and time-resolved water-soluble organic carbon (WSOC) were measured by a Sunset OC/EC and a PILS-TOC (particle-into-liquid sampler coupled with an online total organic carbon) analyzer, respectively, at the Gosan supersite on Jeju Island, Korea, in the summer (May 28–June 17) and fall (August 24–September 30) of 2009. Hourly average OC concentration varied in the range of approximately 0.87–28.38 $\mu$gC m−3, with a mean of 4.07 ± 2.60 $\mu$gC m−3, while the hourly average EC concentration ranged approximately from 0.04 to 8.19 $\mu$gC m−3, with a mean of 1.35 ± 0.71 $\mu$gC m−3, from May 28 to June 17, 2009. During the fall season, OC varied in the approximate range 0.9–9.6 $\mu$gC m−3, with a mean of 2.30 ± 0.80 $\mu$gC m−3, whereas EC ranged approximately from 0.01 to 5.40 $\mu$gC m−3, with a mean of 0.66 ± 0.38 $\mu$gC m−3. Average contributions of EC to TC and WSOC to OC were 26.0{\%} ± 9.7{\%} and 20.6{\%} ± 7.4{\%}, and 37.6{\%} ± 23.5{\%} and 57.2{\%} ± 22.2{\%} during summer and fall seasons, respectively. As expected, clear diurnal variation of WSOC/OC was found in summer, varying from 0.22 during the nighttime up to 0.72 during the daytime, mainly due to the photo-oxidation process. In order to investigate the effect of air mass pathway on the characteristics of carbonaceous aerosol, 5-day back-trajectory analysis was conducted using the HYSPLIT model. The air mass pathways were classified into four types: Continental (CC), Marine (M), East Sea (ES) and Korean Peninsula (KP). The highest OC/EC ratio of 3.63 was observed when air mass originated from the Continental area (CC). The lowest OC/EC ratio of 0.79 was measured when air mass originated from the Marine area (M). A high OC concentration was occasionally observed at Gosan due to local biomass burning activities. The contribution of secondary OC to total OC varied approximately between 8.4{\%} and 32.2{\%} and depended on air mass type. IMPLICATIONS Organic material contributes approximately 20–90{\%} of the total fine particulate mass concentration at different sites over the world depending on location and season. Organic carbon consists of hundreds of compounds with a wide range of chemical and optical properties. A better understanding of the chemical characteristics of carbonaceous aerosol influenced by increasing anthropogenic pollution in the downwind regions of the East Asian continent is needed in order to determine their impacts on regional air quality and climate change. }, author = {Batmunkh, T and Kim, Y J and Lee, K Y and Cayetano, M G and Jung, J S and Kim, S Y and Kim, K C and Lee, S J and Kim, J S and Chang, L S and An, J Y}, doi = {10.1080/10473289.2011.609761}, journal = {Journal of the Air {\&} Waste Management Association}, number = {11}, pages = {1174--1182}, publisher = {Taylor {\&} Francis}, title = {{Time-Resolved Measurements of PM2.5 Carbonaceous Aerosols at Gosan, Korea}}, url = {https://doi.org/10.1080/10473289.2011.609761}, volume = {61}, year = {2011} } @article{Bauer2020, abstract = {Abstract The Earth's climate is rapidly changing. Over the past centuries, aerosols, via their ability to absorb or scatter solar radiation and alter clouds, played an important role in counterbalancing some of the greenhouse gas (GHG) caused global warming. The multicentury anthropogenic aerosol cooling effect prevented present-day climate from reaching even higher surface air temperatures and subsequent more dramatic climate impacts. Trends in aerosol concentrations and optical depth show that in many polluted regions such as Europe and the United States, aerosol precursor emissions decreased back to levels of the 1950s. More recent polluting countries such as China may have reached a turning point in recent years as well, while India still follows an upward trend. Here we study aerosol trends in the Coupled Model Intercomparison Project Phase 6 (CMIP6) simulations of the GISS ModelE2.1 climate model using a fully coupled atmosphere composition configuration, including interactive gas-phase chemistry and either an aerosol microphysical (MATRIX) or a mass-based (One-Moment Aerosol, OMA) aerosol module. Results show that whether global aerosol radiative forcing is already declining depends on the aerosol scheme used. Using the aerosol microphysical scheme, where the aerosol system reacts more strongly to the trend in sulfur dioxide (SO2) emissions, global peak direct aerosol forcing was reached in the 1980s, whereas the mass-based scheme simulates peak direct aerosol forcing around 2010.}, author = {Bauer, Susanne E and Tsigaridis, Kostas and Faluvegi, Greg and Kelley, Maxwell and Lo, Ken K and Miller, Ron L and Nazarenko, Larissa and Schmidt, Gavin A and Wu, Jingbo}, doi = {doi:10.1029/2019MS001978}, issn = {1942-2466}, journal = {Journal of Advances in Modeling Earth Systems}, number = {8}, pages = {e2019MS001978}, title = {{Historical (1850–2014) Aerosol Evolution and Role on Climate Forcing Using the GISS ModelE2.1 Contribution to CMIP6}}, volume = {12}, year = {2020} } @article{Bauer2016, author = {Bauer, Susanne E. and Tsigaridis, Kostas and Miller, Ron}, doi = {10.1002/2016GL068354}, issn = {0094-8276}, journal = {Geophysical Research Letters}, month = {may}, number = {10}, pages = {5394--5400}, title = {{Significant atmospheric aerosol pollution caused by world food cultivation}}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2016GL068354}, volume = {43}, year = {2016} } @article{Bauwens2020a, abstract = {Spaceborne NO2 column observations from two high-resolution instruments, Tropospheric Monitoring Instrument (TROPOMI) on board Sentinel-5 Precursor and Ozone Monitoring Instrument (OMI) on Aura, reveal unprecedented NO2 decreases over China, South Korea, western Europe, and the United States as a result of public health measures enforced to contain the coronavirus disease outbreak (Covid-19) in January–April 2020. The average NO2 column drop over all Chinese cities amounts to −40{\%} relative to the same period in 2019 and reaches up to a factor of {\~{}}2 at heavily hit cities, for example, Wuhan, Jinan, while the decreases in western Europe and the United States are also significant (−20{\%} to −38{\%}). In contrast with this, although Iran is also strongly affected by the disease, the observations do not show evidence of lower emissions, reflecting more limited health measures.}, author = {Bauwens, M and Compernolle, S and Stavrakou, T and M{\"{u}}ller, J F and van Gent, J and Eskes, H and Levelt, P F and van der A, R and Veefkind, J P and Vlietinck, J and Yu, H and Zehner, C}, doi = {10.1029/2020GL087978}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {air quality,coronavirus outbreak,emissions,lockdown,satellite NO2}, month = {jun}, number = {11}, publisher = {Blackwell Publishing Ltd}, title = {{Impact of Coronavirus Outbreak on NO2 Pollution Assessed Using TROPOMI and OMI Observations}}, volume = {47}, year = {2020} } @article{Beekmann2015, abstract = {A detailed characterization of air quality in the megacity of Paris (France) during two 1-month intensive campaigns and from additional 1-year observations revealed that about 70 {\%} of the urban background fine particulate matter (PM) is transported on average into the megacity from upwind regions. This dominant influence of regional sources was confirmed by in situ measurements during short intensive and longer-term campaigns, aerosol optical depth (AOD) measurements from ENVISAT, and modeling results from PMCAMx and CHIMERE chemistry transport models. While advection of sulfate is well documented for other megacities, there was surprisingly high contribution from long-range transport for both nitrate and organic aerosol. The origin of organic PM was investigated by comprehensive analysis of aerosol mass spectrometer (AMS), radiocarbon and tracer measurements during two intensive campaigns. Primary fossil fuel combustion emissions constituted less than 20 {\%} in winter and 40 {\%} in summer of carbonaceous fine PM, unexpectedly small for a megacity. Cooking activities and, during winter, residential wood burning are the major primary organic PM sources. This analysis suggests that the major part of secondary organic aerosol is of modern origin, i.e., from biogenic precursors and from wood burning. Black carbon concentrations are on the lower end of values encountered in megacities worldwide, but still represent an issue for air quality. These comparatively low air pollution levels are due to a combination of low emissions per inhabitant, flat terrain, and a meteorology that is in general not conducive to local pollution build-up. This revised picture of a megacity only being partially responsible for its own average and peak PM levels has important implications for air pollution regulation policies.}, author = {Beekmann, M. and Pr{\'{e}}v{\^{o}}t, A. S.H. and Drewnick, F. and Sciare, J. and Pandis, S. N. and {Denier Van Der Gon}, H. A.C. and Crippa, M. and Freutel, F. and Poulain, L. and Ghersi, V. and Rodriguez, E. and Beirle, S. and Zotter, P. and {Von Der Weiden-Reinm{\"{u}}ller}, S. L. and Bressi, M. and Fountoukis, C. and Petetin, H. and Szidat, S. and Schneider, J. and Rosso, A. and {El Haddad}, I. and Megaritis, A. and Zhang, Q. J. and Michoud, V. and Slowik, J. G. and Moukhtar, S. and Kolmonen, P. and Stohl, A. and Eckhardt, S. and Borbon, A. and Gros, V. and Marchand, N. and Jaffrezo, J. L. and Schwarzenboeck, A. and Colomb, A. and Wiedensohler, A. and Borrmann, S. and Lawrence, M. and Baklanov, A. and Baltensperger, U.}, doi = {10.5194/acp-15-9577-2015}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, pages = {9577--9591}, title = {{In situ, satellite measurement and model evidence on the dominant regional contribution to fine particulate matter levels in the Paris megacity}}, volume = {15}, year = {2015} } @article{Bekki2009, abstract = {Although in relatively low concentration of a few molecules per million of e e air molecules, atmospheric ozone (trioxygen O3) is essential to sustaining life on the surface of the Earth. Indeed, by absorbing solar radiation between 240 and 320 nm, it shields living organisms including humans from the very harmful ultraviolet radiation UV-B. About 90{\%} of the ozone resides in the stratosphere, a region that extends from the tropopause, whose altitude ranges from 7 km at the poles to 17 km in the tropics, to the stratopause located at about 50 km altitude. Stratospheric ozone is communally referred as the « ozone layer ». Unlike the atmosphere surrounding it, the stratosphere is vertically stratified and stable because the temperature increases with height within it. This particularity originates from heating produced by the absorption of UV radiation by stratospheric ozone. The present chapter describes the main mechanisms that govern the natural balance of ozone in the stratosphere, and its disruption under the influence of human activities.}, author = {Bekki, S and Lefevre, F}, doi = {10.1140/epjconf/e2009-00914-y}, issn = {2100-014X}, journal = {EPJ Web of Conferences}, month = {feb}, pages = {113--136}, title = {{Stratospheric ozone: History and concepts and interactions with climate}}, url = {https://doi.org/10.1140/epjconf/e2009-00914-y http://www.epj-conferences.org/10.1140/epjconf/e2009-00914-y}, volume = {1}, year = {2009} } @article{Bekki2013, abstract = {Past stratospheric ozone depletion has acted to cool the Earth's surface. As the result of the phase-out of anthropogenic halogenated compounds emissions, stratospheric ozone is projected to recover and its radiative forcing (RF-O3 ∼ -0.05 W/m2 presently) might therefore be expected to decay in line with ozone recovery itself. Using results from chemistry-climate models, we find that, although model projections using a standard greenhouse gas scenario broadly agree on the future evolution of global ozone, they strongly disagree on RF-O3 because of a large model spread in ozone changes in a narrow (several km thick) layer, in the northern lowermost stratosphere. Clearly, future changes in global stratospheric ozone cannot be considered an indicator of its overall RF. The multi-model mean RF-O3 estimate for 2100 is +0.06 W/m2 but with a range such that it could remain negative throughout this century or change sign and reach up to ∼0.25 W/m2. {\textcopyright} 2013 American Geophysical Union. All Rights Reserved.}, author = {Bekki, S. and Rap, A. and Poulain, V. and Dhomse, S. and Marchand, M. and Lefevre, F. and Forster, P. M. and Szopa, S. and Chipperfield, M. P.}, doi = {10.1002/grl.50358}, issn = {00948276}, journal = {Geophysical Research Letters}, keywords = {climate,stratospheric ozone}, number = {11}, pages = {2796--2800}, title = {{Climate impact of stratospheric ozone recovery}}, volume = {40}, year = {2013} } @article{Bellouin2020, abstract = {Abstract Aerosols interact with radiation and clouds. Substantial progress made over the past 40 years in observing, understanding, and modeling these processes helped quantify the imbalance in the Earth's radiation budget caused by anthropogenic aerosols, called aerosol radiative forcing, but uncertainties remain large. This review provides a new range of aerosol radiative forcing over the industrial era based on multiple, traceable, and arguable lines of evidence, including modeling approaches, theoretical considerations, and observations. Improved understanding of aerosol absorption and the causes of trends in surface radiative fluxes constrain the forcing from aerosol-radiation interactions. A robust theoretical foundation and convincing evidence constrain the forcing caused by aerosol-driven increases in liquid cloud droplet number concentration. However, the influence of anthropogenic aerosols on cloud liquid water content and cloud fraction is less clear, and the influence on mixed-phase and ice clouds remains poorly constrained. Observed changes in surface temperature and radiative fluxes provide additional constraints. These multiple lines of evidence lead to a 68{\%} confidence interval for the total aerosol effective radiative forcing of -1.6 to -0.6 W m?2, or -2.0 to -0.4 W m?2 with a 90{\%} likelihood. Those intervals are of similar width to the last Intergovernmental Panel on Climate Change assessment but shifted toward more negative values. The uncertainty will narrow in the future by continuing to critically combine multiple lines of evidence, especially those addressing industrial-era changes in aerosol sources and aerosol effects on liquid cloud amount and on ice clouds.}, annote = {https://doi.org/10.1029/2019RG000660}, author = {Bellouin, N and Quaas, J and Gryspeerdt, E and Kinne, S and Stier, P and Watson-Parris, D and Boucher, O and Carslaw, K S and Christensen, M and Daniau, A.-L. and Dufresne, J.-L. and Feingold, G and Fiedler, S and Forster, P and Gettelman, A and Haywood, J M and Lohmann, U and Malavelle, F and Mauritsen, T and McCoy, D T and Myhre, G and M{\"{u}}lmenst{\"{a}}dt, J and Neubauer, D and Possner, A and Rugenstein, M and Sato, Y and Schulz, M and Schwartz, S E and Sourdeval, O and Storelvmo, T and Toll, V and Winker, D and Stevens, B}, doi = {https://doi.org/10.1029/2019RG000660}, issn = {8755-1209}, journal = {Reviews of Geophysics}, month = {mar}, number = {1}, pages = {e2019RG000660}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Bounding Global Aerosol Radiative Forcing of Climate Change}}, url = {https://doi.org/10.1029/2019RG000660}, volume = {58}, year = {2020} } @article{Bellouin2013, abstract = {Abstract. The Hadley Centre Global Environmental Model (HadGEM) includes two aerosol schemes: the Coupled Large-scale Aerosol Simulator for Studies in Climate (CLASSIC), and the new Global Model of Aerosol Processes (GLOMAP-mode). GLOMAP-mode is a modal aerosol microphysics scheme that simulates not only aerosol mass but also aerosol number, represents internally-mixed particles, and includes aerosol microphysical processes such as nucleation. In this study, both schemes provide hindcast simulations of natural and anthropogenic aerosol species for the period 2000–2006. HadGEM simulations of the aerosol optical depth using GLOMAP-mode compare better than CLASSIC against a data-assimilated aerosol re-analysis and aerosol ground-based observations. Because of differences in wet deposition rates, GLOMAP-mode sulphate aerosol residence time is two days longer than CLASSIC sulphate aerosols, whereas black carbon residence time is much shorter. As a result, CLASSIC underestimates aerosol optical depths in continental regions of the Northern Hemisphere and likely overestimates absorption in remote regions. Aerosol direct and first indirect radiative forcings are computed from simulations of aerosols with emissions for the year 1850 and 2000. In 1850, GLOMAP-mode predicts lower aerosol optical depths and higher cloud droplet number concentrations than CLASSIC. Consequently, simulated clouds are much less susceptible to natural and anthropogenic aerosol changes when the microphysical scheme is used. In particular, the response of cloud condensation nuclei to an increase in dimethyl sulphide emissions becomes a factor of four smaller. The combined effect of different 1850 baselines, residence times, and abilities to affect cloud droplet number, leads to substantial differences in the aerosol forcings simulated by the two schemes. GLOMAP-mode finds a present-day direct aerosol forcing of −0.49 W m−2 on a global average, 72{\%} stronger than the corresponding forcing from CLASSIC. This difference is compensated by changes in first indirect aerosol forcing: the forcing of −1.17 W m−2 obtained with GLOMAP-mode is 20{\%} weaker than with CLASSIC. Results suggest that mass-based schemes such as CLASSIC lack the necessary sophistication to provide realistic input to aerosol-cloud interaction schemes. Furthermore, the importance of the 1850 baseline highlights how model skill in predicting present-day aerosol does not guarantee reliable forcing estimates. Those findings suggest that the more complex representation of aerosol processes in microphysical schemes improves the fidelity of simulated aerosol forcings.}, author = {Bellouin, N and Mann, G W and Woodhouse, M T and Johnson, C and Carslaw, K S and Dalvi, M}, doi = {10.5194/acp-13-3027-2013}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {6}, pages = {3027--3044}, publisher = {Copernicus Publications}, title = {{Impact of the modal aerosol scheme GLOMAP-mode on aerosol forcing in the Hadley Centre Global Environmental Model}}, url = {https://acp.copernicus.org/articles/13/3027/2013/}, volume = {13}, year = {2013} } @article{Berntsen2008, author = {Berntsen, T. and Fuglestvedt, J.}, doi = {10.1073/pnas.0804844105}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, month = {dec}, number = {49}, pages = {19154--19159}, title = {{Global temperature responses to current emissions from the transport sectors}}, url = {http://www.pnas.org/cgi/doi/10.1073/pnas.0804844105}, volume = {105}, year = {2008} } @article{Bhaskar2017, abstract = {Spatial variation of long term annual precipitation volume weighted concentrations of major chemical constituents (SO4−2, NO3−, Cl−, NH4+, Ca+2, Mg+2, Na+ and K+) at all the ten Global Atmospheric Watch (GAW) stations in India for the period from 1981 to 2012 is studied in this paper. Ionic abundance and balance is studied as well. The range of long term annual mean pH at ten stations was 5.25 ± 0.82 to 6.91 ± 0.76, lowest at Mohanbari and highest at Jodhpur. The long term annual mean pH for the period 1981–2012 showed decreasing trend at all the stations (significant at 5 {\%} level). Decadal mean pH among ten stations for 1981–1990, 1991–2000 and 2001–2012 ranged between 7.31 to 5.76, 7.45 to 4.92 and 6.16 to 4.77 respectively and showed decreasing trend at all the stations during 1981–1990 to 2001–12. The percentage occurrence of acidic pH ({\textless}5.65) at ten stations ranged from 3 to 72 {\%}, lowest at Jodhpur and highest at Mohanbari and it increased from 1981–1990 to 2001–2012 almost at all the stations. Temporal variation of annual mean values of nssSO4−2,NO3−,Ca+2 and pH for the study period were attempted. Variation of nss K (non sea salt Potassium) at all the stations was studied to assess the biomass burning contribution in different regions. Non-marine (terrestrial) contribution dominated for majority of ionic constituents at most of the stations. However marine contribution was found to be dominant for Mg at Port Blair and Minicoy. Also sea salt fraction of SO4 was higher than terrestrial at Minicoy. Sources of measured ionic constituents in rain water are assessed through correlation analysis. The concentrations of all the ionic species were lowest at Kodaikanal, a high altitude hill top station and the total ionic mass was 136.0 $\mu$eq/l. Jodhpur, an arid station not only had highest concentrations of Ca+2,SO4−2 and K+ but also had highest total ionic content (1051.8 $\mu$eq/l) among all the stations. At Srinagar, Jodhpur, Allahabad, Nagpur and Pune stations Ca+2 was the dominant cation while dominant anion was NO3− for Srinagar, Allahabad, and Nagpur and Cl− for Jodhpur and Pune; at Mohanbari NO3− and Ca+2; at Visakhapatnam, Port Blair and Minicoy Na+ and Cl− were abundant. Temporal variation had shown an increasing trend for nssSO4−2 and NO3− and obviously decreasing trend for pH at all the stations. However, Ca+2 showed a decreasing trend at all the stations except at Port Blair. With the exception of Pune and Jodhpur stations, nssK showed a decreasing trend at all the stations revealing decreasing influence of soil/biomass burning over Indian GAW stations. Negative correlation of pH with SO4−2was found to be weak compared to NO3–}, author = {Bhaskar, V. Vizaya and Rao, P. S.P.}, doi = {10.1007/s10874-016-9339-3}, issn = {15730662}, journal = {Journal of Atmospheric Chemistry}, keywords = {Decadal variation,Indian GAW stations,Ionic concentration,Rainwater,pH}, number = {1}, pages = {23--53}, title = {{Annual and decadal variation in chemical composition of rain water at all the ten GAW stations in India}}, volume = {74}, year = {2017} } @article{Bian2017, abstract = {An assessment of global particulate nitrate and ammonium aerosol based on simulations from nine models participating in the Aerosol Comparisons between Observations and Models (AeroCom) phase III study is presented. A budget analysis was conducted to understand the typical magnitude, distribution, and diversity of the aerosols and their precursors among the models. To gain confidence regarding model performance, the model results were evaluated with various observations globally, including ground station measurements over North America, Europe, and east Asia for tracer concentrations and dry and wet depositions, as well as with aircraft measurements in the Northern Hemisphere mid-to-high latitudes for tracer vertical distributions. Given the unique chemical and physical features of the nitrate occurrence, we further investigated the similarity and differentiation among the models by examining (1) the pHdependent NH3 wet deposition; (2) the nitrate formation via heterogeneous chemistry on the surface of dust and sea salt particles or thermodynamic equilibrium calculation including dust and sea salt ions; and (3) the nitrate coarse-mode fraction (i.e., coarse/total). It is found that HNO 3 , which is simulated explicitly based on full O 3 -HOx-NOx-aerosol chemistry by all models, differs by up to a factor of 9 among the models in its global tropospheric burden. This partially contributes to a large difference in NO- 3 , whose atmospheric burden differs by up to a factor of 13. The atmospheric burdens of NH3 and NHC 4 differ by 17 and 4, respectively. Analyses at the process level show that the large diversity in atmospheric burdens of NO- 3 , NH3, and NHC 4 is also related to deposition processes. Wet deposition seems to be the dominant process in determining the diversity in NH 3 and NHC 4 lifetimes. It is critical to correctly account for contributions of heterogeneous chemical production of nitrate on dust and sea salt, because this process overwhelmingly controls atmospheric nitrate production (typically 80 {\%}) and determines the coarse-A nd fine-mode distribution of nitrate aerosol.}, author = {Bian, Huisheng and Chin, Mian and Hauglustaine, Didier A. and Schulz, Michael and Myhre, Gunnar and Bauer, Susanne E. and Lund, Marianne T. and Karydis, Vlassis A. and Kucsera, Tom L. and Pan, Xiaohua and Pozzer, Andrea and Skeie, Ragnhild B. and Steenrod, Stephen D. and Sudo, Kengo and Tsigaridis, Kostas and Tsimpidi, Alexandra P. and Tsyro, Svetlana G.}, doi = {10.5194/acp-17-12911-2017}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {21}, pages = {12911--12940}, title = {{Investigation of global particulate nitrate from the AeroCom phase III experiment}}, volume = {17}, year = {2017} } @article{Bickel2020, address = {Boston MA, USA}, author = {Bickel, Marius and Ponater, Michael and Bock, Lisa and Burkhardt, Ulrike and Reineke, Svenja}, doi = {10.1175/JCLI-D-19-0467.1}, journal = {Journal of Climate}, language = {English}, number = {5}, pages = {1991--2005}, publisher = {American Meteorological Society}, title = {{Estimating the Effective Radiative Forcing of Contrail Cirrus}}, url = {https://journals.ametsoc.org/view/journals/clim/33/5/jcli-d-19-0467.1.xml}, volume = {33}, year = {2020} } @article{Bishop2018, abstract = {The University of Denver has collected on-road fuel specific vehicle emissions measurements in the Chicago area since 1989. This nearly 30 year record illustrates the large reductions in light-duty vehicle tailpipe emissions and the remarkable improvements in emissions control durability to maintain low emissions over increasing periods of time. Since 1989 fuel specific carbon monoxide (CO) emissions have been reduced by an order of magnitude and hydrocarbon (HC) emissions by more than a factor of 20. Nitric oxide (NO) emissions have only been collected since 1997 but have seen reductions of 79{\%}. This has increased the skewness of the emissions distribution where the 2016 fleet's 99th percentile contributes ∼3 times more of the 1990 total for CO and HC emissions. There are signs that these reductions may be leveling out as the emissions durability of Tier 2 vehicles in use today has almost eliminated the emissions reduction benefit of fleet turnover. Since 1997, the average age of the Chicago on-road fleet has increased 2 model years and the percentage of passenger vehicles has dropped from 71 to 52{\%} of the fleet. Emissions are now so well controlled that the influence of driving mode has been completely eliminated as a factor for fuel specific CO and NO emissions.}, author = {Bishop, Gary A. and Haugen, Molly J.}, doi = {10.1021/acs.est.8b00926}, issn = {0013-936X}, journal = {Environmental Science {\&} Technology}, month = {jul}, number = {13}, pages = {7587--7593}, title = {{The Story of Ever Diminishing Vehicle Tailpipe Emissions as Observed in the Chicago, Illinois Area}}, url = {https://pubs.acs.org/doi/10.1021/acs.est.8b00926}, volume = {52}, year = {2018} } @article{Bond2013b, abstract = {Black carbon aerosol plays a unique and important role in Earth's climate system. Black carbon is a type of carbonaceous material with a unique combination of physical properties. This assessment provides an evaluation of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice. These effects are calculated with climate models, but when possible, they are evaluated with both microphysical measurements and field observations. Predominant sources are combustion related, namely, fossil fuels for transportation, solid fuels for industrial and residential uses, and open burning of biomass. Total global emissions of black carbon using bottom-up inventory methods are 7500 Gg yr-1 in the year 2000 with an uncertainty range of 2000 to 29000. However, global atmospheric absorption attributable to black carbon is too low in many models and should be increased by a factor of almost 3. After this scaling, the best estimate for the industrial-era (1750 to 2005) direct radiative forcing of atmospheric black carbon is +0.71 W m-2 with 90{\%} uncertainty bounds of (+0.08, +1.27) W m-2. Total direct forcing by all black carbon sources, without subtracting the preindustrial background, is estimated as +0.88 (+0.17, +1.48) W m-2. Direct radiative forcing alone does not capture important rapid adjustment mechanisms. A framework is described and used for quantifying climate forcings, including rapid adjustments. The best estimate of industrial-era climate forcing of black carbon through all forcing mechanisms, including clouds and cryosphere forcing, is +1.1 W m-2 with 90{\%} uncertainty bounds of +0.17 to +2.1 W m-2. Thus, there is a very high probability that black carbon emissions, independent of co-emitted species, have a positive forcing and warm the climate. We estimate that black carbon, with a total climate forcing of +1.1 W m-2, is the second most important human emission in terms of its climate forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing. Sources that emit black carbon also emit other short-lived species that may either cool or warm climate. Climate forcings from co-emitted species are estimated and used in the framework described herein. When the principal effects of short-lived co-emissions, including cooling agents such as sulfur dioxide, are included in net forcing, energy-related sources (fossil fuel and biofuel) have an industrial-era climate forcing of +0.22 (-0.50 to +1.08) W m-2 during the first year after emission. For a few of these sources, such as diesel engines and possibly residential biofuels, warming is strong enough that eliminating all short-lived emissions from these sources would reduce net climate forcing (i.e., produce cooling). When open burning emissions, which emit high levels of organic matter, are included in the total, the best estimate of net industrial-era climate forcing by all short-lived species from black-carbon-rich sources becomes slightly negative (-0.06 W m-2 with 90{\%} uncertainty bounds of -1.45 to +1.29 W m-2). The uncertainties in net climate forcing from black-carbon-rich sources are substantial, largely due to lack of knowledge about cloud interactions with both black carbon and co-emitted organic carbon. In prioritizing potential black-carbon mitigation actions, non-science factors, such as technical feasibility, costs, policy design, and implementation feasibility play important roles. The major sources of black carbon are presently in different stages with regard to the feasibility for near-term mitigation. This assessment, by evaluating the large number and complexity of the associated physical and radiative processes in black-carbon climate forcing, sets a baseline from which to improve future climate forcing estimates. {\textcopyright}2013 The Authors. Journal of Geophysical Research: Atmospheres published by Wiley on behalf of the American Geophysical Union.}, annote = {From Duplicate 1 (Bounding the role of black carbon in the climate system: A scientific assessment - Bond, T. C.; Doherty, S. J.; Fahey, D. W.; Forster, P. M.; Berntsen, T.; DeAngelo, B. J.; Flanner, M. G.; Ghan, S.; K{\"{a}}rcher, B.; Koch, D.; Kinne, S.; Kondo, Y.; Quinn, P. K.; Sarofim, M. C.; Schultz, M. G.; Schulz, M.; Venkataraman, C.; Zhang, H.; Zhang, S.; Bellouin, N.; Guttikunda, S. K.; Hopke, P. K.; Jacobson, M. Z.; Kaiser, J. W.; Klimont, Z.; Lohmann, U.; Schwarz, J. P.; Shindell, D.; Storelvmo, T.; Warren, S. G.; Zender, C. S.) From Duplicate 3 (Bounding the role of black carbon in the climate system: A scientific assessment - Bond, T. C.; Doherty, S. J.; Fahey, D. W.; Forster, P. M.; Berntsen, T.; Deangelo, B. J.; Flanner, M. G.; Ghan, S.; K{\"{a}}rcher, B.; Koch, D.; Kinne, S.; Kondo, Y.; Quinn, P. K.; Sarofim, M. C.; Schultz, M. G.; Schulz, M.; Venkataraman, C.; Zhang, H.; Zhang, S.; Bellouin, N.; Guttikunda, S. K.; Hopke, P. K.; Jacobson, M. Z.; Kaiser, J. W.; Klimont, Z.; Lohmann, U.; Schwarz, J. P.; Shindell, D.; Storelvmo, T.; Warren, S. G.; Zender, C. S.) From Duplicate 2 (Bounding the role of black carbon in the climate system: A scientific assessment - DuplicateBond, NoCite; Bond, T. C.; Doherty, S. J.; Fahey, D. W.; Forster, P. M.; Berntsen, T.; Deangelo, B. J.; Flanner, M. G.; Ghan, S.; K{\"{a}}rcher, B.; Koch, D.; Kinne, S.; Kondo, Y.; Quinn, P. K.; Sarofim, M. C.; Schultz, M. G.; Schulz, M.; Venkataraman, C.; Zhang, H.; Zhang, S.; Bellouin, N.; Guttikunda, S. K.; Hopke, P. K.; Jacobson, M. Z.; Kaiser, J. W.; Klimont, Z.; Lohmann, U.; Schwarz, J. P.; Shindell, D.; Storelvmo, T.; Warren, S. G.; Zender, C. S.) 228TG Times Cited:405 Cited References Count:868 From Duplicate 2 (Bounding the role of black carbon in the climate system: A scientific assessment - Bond, T. C.; Doherty, S. J.; Fahey, D. W.; Forster, P. M.; Berntsen, T.; Deangelo, B. J.; Flanner, M. G.; Ghan, S.; K{\"{a}}rcher, B.; Koch, D.; Kinne, S.; Kondo, Y.; Quinn, P. K.; Sarofim, M. C.; Schultz, M. G.; Schulz, M.; Venkataraman, C.; Zhang, H.; Zhang, S.; Bellouin, N.; Guttikunda, S. K.; Hopke, P. K.; Jacobson, M. Z.; Kaiser, J. W.; Klimont, Z.; Lohmann, U.; Schwarz, J. P.; Shindell, D.; Storelvmo, T.; Warren, S. G.; Zender, C. S.) From Duplicate 2 (Bounding the role of black carbon in the climate system: A scientific assessment - DuplicateBond, NoCite; Bond, T. C.; Doherty, S. J.; Fahey, D. W.; Forster, P. M.; Berntsen, T.; Deangelo, B. J.; Flanner, M. G.; Ghan, S.; K{\"{a}}rcher, B.; Koch, D.; Kinne, S.; Kondo, Y.; Quinn, P. K.; Sarofim, M. C.; Schultz, M. G.; Schulz, M.; Venkataraman, C.; Zhang, H.; Zhang, S.; Bellouin, N.; Guttikunda, S. K.; Hopke, P. K.; Jacobson, M. Z.; Kaiser, J. W.; Klimont, Z.; Lohmann, U.; Schwarz, J. P.; Shindell, D.; Storelvmo, T.; Warren, S. G.; Zender, C. S.) 228TG Times Cited:405 Cited References Count:868}, author = {Bond, T. C. and Doherty, S. J. and Fahey, D. W. and Forster, P. M. and Berntsen, T. and DeAngelo, B. J. and Flanner, M. G. and Ghan, S. and K{\"{a}}rcher, B. and Koch, D. and Kinne, S. and Kondo, Y. and Quinn, P. K. and Sarofim, M. C. and Schultz, M. G. and Schulz, M. and Venkataraman, C. and Zhang, H. and Zhang, S. and Bellouin, N. and Guttikunda, S. K. and Hopke, P. K. and Jacobson, M. Z. and Kaiser, J. W. and Klimont, Z. and Lohmann, U. and Schwarz, J. P. and Shindell, D. and Storelvmo, T. and Warren, S. G. and Zender, C. S.}, doi = {10.1002/jgrd.50171}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {aerosol,black carbon,climate forcing}, language = {English}, month = {jun}, number = {11}, pages = {5380--5552}, title = {{Bounding the role of black carbon in the climate system: A scientific assessment}}, url = {http://doi.wiley.com/10.1002/jgrd.50171}, volume = {118}, year = {2013} } @article{Bondur2020, abstract = {The features of anomalous Siberian wildfires in 2019 and trends of their changes during 2000–2019 are analyzed on the basis of satellite monitoring data. The average values of wildfire areas; total volumes of CO, CO2, and aerosol PM2.5 emissions; and their density (per area unit) in the Siberian Federal District of Russia and its regions are estimated for a 20-year period, as well as the number, radiative power, and spatial distribution of wildfires on the territory of North Eurasia in 2019. In July 2019, the wildfire area in Irkutsk oblast exceeded the average value for the period of 2001–2019 by more than four times, whereas the related total volumes of emissions of CO, CO2, and PM2.5 aerosol in June 2019 were five times higher than their average values for this period. The regional weather-climate features of summer 2019 were revealed using on-land observations and reanalysis, in particular, atmospheric blocking, which is related to the formation of extreme regimes of wildfires and floods in adjacent territories of Siberia.}, author = {Bondur, V G and Mokhov, I I and Voronova, O S and Sitnov, S A}, doi = {10.1134/S1028334X20050049}, issn = {1531-8354}, journal = {Doklady Earth Sciences}, number = {1}, pages = {370--375}, title = {{Satellite Monitoring of Siberian Wildfires and Their Effects: Features of 2019 Anomalies and Trends of 20-Year Changes}}, url = {https://doi.org/10.1134/S1028334X20050049}, volume = {492}, year = {2020} } @article{Sophie2013, abstract = {Background: Exposure to household air pollution from cooking with solid fuels in simple stoves is a major health risk. Modeling reliable estimates of solid fuel use is needed for monitoring trends and informing policy. Objectives: In order to revise the disease burden attributed to household air pollution for the Global Burden of Disease 2010 project and for international reporting purposes, we estimated annual trends in the world population using solid fuels. Methods: We developed a multilevel model based on national survey data on primary cooking fuel. Results: The proportion of households relying mainly on solid fuels for cooking has decreased from 62{\%} (95{\%} CI: 58, 66{\%}) to 41{\%} (95{\%}37, 44{\%}) between 1980 and 2010. Yet because of population growth, the actual number of persons exposed has remained stable at around 2.8 billion during three decades. Solid fuel use is most prevalent in Africa and Southeast Asia where {\textgreater} 60{\%} of households cook with solid fuels. In other regions, primary solid fuel use ranges from 46{\%} in the Western Pacific, to 35{\%} in the Eastern Mediterranean and {\textless} 20{\%} in the Americas and Europe. Conclusion: Multilevel modeling is a suitable technique for deriving reliable solid-fuel use estimates. Worldwide, the proportion of households cooking mainly with solid fuels is decreasing. The absolute number of persons using solid fuels, however, has remained steady globally and is increasing in some regions. Surveys require enhancement to better capture the health implications of new technologies and multiple fuel use.}, annote = {From Duplicate 1 (Solid Fuel Use for Household Cooking: Country and Regional Estimates for 1980–2010 - Sophie, Bonjour; Heather, Adair-Rohani; Jennyfer, Wolf; G., Bruce Nigel; Sumi, Mehta; Annette, Pr{\"{u}}ss-Ust{\"{u}}n; Maureen, Lahiff; A., Rehfuess Eva; Vinod, Mishra; R., Smith Kirk) doi: 10.1289/ehp.1205987}, author = {Bonjour, Sophie and Adair-Rohani, Heather and Wolf, Jennyfer and Bruce, Nigel G. and Mehta, Sumi and Pr{\"{u}}ss-Ust{\"{u}}n, Annette and Lahiff, Maureen and Rehfuess, Eva A. and Mishra, Vinod and Smith, Kirk R.}, doi = {10.1289/ehp.1205987}, isbn = {0091-6765}, issn = {00916765}, journal = {Environmental Health Perspectives}, keywords = {Biomass fuel,Coal,Cookstoves,Disease burden,Household air pollution,Household energy,Indoor air pollution,MDGs,Millennium development goals}, month = {jul}, number = {7}, pages = {784--790}, publisher = {Environmental Health Perspectives}, title = {{Solid fuel use for household cooking: Country and regional estimates for 1980–2010}}, url = {https://doi.org/10.1289/ehp.1205987}, volume = {121}, year = {2013} } @article{Bopp2004, abstract = {Dimethylsulfide (DMS) is the most abundant volatile sulfur compound at the sea surface and has a strong marine phytoplanktonic origin. Once outgased into the atmosphere, it contributes to the formation of sulfate aerosol particles that affect the radiative budget as precursors of cloud condensation nuclei (CCN). It has been postulated that climate may be partly modulated by variations in DMS production. We test this hypothesis in the context of anthropogenic climate change and present here, modelled for the first time, an estimate of the radiative impact resulting from changes in DMS air-sea fluxes caused by global warming. At 2x CO2, our model estimates a small increase (3{\%}) in the global DMS flux to the atmosphere but with large spatial heterogeneities (from -15{\%} to 30{\%}). The radiative perturbation resulting from the DMS-induced change in cloud albedo is estimated to be -0.05 W{\textperiodcentered}m-2, which represents only a small negative climate feedback on global warming. However, there are large regional changes, such as a perturbation of up to -1.5 W{\textperiodcentered}m-2 in summer between 40°S and 50°S, that can impact the regional climate. In the Southern Ocean, the radiative impact resulting from changes in the DMS cycle may partly alleviate the radiative forcing resulting from anthropogenic CO2.}, author = {Bopp, Laurent and Boucher, Olivier and Aumont, Olivier and Belviso, Sauveur and Dufresne, Jean Louis and Pham, Mai and Monfray, Patrick}, doi = {10.1139/F04-045}, issn = {0706652X}, journal = {Canadian Journal of Fisheries and Aquatic Sciences}, number = {5}, pages = {826--835}, title = {{Will marine dimethylsulfide emissions amplify or alleviate global warming? A model study}}, volume = {61}, year = {2004} } @incollection{Boucher2013a, address = {Cambridge}, author = {Boucher, O and Randall, D and Artaxo, P and Bretherton, C and Feingold, G and Forster, P and Kerminen, V.-M. and Kondo, Y and Liao, H and Lohmann, U and Rasch, P and Satheesh, S K and Sherwood, S and Stevens, B and Zhang, X Y}, booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change}, chapter = {7}, doi = {10.1017/CBO9781107415324.016}, editor = {Stocker, T F and Qin, D and Plattner, G.-K. and Tignor, M and Allen, S K and Boschung, J and Nauels, A and Xia, Y and Bex, V and Midgley, P M}, isbn = {9781107661820}, pages = {571--658}, publisher = {Cambridge University Press}, title = {{Clouds and Aerosols}}, url = {https://www.ipcc.ch/report/ar5/wg1}, year = {2013} } @article{BOUROTTE20072036, abstract = {Air pollutants are associated with adverse respiratory effects mainly in susceptible groups. This study was designed to assess the impact of the ionic composition of particulate matter on asthmatic respiratory functions in S{\~{a}}o Paulo city. From May to July 2002, fine and coarse particulate matter fractions were collected and their respective chemical composition with respect to major ions (Na+, Mg2+, K+, Ca2+, NH4+, Cl−, NO3− and SO42−) were determined in each aqueous-extract fraction. The results showed predominant concentrations of SO42− (48.4{\%}), NO3− (19.6{\%}) and NH4+ (12.5{\%}) in the fine fraction, whereas NO3− (35.3{\%}), SO42− (29.1{\%}), Ca2+ (13.1{\%}) and Cl− (12.5{\%}) were the predominant species in the coarse fraction. The association between the chemical components of both fractions and the daily peak expiratory flow (PEF) measurements (morning and evening) of the 33 asthmatic individuals were assessed through a linear mixed-effects model. The results showed a significant negative correlation (decrease of PEF) between morning PEF and coarse chloride (3-day moving average) and between evening PEF and coarse Na+ (3-day moving average), coarse Mg2+ (3-day moving average) and coarse NH4+ (2- and 3-day moving average). A significant negative correlation has also been observed between morning and evening PEF and Mg2+ in the fine fraction. These results suggest that some particle chemical constituents may increase the responsiveness of airways and that coarse particles that deposit in the upper airways may be more relevant for asthmatic response and irritation. However, the results do not prove a clear causal relationship.}, author = {Bourotte, Christine and Curi-Amarante, Ana-Paula and Forti, Maria-Cristina and Pereira, Luiz A A and Braga, Alf{\'{e}}sio L and Lotufo, Paulo A}, doi = {https://doi.org/10.1016/j.atmosenv.2006.11.004}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Aerosol composition,Aqueous extracts,Major ions,PEF,PM,Urban pollution}, number = {10}, pages = {2036--2048}, title = {{Association between ionic composition of fine and coarse aerosol soluble fraction and peak expiratory flow of asthmatic patients in S{\~{a}}o Paulo city (Brazil)}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231006011083}, volume = {41}, year = {2007} } @article{Bowman2009, abstract = {Fire is a worldwide phenomenon that appears in the geological record soon after the appearance of terrestrial plants. Fire influences global ecosystem patterns and processes, including vegetation distribution and structure, the carbon cycle, and climate. Although humans and fire have always coexisted, our capacity to manage fire remains imperfect and may become more difficult in the future as climate change alters fire regimes. This risk is difficult to assess, however, because fires are still poorly represented in global models. Here, we discuss some of the most important issues involved in developing a better understanding of the role of fire in the Earth system.}, author = {Bowman, David M.J.S. and Balch, Jennifer K. and Artaxo, Paulo and Bond, William J. and Carlson, Jean M. and Cochrane, Mark A. and D'Antonio, Carla M. and DeFries, Ruth S. and Doyle, John C. and Harrison, Sandy P. and Johnston, Fay H. and Keeley, Jon E. and Krawchuk, Meg A. and Kull, Christian A. and Marston, J. Brad and Moritz, Max A. and Prentice, I. Colin and Roos, Christopher I. and Scott, Andrew C. and Swetnam, Thomas W. and {Van Der Werf}, Guido R. and Pyne, Stephen J.}, doi = {10.1126/science.1163886}, issn = {00368075}, journal = {Science}, month = {apr}, number = {5926}, pages = {481--484}, pmid = {19390038}, title = {{Fire in the earth system}}, url = {http://science.sciencemag.org/content/324/5926/481.abstract http://www.sciencemag.org/cgi/doi/10.1126/science.1163886}, volume = {324}, year = {2009} } @article{BraspenningRadu2016, abstract = {In this paper, we present ten scenarios developed using the IMAGE2.4 framework (Integrated Model to Assess the Global Environment) to explore how different assumptions on future climate and air pollution policies influence emissions of greenhouse gases and air pollutants. These scenarios describe emission developments in 26 world regions for the 21st century, using a matrix of climate and air pollution policies. For climate policy, the study uses a baseline resulting in forcing levels slightly above RCP6.0 and an ambitious climate policy scenario similar to RCP2.6. For air pollution, the study explores increasingly tight emission standards, ranging from no improvement, current legislation and three variants assuming further improvements. For all pollutants, the results show that more stringent control policies are needed after 2030 to prevent a rise in emissions due to increased activities and further reduce emissions. The results also show that climate mitigation policies have the highest impact on SO2and NOXemissions, while their impact on BC and OC emissions is relatively low, determined by the overlap between greenhouse gas and air pollutant emission sources. Climate policy can have important co-benefits; a 10{\%} decrease in global CO2emissions by 2100 leads to a decrease of SO2and NOXemissions by about 10{\%} and 5{\%}, respectively compared to 2005 levels. In most regions, low levels of air pollutant emissions can also be achieved by solely implementing stringent air pollution policies. The largest differences across the scenarios are found in Asia and other developing regions, where a combination of climate and air pollution policy is needed to bring air pollution levels below those of today.}, author = {{Braspenning Radu}, Olivia and van den Berg, Maarten and Klimont, Zbigniew and Deetman, Sebastiaan and Janssens-Maenhout, Greet and Muntean, Marilena and Heyes, Chris and Dentener, Frank and van Vuuren, Detlef P.}, doi = {10.1016/j.atmosenv.2016.05.021}, isbn = {1352-2310}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Air pollution policy,Climate policy,Co-benefits,Representative concentration pathways,Scenarios}, pages = {577--591}, title = {{Exploring synergies between climate and air quality policies using long-term global and regional emission scenarios}}, volume = {140}, year = {2016} } @book{Brasseur2017, abstract = {Mathematical modeling of atmospheric composition is a formidable scientific and computational challenge. This comprehensive presentation of the modeling methods used in atmospheric chemistry focuses on both theory and practice, from the fundamental principles behind models, through to their applications in interpreting observations. An encyclopaedic coverage of methods used in atmospheric modeling, including their advantages and disadvantages, makes this a one-stop resource with a large scope. Particular emphasis is given to the mathematical formulation of chemical, radiative, and aerosol processes; advection and turbulent transport; emission and deposition processes; as well as major chapters on model evaluation and inverse modeling. The modeling of atmospheric chemistry is an intrinsically interdisciplinary endeavour, bringing together meteorology, radiative transfer, physical chemistry and biogeochemistry, making the book of value to a broad readership. Introductory chapters and a review of the relevant mathematics make this book instantly accessible to graduate students and researchers in the atmospheric sciences.}, address = {Cambridge, UK}, author = {Brasseur, Guy P. and Jacob, Daniel J.}, doi = {10.1017/9781316544754}, editor = {Brasseur, Guy P. and Jacob, Daniel J.}, isbn = {9781316544754}, pages = {606}, publisher = {Cambridge University Press}, title = {{Modeling of Atmospheric Chemistry}}, year = {2017} } @article{Breider2017a, abstract = {Arctic observations show large decreases in the concentrations of sulfate and black carbon (BC) aerosols since the early 1980s. These near-term climate-forcing pollutants perturb the radiative balance of the atmosphere and may have played an important role in recent Arctic warming. We use the GEOS-Chem global chemical transport model to construct a 3-D representation of Arctic aerosols that is generally consistent with observations and their trends from 1980 to 2010. Observations at Arctic surface sites show significant decreases in sulfate and BC mass concentrations of 2–3{\%} per year. We find that anthropogenic aerosols yield a negative forcing over the Arctic, with an average 2005–2010 Arctic shortwave radiative forcing (RF) of −0.19 ± 0.05 W m−2 at the top of atmosphere (TOA). Anthropogenic sulfate in our study yields more strongly negative forcings over the Arctic troposphere in spring (−1.17 ± 0.10 W m−2) than previously reported. From 1980 to 2010, TOA negative RF by Arctic aerosol declined, from −0.67 ± 0.06 W m−2 to −0.19 ± 0.05 W m−2, yielding a net TOA RF of +0.48 ± 0.06 W m−2. The net positive RF is due almost entirely to decreases in anthropogenic sulfate loading over the Arctic. We estimate that 1980–2010 trends in aerosol-radiation interactions over the Arctic and Northern Hemisphere midlatitudes have contributed a net warming at the Arctic surface of +0.27 ± 0.04 K, roughly one quarter of the observed warming. Our study does not consider BC emissions from gas flaring nor the regional climate response to aerosol-cloud interactions or BC deposition on snow.}, annote = {From Duplicate 1 (Multidecadal trends in aerosol radiative forcing over the Arctic: Contribution of changes in anthropogenic aerosol to Arctic warming since 1980 - Breider, Thomas J; Mickley, Loretta J; Jacob, Daniel J; Ge, Cui; Wang, Jun; Sulprizio, Melissa Payer; Croft, Betty; Ridley, David A; McConnell, Joseph R; Sharma, Sangeeta; Husain, Liaquat; Dutkiewicz, Vincent A; Eleftheriadis, Konstantinos; Skov, Henrik; Hopke, Phillip K) Times Cited: 3 Chem, GEOS/C-5595-2014; Wang, Jun/A-2977-2008; Eleftheriadis, Konstantinos/G-2814-2011; Skov, Henrik/ Wang, Jun/0000-0002-7334-0490; Eleftheriadis, Konstantinos/0000-0003-2265-4905; Skov, Henrik/0000-0003-1167-8696 0 3 2169-8996 From Duplicate 2 (Multidecadal trends in aerosol radiative forcing over the Arctic: Contribution of changes in anthropogenic aerosol to Arctic warming since 1980 - Breider, Thomas J.; Mickley, Loretta J.; Jacob, Daniel J.; Ge, Cui; Wang, Jun; Sulprizio, Melissa Payer; Croft, Betty; Ridley, David A.; McConnell, Joseph R.; Sharma, Sangeeta; Husain, Liaquat; Dutkiewicz, Vincent A.; Eleftheriadis, Konstantinos; Skov, Henrik; Hopke, Phillip K.) From Duplicate 1 (Multidecadal trends in aerosol radiative forcing over the Arctic: Contribution of changes in anthropogenic aerosol to Arctic warming since 1980 - Breider, Thomas J; Mickley, Loretta J; Jacob, Daniel J; Ge, Cui; Wang, Jun; Sulprizio, Melissa Payer; Croft, Betty; Ridley, David A; McConnell, Joseph R; Sharma, Sangeeta; Husain, Liaquat; Dutkiewicz, Vincent A; Eleftheriadis, Konstantinos; Skov, Henrik; Hopke, Phillip K) Times Cited: 3 Chem, GEOS/C-5595-2014; Wang, Jun/A-2977-2008; Eleftheriadis, Konstantinos/G-2814-2011; Skov, Henrik/ Wang, Jun/0000-0002-7334-0490; Eleftheriadis, Konstantinos/0000-0003-2265-4905; Skov, Henrik/0000-0003-1167-8696 0 3 2169-8996}, author = {Breider, Thomas J. and Mickley, Loretta J. and Jacob, Daniel J. and Ge, Cui and Wang, Jun and {Payer Sulprizio}, Melissa and Croft, Betty and Ridley, David A. and McConnell, Joseph R. and Sharma, Sangeeta and Husain, Liaquat and Dutkiewicz, Vincent A. and Eleftheriadis, Konstantinos and Skov, Henrik and Hopke, Phillip K.}, doi = {10.1002/2016JD025321}, isbn = {2169-897X}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {mar}, number = {6}, pages = {3573--3594}, title = {{Multidecadal trends in aerosol radiative forcing over the Arctic: Contribution of changes in anthropogenic aerosol to Arctic warming since 1980}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2016JD025321 https://onlinelibrary.wiley.com/doi/10.1002/2016JD025321}, volume = {122}, year = {2017} } @article{Brown-Steiner2018, author = {Brown-Steiner, Benjamin and Selin, Noelle E and Prinn, Ronald and Tilmes, Simone and Emmons, Louisa and Lamarque, Jean-Fran{\c{c}}ois and Cameron-Smith, Philip}, doi = {10.5194/gmd-11-4155-2018}, issn = {1991-9603}, journal = {Geoscientific Model Development}, month = {oct}, number = {10}, pages = {4155--4174}, publisher = {Copernicus Publications}, title = {{Evaluating simplified chemical mechanisms within present-day simulations of the Community Earth System Model version 1.2 with CAM4 (CESM1.2 CAM-chem): MOZART-4 vs. Reduced Hydrocarbon vs. Super-Fast chemistry}}, url = {https://www.geosci-model-dev.net/11/4155/2018/ https://gmd.copernicus.org/articles/11/4155/2018/}, volume = {11}, year = {2018} } @article{Buchholz2021, abstract = {Following past studies to quantify decadal trends in global carbon monoxide (CO) using satellite observations, we update estimates and find a CO trend in column amounts of about −0.50 {\%} per year between 2002 to 2018, which is a deceleration compared to analyses performed on shorter records that found −1 {\%} per year. Aerosols are co-emitted with CO from both fires and anthropogenic sources but with a shorter lifetime than CO. A combined trend analysis of CO and aerosol optical depth (AOD) measurements from space helps to diagnose the drivers of regional differences in the CO trend. We use the long-term records of CO from the Measurements of Pollution in the Troposphere (MOPITT) and AOD from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. Other satellite instruments measuring CO in the thermal infrared, AIRS, TES, IASI, and CrIS, show consistent hemispheric CO variability and corroborate results from the trend analysis performed with MOPITT CO. Trends are examined by hemisphere and in regions for 2002 to 2018, with uncertainties quantified. The CO and AOD records are split into two sub-periods (2002 to 2010 and 2010 to 2018) in order to assess trend changes over the 16 years. We focus on four major population centers: Northeast China, North India, Europe, and Eastern USA, as well as fire-prone regions in both hemispheres. In general, CO declines faster in the first half of the record compared to the second half, while AOD trends show more variability across regions. We find evidence of the atmospheric impact of air quality management policies. The large decline in CO found over Northeast China is initially associated with an improvement in combustion efficiency, with subsequent additional air quality improvements from 2010 onwards. Industrial regions with minimal emission control measures such as North India become more globally relevant as the global CO trend weakens. We also examine the CO trends in monthly percentile values to understand seasonal implications and find that local changes in biomass burning are sufficiently strong to counteract the global downward trend in atmospheric CO, particularly in late summer.}, author = {Buchholz, Rebecca R. and Worden, Helen M. and Park, Mijeong and Francis, Gene and Deeter, Merritt N. and Edwards, David P. and Emmons, Louisa K. and Gaubert, Benjamin and Gille, John and Mart{\'{i}}nez-Alonso, Sara and Tang, Wenfu and Kumar, Rajesh and Drummond, James R. and Clerbaux, Cathy and George, Maya and Coheur, Pierre-Fran{\c{c}}ois and Hurtmans, Daniel and Bowman, Kevin W. and Luo, Ming and Payne, Vivienne H. and Worden, John R. and Chin, Mian and Levy, Robert C. and Warner, Juying and Wei, Zigang and Kulawik, Susan S.}, doi = {10.1016/j.rse.2020.112275}, issn = {00344257}, journal = {Remote Sensing of Environment}, month = {apr}, pages = {112275}, publisher = {Elsevier}, title = {{Air pollution trends measured from Terra: CO and AOD over industrial, fire-prone, and background regions}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0034425720306489}, volume = {256}, year = {2021} } @article{Bucsela2019, abstract = {Oxides of nitrogen are critical trace gases in the troposphere and are precursors for nitrate aerosol and ozone, which is an important pollutant and greenhouse gas. Lightning is the major source of NOx (NO + NO2) in the middle to upper troposphere. We estimate the production efficiency (PE) of lightning NOx (LNOx) using satellite data from the Ozone Monitoring Instrument and the ground-based World Wide Lightning Location Network in three northern midlatitudes, primarily continental regions that include much of North America, Europe, and East Asia. Data were obtained over five boreal summers, 2007–2011, and comprise the largest number of midlatitude convective events to date for estimating the LNOx PE with satellite NO2 and ground-based lightning measurements. In contrast to some previous studies, the algorithm assumes no minimum flash-rate threshold and estimates freshly produced LNOx by subtracting a background of aged NOx estimated from the Ozone Monitoring Instrument data set itself. We infer an average value of 180 ± 100 moles LNOx produced per lightning flash. We also show evidence of a dependence of PE on lightning flash rate and find an approximate empirical power function relating moles LNOx to flashes. PE decreases by an order of magnitude for a 2 orders of magnitude increase in flash rate. This phenomenon has not been reported in previous satellite LNOx studies but is consistent with ground-based observations suggesting an inverse relationship between flash rate and size.}, annote = {doi: 10.1029/2019JD030561}, author = {Bucsela, Eric J. and Pickering, Kenneth E. and Allen, Dale J. and Holzworth, Robert H. and Krotkov, Nickolay A.}, doi = {10.1029/2019JD030561}, issn = {21698996}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {NOx,OMI,WWLLN,lightning,production}, month = {dec}, number = {23}, pages = {13475--13497}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Midlatitude Lightning NOx Production Efficiency Inferred From OMI and WWLLN Data}}, url = {https://doi.org/10.1029/2019JD030561}, volume = {124}, year = {2019} } @article{Bunzel2013, abstract = {Most climate models simulate a strengthening of the Brewer-Dobson circulation (BDC) under a changing climate. However, the magnitude of the trend as well as the underlying mechanisms varies significantly among the models. In this work the impact of both verticalresolution and vertical extent of a model on the simulated BDC change is investigated by analyzing sensitivity simulations performed with the general circulation model ECHAM6 in three different model configurations for three different climate states. Tropical upwelling velocities and age of stratospheric air are used as measures for the strength of the BDC. Both consistently show a BDC strengthening from the preindustrial to the future climate state for all configurations of the model. However, the amplitude and origin of this change vary between the different setups. Analyses of the tropical upward mass flux indicate that in the model with a lid at 10 hPa the BDC strengthening at 70 hPa is primarily produced by resolved wave drag, while in the model with a higher lid (0.01 hPa) the parameterized wave drag yields the main contribution to the BDC increase. This implies that consistent changes in the BDC originate from different causes when the stratosphere is not sufficiently resolved in a model. Furthermore, the effect of enhancing the horizontal diffusion in the upper model layers to avoid resolved wave reflection at the model lid is quantified, and a possible link to the different behavior of the low-top model with regard to the origin of the BDC change is identified. {\textcopyright} 2013 American Meteorological Society.}, author = {Bunzel, Felix and Schmidt, Hauke}, doi = {10.1175/JAS-D-12-0215.1}, issn = {00224928}, journal = {Journal of the Atmospheric Sciences}, number = {5}, pages = {1437--1455}, title = {{The Brewer-Dobson Circulation in a Changing Climate: Impact of the Model Configuration}}, volume = {70}, year = {2013} } @article{Butler2016a, abstract = {Data from bi-weekly passive samplers from 18 of the longest operating National Atmospheric Deposition Program's (NADP) Ammonia Monitoring Network (AMoN) sites (most operating from 2008 to 2015) show that concentrations of NH3 have been increasing (p-value {\textless} 0.0001) over large regions of the USA. This trend is occurring at a seasonal and annual level of aggregation. Using random coefficient models (RCM), the mean slope for the 18 sites combined shows an increase of NH3 concentration of +7{\%} per year, with a 95{\%} confidence interval (C.I.) from +5{\%} to +9{\%} per year. Travel blank corrected data using the same approach show increasing NH3 concentrations of +9{\%} (95{\%} C.I. +5{\%} to +13{\%}) per year. During a comparable period (2008–2014) NADP precipitation chemistry sites in the same regions show significant increasing (p-value = 0.0001) precipitation NH4+ concentrations trends for all sites combined of +5{\%} (95{\%} C.I. +3{\%} to +7{\%}) per year. Emissions inventory data for the study period show nearly constant rates of NH3 emissions, but large reductions in NOx and SO2 emissions. Seasonal air quality data from the Clean Air Status and Trends Network (CASTNET) sites in these regions show significant declines in atmospheric particulate SO42− and NH4+, and particulate NO3− plus HNO3 (total NO3−) during the same period. Less formation of acidic SO4 and NO3, due to reduced SO2 and NOx emissions, provide less substrate to interact with NH3 and form particulate ammonium species. Thus, concentrations of NH3 can increase in the atmosphere even if emissions remain constant. A likely result may be more localized deposition of NH3, as opposed to the more long-range transport and deposition of ammonium nitrate (NH4NO3) and sulfate (NH4)2SO4). Additionally, the spatial distribution of wet and dry acidic deposition will be impacted.}, author = {Butler, T. and Vermeylen, F. and Lehmann, C. M. and Likens, G. E. and Puchalski, M.}, doi = {10.1016/j.atmosenv.2016.06.033}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Acid Rain 2015,Ammonia emissions,Ammonia monitoring,Ammonia trends,Atmospheric nitrogen,Reduced nitrogen}, pages = {132--140}, title = {{Increasing ammonia concentration trends in large regions of the USA derived from the NADP/AMoN network}}, volume = {146}, year = {2016} } @article{Butt2016, abstract = {Combustion of fuels in the residential sector for cooking and heating, results in the emission of aerosol and aerosol precursors impacting air quality, human health and climate. Residential emissions are dominated by the combustion of solid fuels. We use a global aerosol microphysics model to simulate the uncertainties in the impact of residential fuel combustion on atmospheric aerosol. The model underestimates black carbon (BC) and organic carbon (OC) mass concentrations observed over Asia, Eastern Europe and Africa, with better prediction when carbonaceous emissions from the residential sector are doubled. Observed seasonal variability of BC and OC concentrations are better simulated when residential emissions include a seasonal cycle. The largest contributions of residential emissions to annual surface mean particulate matter (PM2.5) concentrations are simulated for East Asia, South Asia and Eastern Europe. We use a concentration response function to estimate the health impact due to long-term exposure to ambient PM2.5 from residential emissions. We estimate global annual excess adult ({\textgreater} 30 years of age) premature mortality of 308 000 (113 300–497 000, 5th to 95th percentile uncertainty range) for monthly varying residential emissions and 517 000 (192 000–827 000) when residential carbonaceous emissions are doubled. Mortality due to residential emissions is greatest in Asia, with China and India accounting for 50 {\%} of simulated global excess mortality. Using an offline radiative transfer model we estimate that residential emissions exert a global annual mean direct radiative effect of between −66 and +21 mW m-2, with sensitivity to the residential emission flux and the assumed ratio of BC, OC and SO2 emissions. Residential emissions exert a global annual mean first aerosol indirect effect of between −52 and −16 mW m-2, which is sensitive to the assumed size distribution of carbonaceous emissions. Overall, our results demonstrate that reducing residential combustion emissions would have substantial benefits for human health through reductions in ambient PM2.5 concentrations.}, author = {Butt, E. W. and Rap, A. and Schmidt, A. and Scott, C. E. and Pringle, K. J. and Reddington, C. L. and Richards, N. A.D. and Woodhouse, M. T. and Ramirez-Villegas, J. and Yang, H. and Vakkari, V. and Stone, E. A. and Rupakheti, M. and Praveen, P. S. and {Van Zyl}, P. G. and Beukes, J. P. and Josipovic, M. and Mitchell, E. J.S. and Sallu, S. M. and Forster, P. M. and Spracklen, D. V.}, doi = {10.5194/acp-16-873-2016}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {2}, pages = {873--905}, title = {{The impact of residential combustion emissions on atmospheric aerosol, human health, and climate}}, volume = {16}, year = {2016} } @article{ISI:000398263200010, abstract = {The frequency of Beijing winter severe haze episodes has increased substantially over the past decades1–4 , and is com- monly attributed to increased pollutant emissions fromChina's rapid economic development5,6 . During such episodes, levels of fine particulate matter are harmful to human health and the environment, and cause massive disruption to economic activities3,4,7–16 , as occurred in January 201317–21 . Conducive weather conditions are an important ingredient of severe haze episodes3,21 , and include reduced surface winter northerlies3,21 , weakened northwesterlies in the midtroposphere, and en- hanced thermal stability of the lower atmosphere1,3,16,21 . How such weather conditions may respond to climate change is not clear. Here we project a 50{\%} increase in the frequency and an 80{\%} increase in the persistence of conducive weather conditions similar to those in January 2013, in response to climate change. The frequency and persistence between the historical (1950–1999) and future (2050–2099) climate were compared in 15 models under Representative Concentration Pathway 8.5 (RCP8.5)22 .The increased frequency is consistent with large-scale circulation changes, including an Arctic Oscillation upward trend23,24 , weakening East Asian winter monsoon25,26 , and fasterwarming in the lower troposphere27,28 . Thus, circulation changes induced by global greenhouse gas emissions can contribute to the increased Beijing severe haze frequency.}, author = {Cai, Wenju and Li, Ke and Liao, Hong and Wang, Huijun and Wu, Lixin}, doi = {10.1038/nclimate3249}, isbn = {1758-678X}, issn = {17586798}, journal = {Nature Climate Change}, number = {4}, pages = {257--262}, title = {{Weather conditions conducive to Beijing severe haze more frequent under climate change}}, volume = {7}, year = {2017} } @article{Caldeira2013, abstract = {Carbon dioxide emissions from the burning of coal, oil, and gas are increasing atmospheric carbon dioxide concentrations. These increased concentrations cause additional energy to be retained in Earth's climate system, thus increasing Earth's temperature. Various methods have been proposed to prevent this temperature increase either by reflecting to space sunlight that would otherwise warm Earth or by removing carbon dioxide from the atmosphere. Such intentional alteration of planetary-scale processes has been termed geoengineering. The first category of geoengineering method, solar geoengineering (also known as solar radiation management, or SRM), raises novel global-scale governance and environmental issues. Some SRM approaches are thought to be low in cost, so the scale of SRM deployment will likely depend primarily on considerations of risk. The second category of geoengineering method, carbon dioxide removal (CDR), raises issues related primarily to scale, cost, effectiveness, and local environmental consequences. The scale of CDR deployment will likely depend primarily on cost.}, author = {Caldeira, Ken and Bala, Govindasamy and Cao, Long}, doi = {10.1146/annurev-earth-042711-105548}, issn = {0084-6597}, journal = {Annual Review of Earth and Planetary Sciences}, month = {may}, number = {1}, pages = {231--256}, publisher = {Annual Reviews}, title = {{The Science of Geoengineering}}, volume = {41}, year = {2013} } @article{Callaghan2014, abstract = {Air-entraining breaking waves form oceanic whitecaps and play a key role in climate regulation through air-sea bubble-mediated gas transfer, and sea spray aerosol production. The effect of varying sea surface temperature on air entrainment, subsurface bubble plume dynamics, and surface foam evolution intrinsic to oceanic whitecaps has not been well studied. By using a breaking wave analog in the laboratory over a range of water temperatures (Tw?=?5C to Tw?=?30C) and different source waters, we have examined changes in air entrainment, subsurface bubble plumes, and surface foam evolution over the course of a breaking event. For filtered seawater, air entrainment was estimated to increase by 6{\%} between Tw?=?6C and Tw?=?30C, driven by increases of about 43{\%} in the measured surface roughness of the plunging water sheet. After active air entrainment, the rate of loss of air through bubble degassing was more rapid at colder water temperatures within the first 0.5 s of plume evolution. Thereafter, the trend reversed and bubbles degassed more quickly in warmer water. The largest observed temperature-dependent differences in subsurface bubble distributions occurred at radii greater than about 700 $\mu$m. Temperature-dependent trends observed in the subsurface bubble plume were mirrored in the temporal evolution of the surface whitecap foam area demonstrating the intrinsic link between surface whitecap foam and the subsurface bubble plume. Differences in foam and plume characteristics due to different water sources were greater than the temperature dependencies for the filtered seawater examined.}, author = {Callaghan, A. H. and Stokes, M. D. and Deane, G. B.}, doi = {10.1002/2014JC010351}, issn = {21699291}, journal = {Journal of Geophysical Research: Oceans}, keywords = {air entrainment,breaking waves,bubbles,foam,water temperature,whitecaps}, number = {11}, pages = {7463--7482}, title = {{The effect of water temperature on air entrainment, bubble plumes, and surface foam in a laboratory breaking-wave analog}}, volume = {119}, year = {2014} } @incollection{Carpenter2014, address = {Geneva, Switzerland}, author = {Carpenter, Lucy J. and Reimann, S. (Lead Authors) and Burkholder, J.B. and Clerbaux, C. and Hall, B.D. and Hossaini, R. and Laube, J.C. and Yvon-Lewis, S.A.}, booktitle = {Scientific Assessment of Ozone Depletion: 2014}, doi = {https://csl.noaa.gov/assessments/ozone/2014/report/}, isbn = {9789966076014}, pages = {1.1--1.101}, publisher = {World Meteorological Organization (WMO)}, series = {Global Ozone Research and Monitoring Project – Report No. 55}, title = {{Update on Ozone-Depleting Substances (ODSs) and Other Gases of Interest to the Montreal Protocol, Chapter 1}}, url = {https://csl.noaa.gov/assessments/ozone/2014/report/}, year = {2014} } @article{acp-10-1701-2010, abstract = {The natural environment is a major source of atmospheric aerosols, including dust, secondary organic material from terrestrial biogenic emissions, carbonaceous particles from wildfires, and sulphate from marine phytoplankton dimethyl sulphide emissions. These aerosols also have a significant effect on many components of the Earth system such as the atmospheric radiative balance and photosynthetically available radiation entering the biosphere, the supply of nutrients to the ocean, and the albedo of snow and ice. The physical and biological systems that produce these aerosols can be highly susceptible to modification due to climate change so there is the potential for important climate feedbacks. We review the impact of these natural systems on atmospheric aerosol based on observations and models, including the potential for long term changes in emissions and the feedbacks on climate. The number of drivers of change is very large and the various systems are strongly coupled. There have therefore been very few studies that integrate the various effects to estimate climate feedback factors. Nevertheless, available observations and model studies suggest that the regional radiative perturbations are potentially several Watts per square metre due to changes in these natural aerosol emissions in a future climate. Taking into account only the direct radiative effect of changes in the atmospheric burden of natural aerosols, and neglecting potentially large effects on other parts of the Earth system, a global mean radiative perturbation approaching 1 W m-2 is possible by the end of the century. The level of scientific understanding of the climate drivers, interactions and impacts is very low.}, author = {Carslaw, K. S. and Boucher, O. and Spracklen, D. V. and Mann, G. W. and {L. Rae}, J. G. and Woodward, S. and Kulmala, M.}, doi = {10.5194/acp-10-1701-2010}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {feb}, number = {4}, pages = {1701--1737}, title = {{A review of natural aerosol interactions and feedbacks within the Earth system}}, url = {https://www.atmos-chem-phys.net/10/1701/2010/}, volume = {10}, year = {2010} } @article{Cecil2014a, abstract = {Gridded climatologies of total lightning flash rates observed by the spaceborne Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) instruments have been updated. OTD collected data from May 1995 to March 2000. LIS data (equatorward of about 38°) adds the years 1998-2010. Flash counts from each instrument are scaled by the best available estimates of detection efficiency. The long LIS record makes the merged climatology most robust in the tropics and subtropics, while the high latitude data is entirely from OTD. The gridded climatologies include annual mean flash rate on a 0.5° grid, mean diurnal cycle of flash rate on a 2.5° grid with 24. hour resolution, mean annual cycle of flash rate on a 0.5° or 2.5° grid with daily, monthly, or seasonal resolution, mean annual cycle of the diurnal cycle on a 2.5° grid with two hour resolution for each day, and time series of flash rate over the sixteen year record with roughly three-month smoothing. For some of these (e.g., annual cycle of the diurnal cycle), more smoothing is necessary for results to be robust.The mean global flash rate from the merged climatology is 46flashess-1. This varies from around 35flashess-1 in February (austral summer) to 60flashess-1 in August (boreal summer). The peak annual flash rate at 0.5° scale is 160flkm-2yr-1 in eastern Congo. The peak monthly average flash rate at 2.5° scale is 18flkm-2mo-1 from early April to early May in the Brahmaputra Valley of far eastern India. Lightning decreases in this region during the monsoon season, but increases further north and west. An August peak in northern Pakistan also exceeds any monthly averages from Africa, despite central Africa having the greatest yearly average. {\textcopyright} 2012 Elsevier B.V.}, author = {Cecil, Daniel J. and Buechler, Dennis E. and Blakeslee, Richard J.}, doi = {10.1016/j.atmosres.2012.06.028}, isbn = {0169-8095}, issn = {01698095}, journal = {Atmospheric Research}, keywords = {Atmospheric electricity,Lightning,TRMM,Thunderstorm}, pages = {404--414}, title = {{Gridded lightning climatology from TRMM-LIS and OTD: Dataset description}}, volume = {135-136}, year = {2014} } @article{CELIS2004541, abstract = {Inhalable particulate matter (PM10) concentrations were measured over 24-h intervals at six different urban sites in the city of Chill{\'{a}}n from September 2001 to April 2003. Sampling locations were selected to represent central city, commercial, residential, and industrial portions of the city. Chemical composition of PM10 was performed to samples of 47 mm diameter Teflon membranes within the city of Chill{\'{a}}n. The spatial and temporal variability of the chemical composition of PM10 was evaluated taking into account additional data from meteorology and further air pollutants. The majority of PM mass was comprised of carbon, nitrate, sulfate, ammonium, and crustal components but in different proportion on different days and at different sites. The chemical analyses showed that carbonaceous substances and crustal material were the most abundant component of PM10 during the winter and summer, respectively. The concentrations of PM10 were higher during the cold season than during the warm season. The PM10 concentrations were higher in the downtown area of the city of Chill{\'{a}}n, where also the chemical composition was more variable due to urban traffic and other anthropogenic sources.}, author = {Celis, Jos{\'{e}} E and Morales, Jos{\'{e}} R and Zaror, Claudio A and Inzunza, Juan C}, doi = {https://doi.org/10.1016/S0045-6535(03)00711-2}, issn = {0045-6535}, journal = {Chemosphere}, keywords = {Aerosols,Air contamination,Air pollution,Particulate matter,Urban atmosphere}, number = {4}, pages = {541--550}, title = {{A study of the particulate matter PM10 composition in the atmosphere of Chill{\'{a}}n, Chile}}, url = {http://www.sciencedirect.com/science/article/pii/S0045653503007112}, volume = {54}, year = {2004} } @article{Chambliss2014, abstract = {Exposure to ambient fine particular matter (PM2.5) was responsible for 3.2 million premature deaths in 2010 and is among the top ten leading risk factors for early death. Surface transportation is a significant global source of PM2.5emissions and a target for new actions. The objective of this study is to estimate the global and national health burden of ambient PM2.5exposure attributable to surface transportation emissions. This share of health burden is called the transportation attributable fraction (TAF), and is assumed equal to the proportional decrease in modeled ambient particulate matter concentrations when surface transportation emissions are removed. National population-weighted TAFs for 190 countries are modeled for 2005 using the MOZART-4 global chemical transport model. Changes in annual average concentration of PM2.5at 0.5 x 0.67 degree horizontal resolution are based on a global emissions inventory and removal of all surface transportation emissions. Global population-weighted average TAF was 8.5 percent or 1.75 $\mu$g m-3in 2005. Approximately 242 000 annual premature deaths were attributable to surface transportation emissions, dominated by China, the United States, the European Union and India. This application of TAF allows future Global Burden of Disease studies to estimate the sector-specific burden of ambient PM2.5exposure. Additional research is needed to capture intraurban variations in emissions and exposure, and to broaden the range of health effects considered, including the effects of other pollutants.}, author = {Chambliss, S. E. and Silva, R. and West, J. J. and Zeinali, M. and Minjares, R.}, doi = {10.1088/1748-9326/9/10/104009}, issn = {17489326}, journal = {Environmental Research Letters}, keywords = {chemical transport model,fine particulate matter,health impacts,transportation}, month = {oct}, number = {10}, pages = {104009}, title = {{Estimating source-attributable health impacts of ambient fine particulate matter exposure: Global premature mortality from surface transportation emissions in 2005}}, url = {http://stacks.iop.org/1748-9326/9/i=10/a=104009?key=crossref.b9d04e840c23709690602b0413291ef8}, volume = {9}, year = {2014} } @article{ISI:000424391800001, abstract = {Background: Significant mitigation efforts beyond the Nationally Determined Commitments (NDCs) coming out of the 2015 Paris Climate Agreement are required to avoid warming of 2 °C above pre-industrial temperatures. Health co-benefits represent selected near term, positive consequences of climate policies that can offset mitigation costs in the short term before the beneficial impacts of those policies on the magnitude of climate change are evident. The diversity of approaches to modeling mitigation options and their health effects inhibits meta-analyses and syntheses of results useful in policy-making. Methods/Design: We evaluated the range of methods and choices in modeling health co-benefits of climate mitigation to identify opportunities for increased consistency and collaboration that could better inform policy-making. We reviewed studies quantifying the health co-benefits of climate change mitigation related to air quality, transportation, and diet published since the 2009 Lancet Commission ‘Managing the health effects of climate change' through January 2017. We documented approaches, methods, scenarios, health-related exposures, and health outcomes. Results/Synthesis: Forty-two studies met the inclusion criteria. Air quality, transportation, and diet scenarios ranged from specific policy proposals to hypothetical scenarios, and from global recommendations to stakeholder-informed local guidance. Geographic and temporal scope as well as validity of scenarios determined policy relevance. More recent studies tended to use more sophisticated methods to address complexity in the relevant policy system. Discussion: Most studies indicated significant, nearer term, local ancillary health benefits providing impetus for policy uptake and net cost savings. However, studies were more suited to describing the interaction of climate policy and health and the magnitude of potential outcomes than to providing specific accurate estimates of health co-benefits. Modeling the health co-benefits of climate policy provides policy-relevant information when the scenarios are reasonable, relevant, and thorough, and the model adequately addresses complexity. Greater consistency in selected modeling choices across the health co-benefits of climate mitigation research would facilitate evaluation of mitigation options particularly as they apply to the NDCs and promote policy uptake.}, author = {Chang, Kelly M. and Hess, Jeremy J. and Balbus, John M. and Buonocore, Jonathan J. and Cleveland, David A. and Grabow, Maggie L. and Neff, Roni and Saari, Rebecca K. and Tessum, Christopher W. and Wilkinson, Paul and Woodward, Alistair and Ebi, Kristie L.}, doi = {10.1088/1748-9326/aa8f7b}, isbn = {1748-9326}, issn = {17489326}, journal = {Environmental Research Letters}, keywords = {air quality,climate mitigation,diet,greenhouse gases,health co-benefits,modeling,transportation}, month = {nov}, number = {11}, pages = {113001}, title = {{Ancillary health effects of climate mitigation scenarios as drivers of policy uptake: A review of air quality, transportation and diet co-benefits modeling studies}}, volume = {12}, year = {2017} } @article{Chen2016, abstract = {Extreme haze events have occurred frequently over China in recent years. Although many studies have investigated the formation mechanisms associated with PM2.5 for heavily polluted regions in China based on observational data, adequately predicting peak PM2.5 concentrations is still challenging for regional air quality models. In this study, we evaluate the performance of one configuration of the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) and use the model to investigate the sensitivity of heterogeneous reactions on simulated peak sulfate, nitrate, and ammonium concentrations in the vicinity of Beijing during four extreme haze episodes in October 2014 over the North China Plain. The highest observed PM2.5 concentration of 469$\mu$g m-3 occurred in Beijing. Comparisons with observations show that the model reproduced the temporal variability in PM2.5 with the highest PM2.5 values on polluted days (defined as days in which observed PM2.5 is greater than 75$\mu$g m-3), but predictions of sulfate, nitrate, and ammonium were too low on days with the highest observed concentrations. Observational data indicate that the sulfur/nitric oxidation rates are strongly correlated with relative humidity during periods of peak PM2.5; however, the model failed to reproduce the highest PM2.5 concentrations due to missing heterogeneous/aqueous reactions. As the parameterizations of those heterogeneous reactions are not well established yet, estimates of SO2-to-H2SO4 and NO2/NO3-to-HNO3 reaction rates that depend on relative humidity were applied, which improved the simulation of sulfate, nitrate, and ammonium enhancement on polluted days in terms of both concentrations and partitioning among those species. Sensitivity simulations showed that the extremely high heterogeneous reaction rates and also higher emission rates than those reported in the emission inventory were likely important factors contributing to those peak PM2.5 concentrations.}, author = {Chen, Dan and Liu, Zhiquan and Fast, Jerome and Ban, Junmei}, doi = {10.5194/acp-16-10707-2016}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {aug}, number = {16}, pages = {10707--10724}, publisher = {Copernicus {\{}GmbH{\}}}, title = {{Simulations of sulfate-nitrate-ammonium (SNA) aerosols during the extreme haze events over northern China in October 2014}}, volume = {16}, year = {2016} } @article{Chen2018b, abstract = {Patrick Kinney and colleagues model seasonal and annual future ozone-associated mortality in 104 Chinese cities with different population sizes}, author = {Chen, Kai and Fiore, Arlene M and Chen, Renjie and Jiang, Leiwen and Jones, Bryan and Schneider, Alexandra and Peters, Annette and Bi, Jun and Kan, Haidong and Kinney, Patrick L}, doi = {10.1371/journal.pmed.1002598}, journal = {PLOS Medicine}, month = {jul}, number = {7}, pages = {e1002598}, publisher = {Public Library of Science}, title = {{Future ozone-related acute excess mortality under climate and population change scenarios in China: A modeling study}}, url = {https://doi.org/10.1371/journal.pmed.1002598}, volume = {15}, year = {2018} } @article{Chen2017b, abstract = {Many studies have focused on the physicochemical properties of aerosol particles in unusually severe haze episodes in North China instead of the more frequent and less severe hazes. Consistent with this lack of attention, the morphology and mixing state of organic matter (OM) particles in the frequent light and moderate (L {\&} M) hazes in winter in the North China Plain (NCP) have not been examined, even though OM dominates these fine particles. In the present work, morphology, mixing state, and size of organic aerosols in the L {\&} M hazes were systematically characterized using transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy, atomic force microscopy, and nanoscale secondary ion mass spectrometer, with the comparisons among an urban site (Jinan, S1), a mountain site (Mt. Tai, S2), and a background island site (Changdao, S3) in the same hazes. Based on their morphologies, the OM particles were divided into six different types: spherical (type 1), near-spherical (type 2), irregular (type 3), domelike (type 4), dispersed-OM (type 5), and OM-coating (type 6). In the three sampling sites, types 1{\&}ndash;3 of OM particles were most abundant in the L {\&} M hazes and most of them were internally mixed with non-OM particles. The abundant near-spherical OM particles with higher sphericity and lower aspect ratio indicate that these primary OM particles formed in the cooling process after polluted plumes were emitted from coal combustion and biomass burning. Based on the Si-O-C ratio in OM particles, we estimated that 71 {\%} of type 1{\&}ndash;3 OM particles were associated with coal combustion. Our result suggests that coal combustion in residential stoves was a widespread source from urban to rural areas in NCP. Average OM thickness which correlates with the age of the air masses in type 6 particles only slightly increased from S1 to S2 to S3, suggesting that the L {\&} M hazes were usually dry (relative humidity {\textless} 60 {\%}) with weak photochemistry and heterogeneous reactions between particles and gases. We conclude that the direct emissions from these coal stoves without any pollution controls in rural areas and in urban outskirts contribute large amounts of primary OM particles to the regional L {\&} M hazes in North China.}, author = {Chen, Shurui and Xu, Liang and Zhang, Yinxiao and Chen, Bing and Wang, Xinfeng and Zhang, Xiaoye and Zheng, Mei and Chen, Jianmin and Wang, Wenxing and Sun, Yele and Fu, Pingqing and Wang, Zifa and Li, Weijun}, doi = {10.5194/acp-17-1259-2017}, isbn = {17/1259/2017}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {2}, pages = {1259--1270}, title = {{Direct observations of organic aerosols in common wintertime hazes in North China: Insights into direct emissions from Chinese residential stoves}}, url = {www.atmos-chem-phys.net/17/1259/2017/}, volume = {17}, year = {2017} } @article{cheng2016sa_a, abstract = {Fine-particle pollution associated with winter haze threatens the health of more than 400 million people in the North China Plain. Sulfate is a major component of fine haze particles. Record sulfate concentrations of up to {\~{}}300 $\mu$g m −3 were observed during the January 2013 winter haze event in Beijing. State-of-the-art air quality models that rely on sulfate production mechanisms requiring photochemical oxidants cannot predict these high levels because of the weak photochemistry activity during haze events. We find that the missing source of sulfate and particulate matter can be explained by reactive nitrogen chemistry in aerosol water. The aerosol water serves as a reactor, where the alkaline aerosol components trap SO 2 , which is oxidized by NO 2 to form sulfate, whereby high reaction rates are sustained by the high neutralizing capacity of the atmosphere in northern China. This mechanism is self-amplifying because higher aerosol mass concentration corresponds to higher aerosol water content, leading to faster sulfate production and more severe haze pollution.}, author = {Cheng, Yafang and Zheng, Guangjie and Wei, Chao and Mu, Qing and Zheng, Bo and Wang, Zhibin and Gao, Meng and Zhang, Qiang and He, Kebin and Carmichael, Gregory and P{\"{o}}schl, Ulrich and Su, Hang}, doi = {10.1126/sciadv.1601530}, issn = {2375-2548}, journal = {Science Advances}, month = {dec}, number = {12}, pages = {e1601530}, publisher = {American Association for the Advancement of Science ({\{}AAAS{\}})}, title = {{Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China}}, url = {https://doi.org/10.1126/sciadv.1601530 https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.1601530}, volume = {2}, year = {2016} } @article{Cherian2020b, abstract = {Abstract Several regions worldwide have seen significant trends in anthropogenic aerosol emissions during the period of detailed satellite observations since 2001. Over Europe (EUR) and North America (NAM) there were strong declines, over China increases then declines and over India, strong increases. Regional trends in model-simulated aerosol optical depth (AOD) and cloud radiative effects in both the Fifth and Sixth Coupled Model Intercomparison Projects (CMIP5 and CMIP6) are broadly consistent with the ones from satellite retrievals in most parts of EUR, NAM and India. CMIP6 models better match satellite-derived AOD trend in western NAM (increasing) and eastern China (decreasing), where CMIP5 models failed, pointing to improved anthropogenic aerosol emissions. Drop concentration trends in both observations and models qualitatively match AOD trends. The result for solar cloud radiative effect in models, however, is due to compensating errors: Models fail to reproduce observed liquid water path trends and show, in turn, opposite trends in cloud fraction.}, annote = {From Duplicate 3 (Trends in AOD, Clouds, and Cloud Radiative Effects in Satellite Data and CMIP5 and CMIP6 Model Simulations Over Aerosol Source Regions - Cherian, Ribu; Quaas, Johannes) https://doi.org/10.1029/2020GL087132}, author = {Cherian, Ribu and Quaas, Johannes}, doi = {https://doi.org/10.1029/2020GL087132}, issn = {0094-8276}, journal = {Geophysical Research Letters}, keywords = {CDNC,aerosol emission trend,aerosol optical depth,aerosol source regions,climate models,cloud radiative effects}, month = {may}, number = {9}, pages = {e2020GL087132}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Trends in AOD, Clouds, and Cloud Radiative Effects in Satellite Data and CMIP5 and CMIP6 Model Simulations Over Aerosol Source Regions}}, url = {https://doi.org/10.1029/2020GL087132}, volume = {47}, year = {2020} } @article{Chevallier2020, abstract = {We use a global transport model and satellite retrievals of the carbon dioxide (CO2) column average to explore the impact of CO2 emissions reductions that occurred during the economic downturn at the start of the Covid-19 pandemic. The changes in the column averages are substantial in a few places of the model global grid, but the induced gradients are most often less than the random errors of the retrievals. The current necessity to restrict the quality-assured column retrievals to almost cloud-free areas appears to be a major obstacle in identifying changes in CO2 emissions. Indeed, large changes have occurred in the presence of clouds, and in places that were cloud free in 2020, the comparison with previous years is hampered by different cloud conditions during these years. We therefore recommend to favor all-weather CO2 monitoring systems, at least in situ, to support international efforts to reduce emissions.}, author = {Chevallier, Fr{\'{e}}d{\'{e}}ric and Zheng, Bo and Broquet, Gr{\'{e}}goire and Ciais, Philippe and Liu, Zhu and Davis, Steven J. and Deng, Zhu and Wang, Yilong and Br{\'{e}}on, Fran{\c{c}}ois Marie and O'Dell, Christopher W.}, doi = {10.1029/2020GL090244}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {OCO-2,Paris Agreement,carbon dioxide,emissions,plume,satellite}, number = {22}, pages = {e2020GL090244}, title = {{Local Anomalies in the Column-Averaged Dry Air Mole Fractions of Carbon Dioxide Across the Globe During the First Months of the Coronavirus Recession}}, volume = {47}, year = {2020} } @article{Cho2013, abstract = {Measurements of daily PM2.5 were carried out during winter between January 11 and February 27, 2010 in an urban area of Korea, in order to better understand the influence of sources and atmospheric processing of organic aerosols. The aerosol samples were analyzed for organic carbon and elemental carbon (OC and EC), water-soluble OC (WSOC), eight ionic species, and oxalate. The water-soluble fraction of OC was between 33 and 58{\%} with an average of 45{\%}. Strong correlations among WSOC, sulfate (SO42−) (R2 = 0.69), and oxalate (R2 = 0.82) concentrations, and between potassium (K+) and WSOC concentrations (R2 = 0.81) suggest that the observed WSOC could originate from similar oxidation processes to those for SO42− and oxalate, as well as biomass burning. Also moderate correlations of the WSOC with EC and carbon monoxide (CO) indicate that there was some contribution to WSOC from primary fossil fuel combustion. Results from a principle component analysis (PCA) indicate that in addition to the biomass burning and primary non-biomass burning emissions, the observed WSOC could be formed through production pathways similar to secondary organic carbon (SOC), SO42−, and oxalate. Sources of WSOC inferred, based on the correlations, were confirmed by source categories identified by the PCA. Over the study period, three haze episodes exceeding a 24 h PM2.5 concentration of 50 $\mu$g m−3 were identified. Of the major components in PM2.5, EC concentrations were elevated during episode I (18–19 January), while the secondary SO42− concentrations were enhanced during episodes II (30–31 January) and III (22–23 February). However, little difference in OC concentrations among the episodes was observed. It is suggested that the aerosol particles collected during episodes II and III were more aged than those during episode I. Estimates of fossil fuel combustion, biomass burning, and SOC contributions to WSOC indicate that the fossil fuel combustion provided the highest contribution (62.3{\%}) to WSOC in episode I, while the greatest contribution (60.6{\%}) to WSOC from SOC was observed in episode II. The results demonstrate that the sampled aerosol particles were more aged or further processed during episodes II and III than during episode I}, author = {Cho, Sung Yong and Park, Seung Shik}, doi = {10.1039/C2EM30730H}, journal = {Environmental Science: Processes {\&} Impacts}, pages = {524--534}, title = {{Resolving sources of water-soluble organic carbon in fine particulate matter measured at an urban site during winter}}, url = {https://pubs.rsc.org/en/content/articlehtml/2013/em/c2em30730h}, volume = {15}, year = {2013} } @article{Cholakian2018, author = {Cholakian, Arineh and Colette, Augustin and Coll, Isabelle and Ciarelli, Giancarlo and Beekmann, Matthias}, doi = {10.5194/acp-19-4459-2019}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {apr}, number = {7}, pages = {4459--4484}, title = {{Future climatic drivers and their effect on PM10 components in Europe and the Mediterranean Sea}}, url = {https://acp.copernicus.org/articles/19/4459/2019/}, volume = {19}, year = {2019} } @article{Chossiere2018, abstract = {In 2015, diesel cars accounted for 41.3{\%} of the total passenger car fleet in Europe. While harmonized emissions limits are implemented at the EU level, on-road emissions of diesel cars have been found to be up to 16 times higher than those measured in test stands. These excess emissions have been estimated to result in increased PM2.5 and ozone exposure causing approximately 5000 premature mortalities per year in Europe. Interventions aimed at mitigating these damages need to take into account the physical and political boundaries in Europe, where emissions from one country may have an impact on neighboring populaces (trans-boundary impacts). To date, the trans-boundary implications of excess NOx emissions in Europe are not understood and only excess NOx emissions have only been studied at the fleet level and for Volkswagen group cars. In this study, a distribution of emission factors is derived from existing on-road measurements for 10 manufacturers, covering 90{\%} of all new vehicle registrations in Europe from 2000 to 2015. These distributions are combined with inventory data and driving behavior to quantify excess emissions of nitrogen oxides (NOx) in Europe in 2015. To quantify the changes in PM2.5 and ozone concentrations resulting from these emissions, we use a state-of-the-art chemical transport model (GEOS-Chem). Concentration-response functions from the epidemiological literature are applied to estimate the premature mortality outcomes and the number of life-years lost associated with degraded air quality. Uncertainty in the input parameters is propagated through the analysis using a Monte Carlo approach. We find that 70{\%} of the total health impacts from excess NOx are due to trans-boundary emissions. For example, 61{\%} of the impacts in Germany of total excess NOx emissions are caused by emissions released in other countries. These results highlight the need for a coordinated policy response at the European level. In addition, we find that total emissions accounting for country-specific fleet mixes and driving behaviors vary between manufacturers by a factor of 10 and mortality impacts per kilometer driven by a factor of 8. Finally, we find that if all manufacturers reduced emissions of the vehicles currently on the road to those of the best-performing manufacturer in the corresponding Euro standard, approximately 1900 premature deaths per year could be avoided.}, author = {Chossi{\`{e}}re, Guillaume P and Malina, Robert and Allroggen, Florian and Eastham, Sebastian D and Speth, Raymond L and Barrett, Steven R H}, doi = {https://doi.org/10.1016/j.atmosenv.2018.06.047}, issn = {1352-2310}, journal = {Atmospheric Environment}, pages = {89--97}, title = {{Country- and manufacturer-level attribution of air quality impacts due to excess NOx emissions from diesel passenger vehicles in Europe}}, volume = {189}, year = {2018} } @article{Christensen2019, abstract = {Natural methane emissions are noticeably influenced by warming of cold arctic ecosystems and permafrost. An evaluation specifically of Arctic natural methane emissions in relation to our ability to mitigate anthropogenic methane emissions is needed. Here we use empirical scenarios of increases in natural emissions together with maximum technically feasible reductions in anthropogenic emissions to evaluate their potential influence on future atmospheric methane concentrations and associated radiative forcing (RF). The largest amplification of natural emissions yields up to 42{\%} higher atmospheric methane concentrations by the year 2100 compared with no change in natural emissions. The most likely scenarios are lower than this, while anthropogenic emission reductions may have a much greater yielding effect, with the potential of halving atmospheric methane concentrations by 2100 compared to when anthropogenic emissions continue to increase as in a business-as-usual case. In a broader perspective, it is shown that man-made emissions can be reduced sufficiently to limit methane-caused climate warming by 2100 even in the case of an uncontrolled natural Arctic methane emission feedback, but this requires a committed, global effort towards maximum feasible reductions.}, author = {Christensen, Torben R{\o}jle and Arora, Vivek K. and Gauss, Michael and H{\"{o}}glund-Isaksson, Lena and Parmentier, Frans Jan W.}, doi = {10.1038/s41598-018-37719-9}, issn = {20452322}, journal = {Scientific Reports}, number = {1}, pages = {1146}, title = {{Tracing the climate signal: mitigation of anthropogenic methane emissions can outweigh a large Arctic natural emission increase}}, url = {https://doi.org/10.1038/s41598-018-37719-9}, volume = {9}, year = {2019} } @article{Chrysanthou2019, author = {Chrysanthou, Andreas and Maycock, Amanda C and Chipperfield, Martyn P and Dhomse, Sandip and Garny, Hella and Kinnison, Douglas and Akiyoshi, Hideharu and Deushi, Makoto and Garcia, Rolando R and J{\"{o}}ckel, Patrick and Kirner, Oliver and Pitari, Giovanni and Plummer, David A and Revell, Laura and Rozanov, Eugene and Stenke, Andrea and Tanaka, Taichu Y and Visioni, Daniele and Yamashita, Yousuke}, doi = {10.5194/acp-19-11559-2019}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {sep}, number = {17}, pages = {11559--11586}, publisher = {Copernicus Publications}, title = {{The effect of atmospheric nudging on the stratospheric residual circulation in chemistry–climate models}}, url = {https://acp.copernicus.org/articles/19/11559/2019/ https://acp.copernicus.org/articles/19/11559/2019/acp-19-11559-2019.pdf}, volume = {19}, year = {2019} } @article{Chuvieco2019, abstract = {Fire has a diverse range of impacts on Earth's physical and social systems. Accurate and up to date information on areas affected by fire is critical to better understand drivers of fire activity, as well as its relevance for biogeochemical cycles, climate, air quality, and to aid fire management. Mapping burned areas was traditionally done from field sketches. With the launch of the first Earth observation satellites, remote sensing quickly became a more practical alternative to detect burned areas, as they provide timely regional and global coverage of fire occurrence. This review paper explores the physical basis to detect burned area from satellite observations, describes the historical trends of using satellite sensors to monitor burned areas, summarizes the most recent approaches to map burned areas and evaluates the existing burned area products (both at global and regional scales). Finally, it identifies potential future opportunities to further improve burned area detection from Earth observation satellites.}, author = {Chuvieco, Emilio and Mouillot, Florent and van der Werf, Guido R. and {San Miguel}, Jes{\'{u}}s and Tanasse, Mihai and Koutsias, Nikos and Garc{\'{i}}a, Mariano and Yebra, Marta and Padilla, Marc and Gitas, Ioannis and Heil, Angelika and Hawbaker, Todd J. and Giglio, Louis}, doi = {10.1016/j.rse.2019.02.013}, issn = {00344257}, journal = {Remote Sensing of Environment}, keywords = {Burned area,Climate change,Fire,Fire impacts,Lidar,Radar}, month = {may}, number = {November 2018}, pages = {45--64}, publisher = {Elsevier}, title = {{Historical background and current developments for mapping burned area from satellite Earth observation}}, url = {https://doi.org/10.1016/j.rse.2019.02.013 https://linkinghub.elsevier.com/retrieve/pii/S0034425719300689}, volume = {225}, year = {2019} } @article{Chuvieco2016, abstract = {Abstract Aim This paper presents a new global burned area (BA) product developed within the framework of the European Space Agency's Climate Change Initiative (CCI) programme, along with a first assessment of its potentials for atmospheric and carbon cycle modelling. Innovation Methods are presented for generating a new global BA product, along with a comparison with existing BA products, in terms of BA extension, fire size and shapes and emissions derived from biomass burnings. Main conclusions Three years of the global BA product were produced, accounting for a total BA of between 360 and 380 Mha year?1. General omission and commission errors for BA were 0.76 and 0.64, but they decreased to 0.51 and 0.52, respectively, for sites with more than 10{\%} BA. Intercomparison with other existing BA datasets found similar spatial and temporal trends, mainly with the BA included in the Global Fire Emissions Database (GFED4), although regional differences were found (particularly in the 2006 fires of eastern Europe). The simulated carbon emissions from biomass burning averaged 2.1 Pg C year?1.}, annote = {https://doi.org/10.1111/geb.12440}, author = {Chuvieco, Emilio and Yue, Chao and Heil, Angelika and Mouillot, Florent and Alonso-Canas, Itziar and Padilla, Marc and Pereira, Jose Miguel and Oom, Duarte and Tansey, Kevin}, doi = {https://doi.org/10.1111/geb.12440}, issn = {1466-822X}, journal = {Global Ecology and Biogeography}, keywords = {Fire disturbance,MERIS,atmospheric emissions,burned area,essential climate variables,remote sensing,satellite earth observation,wildland fires}, month = {may}, number = {5}, pages = {619--629}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{A new global burned area product for climate assessment of fire impacts}}, url = {https://doi.org/10.1111/geb.12440}, volume = {25}, year = {2016} } @article{Chuwah2013, abstract = {The uncertain, future development of emissions of short-lived trace gases and aerosols forms a key factor for future air quality and climate forcing. The Representative Concentration Pathways (RCPs) only explore part of this range as they all assume that worldwide ambitious air pollution control policies will be implemented. In this study, we explore how different assumptions on future air pollution policy and climate policy lead to different concentrations of air pollutants for a set of RCP-like scenarios developed using the IMAGE model. These scenarios combine low and high air pollution variants of the scenarios with radiative forcing targets in 2100 of 2.6 W m−2 and 6.0 W m−2. Simulations using the global atmospheric chemistry and transport model TM5 for the present-day climate show that both climate mitigation and air pollution control policies have large-scale effects on pollutant concentrations, often of similar magnitude. If no further air pollution policies would be implemented, pollution levels could be considerably higher than in the RCPs, especially in Asia. Air pollution control measures could significantly reduce the warming by tropospheric ozone and black carbon and the cooling by sulphate by 2020, and in the longer term contribute to enhanced warming by methane. These effects tend to cancel each other on a global scale. According to our estimates the effect of the worldwide implementation of air pollution control measures on the total global mean direct radiative forcing in 2050 is +0.09 W m−2 in the 6.0 W m−2 scenario and −0.16 W m−2 in the 2.6 W m−2 scenario.}, author = {Chuwah, Clifford and van Noije, Twan and van Vuuren, Detlef P and Hazeleger, Wilco and Strunk, Achim and Deetman, Sebastiaan and Beltran, Angelica Mendoza and van Vliet, Jasper}, doi = {https://doi.org/10.1016/j.atmosenv.2013.07.008}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Air pollution control,Climate change mitigation,Emission scenarios,Radiative forcing,Representative Concentration Pathways}, pages = {787--801}, title = {{Implications of alternative assumptions regarding future air pollution control in scenarios similar to the Representative Concentration Pathways}}, url = {https://www.sciencedirect.com/science/article/pii/S1352231013005293}, volume = {79}, year = {2013} } @incollection{Ciais2013a, address = {Cambridge, United Kingdom and New York, NY, USA}, author = {Ciais, P and Sabine, C and Bala, G and Bopp, L and Brovkin, V and Canadell, J and Chhabra, A and DeFries, R and Galloway, J and Heimann, M and Jones, C and {Le Quéré}, C and Myneni, R B and Piao, S and Thornton, P}, booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change}, chapter = {6}, doi = {10.1017/CBO9781107415324.015}, editor = {Stocker, T F and Qin, D and Plattner, G.-K. and Tignor, M and Allen, S K and Boschung, J and Nauels, A and Xia, Y and Bex, V and Midgley, P M}, isbn = {9781107661820}, pages = {465--570}, publisher = {Cambridge University Press}, title = {{Carbon and Other Biogeochemical Cycles}}, url = {https://www.ipcc.ch/report/ar5/wg1}, year = {2013} } @article{Cirino2014, abstract = {Abstract. Carbon cycling in the Amazon is closely linked to atmospheric processes and climate in the region as a consequence of the strong coupling between the atmosphere and biosphere. This work examines the effects of changes in net radiation due to atmospheric aerosol particles and clouds on the net ecosystem exchange (NEE) of CO2 in the Amazon region. Some of the major environmental factors affecting the photosynthetic activity of plants, such as air temperature and relative humidity, were also examined. An algorithm for clear-sky irradiance was developed and used to determine the relative irradiance, f, which quantifies the percentage of solar radiation absorbed and scattered due to atmospheric aerosol particles and clouds. Aerosol optical depth (AOD) was calculated from irradiances measured with the MODIS (Moderate Resolution Imaging Spectroradiometer) sensor, onboard the Terra and Aqua satellites, and was validated with ground-based AOD measurements from AERONET (Aerosol Robotic Network) sun photometers. Carbon fluxes were measured using eddy covariance technique at the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) flux towers. Two sites were studied: the Jaru Biological Reserve (RBJ), located in Rondonia, and the Cuieiras Biological Reserve at the K34 LBA tower (located in a preserved region in the central Amazon). Analysis was performed continuously from 1999 to 2009 at K34 and from 1999 to 2002 at RBJ, and includes wet, dry and transition seasons. In the Jaru Biological Reserve, a 29{\%} increase in carbon uptake (NEE) was observed when the AOD ranged from 0.10 to 1.5 at 550 nm. In the Cuieiras Biological Reserve, the aerosol effect on NEE was smaller, accounting for an approximate 20{\%} increase in NEE. High aerosol loading (AOD above 3 at 550 nm) or high cloud cover leads to reductions in solar flux and strong decreases in photosynthesis up to the point where NEE approaches zero. The observed increase in NEE is attributed to an enhancement ({\~{}}50{\%}) in the diffuse fraction of photosynthetic active radiation (PAR). The enhancement in diffuse PAR can be done through increases in aerosols and/or clouds. In the present study, it was not possible to separate these two components. Significant changes in air temperature and relative humidity resulting from changes in solar radiation fluxes under high aerosol loading were also observed at both sites. Considering the long-range transport of aerosols in the Amazon, the observed changes in NEE for these two sites may occur over large areas in the Amazon, significantly altering the carbon balance in the largest rainforest in the world.}, author = {Cirino, G. G. and Souza, R. A. F. and Adams, D. K. and Artaxo, P.}, doi = {10.5194/acp-14-6523-2014}, isbn = {16807316 (ISSN)}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jul}, number = {13}, pages = {6523--6543}, title = {{The effect of atmospheric aerosol particles and clouds on net ecosystem exchange in the Amazon}}, url = {http://www.atmos-chem-phys.net/14/6523/2014/ http://www.atmos-chem-phys-discuss.net/13/28819/2013/ https://www.atmos-chem-phys.net/14/6523/2014/}, volume = {14}, year = {2014} } @article{Clarisse2009, abstract = {Global ammonia emissions have more than doubled since pre-industrial times, largely owing to agricultural intensification and widespread fertilizer use1. In the atmosphere, ammonia accelerates particulate matter formation, thereby reducing air quality. When deposited in nitrogen-limited ecosystems, ammonia can act as a fertilizer. This can lead to biodiversity reductions in terrestrial ecosystems, and algal blooms in aqueous environments2-8. Despite its ecological significance, there are large uncertainties in the magnitude of ammonia emissions, mainly owing to a paucity of ground-based observations and a virtual absence of atmospheric measurements3,8-11. Here we use infrared spectra, obtained by the IASI/MetOp satellite, to map global ammonia concentrations from space over the course of 2008. We identify several ammonia hotspots in middle-low latitudes across the globe. In general, we find a good qualitative agreement between our satellite measurements and simulations made using a global atmospheric chemistry transport model. However, the satellite data reveal substantially higher concentrations of ammonia north of 30° N, compared with model projections. We conclude that ammonia emissions could have been significantly underestimated in the Northern Hemisphere, and suggest that satellite monitoring of ammonia from space will improve our understanding of the global nitrogen cycle. {\textcopyright} 2009 Macmillan Publishers Limited. All rights reserved.}, author = {Clarisse, Lieven and Clerbaux, Cathy and Dentener, Frank and Hurtmans, Daniel and Coheur, Pierre Fran{\c{c}}ois}, doi = {10.1038/ngeo551}, isbn = {1752-0908}, issn = {17520894}, journal = {Nature Geoscience}, number = {7}, pages = {479--483}, publisher = {Nature Publishing Group}, title = {{Global ammonia distribution derived from infrared satellite observations}}, volume = {2}, year = {2009} } @article{Clark2017a, abstract = {In this study we implement eight lightning parameterizations in the Community Atmospheric Model (CAM5), evaluate the performance of the parameterizations in the present climate, and test the sensitivity of future lightning activity to the choice of parameterization. In the present day, the annual mean lightning flash densities in simulations constrained by reanalysis data show the highest spatial correlation to satellite observations for parameterizations based either on cloud top height (0.83) or cold cloud depth (0.80). Under future scenarios using representative concentration pathways, changes in global mean lightning flash density are highly sensitive to the parameterization chosen, with cloud top height schemes, a cold cloud depth scheme, and a scheme based on convective mass flux projecting large increases (36{\%} to 45{\%}), a mild increase (12.6{\%}), and a decrease (−6.7{\%}) in lightning flash density, respectively, under the RCP8.5 scenario, which causes a 3.4 K warming between 1996–2005 and 2079–2088.}, author = {Clark, Spencer K. and Ward, Daniel S. and Mahowald, Natalie M.}, doi = {10.1002/2017GL073017}, isbn = {0094-8276}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {future projections,lightning,parameterization,uncertainty}, number = {6}, pages = {2893--2901}, title = {{Parameterization-based uncertainty in future lightning flash density}}, volume = {44}, year = {2017} } @article{Cochran2017a, abstract = {The oceans, atmosphere, and clouds are all interconnected through the release and deposition of chemical species, which provide critical feedback in controlling the composition of our atmosphere and climate. To better understand the couplings between the ocean and atmosphere, it is critical to improve our understanding of the processes that control sea spray aerosol (SSA) composition and which ones plays the dominate role in regulating atmospheric chemistry and climate.}, annote = {doi: 10.1021/acs.accounts.6b00603}, author = {Cochran, Richard E and Ryder, Olivia S and Grassian, Vicki H and Prather, Kimberly A}, doi = {10.1021/acs.accounts.6b00603}, issn = {0001-4842}, journal = {Accounts of Chemical Research}, month = {mar}, number = {3}, pages = {599--604}, publisher = {American Chemical Society}, title = {{Sea Spray Aerosol: The Chemical Link between the Oceans, Atmosphere, and Climate}}, url = {https://doi.org/10.1021/acs.accounts.6b00603}, volume = {50}, year = {2017} } @article{Cohen2018, abstract = {In situ measurements in the upper troposphere-lower stratosphere (UTLS) have been performed in the framework of the European research infrastructure IAGOS (In-service Aircraft for a Global Observing System) for ozone since 1994 and for carbon monoxide (CO) since 2002. The flight tracks cover a wide range of longitudes in the northern extratropics, extending from the North American western coast (125°ĝ€W) to the eastern Asian coast (135°ĝ€E) and more recently over the northern Pacific Ocean. Several tropical regions are also sampled frequently, such as the Brazilian coast, central and southern Africa, southeastern Asia, and the western half of the Maritime Continent. As a result, a new set of climatologies for O3 (August 1994-December 2013) and CO (December 2001-December 2013) in the upper troposphere (UT), tropopause layer, and lower stratosphere (LS) are made available, including gridded horizontal distributions on a semi-global scale and seasonal cycles over eight well-sampled regions of interest in the northern extratropics. The seasonal cycles generally show a summertime maximum in O3 and a springtime maximum in CO in the UT, in contrast to the systematic springtime maximum in O3 and the quasi-absence of a seasonal cycle of CO in the LS. This study highlights some regional variabilities in the UT, notably (i) a west-east difference of O3 in boreal summer with up to 15ĝ€ppb more O3 over central Russia compared with northeast America, (ii) a systematic west-east gradient of CO from 60 to 140°ĝ€E, especially noticeable in spring and summer with about 5ĝ€ppb by 10 degrees longitude, (iii) a broad spring/summer maximum of CO over northeast Asia, and (iv) a spring maximum of O3 over western North America. Thanks to almost 20 years of O3 and 12 years of CO measurements, the IAGOS database is a unique data set to derive trends in the UTLS at northern midlatitudes. Trends in O3 in the UT are positive and statistically significant in most regions, ranging from +0.25 to +0.45ĝ€ppbĝ€yrĝ'1, characterized by the significant increase in the lowest values of the distribution. No significant trends of O3 are detected in the LS. Trends of CO in the UT, tropopause, and LS are almost all negative and statistically significant. The estimated slopes range from ĝ'1.37 to ĝ'0.59ĝ€ppbĝ€yrĝ'1, with a nearly homogeneous decrease in the lowest values of the monthly distribution (5th percentile) contrasting with the high interregional variability in the decrease in the highest values (95th percentile).}, author = {Cohen, Yann and Petetin, Herv{\'{e}} and Thouret, Val{\'{e}}rie and Mar{\'{e}}cal, Virginie and Josse, B{\'{e}}atrice and Clark, Hannah and Sauvage, Bastien and Fontaine, Alain and Athier, Gilles and Blot, Romain and Boulanger, Damien and Cousin, Jean Marc and N{\'{e}}d{\'{e}}lec, Philippe}, doi = {10.5194/acp-18-5415-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {apr}, number = {8}, pages = {5415--5453}, publisher = {Copernicus GmbH}, title = {{Climatology and long-term evolution of ozone and carbon monoxide in the upper troposphere-lower stratosphere (UTLS) at northern midlatitudes, as seen by IAGOS from 1995 to 2013}}, url = {https://acp.copernicus.org/articles/18/5415/2018/}, volume = {18}, year = {2018} } @article{Colette2015, abstract = {Ozone air pollution is identified as one of the main threats bearing upon human health and ecosystems, with 25 000 deaths in 2005 attributed to surface ozone in Europe (IIASA 2013 TSAP Report {\#}10). In addition, there is a concern that climate change could negate ozone pollution mitigation strategies, making them insufficient over the long run and jeopardising chances to meet the long term objective set by the European Union Directive of 2008 (Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008) (60 ppbv, daily maximum). This effect has been termed the ozone climate penalty. One way of assessing this climate penalty is by driving chemistry-transport models with future climate projections while holding the ozone precursor emissions constant (although the climate penalty may also be influenced by changes in emission of precursors). Here we present an analysis of the robustness of the climate penalty in Europe across time periods and scenarios by analysing the databases underlying 11 articles published on the topic since 2007, i.e. a total of 25 model projections. This substantial body of literature has never been explored to assess the uncertainty and robustness of the climate ozone penalty because of the use of different scenarios, time periods and ozone metrics. Despite the variability of model design and setup in this database of 25 model projection, the present meta-analysis demonstrates the significance and robustness of the impact of climate change on European surface ozone with a latitudinal gradient from a penalty bearing upon large parts of continental Europe and a benefit over the North Atlantic region of the domain. Future climate scenarios present a penalty for summertime (JJA) surface ozone by the end of the century (2071-2100) of at most 5 ppbv. Over European land surfaces, the 95{\%} confidence interval of JJA ozone change is [0.44; 0.64] and [0.99; 1.50] ppbv for the 2041-2070 and 2071-2100 time windows, respectively.}, author = {Colette, Augustin and Andersson, Camilla and Baklanov, Alexander and Bessagnet, Bertrand and Brandt, J{\o}rgen and Christensen, Jesper H. and Doherty, Ruth and Engardt, Magnuz and Geels, Camilla and Giannakopoulos, Christos and Hedegaard, Gitte B. and Katragkou, Eleni and Langner, Joakim and Lei, Hang and Manders, Astrid and Melas, Dimitris and Meleux, Fr{\'{e}}d{\'{e}}rik and Rou{\"{i}}l, Laurence and Sofiev, Mikhail and Soares, Joana and Stevenson, David S. and Tombrou-Tzella, Maria and Varotsos, Konstantinos V. and Young, Paul}, doi = {10.1088/1748-9326/10/8/084015}, issn = {17489326}, journal = {Environmental Research Letters}, keywords = {climate change,ozone,pollution}, month = {aug}, number = {8}, pages = {084015}, title = {{Is the ozone climate penalty robust in Europe?}}, url = {http://stacks.iop.org/1748-9326/10/i=8/a=084015?key=crossref.39c20dd706ad8099e0dc7cf97aaa2cdb}, volume = {10}, year = {2015} } @article{Collins2017a, abstract = {The Aerosol Chemistry Model Intercomparison Project (AerChemMIP) is endorsed by the Coupled-Model Intercomparison Project 6 (CMIP6) and is designed to quantify the climate and air quality impacts of aerosols and chemically-reactive gases. These are specifically near-term climate forcers (NTCFs: tropospheric ozone and aerosols, and their precursors), methane, nitrous oxide and ozone-depleting halocarbons. The aim of AerChemMIP is to answer four scientific questions: 1. How have anthropogenic emissions contributed to global radiative forcing and affected regional climate over the historical period? 2. How will future policies (on climate, air quality and land use) affect these species and their climate impacts? 3. Can the uncertainties associated with anthropogenic emissions be quantified? 4. Can climate feedbacks occurring through changes in natural emissions be quantified? These questions will be addressed through targeted simulations with CMIP6 climate models that include an interactive representation of tropospheric aerosols and atmospheric chemistry. These simulations build on the CMIP6 Diagnostic, Evaluation and Characterization of Klima (DECK) experiments, the CMIP6 historical simulations, and future projections performed elsewhere in CMIP6, allowing the contributions from aerosols and chemistry to be quantified. Specific diagnostics are requested as part of the CMIP6 data request to evaluate the performance of the models, and to understand any differences in behaviour between them.}, author = {Collins, William J. and Lamarque, Jean Fran{\c{c}}ois and Schulz, Michael and Boucher, Olivier and Eyring, Veronika and Hegglin, I. Michaela and Maycock, Amanda and Myhre, Gunnar and Prather, Michael and Shindell, Drew and Smith, J. Steven}, doi = {10.5194/gmd-10-585-2017}, isbn = {1991-9603}, issn = {19919603}, journal = {Geoscientific Model Development}, number = {2}, pages = {585--607}, title = {{AerChemMIP: Quantifying the effects of chemistry and aerosols in CMIP6}}, volume = {10}, year = {2017} } @article{Collins2010, annote = {NULL}, author = {Collins, W. J. and Sitch, S. and Boucher, O.}, doi = {10.1029/2010JD014187}, issn = {0148-0227}, journal = {Journal of Geophysical Research: Atmospheres}, month = {dec}, number = {D23}, pages = {D23308}, title = {{How vegetation impacts affect climate metrics for ozone precursors}}, url = {http://doi.wiley.com/10.1029/2010JD014187}, volume = {115}, year = {2010} } @article{Collins2013, abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} We examine the climate effects of the emissions of near-term climate forcers (NTCFs) from 4 continental regions (East Asia, Europe, North America and South Asia) using results from the Task Force on Hemispheric Transport of Air Pollution Source-Receptor global chemical transport model simulations. We address 3 aerosol species (sulphate, particulate organic matter and black carbon) and 4 ozone precursors (methane, reactive nitrogen oxides (NO{\textless}sub{\textgreater}x{\textless}/sub{\textgreater}), volatile organic compounds and carbon monoxide). We calculate the global climate metrics: global warming potentials (GWPs) and global temperature change potentials (GTPs). For the aerosols these metrics are simply time-dependent scalings of the equilibrium radiative forcings. The GTPs decrease more rapidly with time than the GWPs. The aerosol forcings and hence climate metrics have only a modest dependence on emission region. The metrics for ozone precursors include the effects on the methane lifetime. The impacts via methane are particularly important for the 20 yr GTPs. Emissions of NO{\textless}sub{\textgreater}x{\textless}/sub{\textgreater} and VOCs from South Asia have GWPs and GTPs of higher magnitude than from the other Northern Hemisphere regions. {\textless}br{\textgreater}{\textless}br{\textgreater} The analysis is further extended by examining the temperature-change impacts in 4 latitude bands, and calculating absolute regional temperature-change potentials (ARTPs). The latitudinal pattern of the temperature response does not directly follow the pattern of the diagnosed radiative forcing. We find that temperatures in the Arctic latitudes appear to be particularly sensitive to BC emissions from South Asia. The northern mid-latitude temperature response to northern mid-latitude emissions is approximately twice as large as the global average response for aerosol emission, and about 20–30{\%} larger than the global average for methane, VOC and CO emissions.{\textless}/p{\textgreater}{\textless}/p{\textgreater}}, author = {Collins, W. J. and Fry, M. M. and Yu, H. and Fuglestvedt, J. S. and Shindell, D. T. and West, J. J.}, doi = {10.5194/acp-13-2471-2013}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {5}, pages = {2471--2485}, title = {{Global and regional temperature-change potentials for near-term climate forcers}}, url = {https://www.atmos-chem-phys.net/13/2471/2013/}, volume = {13}, year = {2013} } @article{Collins2018, abstract = {To understand the importance of methane on the levels of carbon emission reductions required to achieve temperature goals, a processed-based approach is necessary rather than reliance on the transient climate response to emissions. We show that plausible levels of methane (CH4) mitigation can make a substantial difference to the feasibility of achieving the Paris climate targets through increasing the allowable carbon emissions. This benefit is enhanced by the indirect effects of CH4 on ozone (O3). Here the differing effects of CH4 and CO2 on land carbon storage, including the effects of surface O3, lead to an additional increase in the allowable carbon emissions with CH4 mitigation. We find a simple robust relationship between the change in the 2100 CH4 concentration and the extra allowable cumulative carbon emissions between now and 2100 (0.27 ± 0.05 GtC per ppb CH4). This relationship is independent of modelled climate sensitivity and precise temperature target, although later mitigation of CH4 reduces its value and thus methane reduction effectiveness. Up to 12{\%} of this increase in allowable emissions is due to the effect of surface ozone. We conclude early mitigation of CH4 emissions would significantly increase the feasibility of stabilising global warming below 1.5 °C, alongside having co-benefits for human and ecosystem health.}, author = {Collins, William J. and Webber, Christopher P. and Cox, Peter M. and Huntingford, Chris and Lowe, Jason and Sitch, Stephen and Chadburn, Sarah E. and Comyn-Platt, Edward and Harper, Anna B. and Hayman, Garry and Powell, Tom}, doi = {10.1088/1748-9326/aab89c}, issn = {17489326}, journal = {Environmental Research Letters}, keywords = {carbon budgets,climate targets,methane mitigation,non-CO2 greenhouse gases}, month = {apr}, number = {5}, pages = {54003}, publisher = {IOP Publishing}, title = {{Increased importance of methane reduction for a 1.5 degree target}}, url = {http://dx.doi.org/10.1088/1748-9326/aab89c http://stacks.iop.org/1748-9326/13/i=5/a=054003?key=crossref.70d07fb114d80fc70bd1b8927f03ac6b}, volume = {13}, year = {2018} } @article{Conrad2017, author = {Conrad, Bradley M and Johnson, Matthew R}, doi = {10.1021/acs.est.6b03690}, issn = {0013-936X}, journal = {Environmental Science {\&} Technology}, number = {3}, pages = {1893--1900}, title = {{Field Measurements of Black Carbon Yields from Gas Flaring}}, url = {http://dx.doi.org/10.1021/acs.est.6b03690}, volume = {51}, year = {2017} } @article{Cooper2020, abstract = {Extracting globally representative trend information from lower tropospheric ozone observations is extremely difficult due to the highly variable distribution and interannual variability of ozone, and the ongoing shift of ozone precursor emissions from high latitudes to low latitudes. Here we report surface ozone trends at 27 globally distributed remote locations (20 in the Northern Hemisphere, 7 in the Southern Hemisphere), focusing on continuous time series that extend from the present back to at least 1995. While these sites are only representative of less than 25{\%} of the global surface area, this analysis provides a range of regional long-term ozone trends for the evaluation of global chemistry-climate models. Trends are based on monthly mean ozone anomalies, and all sites have at least 20 years of data, which improves the likelihood that a robust trend value is due to changes in ozone precursor emissions and/or forced climate change rather than naturally occurring climate variability. Since 1995, the Northern Hemisphere sites are nearly evenly split between positive and negative ozone trends, while 5 of 7 Southern Hemisphere sites have positive trends. Positive trends are in the range of 0.5-2 ppbv decade-1, with ozone increasing at Mauna Loa by roughly 50{\%} since the late 1950s. Two high elevation Alpine sites, discussed by previous assessments, exhibit decreasing ozone trends in contrast to the positive trend observed by IAGOS commercial aircraft in the European lower free-troposphere. The Alpine sites frequently sample polluted European boundary layer air, especially in summer, and can only be representative of lower free tropospheric ozone if the data are carefully filtered to avoid boundary layer air. The highly variable ozone trends at these 27 surface sites are not necessarily indicative of free tropospheric trends, which have been overwhelmingly positive since the mid-1990s, as shown by recent studies of ozonesonde and aircraft observations.}, author = {Cooper, Owen R. and Schultz, Martin G. and Schroeder, Sabine and Chang, Kai-Lan and Gaudel, Audrey and Ben{\'{i}}tez, Gerardo Carbajal and Cuevas, Emilio and Fr{\"{o}}hlich, Marina and Galbally, Ian E. and Molloy, Suzie and Kubistin, Dagmar and Lu, Xiao and McClure-Begley, Audra and N{\'{e}}d{\'{e}}lec, Philippe and O'Brien, Jason and Oltmans, Samuel J. and Petropavlovskikh, Irina and Ries, Ludwig and Senik, Irina and Sj{\"{o}}berg, Karin and Solberg, Sverre and Spain, Gerard T. and Spangl, Wolfgang and Steinbacher, Martin and Tarasick, David and Thouret, Valerie and Xu, Xiaobin}, doi = {10.1525/elementa.420}, issn = {2325-1026}, journal = {Elementa: Science of the Anthropocene}, keywords = {Cooper2020}, month = {jun}, number = {1}, pages = {23}, title = {{Multi-decadal surface ozone trends at globally distributed remote locations}}, url = {http://doi.org/10.1525/elementa.420 https://www.elementascience.org/article/10.1525/elementa.420/}, volume = {8}, year = {2020} } @article{Corbett2007, abstract = {Epidemiological studies consistently link ambient concentrations of particulate matter (PM) to negative health impacts, including asthma, heart attacks, hospital admissions, and premature mortality. We model ambient PM concentrations from oceangoing ships using two geospatial emissions inventories and two global aerosol models. We estimate global and regional mortalities by applying ambient PM increases due to ships to cardiopulmonary and lung cancer concentration-risk functions and population models. Our results indicate that shipping-related PM emissions are responsible for approximately 60,000 cardiopulmonary and lung cancer deaths annually, with most deaths occurring near coastlines in Europe, East Asia, and South Asia. Under current regulation and with the expected growth in shipping activity, we estimate that annual mortalities could increase by 40{\%} by 2012.}, annote = {doi: 10.1021/es071686z}, author = {Corbett, James J and Winebrake, James J and Green, Erin H and Kasibhatla, Prasad and Eyring, Veronika and Lauer, Axel}, doi = {10.1021/es071686z}, issn = {0013-936X}, journal = {Environmental Science {\&} Technology}, month = {dec}, number = {24}, pages = {8512--8518}, publisher = {American Chemical Society}, title = {{Mortality from Ship Emissions: A Global Assessment}}, url = {https://doi.org/10.1021/es071686z}, volume = {41}, year = {2007} } @article{Cox2008, author = {Cox, Peter M. and Harris, Phil P. and Huntingford, Chris and Betts, Richard A. and Collins, Matthew and Jones, Chris D. and Jupp, Tim E. and Marengo, Jos{\'{e}} A. and Nobre, Carlos A.}, doi = {10.1038/nature06960}, issn = {0028-0836}, journal = {Nature}, month = {may}, number = {7192}, pages = {212--215}, title = {{Increasing risk of Amazonian drought due to decreasing aerosol pollution}}, url = {http://www.nature.com/doifinder/10.1038/nature06960}, volume = {453}, year = {2008} } @article{Cravigan2020a, abstract = {Abstract. The aerosol-driven radiative effects on marine low-level cloud represent a large uncertainty in climate simulations, in particular over the Southern Ocean, which is also an important region for sea spray aerosol production. Observations of sea spray aerosol organic enrichment and the resulting impact on water uptake over the remote Southern Hemisphere are scarce, and therefore the region is under-represented in existing parameterisations. The Surface Ocean Aerosol Production (SOAP) voyage was a 23 d voyage which sampled three phytoplankton blooms in the highly productive water of the Chatham Rise, east of New Zealand. In this study we examined the enrichment of organics to nascent sea spray aerosol and the modifications to sea spray aerosol water uptake using in situ chamber measurements of seawater samples taken during the SOAP voyage. Primary marine organics contributed up to 23 {\%} of the sea spray mass for particles with diameter less than approximately 1 µm and up to 79 {\%} of the particle volume for 50 nm diameter sea spray. The composition of the submicron organic fraction was consistent throughout the voyage and was largely composed of a polysaccharide-like component, characterised by very low alkane-to-hydroxyl-concentration ratios of approximately 0.1–0.2. The enrichment of organics was compared to the output from the chlorophyll-a-based sea spray aerosol parameterisation suggested by Gantt et al. (2011) and the OCEANFILMS (Organic Compounds from Ecosystems to Aerosols: Natural Films and Interfaces via Langmuir Molecular Surfactants) models. OCEANFILMS improved on the representation of the organic fraction predicted using chlorophyll a, in particular when the co-adsorption of polysaccharides was included; however, the model still under-predicted the proportion of polysaccharides by an average of 33 {\%}. Nascent 50 nm diameter sea spray aerosol hygroscopic growth factors measured at 90 {\%} relative humidity averaged 1.93±0.08 and did not decrease with increasing sea spray aerosol organic fractions. The observed hygroscopicity was greater than expected from the assumption of full solubility, particularly during the most productive phytoplankton bloom (B1), during which organic fractions were greater than approximately 0.4. The water uptake behaviour observed in this study is consistent with that observed for other measurements of phytoplankton blooms and can be partially attributed to the presence of sea salt hydrates, which lowers the sea spray aerosol hygroscopicity when the organic enrichment is low. The inclusion of surface tension effects only marginally improved the modelled hygroscopicity, and a significant discrepancy between the observed and modelled hygroscopicity at high organic volume fractions remained. The findings from the SOAP voyage highlight the influence of biologically sourced organics on sea spray aerosol composition; these data improve the capacity to parameterise sea spray aerosol organic enrichment and water uptake.}, author = {Cravigan, Luke T and Mallet, Marc D and Vaattovaara, Petri and Harvey, Mike J and Law, Cliff S and Modini, Robin L and Russell, Lynn M and Stelcer, Ed and Cohen, David D and Olsen, Greg and Safi, Karl and Burrell, Timothy J and Ristovski, Zoran}, doi = {10.5194/acp-20-7955-2020}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jul}, number = {13}, pages = {7955--7977}, publisher = {Copernicus Publications}, title = {{Sea spray aerosol organic enrichment, water uptake and surface tension effects}}, url = {https://acp.copernicus.org/articles/20/7955/2020/}, volume = {20}, year = {2020} } @article{Crippa2016, author = {Crippa, M and Janssens-Maenhout, G and Dentener, F and Guizzardi, D and Sindelarova, K and Muntean, M and {Van Dingenen}, R and Granier, C}, doi = {10.5194/acp-16-3825-2016}, journal = {Atmospheric Chemistry and Physics}, number = {6}, pages = {3825--3841}, title = {{Forty years of improvements in European air quality: regional policy-industry interactions with global impacts}}, url = {http://www.atmos-chem-phys.net/16/3825/2016/}, volume = {16}, year = {2016} } @article{essd-10-1987-2018, author = {Crippa, M and Guizzardi, D and Muntean, M and Schaaf, E and Dentener, F and van Aardenne, J A and Monni, S and Doering, U and Olivier, J G J and Pagliari, V and Janssens-Maenhout, G}, doi = {10.5194/essd-10-1987-2018}, journal = {Earth System Science Data}, number = {4}, pages = {1987--2013}, title = {{Gridded emissions of air pollutants for the period 1970–2012 within EDGAR v4.3.2}}, url = {https://www.earth-syst-sci-data.net/10/1987/2018/}, volume = {10}, year = {2018} } @techreport{Crippa2020, address = {Luxembourg}, author = {Crippa, M and Oreggioni, G and Guizzardi, D and Muntean, M and Schaaf, E and {Lo Vullo}, E and Solazzo, E and Monforti-Ferrario, F and Olivier, J.G.J. and Vignati, E}, doi = {10.2760/687800}, isbn = {978-92-76-11100-9}, pages = {251}, publisher = {Publications Office of the European Union}, series = {JRC117610}, title = {{Fossil CO2 and GHG emissions of all world countries – 2019 Report}}, year = {2019} } @techreport{Crippa2020, address = {Luxembourg}, author = {Crippa, M and Guizzardi, D and Muntean, M and Schaaf, E and Solazzo, E and Monforti-Ferrario, F and Olivier, J G J and Vignati, E}, doi = {10.2760/143674}, isbn = {978-92-76-21515-8}, pages = {244}, publisher = {Publications Office of the European Union}, series = {JRC121460}, title = {{Fossil CO2 emissions of all world countries – 2020 Report}}, year = {2020} } @article{Dai2018, abstract = {We study the possibility of designing solar radiation management schemes to achieve a desired meridional radiative forcing (RF) profile using a two-dimensional chemistry-transport-aerosol model. Varying SO2 or H2SO4 injection latitude, altitude, and season, we compute RF response functions for a broad range of possible injection schemes, finding that linear combinations of these injection cases can roughly achieve RF profiles that have been proposed to accomplish various climate objectives. Globally averaged RF normalized by the sulfur injection rate (the radiative efficacy) is largest for injections at high altitudes, near the equator, and using emission of H2SO4 vapor into an aircraft wake to produce accumulation-mode particles. There is a trade-off between radiative efficacy and control as temporal and spatial control is best achieved with injections at lower altitudes and higher latitudes. These results may inform studies using more realistic models that couple aerosol microphysics, chemistry, and stratospheric dynamics.}, author = {Dai, Z. and Weisenstein, D. K. and Keith, D. W.}, doi = {10.1002/2017GL076472}, issn = {0094-8276}, journal = {Geophysical Research Letters}, keywords = {solar geoengineering,stratospheric H2SO4 injection,stratospheric SO2 injection}, month = {jan}, number = {2}, pages = {1030--1039}, title = {{Tailoring Meridional and Seasonal Radiative Forcing by Sulfate Aerosol Solar Geoengineering}}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2017GL076472}, volume = {45}, year = {2018} } @article{Dalsøren2018, abstract = {Ethane and propane are the most abundant non-methane hydrocarbons in the atmosphere. However, their emissions, atmospheric distribution, and trends in their atmospheric concentrations are insufficiently understood. Atmospheric model simulations using standard community emission inventories do not reproduce available measurements in the Northern Hemisphere. Here, we show that observations of pre-industrial and present-day ethane and propane can be reproduced in simulations with a detailed atmospheric chemistry transport model, provided that natural geologic emissions are taken into account and anthropogenic fossil fuel emissions are assumed to be two to three times higher than is indicated in current inventories. Accounting for these enhanced ethane and propane emissions results in simulated surface ozone concentrations that are 5–13{\%} higher than previously assumed in some polluted regions in Asia. The improved correspondence with observed ethane and propane in model simulations with greater emissions suggests that the level of fossil (geologic + fossil fuel) methane emissions in current inventories may need re-evaluation.}, author = {Dals{\o}ren, Stig B and Myhre, Gunnar and Hodnebrog, {\O}ivind and Myhre, Cathrine Lund and Stohl, Andreas and Pisso, Ignacio and Schwietzke, Stefan and H{\"{o}}glund-Isaksson, Lena and Helmig, Detlev and Reimann, Stefan and Sauvage, St{\'{e}}phane and Schmidbauer, Norbert and Read, Katie A and Carpenter, Lucy J and Lewis, Alastair C and Punjabi, Shalini and Wallasch, Markus}, doi = {10.1038/s41561-018-0073-0}, issn = {1752-0908}, journal = {Nature Geoscience}, number = {3}, pages = {178--184}, title = {{Discrepancy between simulated and observed ethane and propane levels explained by underestimated fossil emissions}}, url = {https://doi.org/10.1038/s41561-018-0073-0}, volume = {11}, year = {2018} } @article{Dalsøren2016, abstract = {Observations at surface sites show an increase in global mean surface methane (CH4) of about 180 parts per billion (ppb) (above 10 {\%}) over the period 1984-2012. Over this period there are large fluctuations in the annual growth rate. In this work, we investigate the atmospheric CH4 evolution over the period 1970-2012 with the Oslo CTM3 global chemical transport model (CTM) in a bottom-up approach. We thoroughly assess data from surface measurement sites in international networks and select a subset suited for comparisons with the output from the CTM. We compare model results and observations to understand causes for both long-term trends and short-term variations. Employing Oslo CTM3 we are able to reproduce the seasonal and year-to-year variations and shifts between years with consecutive growth and stagnation, both at global and regional scales. The overall CH4 trend over the period is reproduced, but for some periods the model fails to reproduce the strength of the growth. The model overestimates the observed growth after 2006 in all regions. This seems to be explained by an overly strong increase in anthropogenic emissions in Asia, having global impact. Our findings confirm other studies questioning the timing or strength of the emission changes in Asia in the EDGAR v4.2 emission inventory over recent decades. The evolution of CH4 is not only controlled by changes in sources, but also by changes in the chemical loss in the atmosphere and soil uptake. The atmospheric CH4 lifetime is an indicator of the CH4 loss. In our simulations, the atmospheric CH4 lifetime decreases by more than 8 {\%} from 1970 to 2012, a significant reduction of the residence time of this important greenhouse gas. Changes in CO and NOx emissions, specific humidity, and ozone column drive most of this, and we provide simple prognostic equations for the relations between those and the CH4 lifetime. The reduced lifetime results in substantial growth in the chemical CH4 loss (relative to its burden) and dampens the CH4 growth.}, annote = {From Duplicate 1 (Atmospheric methane evolution the last 40 years - DuplicateDalsoren, NoCite; Dalsoren, Stig B; Myhre, Cathrine L; Myhre, Gunnar; Gomez-Pelaez, Angel J; Sovde, Ole A; Isaksen, Ivar S A; Weiss, Ray F; Harth, Christina M) Times Cited: 19 Myhre, Gunnar/A-3598-2008; Lund Myhre, Cathrine/M-4508-2014; Gomez-Pelaez, Angel/L-9268-2015; Jain, Atul/D-2851-2016; Sovde Haslerud, Amund/; Dalsoren, Stig/ Myhre, Gunnar/0000-0002-4309-476X; Lund Myhre, Cathrine/0000-0003-3587-5926; Gomez-Pelaez, Angel/0000-0003-4881-2975; Jain, Atul/0000-0002-4051-3228; Sovde Haslerud, Amund/0000-0002-3812-3837; Dalsoren, Stig/0000-0002-6752-4728 0 19 1680-7324}, author = {Dals{\o}ren, Stig B. and Myhre, Cathrine L. and Myhre, Gunnar and Gomez-Pelaez, Angel J. and S{\o}vde, Ole A. and Isaksen, Ivar S.A. and Weiss, Ray F. and Harth, Christina M.}, doi = {10.5194/acp-16-3099-2016}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {5}, pages = {3099--3126}, title = {{Atmospheric methane evolution the last 40 years}}, url = {https://www.atmos-chem-phys.net/16/3099/2016/}, volume = {16}, year = {2016} } @article{Dameris2013, abstract = {This paper reviews the current state and development of different numerical model classes that are used to simulate the global atmospheric system, particularly Earth's climate and climate-chemistry connections. The focus is on Chemistry-Climate Models. In general, these serve to examine dynamical and chemical processes in the Earth atmosphere, their feedback, and interaction with climate. Such models have been established as helpful tools in addition to analyses of observational data. Definitions of the global model classes are given and their capabilities as well as weaknesses are discussed. Examples of scientific studies indicate how numerical exercises contribute to an improved understanding of atmospheric behavior. There, the focus is on synergistic investigations combining observations and model results. The possible future developments and challenges are presented, not only from the scientific point of view but also regarding the computer technology and respective consequences for numerical modeling of atmospheric processes. In the future, a stronger cross-linkage of subject-specific scientists is necessary, to tackle the looming challenges. It should link the specialist discipline and applied computer science. {\textcopyright} 2013 by the authors; licensee MDPI, Basel, Switzerland.}, author = {Dameris, Martin and J{\"{o}}ckel, Patrick}, doi = {10.3390/atmos4020132}, isbn = {2073-4433}, issn = {20734433}, journal = {Atmosphere}, keywords = {Atmospheric circulation,Climate change,Earth-System Model,Future projection,High-performance computing,Ozone layer,Ozone-climate connection,Stratosphere,Stratospheric water vapor,Troposphere}, number = {2}, pages = {132--156}, title = {{Numerical modeling of climate–chemistry connections: Recent developments and future challenges}}, volume = {4}, year = {2013} } @article{Dang2019, abstract = {We applied the chemical transport model GEOS-Chem to examine the changes in aerosols and tropospheric O3 in China from 2012–2017 and the associated radiative forcing and health impact. Simulated surface layer concentrations and column burdens of aerosols and O3 were evaluated by comparing with ground-based and satellite-retrieved measurements. Between 2012 and 2017, simulated annual mean concentrations of PM2.5 decreased by 21.0{\%}, while O3 increased by 11.9{\%} over eastern China (20–45°N, 105–122.5°E). Changes in aerosols and O3 over 2012–2017 jointly exerted a positive radiative forcing of 1.26 W/m2 over eastern China, which was dominated by the less cooling from PM2.5 reductions (1.18 W/m2). The Global Exposure Mortality Model predicted 268.3 (247.3–291.6) thousand (9.6{\%}) fewer deaths in eastern China in 2017 relative to 2012. These results suggest an appreciable health benefit and a potential warming as a consequence of clean air actions.}, author = {Dang, Ruijun and Liao, Hong}, doi = {10.1029/2019GL084605}, issn = {19448007}, journal = {Geophysical Research Letters}, month = {nov}, number = {21}, pages = {12511--12519}, title = {{Radiative Forcing and Health Impact of Aerosols and Ozone in China as the Consequence of Clean Air Actions over 2012–2017}}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019GL084605}, volume = {46}, year = {2019} } @incollection{Coninck2018, author = {de Coninck, H. and Revi, A. and Babiker, M. and Bertoldi, P. and Buckeridge, M. and Cartwright, A. and Dong, W. and Ford, J. and Fuss, S. and Hourcade, JC. and Ley, D. and Mechler, R. and Newman, P. and Revokatova, A. and Schultz, S. and Steg, L. and Sugiyama, T.}, booktitle = {Global warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change,}, doi = {https://www.ipcc.ch/sr15/chapter/chapter-4}, editor = {Masson-Delmotte, V. and Zhai, P. and Pörtner, H. O. and Roberts, D. and Skea, J. and Shukla, P.R. and Pirani, A. and Moufouma-Okia, W. and Péan, C. and Pidcock, R. and Connors, S. and Matthews, J. B. R. and Chen, Y. and Zhou, X. and Gomis, M. I. and Lonnoy, E. and Maycock, T. and Tignor, M. and Waterfield, T.}, pages = {313--443}, publisher = {In Press}, title = {{Strengthening and Implementing the Global Response}}, url = {https://www.ipcc.ch/sr15/chapter/chapter-4}, year = {2018} } @article{DeFoy2016a, abstract = {China's twelfth Five-Year Plan included pollution control measures with a goal of reducing national emissions of nitrogen oxides (NOx) by 10{\%} by 2015 compared with 2010. Multiple linear regression analysis was used on 11-year time series of all nitrogen dioxide (NO2) pixels from the Ozone Monitoring Instrument (OMI) over 18 NO2 hotspots in China. The regression analysis accounted for variations in meteorology, pixel resolution, seasonal effects, weekday variability and year-to-year variability. The NO2 trends suggested that there was an increase in NO2 columns in most areas from 2005 to around 2011 which was followed by a strong decrease continuing through 2015. The satellite results were in good agreement with the annual official NOx emission inventories which were available up until 2014. This shows the value of evaluating trends in emission inventories using satellite retrievals. It further shows that recent control strategies were effective in reducing emissions and that recent economic transformations in China may be having an effect on NO2 columns. Satellite information for 2015 suggests that emissions have continued to decrease since the latest inventories available and have surpassed the goals of the twelfth Five-Year Plan.}, annote = {Times Cited: 21 Lu, Zifeng/F-3266-2012; de Foy, Benjamin/A-9902-2010 de Foy, Benjamin/0000-0003-4150-9922 0 21}, author = {de Foy, Benjamin and Lu, Zifeng and Streets, David G}, doi = {10.1038/srep35912}, isbn = {2045-2322}, issn = {2045-2322}, journal = {Scientific Reports}, month = {dec}, number = {1}, pages = {35912}, title = {{Satellite NO2 retrievals suggest China has exceeded its NOx reduction goals from the twelfth Five-Year Plan}}, url = {http://www.nature.com/articles/srep35912}, volume = {6}, year = {2016} } @article{DeSmedt2015, abstract = {We present the new version (v14) of the BIRA-IASB algorithm for the retrieval of formaldehyde (H2CO) columns from spaceborne UV-visible sensors. Applied to OMI measurements from Aura and to GOME-2 measurements from MetOp-A and MetOp-B, this algorithm is used to produce global distributions of H2CO representative of mid-morning and early afternoon conditions. Its main features include (1) a new iterative DOAS scheme involving three fitting intervals to better account for the O2-O2 absorption, (2) the use of earthshine radiances averaged in the equatorial Pacific as reference spectra, and (3) a destriping correction and background normalisation resolved in the across-swath position. For the air mass factor calculation, a priori vertical profiles calculated by the IMAGES chemistry transport model at 09:30 and 13:30 LT are used. Although the resulting GOME-2 and OMI H2CO vertical columns are found to be highly correlated, some systematic differences are observed. Afternoon columns are generally larger than morning ones, especially in mid-latitude regions. In contrast, over tropical rainforests, morning H2CO columns significantly exceed those observed in the afternoon. These differences are discussed in terms of the H2CO column variation between mid-morning and early afternoon, using ground-based MAX-DOAS measurements available from seven stations in Europe, China and Africa. Validation results confirm the capacity of the combined satellite measurements to resolve diurnal variations in H2CO columns. Furthermore, vertical profiles derived from MAX-DOAS measurements in the Beijing area and in Bujumbura are used for a more detailed validation exercise. In both regions, we find an agreement better than 15 {\%} when MAX-DOAS profiles are used as a priori for the satellite retrievals. Finally, regional trends in H2CO columns are estimated for the 2004-2014 period using SCIAMACHY and GOME-2 data for morning conditions, and OMI for early afternoon conditions. Consistent features are observed, such as an increase of the columns in India and central-eastern China, and a decrease in the eastern US and Europe. We find that the higher horizontal resolution of OMI combined with a better sampling and a more favourable illumination at midday allow for more significant trend estimates, especially over Europe and North America. Importantly, in some parts of the Amazonian forest, we observe with both time series a significant downward trend in H2CO columns, spatially correlated with areas affected by deforestation.}, author = {{De Smedt}, I. and Stavrakou, T. and Hendrick, F. and Danckaert, T. and Vlemmix, T. and Pinardi, G. and Theys, N. and Lerot, C. and Gielen, C. and Vigouroux, C. and Hermans, C. and Fayt, C. and Veefkind, P. and M{\"{u}}ller, J. F. and {Van Roozendael}, M.}, doi = {10.5194/acp-15-12519-2015}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {21}, pages = {12519--12545}, title = {{Diurnal, seasonal and long-term variations of global formaldehyde columns inferred from combined OMI and GOME-2 observations}}, volume = {15}, year = {2015} } @article{souza2010caracterizaccao, abstract = {CARACTERIZATION OF FINE AND COARSE PARTICULATE MATTER AND COMPOSITION OF THE WATER-SOLUBLE INORGANIC FRACTION IN SÃO JOSÉ DOS CAMPOS (SP). Air samples of fine (PM2,5) and coarse (PM2,5-10) particulate matter were collected in São José dos Campos from February 2004 to February 2005. Average PM10 mass concentrations was 31.2 ± 14.0 $\mu$g m-3, half of which belonging to the PM fraction. Ammonium and SO 2- were predominantly found in the fine fraction. Average 2.5 4 (NH ) SO concentration was estimated to be about 2.9 $\mu$g m-3. Chloride, Na+ and NO - were mostly associated with PM . Chloride 42 4 3 2,5-10 deficits with respect to sea-salt Cl/Na ratio were found in both size fractions.}, author = {de Souza, P A and de Mello, W Z and Mariani, Rauda L{\'{u}}cia and Sella, Silvia Maria}, doi = {10.1590/S0100-40422010000600005}, journal = {Quimica Nova}, number = {6}, pages = {1247--1253}, title = {{Caracteriza{\c{c}}{\~{a}}o do material particulado fino e grosso e composi{\c{c}}{\~{a}}o da fra{\c{c}}{\~{a}}o inorg{\^{a}}nica sol{\'{u}}vel em {\'{a}}gua em S{\~{a}}o Jos{\'{e}} dos Campos (SP)}}, volume = {33}, year = {2010} } @article{DeVries2017, author = {de Vries, Wim and Posch, Maximilian and Simpson, David and Reinds, Gert Jan}, doi = {10.1016/j.scitotenv.2017.06.132}, issn = {00489697}, journal = {Science of The Total Environment}, month = {dec}, pages = {1097--1116}, title = {{Modelling long-term impacts of changes in climate, nitrogen deposition and ozone exposure on carbon sequestration of European forest ecosystems}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S004896971731536X}, volume = {605-606}, year = {2017} } @article{Deeter2017, abstract = {The MOPITT (Measurements of Pollution in the Troposphere) satellite instrument has been making observations of atmospheric carbon monoxide since 2000. Recent enhancements to the MOPITT retrieval algorithm have resulted in the release of the version 7 (V7) product. Improvements include (1) representation of growing atmospheric concentrations of N2O, (2) use of meteorological fields from the MERRA-2 (Modern-Era Retrospective Analysis for Research and Applications) reanalysis for the entire MOPITT mission (instead of MERRA), (3) use of the MODIS (Moderate-Resolution Imaging Spectroradiometer) Collection 6 cloud mask product (instead of Collection 5), (4) a new strategy for radiance-bias correction and (5) an improved method for calibrating MOPITT's near-infrared (NIR) radiances. Statistical comparisons of V7 validation results with corresponding V6 results are presented, using aircraft in situ measurements as the reference. Clear improvements are demonstrated for V7 products with respect to overall retrieval biases, bias variability and bias drift uncertainty.}, author = {Deeter, Merritt N. and Edwards, David P. and Francis, Gene L. and Gille, John C. and Mart{\'{i}}nez-Alonso, Sara and Worden, Helen M. and Sweeney, Colm}, doi = {10.5194/amt-10-2533-2017}, issn = {18678548}, journal = {Atmospheric Measurement Techniques}, number = {7}, pages = {2533--2555}, title = {{A climate-scale satellite record for carbon monoxide: The MOPITT Version 7 product}}, volume = {10}, year = {2017} } @article{DeMott5797, abstract = {Ice nucleating particles (INPs) are vital for ice initiation in, and precipitation from, mixed-phase clouds. A source of INPs from oceans within sea spray aerosol (SSA) emissions has been suggested in previous studies but remained unconfirmed. Here, we show that INPs are emitted using real wave breaking in a laboratory flume to produce SSA. The number concentrations of INPs from laboratory-generated SSA, when normalized to typical total aerosol number concentrations in the marine boundary layer, agree well with measurements from diverse regions over the oceans. Data in the present study are also in accord with previously published INP measurements made over remote ocean regions. INP number concentrations active within liquid water droplets increase exponentially in number with a decrease in temperature below 0 {\{}$\backslash$textdegree{\}}C, averaging an order of magnitude increase per 5 {\{}$\backslash$textdegree{\}}C interval. The plausibility of a strong increase in SSA INP emissions in association with phytoplankton blooms is also shown in laboratory simulations. Nevertheless, INP number concentrations, or active site densities approximated using {\{}$\backslash$textquotedblleft{\}}dry{\{}$\backslash$textquotedblright{\}} geometric SSA surface areas, are a few orders of magnitude lower than corresponding concentrations or site densities in the surface boundary layer over continental regions. These findings have important implications for cloud radiative forcing and precipitation within low-level and midlevel marine clouds unaffected by continental INP sources, such as may occur over the Southern Ocean.}, author = {DeMott, Paul J and Hill, Thomas C J and McCluskey, Christina S and Prather, Kimberly A and Collins, Douglas B and Sullivan, Ryan C and Ruppel, Matthew J and Mason, Ryan H and Irish, Victoria E and Lee, Taehyoung and Hwang, Chung Yeon and Rhee, Tae Siek and Snider, Jefferson R and McMeeking, Gavin R and Dhaniyala, Suresh and Lewis, Ernie R and Wentzell, Jeremy J B and Abbatt, Jonathan and Lee, Christopher and Sultana, Camille M and Ault, Andrew P and Axson, Jessica L and {Diaz Martinez}, Myrelis and Venero, Ingrid and Santos-Figueroa, Gilmarie and Stokes, M Dale and Deane, Grant B and Mayol-Bracero, Olga L and Grassian, Vicki H and Bertram, Timothy H and Bertram, Allan K and Moffett, Bruce F and Franc, Gary D}, doi = {10.1073/pnas.1514034112}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, number = {21}, pages = {5797--5803}, publisher = {National Academy of Sciences}, title = {{Sea spray aerosol as a unique source of ice nucleating particles}}, url = {https://www.pnas.org/content/113/21/5797}, volume = {113}, year = {2016} } @article{Dhaka2020, abstract = {Delhi, a tropical Indian megacity, experiences one of the most severe air pollution in the world, linked with diverse anthropogenic and biomass burning emissions. First phase of COVID-19 lockdown in India, implemented during 25 March to 14 April 2020 resulted in a dramatic near-zeroing of various activities (e.g. traffic, industries, constructions), except the “essential services”. Here, we analysed variations in the fine particulate matter (PM2.5) over the Delhi-National Capital Region. Measurements revealed large reductions (by 40–70{\%}) in PM2.5 during the first week of lockdown (25–31 March 2020) as compared to the pre-lockdown conditions. However, O3 pollution remained high during the lockdown due to non-linear chemistry and dynamics under low aerosol loading. Notably, events of enhanced PM2.5 levels (300–400 µg m−3) were observed during night and early morning hours in the first week of April after air temperatures fell close to the dew-point ({\~{}} 15–17 °C). A haze formation mechanism is suggested through uplifting of fine particles, which is reinforced by condensation of moisture following the sunrise. The study highlights a highly complex interplay between the baseline pollution and meteorology leading to counter intuitive enhancements in pollution, besides an overall improvement in air quality during the COVID-19 lockdown in this part of the world.}, author = {Dhaka, Surendra K. and Chetna and Kumar, Vinay and Panwar, Vivek and Dimri, A. P. and Singh, Narendra and Patra, Prabir K. and Matsumi, Yutaka and Takigawa, Masayuki and Nakayama, Tomoki and Yamaji, Kazuyo and Kajino, Mizuo and Misra, Prakhar and Hayashida, Sachiko}, doi = {10.1038/s41598-020-70179-8}, issn = {2045-2322}, journal = {Scientific Reports}, month = {dec}, number = {1}, pages = {13442}, pmid = {32778673}, publisher = {Nature Research}, title = {{PM2.5 diminution and haze events over Delhi during the COVID-19 lockdown period: an interplay between the baseline pollution and meteorology}}, url = {http://www.nature.com/articles/s41598-020-70179-8}, volume = {10}, year = {2020} } @article{Dietmuller2014, abstract = {Interactively coupled climate chemistry models (CCMs) extend the number of feedback mechanisms in climate change simulations by including chemical feedback. In this study the radiative feedback from ozone changes on climate response and climate sensitivity is quantified for a series of simulations driven by CO2 increases on top of a present-day reference concentration level. Other possibly relevant feedback via atmospheric chemistry, e.g., via CH4 and N2 O, is not fully quantified in the CCM setup as their concentrations are essentially fixed at the surface. In case of a CO2 -doubling simulation, the ozone feedback reduces the climate sensitivity parameter by 3.4{\%}, from 0.70 K/(W m−2) without interactive chemistry to 0.68 K/(W m−2). In case of a 4*CO2 simulation, the reduction of the climate sensitivity parameter increases to 8.4{\%}. An analysis of feedback reveals that the negative feedback of stratospheric ozone and the associated negative feedback change in stratospheric water vapor are mainly responsible for this damping. The feedback from tropospheric ozone changes is positive but much smaller. The nonlinearity in the climate sensitivity damping with increased CO2 concentrations is shown to be due to nonlinear feedback of ozone and stratospheric water vapor.}, author = {Dietm{\"{u}}ller, S. and Ponater, M. and Sausen, R.}, doi = {10.1002/2013JD020575}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {feb}, number = {4}, pages = {1796--1805}, title = {{Interactive ozone induces a negative feedback in CO2-driven climate change simulations}}, url = {http://doi.wiley.com/10.1002/2013JD020575}, volume = {119}, year = {2014} } @article{Ding2019a, abstract = {Wet scavenging of black carbon (BC) has been subject to large uncertainty, which importantly determines its atmospheric lifetime and indirect forcing impact on cloud microphysics. This study reveals the complex BC-hydrometeor interactions in mixed-phase clouds via single particle measurements in the real-world environment, by capturing precipitation processes throughout cloud formation, cold rain/graupel, and subsequent snow events at a mountain site influenced by anthropogenic sources in wintertime. We found highly efficient BC wet scavenging during cloud formation, with large and thickly coated BC preferentially incorporated into droplets. During snow processes, BC core sizes in the interstitial phase steadily increased. A mechanism was proposed whereby the BC mass within each droplet was accumulated through droplet collision, leading to larger BC cores, which were then released back to the interstitial air through the Wegener-Bergeron-Findeisen processes when ice dominated. These results provide fundamental basis for constraining BC wet scavenging.}, author = {Ding, Shuo and Zhao, Delong and He, Cenlin and Huang, Mengyu and He, Hui and Tian, Ping and Liu, Quan and Bi, Kai and Yu, Chenjie and Pitt, Joseph and Chen, Ying and Ma, Xincheng and Chen, Yunbo and Jia, Xingcan and Kong, Shaofei and Wu, Jian and Hu, Dawei and Hu, Kang and Ding, Deping and Liu, Dantong}, doi = {10.1029/2019GL083171}, issn = {0094-8276}, journal = {Geophysical Research Letters}, keywords = {WBF process,aerosol-cloud interaction,black carbon,wet scavenging}, month = {jul}, number = {14}, pages = {8453--8463}, title = {{Observed Interactions Between Black Carbon and Hydrometeor During Wet Scavenging in Mixed‐Phase Clouds}}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2019GL083171}, volume = {46}, year = {2019} } @misc{Dlugokencky2021, author = {Dlugokencky, Ed and Tans, Pieter}, publisher = {Global Monitoring Laboratory, National Oceanic {\&} Atmospheric Administration Earth System Research Laboratories (NOAA/ESRL)}, title = {{Trends in Atmospheric Carbon Dioxide, Methane and Nitrous Oxide}}, url = {www.esrl.noaa.gov/gmd/ccgg/trends/}, urldate = {2021-03-04}, year = {2021} } @article{Duncan2013, abstract = {Abstract We show that Aura Ozone Monitoring Instrument (OMI) nitrogen dioxide (NO2) tropospheric column data may be used to assess changes of the emissions of nitrogen oxides (NOx) from power plants in the United States, though careful interpretation of the data is necessary. There is a clear response for OMI NO2 data to NOx emission reductions from power plants associated with the implementation of mandated emission control devices (ECDs) over the OMI record (2005–2011). This response is scalar for all intents and purposes, whether the reduction is rapid or incremental over several years. However, it is variable among the power plants, even for those with the greatest absolute decrease in emissions. We document the primary causes of this variability, presenting case examples for specific power plants.}, author = {Duncan, Bryan N and Yoshida, Yasuko and de Foy, Benjamin and Lamsal, Lok N and Streets, David G and Lu, Zifeng and Pickering, Kenneth E and Krotkov, Nickolay A}, doi = {http://dx.doi.org/10.1016/j.atmosenv.2013.08.068}, isbn = {1352-2310}, journal = {Atmospheric Environment}, pages = {102--111}, title = {{The observed response of Ozone Monitoring Instrument (OMI) NO2 columns to NOx emission controls on power plants in the United States: 2005–2011}}, volume = {81}, year = {2013} } @article{Duncan2016, abstract = {Nitrogen oxides (NOx = NO + NO2) are produced during combustion processes and, thus may serve as a proxy for fossil fuel-based energy usage and coemitted greenhouse gases and other pollutants. We use high-resolution nitrogen dioxide (NO2) data from the Ozone Monitoring Instrument (OMI) to analyze changes in urban NO2 levels around the world from 2005 to 2014, finding complex heterogeneity in the changes. We discuss several potential factors that seem to determine these NOx changes. First, environmental regulations resulted in large decreases. The only large increases in the United States may be associated with three areas of intensive energy activity. Second, elevated NO2 levels were observed over many Asian, tropical, and subtropical cities that experienced rapid economic growth. Two of the largest increases occurred over recently expanded petrochemical complexes in Jamnagar (India) and Daesan (Korea). Third, pollution transport from China possibly influenced the Republic of Korea and Japan, diminishing the impact of local pollution controls. However, in China, there were large decreases over Beijing, Shanghai, and the Pearl River Delta, which were likely associated with local emission control efforts. Fourth, civil unrest and its effect on energy usage may have resulted in lower NO2 levels in Libya, Iraq, and Syria. Fifth, spatial heterogeneity within several megacities may reflect mixed efforts to cope with air quality degradation. We also show the potential of high-resolution data for identifying NOx emission sources in regions with a complex mix of sources. Intensive monitoring of the world's tropical/subtropical megacities will remain a priority, as their populations and emissions of pollutants and greenhouse gases are expected to increase significantly.}, author = {Duncan, Bryan N. and Lamsal, Lok N. and Thompson, Anne M. and Yoshida, Yasuko and Lu, Zifeng and Streets, David G. and Hurwitz, Margaret M. and Pickering, Kenneth E.}, doi = {10.1002/2015JD024121}, isbn = {2169-9291}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {0322 Constituent sources and sinks,0345 Pollution: urban and regional,0365 Troposphere: composition and chemistry,Aura,NO2 emissions,OMI,global changes}, month = {jan}, number = {2}, pages = {976--996}, title = {{A space-based, high-resolution view of notable changes in urban NOx pollution around the world (2005–2014)}}, url = {http://dx.doi.org/10.1002/2015JD024121 http://doi.wiley.com/10.1002/2015JD024121}, volume = {121}, year = {2016} } @article{DUNCAN2014647, abstract = {Satellite data of atmospheric pollutants are becoming more widely used in the decision-making and environmental management activities of public, private sector and non-profit organizations. They are employed for estimating emissions, tracking pollutant plumes, supporting air quality forecasting activities, providing evidence for “exceptional event” declarations, monitoring regional long-term trends, and evaluating air quality model output. However, many air quality managers are not taking full advantage of the data for these applications nor has the full potential of satellite data for air quality applications been realized. A key barrier is the inherent difficulties associated with accessing, processing, and properly interpreting observational data. A degree of technical skill is required on the part of the data end-user, which is often problematic for air quality agencies with limited resources. Therefore, we 1) review the primary uses of satellite data for air quality applications, 2) provide some background information on satellite capabilities for measuring pollutants, 3) discuss the many resources available to the end-user for accessing, processing, and visualizing the data, and 4) provide answers to common questions in plain language.}, author = {Duncan, Bryan N and Prados, Ana I and Lamsal, Lok N and Liu, Yang and Streets, David G and Gupta, Pawan and Hilsenrath, Ernest and Kahn, Ralph A and Nielsen, J Eric and Beyersdorf, Andreas J and Burton, Sharon P and Fiore, Arlene M and Fishman, Jack and Henze, Daven K and Hostetler, Chris A and Krotkov, Nickolay A and Lee, Pius and Lin, Meiyun and Pawson, Steven and Pfister, Gabriele and Pickering, Kenneth E and Pierce, R Bradley and Yoshida, Yasuko and Ziemba, Luke D}, doi = {https://doi.org/10.1016/j.atmosenv.2014.05.061}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Air quality,End-user resources,Remote sensing,Satellite data}, pages = {647--662}, title = {{Satellite data of atmospheric pollution for U.S. air quality applications: Examples of applications, summary of data end-user resources, answers to FAQs, and common mistakes to avoid}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231014004270}, volume = {94}, year = {2014} } @article{Dutkiewicz2014, abstract = {Concentrations of atmospheric black carbon, [BC], were determined from filter samples collected weekly at Kevo, Finland (69°45′N, 27°02′E), from 1964 to 2010 using optical and thermal optical methods. The data provide the longest record of directly measured [BC] in the Arctic. The mean winter, spring, summer, and autumn [BC] based on the entire data set were 339, 199, 127, and 213 ng m-3, respectively. Annual mean [BC] decreased from {\~{}}300 in {\~{}}1970 to 82 ng m-3 in 2010. [BC] data sets from other Arctic sites show similar trends, but concentrations at Kevo are generally higher. From {\~{}}1970 to 2010 the [BC] decreased by {\~{}}1.8{\%} yr-1. However, [BC] did not decrease monotonically. Instead, cyclical peaks occurred around 1976–1977, 1985–1987, and 1999. During such periods, nickel concentrations were well correlated with [BC]. This suggests that emissions from extensive ore smelting on the Kola Peninsula were significant contributors of particulate matter observed at Kevo. Simulations of [BC] at Kevo using the OsloCTM3 model using different emission inventories and meteorological data sets were performed. Modeled concentrations were lower than observed by a factor of 4. The results indicated that circulation changes can explain year to year variability, but the downward trend in the observations is mostly explained by emissions. Emission inventories in Europe, Russia, and the former Soviet Union are poorly constrained and appear to need revision in order to match observed trends in BC atmospheric concentrations.}, author = {Dutkiewicz, Vincent A. and DeJulio, Anthony M. and Ahmed, Tanveer and Laing, James and Hopke, Philip K. and Skeie, Ragnhild B. and Viisanen, Yrj{\"{o}} and Paatero, Jussi and Husain, Liaquat}, doi = {10.1002/2014JD021790}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {jun}, number = {12}, pages = {7667--7683}, title = {{Forty-seven years of weekly atmospheric black carbon measurements in the Finnish Arctic: Decrease in black carbon with declining emissions}}, url = {http://doi.wiley.com/10.1002/2014JD021790}, volume = {119}, year = {2014} } @article{Dykema2016, abstract = {Side effects resulting from the deliberate injection of sulfate aerosols intended to partially offset climate change have motivated the investigation of alternatives, including solid aerosol materials. Sulfate aerosols warm the tropical tropopause layer, increasing the flux of water vapor into the stratosphere, accelerating ozone loss, and increasing radiative forcing. The high refractive index of some solid materials may lead to reduction in these risks. We present a new analysis of the scattering efficiency and absorption of a range of candidate solid aerosols. We utilize a comprehensive radiative transfer model driven by updated, physically consistent estimates of optical properties. We compute the potential increase in stratospheric water vapor and associated longwave radiative forcing. We find that the stratospheric heating calculated in this analysis indicates some materials to be substantially riskier than previous work. We also find that there are Earth-abundant materials that may reduce some principal known risks relative to sulfate aerosols.}, author = {Dykema, J. A. and Keith, D. W. and Keutsch, F. N.}, doi = {10.1002/2016GL069258}, issn = {00948276}, journal = {Geophysical Research Letters}, keywords = {aerosol,geonegineering,optical properties,solar radiation management,stratosphere,water vapor}, month = {jul}, number = {14}, pages = {7758--7766}, title = {{Improved aerosol radiative properties as a foundation for solar geoengineering risk assessment}}, url = {http://doi.wiley.com/10.1002/2016GL069258}, volume = {43}, year = {2016} } @misc{EC-JRC/PBL2020, author = {{EC-JRC / PBL}}, doi = {10.2904/JRC_DATASET_EDGAR}, publisher = {European Commission, Joint Research Centre (EC-JRC) / Netherlands Environmental Assessment Agency (PBL)}, title = {{EDGAR v5.0 Global Air Pollutant Emissions}}, url = {https://edgar.jrc.ec.europa.eu/overview.php?v=50{\_}AP}, year = {2020} } @article{doi:10.1002/2013JD020511, abstract = {Model output from the Coupled Model Intercomparison Project phase 5 (CMIP5) archive was compared with the observed latitudinal distribution of surface temperature trends between the years 1965 and 2004. By comparing model simulations that only consider changes in greenhouse gas forcing (GHG) with simulations that also consider the time evolution of anthropogenic aerosol emissions (GHGAERO), the influence of aerosol forcing on modeled surface temperature trends, and the dependence of the forcing on the model representation of aerosols and aerosol indirect effects, was evaluated. One group of models include sophisticated parameterizations of aerosol activation into cloud droplets; viz., the cloud droplet number concentration (CDNC) is a function of the modeled supersaturation as well as the aerosol concentration. In these models, the temperature trend bias was reduced in GHGAERO compared to GHG in more regions than in the other models. The ratio between high- and low-latitude warming also improved compared to observations. In a second group of models, the CDNC is diagnosed using an empirical relationship between the CDNC and the aerosol concentration. In this group, the temperature trend bias was reduced in more regions than in the model group where no aerosol indirect effects are considered. No clear difference could be found between models that include an explicit aerosol module and the ones that utilize prescribed aerosol. There was also no clear difference between models that include aerosol effects on the precipitation formation rate and the ones that do not. The results indicate that the best representation of recent observed surface temperature trends is obtained if the modeled CDNC is a function of both the aerosol concentration and the supersaturation.}, author = {Ekman, Annica M L}, doi = {10.1002/2013JD020511}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {CMIP5,aerosol,cloud,temperature trend}, number = {2}, pages = {817--832}, title = {{Do sophisticated parameterizations of aerosol–cloud interactions in CMIP5 models improve the representation of recent observed temperature trends?}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2013JD020511}, volume = {119}, year = {2014} } @article{Elguindi2020, abstract = {Abstract This study compares recent CO, NOx, NMVOC, SO2, BC, and OC anthropogenic emissions from several state-of-the-art top-down estimates to global and regional bottom-up inventories and projections from five Shared Socioeconomic Pathways (SSPs) in several regions. Results show that top-down emissions derived in several recent studies exhibit similar uncertainty as bottom-up inventories in some regions for certain species and even less in the case of Chinese CO emissions. In general, the largest discrepancies are found outside of regions such as the United States, Europe, and Japan where the most accurate and detailed information on emissions is available. In some regions such as China, which has recently undergone dynamical economic growth and changes in air quality regulations, the top-down estimates better capture recent emission trends than global bottom-up inventories. These results show the potential of top-down estimates to complement bottom-up inventories and to aide in the development of emission scenarios, particularly in regions where global inventories lack the necessary up-to-date and accurate information regarding regional activity data and emission factors such as Africa and India. Areas of future work aimed at quantifying and reducing uncertainty are also highlighted. A regional comparison of recent CO and NOx trends in the five SSPs indicate that SSP126, a strong pollution control scenario, best represents the trends from the top-down and regional bottom-up inventories in the United States, Europe, and China, while SSP460, a low-pollution control scenario, lies closest to actual trends in West Africa. This analysis can be useful for air quality forecasting and near-future pollution control/mitigation policy studies.}, annote = {https://doi.org/10.1029/2020EF001520}, author = {Elguindi, N and Granier, C and Stavrakou, T and Darras, S and Bauwens, M and Cao, H and Chen, C and {Denier van der Gon}, H A C and Dubovik, O and Fu, T M and Henze, D K and Jiang, Z and Keita, S and Kuenen, J J P and Kurokawa, J and Liousse, C and Miyazaki, K and M{\"{u}}ller, J.-F. and Qu, Z and Solmon, F and Zheng, B}, doi = {https://doi.org/10.1029/2020EF001520}, issn = {2328-4277}, journal = {Earth's Future}, keywords = {Air quality modelling,Anthropogenic surface emissions,Emission inventories,Inverse Modelling,Shared Socioeconomic Pathways}, month = {aug}, number = {8}, pages = {e2020EF001520}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Intercomparison of Magnitudes and Trends in Anthropogenic Surface Emissions From Bottom-Up Inventories, Top-Down Estimates, and Emission Scenarios}}, url = {https://doi.org/10.1029/2020EF001520}, volume = {8}, year = {2020} } @article{LeedhamElvidge2015, abstract = {Abstract. Atmospheric concentrations of dichloromethane, CH2Cl2, a regulated toxic air pollutant and minor contributor to stratospheric ozone depletion, were reported to have peaked around 1990 and to be declining in the early part of the 21st century. Recent observations suggest this trend has reversed and that CH2Cl2 is once again increasing in the atmosphere. Despite the importance of ongoing monitoring and reporting of atmospheric CH2Cl2, no time series has been discussed in detail since 2006. The CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) has analysed the halocarbon content of whole-air samples collected at altitudes of between {\~{}} 10–12 km via a custom-built container installed on commercial passenger aircraft since 1998, providing a long-term record of CH2Cl2 observations. In this paper we present this unique CH2Cl2 time series, discussing key flight routes which have been used at various times over the past 15 years. Between 1998 and 2012 increases were seen in all northern hemispheric regions and at different altitudes, ranging from {\~{}} 7–10 ppt in background air to {\~{}} 13–15 ppt in regions with stronger emissions (equating to a 38–69{\%} increase). Of particular interest is the rising importance of India as a source of atmospheric CH2Cl2: based on CARIBIC data we provide regional emission estimates for the Indian subcontinent and show that regional emissions have increased from 3–14 Gg yr−1 (1998–2000) to 16–25 Gg yr−1 (2008). Potential causes of the increasing atmospheric burden of CH2Cl2 are discussed. One possible source is the increased use of CH2Cl2 as a feedstock for the production of HFC-32, a chemical used predominantly as a replacement for ozone-depleting substances in a variety of applications including air conditioners and refrigeration.}, author = {Elvidge, E. C. Leedham and Oram, D. E. and Laube, J. C. and Baker, A. K. and Montzka, S. A. and Humphrey, S. and O{\&}apos;Sullivan, D. A. and Brenninkmeijer, C. A. M.}, doi = {10.5194/acp-15-1939-2015}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {feb}, number = {4}, pages = {1939--1958}, title = {{Increasing concentrations of dichloromethane, CH2Cl2, inferred from CARIBIC air samples collected 1998–2012}}, url = {https://www.atmos-chem-phys.net/15/1939/2015/}, volume = {15}, year = {2015} } @article{LeedhamElvidge2015a, abstract = {Abstract. Exposure of intertidal macroalgae during low tide has been linked to the emission of a variety of atmospherically-important trace gases into the coastal atmosphere. In recent years, several studies have investigated the role of inorganic iodine and organoiodides as antioxidants and their emission during exposure to combat oxidative stress, yet the role of organic bromine species during desiccation is less well understood. In this study the emission of dibromomethane (CH2Br2) and bromoform (CHBr3) during exposure and desiccation of two common temperate macroalgae, Fucus vesiculosus and Ulva intestinalis, is reported. Determination of the impact exposure may have on algal physiological processes is difficult as intertidal species are adapted to desiccation and may undergo varying degrees of desiccation before their physiology is affected. For this reason we include comparisons between photosynthetic capacity (Fv/Fm) and halocarbon emissions during a desiccation time series. In addition, the role of rewetting with freshwater to simulate exposure to rain was also investigated. Our results show that an immediate flux of bromocarbons occurs upon exposure, followed by a decline in bromocarbon emissions. We suggest that this immediate bromocarbon pulse may be linked to volatilisation or emissions of existing bromocarbon stores from the algal surface rather than the production of bromocarbons as an antioxidant response.}, author = {Elvidge, E. C. Leedham and Phang, S.-M. and Sturges, W. T. and Malin, G.}, doi = {10.5194/bg-12-387-2015}, issn = {1726-4189}, journal = {Biogeosciences}, month = {jan}, number = {2}, pages = {387--398}, title = {{The effect of desiccation on the emission of volatile bromocarbons from two common temperate macroalgae}}, url = {https://www.biogeosciences.net/12/387/2015/}, volume = {12}, year = {2015} } @article{EMBERSON2018, author = {Emberson, Lisa D and Pleijel, H{\aa}kan and Ainsworth, Elizabeth A and van den Berg, Maurits and Ren, Wei and Osborne, Stephanie and Mills, Gina and Pandey, Divya and Dentener, Frank and B{\"{u}}ker, Patrick and Ewert, Frank and Koeble, Renate and {Van Dingenen}, Rita}, doi = {10.1016/j.eja.2018.06.002}, issn = {11610301}, journal = {European Journal of Agronomy}, keywords = {Biomass,Crop modelling,Ozone pollution,Risk assessment,Yield}, month = {oct}, pages = {19--34}, title = {{Ozone effects on crops and consideration in crop models}}, url = {http://www.sciencedirect.com/science/article/pii/S1161030118301606 https://linkinghub.elsevier.com/retrieve/pii/S1161030118301606}, volume = {100}, year = {2018} } @article{acp-9-1831-2009, abstract = {Methane and ozone are two important climate gases with significant tropospheric chemistry. Within chemistry-climate and transport models this chemistry is simplified for computational expediency. We compare the state of the art Master Chemical Mechanism (MCM) with six tropospheric chemistry schemes (CRI-reduced, GEOSCHEM and a GEOS-CHEM adduct, MOZART-2, TOMCAT and CBM-IV) that could be used within composition transport models. We test the schemes within a box model framework under conditions derived from a composition transport model and from field observations from a regional scale pollution event. We find that CRI-reduced provides much skill in simulating the full chemistry, yet with greatly reduced complexity. We find significant variations between the other chemical schemes, and reach the following conclusions. (1) The inclusion of a gas phase N2O5+H2O reaction in one scheme and not others is a large source of uncertainty in the inorganic chemistry. ( 2) There are significant variations in the calculated concentration of PAN between the schemes, which will affect the long range transport of reactive nitrogen in global models. ( 3) The representation of isoprene chemistry differs hugely between the schemes, leading to significant uncertainties on the impact of isoprene on composition. (4) Differences are found in NO3 concentrations in the nighttime chemistry. Resolving these four issues through further investigative laboratory studies will reduce the uncertainties within the chemical schemes of global tropospheric models.}, author = {Emmerson, K. M. and Evans, M. J.}, doi = {10.5194/acp-9-1831-2009}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {5}, pages = {1831--1845}, title = {{Comparison of tropospheric gas-phase chemistry schemes for use within global models}}, url = {https://www.atmos-chem-phys.net/9/1831/2009/}, volume = {9}, year = {2009} } @article{Emmons2020, abstract = {Abstract The Community Earth System Model version 2 (CESM2) includes a detailed representation of chemistry throughout the atmosphere in the Community Atmosphere Model with chemistry and Whole Atmosphere Community Climate Model configurations. These model configurations use the Model for Ozone and Related chemical Tracers (MOZART) family of chemical mechanisms, covering the troposphere, stratosphere, mesosphere, and lower thermosphere. The new MOZART tropospheric chemistry scheme (T1) has a number of updates over the previous version (MOZART-4) in CESM, including improvements to the oxidation of isoprene and terpenes, organic nitrate speciation, and aromatic speciation and oxidation and thus improved representation of ozone and secondary organic aerosol precursors. An evaluation of the present-day simulations of CESM2 being provided for Climate Model Intercomparison Project round 6 (CMIP6) is presented. These simulations, using the anthropogenic and biomass burning emissions from the inventories specified for CMIP6, as well as online calculation of emissions of biogenic compounds, lightning NO, dust, and sea salt, indicate an underestimate of anthropogenic emissions of a variety of compounds, including carbon monoxide and hydrocarbons. The simulation of surface ozone in the southeast United States is improved over previous model versions, largely due to the improved representation of reactive nitrogen and organic nitrate compounds resulting in a lower ozone production rate than in CESM1 but still overestimates observations in summer. The simulation of tropospheric ozone agrees well with ozonesonde observations in many parts of the globe. The comparison of NOx and PAN to aircraft observations indicates the model simulates the nitrogen budget well.}, annote = {https://doi.org/10.1029/2019MS001882}, author = {Emmons, Louisa K and Schwantes, Rebecca H and Orlando, John J and Tyndall, Geoff and Kinnison, Douglas and Lamarque, Jean-Fran{\c{c}}ois and Marsh, Daniel and Mills, Michael J and Tilmes, Simone and Bardeen, Charles and Buchholz, Rebecca R and Conley, Andrew and Gettelman, Andrew and Garcia, Rolando and Simpson, Isobel and Blake, Donald R and Meinardi, Simone and P{\'{e}}tron, Gabrielle}, doi = {https://doi.org/10.1029/2019MS001882}, issn = {1942-2466}, journal = {Journal of Advances in Modeling Earth Systems}, keywords = {atmospheric chemistry,chemical mechanism,tropospheric ozone}, month = {apr}, number = {4}, pages = {e2019MS001882}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{The Chemistry Mechanism in the Community Earth System Model Version 2 (CESM2)}}, url = {https://doi.org/10.1029/2019MS001882}, volume = {12}, year = {2020} } @article{Engardt2017, abstract = {As a contribution to an EU project which dealt with the effects of climate change, air pollution impacts and ecosystems, two different atmospheric chemical transport models were used to simulate the depositions of acidifying and eutrophying pollutants over Europe for the period 1900–2050. Given the unavoidable uncertainties in the historical inputs to these simulations (emissions, meteorology), we generated a new and unique data-set for the purposes of model evaluation; comprising data from the European Air Chemistry Network (EACN) in operation from 1955 to early 1980s and more recent data from the EMEP monitoring network. The two models showed similar and reasonable skills in reproducing both the EACN and EMEP observational data although the MATCH model consistently simulates higher concentrations and depositions than the EMEP model. To further assess the models' ability to reproduce the long-term trend in sulphur and nitrogen deposition we compared modelled concentrations of major ions in precipitation with data extracted from a glacier in the European Alps. While, the shape and timing of the nss-sulphate data agrees reasonably, the ice core data indicate persistently high nitrogen concentrations of oxidised and reduced nitrogen after the 1980s which does not correspond to the model simulations or data from Western Europe in the EMEP monitoring network. This study concludes that nss-sulphate deposition to Europe was already clearly elevated in the year 1900, but has now (mid-2010s) decreased to about 70{\%} of what it was at the beginning of the last century. The deposition of oxidised nitrogen to Europe peaked during the 1980s but has since decreased to half of its maximum value; still it is 3–4 times higher than in the year 1900. The annual deposition of reduced nitrogen to Europe is currently more than two times as high as the conditions in the year 1900.}, author = {Engardt, Magnuz and Simpson, David and Schwikowski, Margit and Granat, Lennart}, doi = {10.1080/16000889.2017.1328945}, issn = {1600-0889}, journal = {Tellus B: Chemical and Physical Meteorology}, keywords = {EACN,ECLAIRE,EMEP,European Air Chemistry Network,MATCH}, month = {jan}, number = {1}, pages = {1328945}, publisher = {Taylor {\&} Francis}, title = {{Deposition of sulphur and nitrogen in Europe 1900–2050. Model calculations and comparison to historical observations}}, url = {https://www.tandfonline.com/doi/full/10.1080/16000889.2017.1328945}, volume = {69}, year = {2017} } @incollection{Engel2018, address = {Geneva, Switzerland}, author = {Engel, A. and Rigby, M. (Lead Authors) and Burkholder, J.B. and Fernandez, R.P. and Froidevaux, L. and Hall, B.D. and Hossaini, R. and Saito, T. and Vollmer, M.K. and Yao, B.}, booktitle = {Scientific Assessment of Ozone Depletion: 2018}, doi = {https://csl.noaa.gov/assessments/ozone/2018/downloads/}, isbn = {978-1-7329317-1-8}, pages = {1.1--1.87}, publisher = {World Meteorological Organization (WMO)}, series = {Global Ozone Research and Monitoring Project – Report No. 58}, title = {{Update on Ozone-Depleting Substances (ODSs) and Other Gases of Interest to the Montreal Protocol}}, url = {https://csl.noaa.gov/assessments/ozone/2018/downloads/}, year = {2018} } @techreport{EPA2019, address = {Washington, DC, USA}, author = {EPA}, doi = {https://www.epa.gov/sites/production/files/2019-09/documents/epa_non-co2_greenhouse_gases_rpt-epa430r19010.pdf}, isbn = {EPA-430-R-19-010}, month = {oct}, pages = {84}, publisher = {United States Environmental Protection Agency (EPA), Office of Atmospheric Programs (6207A)}, series = {EPA-430-R-19-010}, title = {{Global Non-CO2 Greenhouse Gas Emission Projections {\&} Mitigation: 2015–2020}}, url = {https://www.epa.gov/sites/production/files/2019-09/documents/epa{\_}non-co2{\_}greenhouse{\_}gases{\_}rpt-epa430r19010.pdf}, year = {2019} } @article{Erisman2008, author = {Erisman, Jan Willem and Sutton, Mark A. and Galloway, James and Klimont, Zbigniew and Winiwarter, Wilfried}, doi = {10.1038/ngeo325}, issn = {1752-0894}, journal = {Nature Geoscience}, month = {oct}, number = {10}, pages = {636--639}, title = {{How a century of ammonia synthesis changed the world}}, url = {http://www.nature.com/articles/ngeo325}, volume = {1}, year = {2008} } @article{Etiope2009, author = {Etiope, Giuseppe and Ciccioli, Paolo}, doi = {10.1126/science.1165904}, issn = {00368075}, journal = {Science}, number = {5913}, pages = {478}, title = {{Earth's degassing: A missing ethane and propane source}}, volume = {323}, year = {2009} } @article{Evan2014, abstract = {Aeolian dust is a key aspect of the climate system. Dust can modify the Earth's energy budget, provide long-range transport of nutrients, and influence land surface processes via erosion. Consequently, effective modeling of the climate system, particularly at regional scales, requires a reasonably accurate representation of dust emission, transport, and deposition. Here we evaluate African dust in 23 state-of-the-art global climate models used in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. We find that all models fail to reproduce basic aspects of dust emission and transport over the second half of the twentieth century. The models systematically underestimate dust emission, transport, and optical depth, and year-to-year changes in these properties bear little resemblance to observations. These findings cast doubt on the ability of these models to simulate the regional climate and the response of African dust to future climate change.}, author = {Evan, Amato T. and Flamant, Cyrille and Fiedler, Stephanie and Doherty, Owen}, doi = {10.1002/2014GL060545}, issn = {19448007}, journal = {Geophysical Research Letters}, month = {aug}, number = {16}, pages = {5996--6001}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{An analysis of aeolian dust in climate models}}, volume = {41}, year = {2014} } @article{Evans2017, abstract = {This study presents a comprehensive review of estimated black carbon (BC) emissions in Russia from a range of studies. Russia has an important role regarding BC emissions given the extent of its territory above the Arctic Circle, where BC emissions have a particularly pronounced effect on the climate. We assess underlying methodologies and data sources for each major emissions source based on their level of detail, accuracy and extent to which they represent current conditions. We then present reference values for each major emissions source. In the case of flaring, the study presents new estimates drawing on data on Russia's associated petroleum gas and the most recent satellite data on flaring. We also present estimates of organic carbon (OC) for each source, either based on the reference studies or from our own calculations. In addition, the study provides uncertainty estimates for each source. Total BC emissions are estimated at 688 Gg in 2014, with an uncertainty range 401 Gg-1453 Gg, while OC emissions are 9224 Gg with uncertainty ranging between 5596 Gg and 14,736 Gg. Wildfires dominated and contributed about 83{\%} of the total BC emissions: however, the effect on radiative forcing is mitigated in part by OC emissions. We also present an adjusted estimate of Arctic forcing from Russia's BC and OC emissions. In recent years, Russia has pursued policies to reduce flaring and limit particulate emissions from on-road transport, both of which appear to significantly contribute to the lower emissions and forcing values found in this study.}, author = {Evans, Meredydd and Kholod, Nazar and Kuklinski, Teresa and Denysenko, Artur and Smith, Steven J. and Staniszewski, Aaron and Hao, Wei Min and Liu, Liang and Bond, Tami C.}, doi = {10.1016/j.atmosenv.2017.05.026}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Black carbon,Emission inventory,Organic carbon,Radiative forcing,Russia}, pages = {9--21}, title = {{Black carbon emissions in Russia: A critical review}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231017303278}, volume = {163}, year = {2017} } @article{Evans2016, abstract = {Observations show that Australian dust activity varies by a factor of 4 on decadal timescales. General circulation models, however, typically fail to simulate this variability. Here we introduce a new dust parameterization into the NOAA/Geophysical Fluid Dynamics Laboratory climate model CM3 that represents land surface processes controlling dust sources including soil water and ice, snow cover, vegetation characteristics, and land type. In an additional novel step, we couple this new dust parameterization to the dynamic vegetation model LM3. In Australia, the new parameterization amplifies the magnitude and timescale of dust variability and better simulates the El Ni{\~{n}}o–Southern Oscillation-dust relationship by more than doubling its strength. We attribute these improvements primarily to the slow response time of vegetation to precipitation anomalies and show that vegetation changes account for approximately 50{\%} of enhanced dust emission during El Ni{\~{n}}o events. The amplified dust leads to radiative forcing over Australia greater than −1 and −20 W/m2 at top of atmosphere and surface, respectively.}, author = {Evans, Stuart and Ginoux, Paul and Malyshev, Sergey and Shevliakova, Elena}, doi = {10.1002/2016GL071016}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {Australia,ENSO,dust emission,dust variability,dynamic vegetation,parameterization}, number = {22}, pages = {11823--11830}, title = {{Climate-vegetation interaction and amplification of Australian dust variability}}, volume = {43}, year = {2016} } @article{Eyring2010, author = {Eyring, Veronika and Isaksen, Ivar S.A. and Berntsen, Terje and Collins, William J. and Corbett, James J. and Endresen, Oyvind and Grainger, Roy G. and Moldanova, Jana and Schlager, Hans and Stevenson, David S.}, doi = {10.1016/j.atmosenv.2009.04.059}, issn = {13522310}, journal = {Atmospheric Environment}, month = {dec}, number = {37}, pages = {4735--4771}, title = {{Transport impacts on atmosphere and climate: Shipping}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1352231009003379}, volume = {44}, year = {2010} } @article{acp-19-8591-2019, abstract = {A total of 16 global chemistry transport models and general circulation models have participated in this study; 14 models have been evaluated with regard to their ability to reproduce the near-surface observed number concentration of aerosol particles and cloud condensation nuclei (CCN), as well as derived cloud droplet number concentration (CDNC). Model results for the period 2011–2015 are compared with aerosol measurements (aerosol particle number, CCN and aerosol particle composition in the submicron fraction) from nine surface stations located in Europe and Japan. The evaluation focuses on the ability of models to simulate the average across time state in diverse environments and on the seasonal and short-term variability in the aerosol properties. There is no single model that systematically performs best across all environments represented by the observations. Models tend to underestimate the observed aerosol particle and CCN number concentrations, with average normalized mean bias (NMB) of all models and for all stations, where data are available, of −24 {\%} and −35 {\%} for particles with dry diameters {\textgreater}50 and {\textgreater}120 nm, as well as −36 {\%} and −34 {\%} for CCN at supersaturations of 0.2 {\%} and 1.0 {\%}, respectively. However, they seem to behave differently for particles activating at very low supersaturations ({\textless}0.1 {\%}) than at higher ones. A total of 15 models have been used to produce ensemble annual median distributions of relevant parameters. The model diversity (defined as the ratio of standard deviation to mean) is up to about 3 for simulated N3 (number concentration of particles with dry diameters larger than 3 nm) and up to about 1 for simulated CCN in the extra-polar regions. A global mean reduction of a factor of about 2 is found in the model diversity for CCN at a supersaturation of 0.2 {\%} (CCN0.2) compared to that for N3, maximizing over regions where new particle formation is important. An additional model has been used to investigate potential causes of model diversity in CCN and bias compared to the observations by performing a perturbed parameter ensemble (PPE) accounting for uncertainties in 26 aerosol-related model input parameters. This PPE suggests that biogenic secondary organic aerosol formation and the hygroscopic properties of the organic material are likely to be the major sources of CCN uncertainty in summer, with dry deposition and cloud processing being dominant in winter. Models capture the relative amplitude of the seasonal variability of the aerosol particle number concentration for all studied particle sizes with available observations (dry diameters larger than 50, 80 and 120 nm). The short-term persistence time (on the order of a few days) of CCN concentrations, which is a measure of aerosol dynamic behavior in the models, is underestimated on average by the models by 40 {\%} during winter and 20 {\%} in summer. In contrast to the large spread in simulated aerosol particle and CCN number concentrations, the CDNC derived from simulated CCN spectra is less diverse and in better agreement with CDNC estimates consistently derived from the observations (average NMB −13 {\%} and −22 {\%} for updraft velocities 0.3 and 0.6 m s−1, respectively). In addition, simulated CDNC is in slightly better agreement with observationally derived values at lower than at higher updraft velocities (index of agreement 0.64 vs. 0.65). The reduced spread of CDNC compared to that of CCN is attributed to the sublinear response of CDNC to aerosol particle number variations and the negative correlation between the sensitivities of CDNC to aerosol particle number concentration (∂Nd/∂Na) and to updraft velocity (∂Nd/∂w). Overall, we find that while CCN is controlled by both aerosol particle number and composition, CDNC is sensitive to CCN at low and moderate CCN concentrations and to the updraft velocity when CCN levels are high. Discrepancies are found in sensitivities ∂Nd/∂Na and ∂Nd/∂w; models may be predisposed to be too “aerosol sensitive” or “aerosol insensitive” in aerosol–cloud–climate interaction studies, even if they may capture average droplet numbers well. This is a subtle but profound finding that only the sensitivities can clearly reveal and may explain inter-model biases on the aerosol indirect effect.}, author = {Fanourgakis, G S and Kanakidou, M and Nenes, A and Bauer, S E and Bergman, T and Carslaw, K S and Grini, A and Hamilton, D S and Johnson, J S and Karydis, V A and Kirkev{\aa}g, A and Kodros, J K and Lohmann, U and Luo, G and Makkonen, R and Matsui, H and Neubauer, D and Pierce, J R and Schmale, J and Stier, P and Tsigaridis, K and van Noije, T and Wang, H and Watson-Parris, D and Westervelt, D M and Yang, Y and Yoshioka, M and Daskalakis, N and Decesari, S and Gysel-Beer, M and Kalivitis, N and Liu, X and Mahowald, N M and Myriokefalitakis, S and Schr{\"{o}}dner, R and Sfakianaki, M and Tsimpidi, A P and Wu, M and Yu, F}, doi = {10.5194/acp-19-8591-2019}, journal = {Atmospheric Chemistry and Physics}, number = {13}, pages = {8591--8617}, title = {{Evaluation of global simulations of aerosol particle and cloud condensation nuclei number, with implications for cloud droplet formation}}, url = {https://acp.copernicus.org/articles/19/8591/2019/}, volume = {19}, year = {2019} } @article{FAVEZ20081503, abstract = {Bulk aerosols sampled on a weekly basis at two Cairo (Egypt) urban sites from January 2003 to May 2006 were analysed for their chemical composition of major aerosol species (elemental carbon, water soluble/insoluble organic carbon, nitrate, sulphate, ammonium, chloride, sodium and calcium). Data subsequently obtained constitute one of the longest and more detailed dataset related to Cairo aerosols, and offer the opportunity to investigate seasonal trends. Dust aerosols (derived from calcium measurements) displayed maximum concentrations in spring and winter, due to frequent dust storms, but also high background concentration levels (∼50$\mu$gm−3) all year long. Within these particles, about 40{\%} on average of Ca2+ was found to be associated with SO42−, NO3− and/or Cl−, pointing out “dust anthropization” processes and their subsequent climatic impact on a regional scale. Seasonal variations of non-dust aerosols, equally distributed between carbonaceous aerosols and ions, were also observed, with concentrations of the order of 100$\mu$gm−3 in autumn and winter, and of 60$\mu$gm−3 in spring and summer. High concentration levels of non-sea-salt chloride (up to 15$\mu$gm−3 on a monthly basis), likely of industrial origin, were observed in autumn and winter. During the autumn “Black Cloud” event, biomass burning aerosols originating from rice straw burning in the Nile Delta have shown to account for 12{\%}, 35{\%} and 50{\%} of Cairo EC, WIOC and WSOC mass concentrations, respectively. Finally, relatively low WSOC/OC ratios (∼1/3) were obtained all the year long, calling for more investigation on the water-solubility of organic aerosols originating from the burning of agricultural waste, and on that of secondary organic aerosols formed in dry urban atmospheres.}, author = {Favez, Olivier and Cachier, H{\'{e}}l{\`{e}}ne and Sciare, Jean and Alfaro, St{\'{e}}phane C and El-Araby, Tarek M and Harhash, Maha A and Abdelwahab, Magdy M}, doi = {https://doi.org/10.1016/j.atmosenv.2007.10.081}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Aerosol chemical composition,Biomass burning,Dust material,Greater Cairo,Water soluble organic carbon}, number = {7}, pages = {1503--1516}, title = {{Seasonality of major aerosol species and their transformations in Cairo megacity}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231007010175}, volume = {42}, year = {2008} } @article{McCollum2018, abstract = {Low-carbon investments are necessary for driving the energy system transformation that is called for by both the Paris Agreement and Sustainable Development Goals. Improving understanding of the scale and nature of these investments under diverging technology and policy futures is therefore of great importance to decision makers. Here, using six global modelling frameworks, we show that the pronounced reallocation of the investment portfolio required to transform the energy system will not be initiated by the current suite of countries' Nationally Determined Contributions. Charting a course toward ‘well below 2 °C' instead sees low-carbon investments overtaking fossil investments globally by around 2025 or before and growing thereafter. Pursuing the 1.5 °C target demands a marked upscaling in low-carbon capital beyond that of a 2 °C-consistent future. Actions consistent with an energy transformation would increase the costs of achieving the goals of energy access and food security, but reduce the costs of achieving air-quality goals.}, author = {Fay, Marianne and Poblete-Cazenave, Miguel and Kriegler, Elmar and Despr{\'{e}}s, Jacques and Pachauri, Shonali and Riahi, Keywan and Huppmann, Daniel and Fujimori, Shinichiro and Busch, Sebastian and Rao, Narasimha and McCollum, David L. and Schmitz, Andreas and Parkinson, Simon and Nicolas, Claire and de Boer, Harmen-Sytze and Emmerling, Johannes and Iyer, Gokul and Drouet, Laurent and Zhou, Wenji and Harmsen, Mathijs and Fricko, Oliver and Bertram, Christoph and Gidden, Matthew and Krey, Volker and van Vuuren, Detlef and Schoepp, Wolfgang and Bosetti, Valentina and Rozenberg, Julie and Rafaj, Peter}, doi = {10.1038/s41560-018-0179-z}, issn = {2058-7546}, journal = {Nature Energy}, number = {7}, pages = {589--599}, title = {{Energy investment needs for fulfilling the Paris Agreement and achieving the Sustainable Development Goals}}, volume = {3}, year = {2018} } @article{Felzer2007, author = {Felzer, Benjamin S. and Cronin, Timothy and Reilly, John M. and Melillo, Jerry M. and Wang, Xiaodong}, doi = {10.1016/j.crte.2007.08.008}, issn = {16310713}, journal = {Comptes Rendus Geoscience}, month = {oct}, number = {11-12}, pages = {784--798}, title = {{Impacts of ozone on trees and crops}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S163107130700226X}, volume = {339}, year = {2007} } @article{Feng2020, abstract = {Abstract. Spatially distributed anthropogenic and open burning emissions are fundamental data needed by Earth system models. We describe the methods used for generating gridded data sets produced for use by the modelling community, particularly for the Coupled Model Inter-comparison Project Phase 6. The development of three sets of gridded data for historical open burning, historical anthropogenic, and future scenarios were coordinated to produce consistent data over 1750{\&}ndash;2100. Historical data up to 2014 were provided with annual resolution and future scenario data in 10-year intervals. Emissions are provided on a sectoral basis, along with additional files for speciated non-Methane Volatile Organic Compounds (NMVOCs). An automated framework was developed to produce these datasets to ensure that they are reproducible and facilitate future improvements. We discuss the methodologies used to produce these data along with limitations and potential for future work.}, author = {Feng, Leyang and Smith, Steve J and Braun, Caleb and Crippa, Monica and Gidden, Matthew J. and Hoesly, Rachel and Klimont, Zbigniew and van Marle, Margreet and van den Berg, Maarten and van der Werf, Guido R.}, doi = {10.5194/gmd-13-461-2020}, issn = {1991-962X}, journal = {Geoscientific Model Development}, number = {2}, pages = {461--482}, title = {{Gridded Emissions for CMIP6}}, volume = {13}, year = {2020} } @article{Feng2009, abstract = {Meta-analysis was conducted to quantitatively assess the effects of rising ozone concentrations ([O3]) on yield and yield components of major food crops: potato, barley, wheat, rice, bean and soybean in 406 experimental observations. Yield loss of the crops under current and future [O3] was expressed relative to the yield under base [O3] (≤26ppb). With potato, current [O3] (31–50ppb) reduced the yield by 5.3{\%}, and it reduced the yield of barley, wheat and rice by 8.9{\%}, 9.7{\%} and 17.5{\%}, respectively. In bean and soybean, the yield losses were 19.0{\%} and 7.7{\%}, respectively. Compared with yield loss at current [O3], future [O3] (51–75ppb) drove a further 10{\%} loss in yield of soybean, wheat and rice, and 20{\%} loss in bean. Mass of individual grain, seed, or tuber was often the major cause of the yield loss at current and future [O3], whereas other yield components also contributed to the yield loss in some cases. No significant difference was found between the responses in crops grown in pots and those in the ground for any yield parameters. The ameliorating effect of elevated [CO2] was significant in the yields of wheat and potato, and the individual grain weight in wheat exposed to future [O3]. These findings confirm the rising [O3] as a threat to food security for the growing global population in this century.}, author = {Feng, Zhaozhong and Kobayashi, Kazuhiko}, doi = {10.1016/j.atmosenv.2008.11.033}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Barley,Bean,Ozone,Potato,Rice,Soybean,Wheat}, number = {8}, pages = {1510--1519}, title = {{Assessing the impacts of current and future concentrations of surface ozone on crop yield with meta-analysis}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231008010972}, volume = {43}, year = {2009} } @article{FENG20063983, abstract = {Organic matter in PM2.5 collected in 2002 and 2003 from three megacities in different climatic zones in China, Beijing (40°N), Shanghai (31°N) and Guangzhou (23°N), was characterized. The focus was on solvent-extractable organic compounds (SEOC), which were used to identify the influences of geography, variation of the season, sources and transport on the concentration and distribution of these homologues. Organic carbon, elemental carbon, and water-soluble organic carbon concentrations were analyzed only for the substantiation of the SEOC findings. Analysis of the fossil fuel residues and the plant wax components in n-alkanes, PAHs, fatty acids and n-alkanols allowed the identification of anthropogenic (coal and petroleum combustion processes, and kitchen emissions) and biogenic (vegetation and microbial) sources. The influence of temperature on the distribution of the SEOC was exemplified by the negative correlation between the relative concentrations of the semivolatile homologues (alkanes and PAHs) and ambient temperature. This is attributable to gas–particle partitioning. Indirectly, ambient temperature dictates the type of vegetation that can grow in a geographical zone. This would influence the distribution of the plant waxes, and finally, it plays a role in the aerosol loading due to energy usage.}, author = {Feng, Jialiang and Hu, Min and Chan, Chak K and Lau, P S and Fang, Ming and He, Lingyan and Tang, Xiaoyan}, doi = {https://doi.org/10.1016/j.atmosenv.2006.02.017}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Beijing,China,Climatic zone,Guangzhou,OC/EC,PM,SEOC,Shanghai,WSOC}, number = {21}, pages = {3983--3994}, title = {{A comparative study of the organic matter in PM2.5 from three Chinese megacities in three different climatic zones}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231006002159}, volume = {40}, year = {2006} } @article{Ferek2000, abstract = {Although drizzle was a relatively infrequent occurrence during the Monterey Area Ship Track study, diverse measurements from several sources produced data signals consistent with a reduction in drizzle drops in stratus clouds affected by ship effluents. Concurrent increases in liquid water in the cloud droplet size range, due to redistribution from the drizzle mode, were not always observed, possibly because of the relatively small and often negligible amounts of water in the drizzle mode. Significant changes in cloud droplet size distribution, as well as reductions in drizzle flux and concentrations of drops {\textgreater}50-$\mu$m radius, were observed in ship tracks when drizzle was more uniformly present in the ambient cloud. Radiometric measurements showed that increased droplet concentrations in ship tracks, which resulted in reduced droplet sizes, can significantly alter the liquid water path. Radar observations indicated that the reduced reflectivities of ship tracks compared with ambient clouds may be due to reductions in the concentrations of larger drops and/or reductions in the sizes of these drops. Two independent modeling studies showed decreases in drizzle in ship tracks due to the presence of smaller cloud droplets that reduced the efficiency of drop growth by collisions.}, author = {Ferek, Ronald J. and Garrett, Timothy and Hobbs, Peter V. and Strader, Scott and Johnson, Doug and Taylor, Jonathan P. and Nielsen, Kurt and Ackerman, Andrew S. and Kogan, Yefim and Liu, Qingfu and Albrecht, Bruce A. and Babb, David}, doi = {10.1175/1520-0469(2000)057<2707:DSIST>2.0.CO;2}, issn = {0022-4928}, journal = {Journal of the Atmospheric Sciences}, month = {aug}, number = {16}, pages = {2707--2728}, title = {{Drizzle Suppression in Ship Tracks}}, url = {http://journals.ametsoc.org/doi/10.1175/1520-0469(2000)057{\%}3C2707:DSIST{\%}3E2.0.CO;2}, volume = {57}, year = {2000} } @article{Ferraro2011, abstract = {A fixed dynamical heating model is used to investigate the pattern of zonal-mean stratospheric temperature change resulting from geoengineering with aerosols composed of sulfate, titania, limestone and soot. Aerosol always heats the tropical lower stratosphere, but at the poles the response can be either heating, cooling, or neutral. The sign of the change in stratospheric Pole-Equator temperature difference depends on aerosol type, size and season. This has implications for modeling geoengineering impacts and the response of the stratospheric circulation. Copyright {\textcopyright} 2011 by the American Geophysical Union.}, author = {Ferraro, A. J. and Highwood, E. J. and Charlton-Perez, A. J.}, doi = {10.1029/2011GL049761}, issn = {00948276}, journal = {Geophysical Research Letters}, month = {dec}, number = {24}, pages = {L24706}, title = {{Stratospheric heating by potential geoengineering aerosols}}, url = {http://doi.wiley.com/10.1029/2011GL049761}, volume = {38}, year = {2011} } @article{Fiebig2014, abstract = {In the last 30 years, diesel engines have made rapid progress to increased efficiency, environmental protection and comfort for both light- and heavy-duty applications. The technical developments include all issues from fuel to combustion process to exhaust gas aftertreatment. This paper provides a comprehensive summary of the available literature regarding technical developments and their impact on the reduction of pollutant emission. This includes emission legislation, fuel quality, diesel engine- and exhaust gas aftertreatment technologies, as well as particulate composition, with a focus on the mass-related particulate emission of on-road vehicle applications. Diesel engine technologies representative of real-world on-road applications will be highlighted.}, author = {Fiebig, Michael and Wiartalla, Andreas and Holderbaum, Bastian and Kiesow, Sebastian}, doi = {10.1186/1745-6673-9-6}, issn = {1745-6673}, journal = {Journal of Occupational Medicine and Toxicology}, month = {mar}, number = {1}, pages = {6}, title = {{Particulate emissions from diesel engines: correlation between engine technology and emissions}}, url = {https://doi.org/10.1186/1745-6673-9-6}, volume = {9}, year = {2014} } @article{Finney2016a, abstract = {Results from an ensemble of models are used to investigate the response of lightning nitrogen oxide emissions to climate change and the consequent impacts on ozone production. Most models generate lightning using a parameterization based on cloud top height. With this approach and a present-day global emission of 5 TgN, we estimate a linear response with respect to changes in global surface temperature of +0.44 ± 0.05 TgN K−1. However, two models using alternative approaches give +0.14 and −0.55 TgN K−1 suggesting that the simulated response is highly dependent on lightning parameterization. Lightning NOx is found to have an ozone production efficiency of 6.5 ± 4.7 times that of surface NOx sources. This wide range of efficiencies across models is partly due to the assumed vertical distribution of the lightning source and partly to the treatment of nonmethane volatile organic compound (NMVOC) chemistry. Careful consideration of the vertical distribution of emissions is needed, given its large influence on ozone production.}, annote = {From Duplicate 1 (Response of lightning NOx emissions and ozone production to climate change: Insights from the Atmospheric Chemistry and Climate Model Intercomparison Project - Finney, D L; Doherty, R M; Wild, O; Young, P J; Butler, A) Times Cited: 11 Young, Paul/E-8739-2010; Finney, Declan/B-1473-2013; Wild, Oliver/A-4909-2009 Young, Paul/0000-0002-5608-8887; Finney, Declan/0000-0002-3334-6935; Wild, Oliver/0000-0002-6227-7035 0 11 1944-8007 From Duplicate 2 (Response of lightning NOx emissions and ozone production to climate change: Insights from the Atmospheric Chemistry and Climate Model Intercomparison Project - Finney, D L; Doherty, R M; Wild, O; Young, P J; Butler, A) From Duplicate 2 (Response of lightning NOx emissions and ozone production to climate change: Insights from the Atmospheric Chemistry and Climate Model Intercomparison Project - Finney, D L; Doherty, R M; Wild, O; Young, P J; Butler, A) Times Cited: 11 Young, Paul/E-8739-2010; Finney, Declan/B-1473-2013; Wild, Oliver/A-4909-2009 Young, Paul/0000-0002-5608-8887; Finney, Declan/0000-0002-3334-6935; Wild, Oliver/0000-0002-6227-7035 0 11 1944-8007}, author = {Finney, D. L. and Doherty, R. M. and Wild, O. and Young, P. J. and Butler, A.}, doi = {10.1002/2016GL068825}, isbn = {0094-8276}, issn = {00948276}, journal = {Geophysical Research Letters}, keywords = {ACCMIP,climate change,lightning,linear mixed effect model,ozone}, number = {10}, pages = {5492--5500}, title = {{Response of lightning NOx emissions and ozone production to climate change: Insights from the Atmospheric Chemistry and Climate Model Intercomparison Project}}, url = {http://doi.wiley.com/10.1002/2016GL068825}, volume = {43}, year = {2016} } @article{Finney2018a, abstract = {Lightning strongly influences atmospheric chemistry1–3, and impacts the frequency of natural wildfires 4 . Most previous studies project an increase in global lightning with climate change over the coming century1,5–7, but these typically use parameterizations of lightning that neglect cloud ice fluxes, a component generally considered to be fundamental to thunderstorm charging 8 . As such, the response of lightning to climate change is uncertain. Here, we compare lightning projections for 2100 using two parameterizations: the widely used cloud-top height (CTH) approach 9 , and a new upward cloud ice flux (IFLUX) approach 10 that overcomes previous limitations. In contrast to the previously reported global increase in lightning based on CTH, we find a 15{\%} decrease in total lightning flash rate with IFLUX in 2100 under a strong global warming scenario. Differences are largest in the tropics, where most lightning occurs, with implications for the estimation of future changes in tropospheric ozone and methane, as well as differences in their radiative forcings. These results suggest that lightning schemes more closely related to cloud ice and microphysical processes are needed to robustly estimate future changes in lightning and atmospheric composition.}, author = {Finney, Declan L. and Doherty, Ruth M. and Wild, Oliver and Stevenson, David S. and MacKenzie, Ian A. and Blyth, Alan M.}, doi = {10.1038/s41558-018-0072-6}, isbn = {1758-6798}, issn = {17586798}, journal = {Nature Climate Change}, number = {3}, pages = {210--213}, title = {{A projected decrease in lightning under climate change}}, volume = {8}, year = {2018} } @article{Finney2016b, abstract = {A lightning parametrisation based on upward cloud ice flux is implemented in a chemistry-climate model (CCM) for the first time. The UK Chemistry and Aerosols model is used to study the impact of these lightning nitric oxide (NO) emissions on ozone. Comparisons are then made between the new ice flux parametrisation and the commonly-used, cloud-top height parametrisation. The ice flux approach improves the simulation of lightning and the temporal correlations with ozone sonde measurements in the middle and upper troposphere. Peak values of ozone in these regions are attributed to high lightning NO emissions. The ice flux approach reduces the overestimation of tropical lightning apparent in this CCM when using the cloud-top approach. This results in less emission in the tropical upper troposphere and more in the extratropics when using the ice flux scheme. In the tropical upper troposphere the reduction in ozone concentration is around 5{\&}ndash;10 {\%}. Surprisingly, there is only a small reduction in tropospheric ozone burden when using the ice flux approach. The greatest absolute change in ozone burden is found in the lower stratosphere suggesting that much of the ozone produced in the upper troposphere is transported to higher altitudes. Major differences in the frequency distribution of flash rates for the two approaches are found. The cloud-top height scheme has lower maximum flash rates and more mid-range flash rates than the ice flux scheme. The initial O{\textless}sub{\textgreater}x{\textless}/sub{\textgreater} (odd oxygen species) production associated with the frequency distribution of continental lightning is analysed to show that higher flash rates are less efficient at producing O{\textless}sub{\textgreater}x{\textless}/sub{\textgreater} {\&}ndash; low flash rates produce around 10 times more O{\textless}sub{\textgreater}x{\textless}/sub{\textgreater} per flash than high-end flash rates. We find that the newly implemented lightning scheme performs favourably compared to the cloud-top scheme with respect to simulation of lightning and tropospheric ozone. This alternative lightning scheme shows spatial and temporal differences in ozone chemistry which may have implications for comparison on models and observations and for simulation of future changes in tropospheric ozone.}, author = {Finney, D. L. and Doherty, R. M. and Wild, O. and Abraham, N. L.}, doi = {10.5194/acp-16-7507-2016}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {12}, pages = {7507--7522}, title = {{The impact of lightning on tropospheric ozone chemistry using a new global lightning parametrisation}}, volume = {16}, year = {2016} } @article{acp-16-11497-2016, author = {Fioletov, V E and McLinden, C A and Krotkov, N and Li, C and Joiner, J and Theys, N and Carn, S and Moran, M D}, doi = {10.5194/acp-16-11497-2016}, journal = {Atmospheric Chemistry and Physics}, number = {18}, pages = {11497--11519}, title = {{A global catalogue of large SO2 sources and emissions derived from the Ozone Monitoring Instrument}}, url = {https://www.atmos-chem-phys.net/16/11497/2016/}, volume = {16}, year = {2016} } @article{Fiore2015b, abstract = {Multiple linkages connect air quality and climate change. Many air pollutant sources also emit carbon dioxide (CO2), the dominant anthropogenic greenhouse gas (GHG). The two main contributors to non-attainment of U.S. ambient air quality standards, ozone (O3) and particulate matter (PM), interact with radiation, forcing climate change. PM warms by absorbing sunlight (e.g., black carbon) or cools by scattering sunlight (e.g., sulfates) and interacts with clouds; these radiative and microphysical interactions can induce changes in precipitation and regional circulation patterns. Climate change is expected to degrade air quality in many polluted regions by changing air pollution meteorology (ventilation and dilution), precipitation and other removal processes, and by triggering some amplifying responses in atmospheric chemistry and in anthropogenic and natural sources. Together, these processes shape distributions and extreme episodes of O3 and PM. Global modeling indicates that as air pollution programs reduce SO2 to meet health and other air quality goals, near-term warming accelerates due to “unmasking” of warming induced by rising CO2. Air pollutant controls on CH4, a potent GHG and precursor to global O3 levels, and on sources with high black carbon (BC) to organic carbon (OC) ratios could offset near-term warming induced by SO2 emission reductions, while reducing global background O3 and regionally high levels of PM. Lowering peak warming requires decreasing atmospheric CO2, which for some source categories would also reduce co-emitted air pollutants or their precursors. Model projections for alternative climate and air quality scenarios indicate a wide range for U.S. surface O3 and fine PM, although regional projections may be confounded by interannual to decadal natural climate variability. Continued implementation of U.S. NOx emission controls guards against rising pollution levels triggered either by climate change or by global emission growth. Improved accuracy and trends in emission inventories are critical for accountability analyses of historical and projected air pollution and climate mitigation policies.}, annote = {Fiore, Arlene M Naik, Vaishali Leibensperger, Eric M eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. Review J Air Waste Manag Assoc. 2015 Jun;65(6):645-85. doi: 10.1080/10962247.2015.1040526.}, author = {Fiore, Arlene M. and Naik, Vaishali and Leibensperger, Eric M.}, doi = {10.1080/10962247.2015.1040526}, edition = {2015/05/16}, isbn = {1096-2247}, issn = {1096-2247}, journal = {Journal of the Air {\&} Waste Management Association}, keywords = {*Climate Change,Air Pollutants/*analysis,Air Pollution/*analysis,Ozone/*analysis,Particulate Matter/*analysis,United States}, number = {6}, pages = {645--685}, pmid = {25976481}, title = {{Air Quality and Climate Connections}}, url = {http://www.tandfonline.com/doi/full/10.1080/10962247.2015.1040526}, volume = {65}, year = {2015} } @article{Fiore2012, abstract = {Emissions of air pollutants and their precursors determine regional air quality and can alter climate. Climate change can perturb the long-range transport, chemical processing, and local meteorology that influence air pollution. We review the implications of projected changes in methane (CH4), ozone precursors (O3), and aerosols for climate (expressed in terms of the radiative forcing metric or changes in global surface temperature) and hemispheric-to-continental scale air quality. Reducing the O3 precursor CH4 would slow near-term warming by decreasing both CH4 and tropospheric O3. Uncertainty remains as to the net climate forcing from anthropogenic nitrogen oxide (NOx) emissions, which increase tropospheric O3 (warming) but also increase aerosols and decrease CH4 (both cooling). Anthropogenic emissions of carbon monoxide (CO) and non-CH4 volatile organic compounds (NMVOC) warm by increasing both O3 and CH4. Radiative impacts from secondary organic aerosols (SOA) are poorly understood. Black carbon emission controls, by reducing the absorption of sunlight in the atmosphere and on snow and ice, have the potential to slow near-term warming, but uncertainties in coincident emissions of reflective (cooling) aerosols and poorly constrained cloud indirect effects confound robust estimates of net climate impacts. Reducing sulfate and nitrate aerosols would improve air quality and lessen interference with the hydrologic cycle, but lead to warming. A holistic and balanced view is thus needed to assess how air pollution controls influence climate; a first step towards this goal involves estimating net climate impacts from individual emission sectors. Modeling and observational analyses suggest a warming climate degrades air quality (increasing surface O3 and particulate matter) in many populated regions, including during pollution episodes. Prior Intergovernmental Panel on Climate Change (IPCC) scenarios (SRES) allowed unconstrained growth, whereas the Representative Concentration Pathway (RCP) scenarios assume uniformly an aggressive reduction, of air pollutant emissions. New estimates from the current generation of chemistry–climate models with RCP emissions thus project improved air quality over the next century relative to those using the IPCC SRES scenarios. These two sets of projections likely bracket possible futures. We find that uncertainty in emission-driven changes in air quality is generally greater than uncertainty in climate-driven changes. Confidence in air quality projections is limited by the reliability of anthropogenic emission trajectories and the uncertainties in regional climate responses, feedbacks with the terrestrial biosphere, and oxidation pathways affecting O3 and SOA. {\textcopyright} 2012 The Royal Society of Chemistry.}, author = {Fiore, Arlene M. and Naik, Vaishali and Spracklen, Dominick V. and Steiner, Allison and Unger, Nadine and Prather, Michael and Bergmann, Dan and Cameron-Smith, Philip J. and Cionni, Irene and Collins, William J. and Dals{\o}ren, Stig and Eyring, Veronika and Folberth, Gerd A. and Ginoux, Paul and Horowitz, Larry W. and Josse, B{\'{e}}atrice and Lamarque, Jean Fran{\c{c}}ois and {Mac Kenzie}, Ian A. and Nagashima, Tatsuya and O'connor, Fiona M. and Righi, Mattia and Rumbold, Steven T. and Shindell, Drew T. and Skeie, Ragnhild B. and Sudo, Kengo and Szopa, Sophie and Takemura, Toshihiko and Zeng, Guang}, doi = {10.1039/c2cs35095e}, isbn = {0306-0012; 1460-4744}, issn = {14604744}, journal = {Chemical Society Reviews}, number = {19}, pages = {6663--6683}, pmid = {22868337}, title = {{Global air quality and climate}}, volume = {41}, year = {2012} } @article{Flechard2020, author = {Flechard, C R and Ibrom, A and Skiba, U M and de Vries, W and van Oijen, M and Cameron, D R and Dise, N B and Korhonen, J F J and Buchmann, N and Legout, A and Simpson, D and Sanz, M J and Aubinet, M and Loustau, D and Montagnani, L and Neirynck, J and Janssens, I A and Pihlatie, M and Kiese, R and Siemens, J and Francez, A.-J. and Augustin, J and Varlagin, A and Olejnik, J and Juszczak, R and Aurela, M and Berveiller, D and Chojnicki, B H and D{\"{a}}mmgen, U and Delpierre, N and Djuricic, V and Drewer, J and Dufr{\^{e}}ne, E and Eugster, W and Fauvel, Y and Fowler, D and Frumau, A and Granier, A and Gross, P and Hamon, Y and Helfter, C and Hensen, A and Horv{\'{a}}th, L and Kitzler, B and Kruijt, B and Kutsch, W L and Lobo-do-Vale, R and Lohila, A and Longdoz, B and Marek, M V and Matteucci, G and Mitosinkova, M and Moreaux, V and Neftel, A and Ourcival, J.-M. and Pilegaard, K and Pita, G and Sanz, F and Schjoerring, J K and Sebasti{\`{a}}, M.-T. and Tang, Y S and Uggerud, H and Urbaniak, M and van Dijk, N and Vesala, T and Vidic, S and Vincke, C and Weidinger, T and Zechmeister-Boltenstern, S and Butterbach-Bahl, K and Nemitz, E and Sutton, M A}, doi = {10.5194/bg-17-1583-2020}, issn = {1726-4189}, journal = {Biogeosciences}, month = {mar}, number = {6}, pages = {1583--1620}, publisher = {Copernicus Publications}, title = {{Carbon–nitrogen interactions in European forests and semi-natural vegetation – Part 1: Fluxes and budgets of carbon, nitrogen and greenhouse gases from ecosystem monitoring and modelling}}, volume = {17}, year = {2020} } @article{Flemming2017, abstract = {A new global reanalysis data set of atmospheric composition (AC) for the period 2003–2015 has been produced by the Copernicus Atmosphere Monitoring Service (CAMS). Satellite observations of total column (TC) carbon monoxide (CO) and aerosol optical depth (AOD), as well as several TC and profile observations of ozone, have been assimilated with the Integrated Forecasting System for Composition (C-IFS) of the European Centre for Medium-Range Weather Forecasting. Compared to the previous Monitoring Atmospheric Composition and Climate (MACC) reanalysis (MACCRA), the new CAMS interim reanalysis (CAMSiRA) is of a coarser horizontal resolution of about 110 km, compared to 80 km, but covers a longer period with the intent to be continued to present day. This paper compares CAMSiRA with MACCRA and a control run experiment (CR) without assimilation of AC retrievals. CAMSiRA has smaller biases than the CR with respect to independent observations of CO, AOD and stratospheric ozone. However, ozone at the surface could not be improved by the assimilation because of the strong impact of surface processes such as dry deposition and titration with nitrogen monoxide (NO), which were both unchanged by the assimilation. The assimilation of AOD led to a global reduction of sea salt and desert dust as well as an exaggerated increase in sulfate. Compared to MACCRA, CAMSiRA had smaller biases for AOD, surface CO and TC ozone as well as for upper stratospheric and tropospheric ozone. Finally, the temporal consistency of CAMSiRA was better than the one of MACCRA. This was achieved by using a revised emission data set as well as by applying careful selection and bias correction to the assimilated retrievals. CAMSiRA is therefore better suited than MACCRA for the study of interannual variability, as demonstrated for trends in surface CO.}, author = {Flemming, Johannes and Benedetti, Angela and Inness, Antje and {Engelen J}, Richard and Jones, Luke and Huijnen, Vincent and Remy, Samuel and Parrington, Mark and Suttie, Martin and Bozzo, Alessio and Peuch, Vincent Henri and Akritidis, Dimitris and Katragkou, Eleni}, doi = {10.5194/acp-17-1945-2017}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {3}, pages = {1945--1983}, title = {{The CAMS interim Reanalysis of Carbon Monoxide, Ozone and Aerosol for 2003–2015}}, volume = {17}, year = {2017} } @article{forestieri2018grl_a, author = {Forestieri, S D and Moore, K A and {Martinez Borrero}, R. and Wang, A and Stokes, M D and Cappa, C D}, doi = {10.1029/2018GL078193}, issn = {0094-8276}, journal = {Geophysical Research Letters}, month = {jul}, number = {14}, pages = {7218--7225}, publisher = {American Geophysical Union ({\{}AGU{\}})}, title = {{Temperature and Composition Dependence of Sea Spray Aerosol Production}}, url = {https://doi.org/10.1029/2018gl078193 https://onlinelibrary.wiley.com/doi/abs/10.1029/2018GL078193}, volume = {45}, year = {2018} } @article{doi:10.1002/2016JD025320, abstract = {The usefulness of previous Coupled Model Intercomparison Project (CMIP) exercises has been hampered by a lack of radiative forcing information. This has made it difficult to understand reasons for differences between model responses. Effective radiative forcing (ERF) is easier to diagnose than traditional radiative forcing in global climate models (GCMs) and is more representative of the eventual temperature response. Here we examine the different methods of computing ERF in two GCMs. We find that ERF computed from a fixed sea surface temperature (SST) method (ERF{\_}fSST) has much more certainty than regression based methods. Thirty year integrations are sufficient to reduce the 5-95{\%} confidence interval in global ERF{\_}fSST to 0.1Wm-2. For 2xCO2 ERF, 30 year integrations are needed to ensure that the signal is larger than the local confidence interval over more than 90{\%} of the globe. Within the ERF{\_}fSST method there are various options for prescribing SSTs and sea ice. We explore these and find that ERF is only weakly dependent on the methodological choices. Prescribing the monthly averaged seasonally varying model's preindustrial climatology is recommended for its smaller random error and easier implementation. As part of CMIP6, the Radiative Forcing Model Intercomparison Project (RFMIP) asks models to conduct 30 year ERF{\_}fSST experiments using the model's own preindustrial climatology of SST and sea ice. The Aerosol and Chemistry Model Intercomparison Project (AerChemMIP) will also mainly use this approach. We propose this as a standard method for diagnosing ERF and recommend that it be used across the climate modeling community to aid future comparisons.}, author = {Forster, Piers M. and Richardson, Thomas and Maycock, Amanda C. and Smith, Christopher J. and Samset, Bjorn H. and Myhre, Gunnar and Andrews, Timothy and Pincus, Robert and Schulz, Michael}, doi = {10.1002/2016JD025320}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {AerChemMIP,CMIP6,RFMIP,climate models,effective radiative forcing,radiative forcing}, month = {oct}, number = {20}, pages = {12460--12475}, title = {{Recommendations for diagnosing effective radiative forcing from climate models for CMIP6}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2016JD025320 http://doi.wiley.com/10.1002/2016JD025320}, volume = {121}, year = {2016} } @article{Forster2020, abstract = {The global response to the COVID-19 pandemic has led to a sudden reduction of both GHG emissions and air pollutants. Here, using national mobility data, we estimate global emission reductions for ten species during the period February to June 2020. We estimate that global NOx emissions declined by as much as 30{\%} in April, contributing a short-term cooling since the start of the year. This cooling trend is offset by {\~{}}20{\%} reduction in global SO2 emissions that weakens the aerosol cooling effect, causing short-term warming. As a result, we estimate that the direct effect of the pandemic-driven response will be negligible, with a cooling of around 0.01 ± 0.005 °C by 2030 compared to a baseline scenario that follows current national policies. In contrast, with an economic recovery tilted towards green stimulus and reductions in fossil fuel investments, it is possible to avoid future warming of 0.3 °C by 2050.}, author = {Forster, Piers M. and Forster, Harriet I and Evans, Mat J and Gidden, Matthew J and Jones, Chris D and Keller, Christoph A and Lamboll, Robin D and Qu{\'{e}}r{\'{e}}, Corinne Le and Rogelj, Joeri and Rosen, Deborah and Schleussner, Carl-Friedrich and Richardson, Thomas B and Smith, Christopher J and Turnock, Steven T}, doi = {10.1038/s41558-020-0883-0}, issn = {1758-678X}, journal = {Nature Climate Change}, month = {oct}, number = {10}, pages = {913--919}, publisher = {Nature Research}, title = {{Current and future global climate impacts resulting from COVID-19}}, url = {https://www.nature.com/articles/s41558-020-0883-0}, volume = {10}, year = {2020} } @article{Fortems-Cheiney2017, abstract = {{\textcopyright} 2017 The Author(s). Despite the international agreement to reduce global warming to below 2 °C, the Intended Nationally Determined Contributions submitted for the COP21 would lead to a global temperature rise of about 3 °C. The relative consequences of such a one-degree additional warming have not yet been investigated for regional air quality. Here we found that a + 3 °C global pollutant emission trajectory with respect to pre-industrial climate (reached along the 2040-2069 period under a RCP8.5 scenario) would significantly increase European ozone levels relative to a 2 °C one (reached along the 2028-2057 period under a RCP4.5 scenario). This increase is particularly high over industrial regions, large urban areas, and over Southern Europe and would annihilate the benefits of emission reduction policies. The regional ozone increase mainly stems from the advection of ozone at Europe's boundaries, themselves due to high global methane concentrations associated with the RCP8.5 emission scenario. These results make regional emission regulation, combined with emissions-reduction policies for global methane, of crucial importance.}, author = {Fortems-Cheiney, A. and Foret, G. and Siour, G. and Vautard, R. and Szopa, S. and Dufour, G. and Colette, A. and Lacressonniere, G. and Beekmann, M.}, doi = {10.1038/s41467-017-00075-9}, issn = {20411723}, journal = {Nature Communications}, number = {1}, pages = {89}, title = {{A 3°C global RCP8.5 emission trajectory cancels benefits of European emission reductions on air quality}}, volume = {8}, year = {2017} } @article{acp-15-13849-2015, author = {Fowler, D and Steadman, C E and Stevenson, D and Coyle, M and Rees, R M and Skiba, U M and Sutton, M A and Cape, J N and Dore, A J and Vieno, M and Simpson, D and Zaehle, S and Stocker, B D and Rinaldi, M and Facchini, M C and Flechard, C R and Nemitz, E and Twigg, M and Erisman, J W and Butterbach-Bahl, K and Galloway, J N}, doi = {10.5194/acp-15-13849-2015}, journal = {Atmospheric Chemistry and Physics}, number = {24}, pages = {13849--13893}, title = {{Effects of global change during the 21st century on the nitrogen cycle}}, url = {https://www.atmos-chem-phys.net/15/13849/2015/}, volume = {15}, year = {2015} } @article{Fowler2009, abstract = {Ecosystems and the atmosphere: This review describes the state of understanding the processes involved in the exchange of trace gases and aerosols between the earth's surface and the atmosphere. The gases covered include NO, NO2, HONO, HNO3, NH3, SO2, DMS, Biogenic VOC, O3, CH4, N2O and particles in the size range 1 nm-10 $\mu$m including organic and inorganic chemical species. The main focus of the review is on the exchange between terrestrial ecosystems, both managed and natural and the atmosphere, although some new developments in ocean-atmosphere exchange are included. The material presented is biased towards the last decade, but includes earlier work, where more recent developments are limited or absent. New methodologies and instrumentation have enabled, if not driven technical advances in measurement. These developments have advanced the process understanding and upscaling of fluxes, especially for particles, VOC and NH3. Examples of these applications include mass spectrometric methods, such as Aerosol Mass Spectrometry (AMS) adapted for field measurement of atmosphere-surface fluxes using micrometeorological methods for chemically resolved aerosols. Also briefly described are some advances in theory and techniques in micrometeorology. For some of the compounds there have been paradigm shifts in approach and application of both techniques and assessment. These include flux measurements over marine surfaces and urban areas using micrometeorological methods and the up-scaling of flux measurements using aircraft and satellite remote sensing. The application of a flux-based approach in assessment of O3 effects on vegetation at regional scales is an important policy linked development secured through improved quantification of fluxes. The coupling of monitoring, modelling and intensive flux measurement at a continental scale within the NitroEurope network represents a quantum development in the application of research teams to address the underpinning science of reactive nitrogen in the cycling between ecosystems and the atmosphere in Europe. Some important developments of the science have been applied to assist in addressing policy questions, which have been the main driver of the research agenda, while other developments in understanding have not been applied to their wider field especially in chemistry-transport models through deficiencies in obtaining appropriate data to enable application or inertia within the modelling community. The paper identifies applications, gaps and research questions that have remained intractable at least since 2000 within the specialized sections of the paper, and where possible these have been focussed on research questions for the coming decade. {\textcopyright} 2009.}, author = {Fowler, D. and Pilegaard, K. and Sutton, M. A. and Ambus, P. and Raivonen, M. and Duyzer, J. and Simpson, D. and Fagerli, H. and Fuzzi, S. and Schjoerring, J. K. and Granier, C. and Neftel, A. and Isaksen, I. S.A. and Laj, P. and Maione, M. and Monks, P. S. and Burkhardt, J. and Daemmgen, U. and Neirynck, J. and Personne, E. and Wichink-Kruit, R. and Butterbach-Bahl, K. and Flechard, C. and Tuovinen, J. P. and Coyle, M. and Gerosa, G. and Loubet, B. and Altimir, N. and Gruenhage, L. and Ammann, C. and Cieslik, S. and Paoletti, E. and Mikkelsen, T. N. and Ro-Poulsen, H. and Cellier, P. and Cape, J. N. and Horv{\'{a}}th, L. and Loreto, F. and Niinemets, {\"{U}} and Palmer, P. I. and Rinne, J. and Misztal, P. and Nemitz, E. and Nilsson, D. and Pryor, S. and Gallagher, M. W. and Vesala, T. and Skiba, U. and Br{\"{u}}ggemann, N. and Zechmeister-Boltenstern, S. and Williams, J. and O'Dowd, C. and Facchini, M. C. and de Leeuw, G. and Flossman, A. and Chaumerliac, N. and Erisman, J. W.}, doi = {10.1016/j.atmosenv.2009.07.068}, isbn = {1352-2310}, issn = {13522310}, journal = {Atmospheric Environment}, keywords = {Biogenic emissions,Compensation points,Dry deposition,Resuspension,Trace gas fluxes}, number = {33}, pages = {5193--5267}, title = {{Atmospheric composition change: Ecosystems–Atmosphere interactions}}, volume = {43}, year = {2009} } @article{Fowler2020, annote = {doi: 10.1098/rsta.2019.0314}, author = {Fowler, David and Brimblecombe, Peter and Burrows, John and Heal, Mathew R and Grennfelt, Peringe and Stevenson, David S and Jowett, Alan and Nemitz, Eiko and Coyle, Mhairi and Lui, Xuejun and Chang, Yunhua and Fuller, Gary W and Sutton, Mark A and Klimont, Zbigniew and Unsworth, Mike H and Vieno, Massimo}, doi = {10.1098/rsta.2019.0314}, journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences}, month = {oct}, number = {2183}, pages = {20190314}, publisher = {Royal Society}, title = {{A chronology of global air quality}}, url = {https://doi.org/10.1098/rsta.2019.0314}, volume = {378}, year = {2020} } @article{Franchin2018, author = {Franchin, Alessandro and Fibiger, Dorothy L. and Goldberger, Lexie and McDuffie, Erin E. and Moravek, Alexander and Womack, Caroline C. and Crosman, Erik T. and Docherty, Kenneth S. and Dube, William P. and Hoch, Sebastian W. and Lee, Ben H. and Long, Russell and Murphy, Jennifer G. and Thornton, Joel A. and Brown, Steven S. and Baasandorj, Munkhbayar and Middlebrook, Ann M.}, doi = {10.5194/acp-18-17259-2018}, journal = {Atmospheric Chemistry and Physics}, month = {dec}, number = {23}, pages = {17259--17276}, publisher = {Copernicus {\{}GmbH{\}}}, title = {{Airborne and ground-based observations of ammonium-nitrate-dominated aerosols in a shallow boundary layer during intense winter pollution episodes in northern Utah}}, volume = {18}, year = {2018} } @article{Franco2016, abstract = {Sharp rises in the atmospheric abundance of ethane (C2H6) have been detected from 2009 onwards in the Northern Hemisphere as a result of the unprecedented growth in the exploitation of shale gas and tight oil reservoirs in North America. Using time series of C2H6 total columns derived from ground-based Fourier transform infrared (FTIR) observations made at five selected Network for the Detection of Atmospheric Composition Change sites, we characterize the recent C2H6 evolution and determine growth rates of ∼5{\%} yr-1 at mid-latitudes and of ∼3{\%} yr-1 at remote sites. Results from CAM-chem simulations with the Hemispheric Transport of Air Pollutants, Phase II bottom-up inventory for anthropogenic emissions are found to greatly underestimate the current C2H6 abundances. Doubling global emissions is required to reconcile the simulations and the observations prior to 2009. We further estimate that North American anthropogenic C2H6 emissions have increased from 1.6 Tg yr-1 in 2008 to 2.8 Tg yr-1 in 2014, i.e. by 75{\%} over these six years. We also completed a second simulation with new top-down emissions of C2H6 from North American oil and gas activities, biofuel consumption and biomass burning, inferred from space-borne observations of methane (CH4) from Greenhouse Gases Observing SATellite. In this simulation, GEOS-Chem is able to reproduce FTIR measurements at the mid-latitudinal sites, underscoring the impact of the North American oil and gas development on the current C2H6 abundance. Finally we estimate that the North American oil and gas emissions of CH4, a major greenhouse gas, grew from 20 to 35 Tg yr-1 over the period 2008-2014, in association with the recent C2H6 rise.}, author = {Franco, B. and Mahieu, E. and Emmons, L. K. and Tzompa-Sosa, Z. A. and Fischer, E. V. and Sudo, K. and Bovy, B. and Conway, S. and Griffin, D. and Hannigan, J. W. and Strong, K. and Walker, K. A.}, doi = {10.1088/1748-9326/11/4/044010}, issn = {17489326}, journal = {Environmental Research Letters}, keywords = {North American anthropogenic emissions,atmospheric ethane and methane,shale gas and tight oil reservoirs,trend}, number = {4}, pages = {044010}, title = {{Evaluating ethane and methane emissions associated with the development of oil and natural gas extraction in North America}}, volume = {11}, year = {2016} } @article{Freedman2019, abstract = {pH is one of the most basic chemical properties of aqueous solution, but its measurement in nanoscale aerosol particles presents many challenges. The pH of aerosol particles is of growing interest in the atmospheric chemistry community because of its demonstrated effects on heterogeneous chemistry and human health, as well as potential effects on climate. The authors have shown that phase transitions of aerosol particles are sensitive to pH, focusing on systems that undergo liquid-liquid phase separation. Currently, aerosol pH is calculated indirectly from knowledge of species present in the gas and aerosol phases through the use of thermodynamic models. From these models, ambient aerosol is expected to be highly acidic (pH0-3). Direct measurements have focused on model systems due to the difficulty of this measurement. This area is one in which physical chemists should be encouraged to contribute because of the potential consequences for aerosol processes in the environment.}, author = {Freedman, Miriam Arak and Ott, Emily Jean E. and Marak, Katherine E.}, doi = {10.1021/acs.jpca.8b10676}, issn = {15205215}, journal = {Journal of Physical Chemistry A}, month = {dec}, number = {7}, pages = {1275--1284}, publisher = {American Chemical Society}, title = {{Role of pH in Aerosol Processes and Measurement Challenges}}, volume = {123}, year = {2019} } @article{Freney2018, abstract = {Abstract. As part of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx), a series of aerosol and gas-phase measurements were deployed aboard the SAFIRE ATR42 research aircraft in summer 2014. The present study focuses on the four flights performed in late June early July over two forested regions in the south of France. We combine in situ observations and model simulations to aid in the understanding of secondary organic aerosol (SOA) formation over these forested areas in the Mediterranean and to highlight the role of different gas-phase precursors. The non-refractory particulate species measured by a compact aerosol time-of-flight mass spectrometer (cToF-AMS) were dominated by organics (60 to 72 {\%}) followed by a combined contribution of 25 {\%} by ammonia and sulfate aerosols. The contribution from nitrate and black carbon (BC) particles was less than 5 {\%} of the total PM1 mass concentration. Measurements of non-refractory species from off-line transmission electron microscopy (TEM) showed that particles have different mixing states and that large fractions (35 {\%}) of the measured particles were organic aerosol containing C, O, and S but without inclusions of crystalline sulfate particles. The organic aerosol measured using the cToF-AMS contained only evidence of oxidized organic aerosol (OOA), without a contribution of fresh primary organic aerosol. Positive matrix factorization (PMF) on the combined organic–inorganic matrices separated the oxidized organic aerosol into a more-oxidized organic aerosol (MOOA), and a less-oxidized organic aerosol (LOOA). The MOOA component is associated with inorganic species and had higher contributions of m∕z 44 than the LOOA factor. The LOOA factor is not associated with inorganic species and correlates well with biogenic volatile organic species measured with a proton-transfer-reaction mass spectrometer, such as isoprene and its oxidation products (methyl vinyl ketone, MVK; methacroleine, MACR; and isoprene hydroxyhydroperoxides, ISOPOOH). Despite a significantly high mixing ratio of isoprene (0.4 to 1.2 ppbV) and its oxidation products (0.2 and 0.8 ppbV), the contribution of specific signatures for isoprene epoxydiols SOA (IEPOX-SOA) within the aerosol organic mass spectrum (m∕z 53 and m∕z 82) were very weak, suggesting that the presence of isoprene-derived SOA was either too low to be detected by the cToF-AMS, or that SOA was not formed through IEPOX. This was corroborated through simulations performed with the Polyphemus model showing that although 60 to 80 {\%} of SOA originated from biogenic precursors, only about 15 to 32 {\%} was related to isoprene (non-IEPOX) SOA; the remainder was 10 {\%} sesquiterpene SOA and 35 to 40 {\%} monoterpene SOA. The model results show that despite the zone of sampling being far from industrial or urban sources, a total contribution of 20 to 34 {\%} of the SOA was attributed to purely anthropogenic precursors (aromatics and intermediate or semi-volatile compounds). The measurements obtained during this study allow us to evaluate how biogenic emissions contribute to increasing SOA concentrations over Mediterranean forested areas. Directly comparing these measurements with the Polyphemus model provides insight into the SOA formation pathways that are prevailing in these forested areas as well as processes that need to be implemented in future simulations.}, author = {Freney, Evelyn and Sellegri, Karine and Chrit, Mounir and Adachi, Kouji and Brito, Joel and Waked, Antoine and Borbon, Agn{\`{e}}s and Colomb, Aur{\'{e}}lie and Dupuy, R{\'{e}}gis and Pichon, Jean-Marc and Bouvier, Laetitia and Delon, Claire and Jambert, Corinne and Durand, Pierre and Bourianne, Thierry and Gaimoz, C{\'{e}}cile and Triquet, Sylvain and F{\'{e}}ron, Ana{\"{i}}s and Beekmann, Matthias and Dulac, Fran{\c{c}}ois and Sartelet, Karine}, doi = {10.5194/acp-18-7041-2018}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {10}, pages = {7041--7056}, title = {{Aerosol composition and the contribution of SOA formation over Mediterranean forests}}, url = {https://acp.copernicus.org/articles/18/7041/2018/}, volume = {18}, year = {2018} } @article{Friedlingstein2020, author = {Friedlingstein, Pierre and O'Sullivan, Michael and Jones, Matthew W and Andrew, Robbie M and Hauck, Judith and Olsen, Are and Peters, Glen P. and Peters, Wouter and Pongratz, Julia and Sitch, Stephen and {Le Qu{\'{e}}r{\'{e}}}, Corinne and Canadell, Josep G. and Ciais, Philippe and Jackson, Robert B. and Alin, Simone and Arag{\~{a}}o, Luiz E. O. C. and Arneth, Almut and Arora, Vivek and Bates, Nicholas R. and Becker, Meike and Benoit-Cattin, Alice and Bittig, Henry C. and Bopp, Laurent and Bultan, Selma and Chandra, Naveen and Chevallier, Fr{\'{e}}d{\'{e}}ric and Chini, Louise P. and Evans, Wiley and Florentie, Liesbeth and Forster, Piers M. and Gasser, Thomas and Gehlen, Marion and Gilfillan, Dennis and Gkritzalis, Thanos and Gregor, Luke and Gruber, Nicolas and Harris, Ian and Hartung, Kerstin and Haverd, Vanessa and Houghton, Richard A. and Ilyina, Tatiana and Jain, Atul K. and Joetzjer, Emilie and Kadono, Koji and Kato, Etsushi and Kitidis, Vassilis and Korsbakken, Jan Ivar and Landsch{\"{u}}tzer, Peter and Lef{\`{e}}vre, Nathalie and Lenton, Andrew and Lienert, Sebastian and Liu, Zhu and Lombardozzi, Danica and Marland, Gregg and Metzl, Nicolas and Munro, David R. and Nabel, Julia E. M. S. and Nakaoka, Shin-Ichiro and Niwa, Yosuke and O'Brien, Kevin and Ono, Tsuneo and Palmer, Paul I. and Pierrot, Denis and Poulter, Benjamin and Resplandy, Laure and Robertson, Eddy and R{\"{o}}denbeck, Christian and Schwinger, J{\"{o}}rg and S{\'{e}}f{\'{e}}rian, Roland and Skjelvan, Ingunn and Smith, Adam J. P. and Sutton, Adrienne J. and Tanhua, Toste and Tans, Pieter P. and Tian, Hanqin and Tilbrook, Bronte and van der Werf, Guido and Vuichard, Nicolas and Walker, Anthony P. and Wanninkhof, Rik and Watson, Andrew J. and Willis, David and Wiltshire, Andrew J. and Yuan, Wenping and Yue, Xu and Zaehle, S{\"{o}}nke}, doi = {10.5194/essd-12-3269-2020}, file = {::}, issn = {1866-3516}, journal = {Earth System Science Data}, month = {dec}, number = {4}, pages = {3269--3340}, title = {{Global Carbon Budget 2020}}, url = {https://essd.copernicus.org/articles/12/3269/2020/}, volume = {12}, year = {2020} } @article{Froyd2009, abstract = {Aerosol composition was measured by the NOAA single-particle mass spectrometer (PALMS) aboard the NASA WB-57 high altitude aircraft platform during two Aura Validation Experiment (AVE) campaigns based in Costa Rica in 2004 and 2006. These studies yielded the most complete set of aerosol composition measurements to date throughout the tropical tropopause layer (TTL) and tropical lower stratosphere. We describe the aerosol properties of the tropical atmosphere and use composition tracers to examine particle sources, the role of recent convection, and cirrus-forming potential in the TTL. Tropical dynamics and regional air sources played principal roles in dictating tropospheric aerosol properties. There was a sharp change in aerosol chemical composition at about 12 km altitude coincident with a change in convective influence. Below this level, maritime convection lofted condensable material that generated acidic, sulfate-rich aerosol. These particles contained significant amounts of methanesulfonic acid (MSA) and showed evidence of cloud processes. In contrast, continental convection injected particles and precursors directly into the TTL, yielding a population of neutralized, organic-rich aerosol. The organics were often highly oxidized and particles with oxidized organics also contained nitrate. Above the tropopause, chemical composition gradually changed toward sulfuric acid particles but neutralized particles were still abundant 2 km above the tropopause. Deep continental convection, though sporadic and geographically localized, may strongly influence TTL aerosol properties on a global scale. The abundance of organic-rich aerosol may inhibit ice nucleation and formation of tropopause level cirrus. {\textcopyright} 2009 Author(s).}, author = {Froyd, K. D. and Murphy, D. M. and Sanford, T. J. and Thomson, D. S. and Wilson, J. C. and Pfister, L. and Lait, L.}, doi = {10.5194/acp-9-4363-2009}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, month = {jul}, number = {13}, pages = {4363--4385}, publisher = {Copernicus GmbH}, title = {{Aerosol composition of the tropical upper troposphere}}, volume = {9}, year = {2009} } @article{Fu2019, abstract = {Purpose of Review: Climate warming may bear a penalty on future ozone air quality, even in the absence of changes in anthropogenic activities. This penalty has important implications for policy-making, but its quantification involves complex meteorological, chemical, and biological processes and feedbacks that are not well understood. We examined how climate-sensitive processes may affect surface ozone, identified key knowledge gaps uncovered by recent studies, and summarized latest assessments of the climate change penalty on ozone air quality. Recent Findings: Recent analyses have challenged earlier paradigms on how climate change may affect surface ozone. The widely accepted associations of high ozone events with stagnation and heat waves require re-examination. Emission responses of natural precursors to climate warming may be significantly modulated by CO2 levels and ecosystem feedbacks, such that the direction of emission changes cannot be robustly determined at this time. Climate variability may drive fluctuations in surface ozone, which has implications for near-term air quality management. Recent studies have generally projected a climate change penalty on ozone air quality, although the magnitudes are smaller than those projected by earlier studies. Summary: This review examined the latest understanding on the climate change penalty to surface ozone. Critical uncertainties are associated with the meteorological, chemical, and biological processes linking climate warming and ozone, and many of the known feedbacks are not yet included in models. Further research is needed to examine those processes in order to better quantify the climate change penalty on surface ozone to inform policy-making.}, author = {Fu, Tzung May and Tian, Heng}, doi = {10.1007/s40726-019-00115-6}, issn = {21986592}, journal = {Current Pollution Reports}, keywords = {Air quality,Climate change,Climate policy,Ozone}, number = {3}, pages = {159--171}, title = {{Climate Change Penalty to Ozone Air Quality: Review of Current Understandings and Knowledge Gaps}}, url = {https://doi.org/10.1007/s40726-019-00115-6}, volume = {5}, year = {2019} } @article{Fu2019b, author = {Fu, Dejian and Millet, Dylan B. and Wells, Kelley C. and Payne, Vivienne H. and Yu, Shanshan and Guenther, Alex and Eldering, Annmarie}, doi = {10.1038/s41467-019-11835-0}, issn = {2041-1723}, journal = {Nature Communications}, month = {dec}, number = {1}, pages = {3811}, title = {{Direct retrieval of isoprene from satellite-based infrared measurements}}, volume = {10}, year = {2019} } @article{Fuchs2013, author = {Fuchs, H and Hofzumahaus, A and Rohrer, F and Bohn, B and Brauers, T and Dorn, H-P. and H{\"{a}}seler, R and Holland, F and Kaminski, M and Li, X and Lu, K and Nehr, S and Tillmann, R and Wegener, R and Wahner, A}, doi = {10.1038/ngeo1964}, issn = {1752-0894}, journal = {Nature Geoscience}, month = {dec}, number = {12}, pages = {1023--1026}, publisher = {Nature Publishing Group}, title = {{Experimental evidence for efficient hydroxyl radical regeneration in isoprene oxidation}}, url = {http://dx.doi.org/10.1038/ngeo1964 http://10.0.4.14/ngeo1964 http://www.nature.com/articles/ngeo1964}, volume = {6}, year = {2013} } @article{Fuglestvedt1996a, abstract = {Emissions may affect climate indirectly through chemical interactions in the atmosphere, but quantifications of such effects are difficult and uncertain due to incomplete knowledge and inadequate methods. A preliminary assessment of the climatic impact of changes in tropospheric O3 and CH4 in response to various emissions is given. For a 10{\%} increase in the CH4 emissions the relative increase in concentration has been estimated to be 37{\%} larger. The radiative forcing from enhanced levels of tropospheric O3 is estimated to 37{\%} of the forcing from changes in CH4. Inclusion of indirect effects approximately doubles the climatic impact of CH4 emissions. Emissions of NOx increase tropospheric O3, while the levels of CH4 are reduced. For emissions of NOx from aircraft, the positive effects via O3 changes are significantly larger than the negative through changes in CH4. For NOx emitted from surface sources, the effects through changes in O3 and CH4 are estimated to be of similar magnitude and large uncertainty is connected to the sign of the net effect. Emissions of CO have positive indirect effects on climate through enhanced levels of tropospheric O3 and increased lifetime of CH4. These results form the basis for estimates of global warming potentials for sustained step increases in emissions. {\textcopyright} 1996 Kluwer Academic Publishers.}, author = {Fuglestvedt, J. S. and Isaksen, I. S.A. and Wang, W. C.}, doi = {10.1007/BF00139300}, issn = {01650009}, journal = {Climatic Change}, number = {3-4}, pages = {405--437}, title = {{Estimates of indirect global warming potentials for CH4, CO and NOx}}, volume = {34}, year = {1996} } @article{Fuglestvedt2008, abstract = {Although the transport sector is responsible for a large and growing share of global emissions affecting climate, its overall contribution has not been quantified. We provide a comprehensive analysis of radiative forcing from the road transport, shipping, aviation, and rail subsectors, using both past- and forward-looking perspectives. We find that, since preindustrial times, transport has contributed ≈15{\%} and 31{\%} of the total man-made CO2 and O 3 forcing, respectively. A forward-looking perspective shows that the current emissions from transport are responsible for ≈16{\%} of the integrated net forcing over 100 years from all current manmade emissions. The dominating contributor to positive forcing (warming) is CO2, followed by tropospheric O3. By subsector, road transport is the largest contributor to warming. The transport sector also exerts cooling through reduced methane lifetime and atmospheric aerosol effects. Shipping causes net cooling, except on future time scales of several centuries. Much of the forcing from transport comes from emissions not covered by the Kyoto Protocol. {\textcopyright} 2008 by The National Academy of Sciences of the USA.}, author = {Fuglestvedt, Jan S. and Berntsen, Terje and Myhre, Gunnar and Rypdal, Kristin and Skeie, Ragnhild Bieltvedt}, doi = {10.1073/pnas.0702958104}, issn = {00278424}, journal = {Proceedings of the National Academy of Sciences}, keywords = {Aerosols,Emissions,GWP,Greenhouse gases,Radiative forcing}, number = {2}, pages = {454--458}, title = {{Climate forcing from the transport sectors}}, volume = {105}, year = {2008} } @article{FUJIMORI2017268, abstract = {This study quantifies the Shared Socioeconomic Pathways (SSPs) using AIM/CGE (Asia-Pacific Integrated Assessment/Computable General Equilibrium). SSP3 (regional rivalry) forms the main focus of the study, which is supposed to face high challenges both in mitigation and adaptation. The AIM model has been selected as the model to quantify the SSP3 marker scenario, a representative case illustrating a particular narrative. Multiple parameter assumptions in AIM/CGE were differentiated across the SSPs for quantification. We confirm that SSP3 quantitative scenarios outcomes are consistent with its narrative. Moreover, four key features of SSP3 are observed. First, as SSP3 was originally designed to contain a high level of challenges to mitigation, mitigation costs in SSP3 were relatively high. This results from the combination of high greenhouse gas emissions in the baseline (no climate mitigation policy) scenario and low mitigative capacity. Second, the climate forcing level in 2100 for the baseline scenarios of SSP3 was similar to that of SSP2, whereas CO2 emissions in SSP3 are higher than those in SSP2. This is mainly due to high aerosol emissions in SSP3. A third feature was the high air pollutant emissions associated with weak implementation of air quality legislation and a high level of coal dependency. Fourth, forest area steadily decreases with a large expansion of cropland and pasture land. These characteristics indicate at least four potential uses for SSP3. First, SSP3 is useful for both IAM and impact, adaptation, vulnerability (IAV) analyses to present the worst-case scenario. Second, by comparing SSP2 and SSP3, IAV analyses can clarify the influences of socioeconomic elements under similar climatic conditions. Third, the high air pollutant emissions would be of interest to atmospheric chemistry climate modelers. Finally, in addition to climate change studies, many other environmental studies could benefit from the meaningful insights available from the large-scale land use change resulting in SSP3.}, author = {Fujimori, Shinichiro and Hasegawa, Tomoko and Masui, Toshihiko and Takahashi, Kiyoshi and Herran, Diego Silva and Dai, Hancheng and Hijioka, Yasuaki and Kainuma, Mikiko}, doi = {https://doi.org/10.1016/j.gloenvcha.2016.06.009}, issn = {0959-3780}, journal = {Global Environmental Change}, keywords = {AIM,Climate mitigation,Computable general equilibrium model,Integrated assessment model,SSPs,Socioeconomic scenarios}, pages = {268--283}, title = {{SSP3: AIM implementation of Shared Socioeconomic Pathways}}, url = {https://www.sciencedirect.com/science/article/pii/S0959378016300838}, volume = {42}, year = {2017} } @article{doi:10.1029/2005JD006741, abstract = {The aerosol characterization experiment performed within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia–Smoke, Aerosols, Clouds, Rainfall and Climate (LBA-SMOCC) field experiment carried out in Rond{\^{o}}nia, Brazil, in the period from September to November 2002 provides a unique data set of size-resolved chemical composition of boundary layer aerosol over the Amazon Basin from the intense biomass-burning period to the onset of the wet season. Three main periods were clearly distinguished on the basis of the PM10 concentration trend during the experiment: (1) dry period, with average PM10 well above 50 $\mu$g m−3; (2) transition period, during which the 24-hour-averaged PM10 never exceeded 40 $\mu$g m−3 and never dropped below 10 $\mu$g m−3; (3) and wet period, characterized by 48-hour-averaged concentrations of PM10 below 12 $\mu$g m−3 and sometimes as low as 2 $\mu$g m−3. The trend of PM10 reflects that of CO concentration and can be directly linked to the decreasing intensity of the biomass-burning activities from September through November, because of the progressive onset of the wet season. Two prominent aerosol modes, in the submicron and supermicron size ranges, were detected throughout the experiment. Dry period size distributions are dominated by the fine mode, while the fine and coarse modes show almost the same concentrations during the wet period. The supermicron fraction of the aerosol is composed mainly of primary particles of crustal or biological origin, whereas submicron particles are produced in high concentrations only during the biomass-burning periods and are mainly composed of organic material, mostly water-soluble, and ∼10{\%} of soluble inorganic salts, with sulphate as the major anion. Size-resolved average aerosol chemical compositions are reported for the dry, transition, and wet periods. However, significant variations in the aerosol composition and concentrations were observed within each period, which can be classified into two categories: (1) diurnal oscillations, caused by the diurnal cycle of the boundary layer and the different combustion phase active during day (flaming) or night (smouldering); and (2) day-to-day variations, due to alternating phases of relatively wet and dry conditions. In a second part of the study, three subperiods representative of the conditions occurring in the dry, transition, and wet periods were isolated to follow the evolution of the aerosol chemical composition as a function of changes in rainfall rate and in the strength of the sources of particulate matter. The chemical data set provided by the SMOCC field experiment will be useful to characterize the aerosol hygroscopic properties and the ability of the particles to act as cloud condensation nuclei.}, author = {Fuzzi, Sandro and Decesari, Stefano and Facchini, Maria Cristina and Cavalli, Fabrizia and Emblico, Lorenza and Mircea, Mihaiela and Andreae, Meinrat O and Trebs, Ivonne and Hoffer, Andr{\'{a}}s and Guyon, Pascal and Artaxo, Paulo and Rizzo, Luciana V and Lara, Luciene L and Pauliquevis, Theotonio and Maenhaut, Willy and Raes, Nico and Chi, Xuguang and Mayol-Bracero, Olga L and Soto-Garc{\'{i}}a, Lydia L and Claeys, Magda and Kourtchev, Ivan and Rissler, Jenny and Swietlicki, Erik and Tagliavini, Emilio and Schkolnik, Gal and Falkovich, Alla H and Rudich, Yinon and Fisch, Gilberto and Gatti, Luciana V}, doi = {10.1029/2005JD006741}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {aerosol chemical composition,biomass burning,organic aerosol}, number = {D1}, pages = {D01201}, title = {{Overview of the inorganic and organic composition of size-segregated aerosol in Rond{\^{o}}nia, Brazil, from the biomass-burning period to the onset of the wet season}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2005JD006741}, volume = {112}, year = {2007} } @article{Fyfeeabf7133, abstract = {The COVID-19 (coronavirus disease 2019) pandemic has resulted in a marked slowdown in greenhouse gas and aerosol emissions. Although the resulting emission reductions will continue to evolve, this will presumably be temporary. Here, we provide estimates of the potential effect of such short-term emission reductions on global and regional temperature and precipitation by analyzing the response of an Earth System Model to a range of idealized near-term emission pathways not considered in available model intercomparison projects. These estimates reveal the modest impact that temporary emission reductions associated with the COVID-19 pandemic will have on global and regional climate. Our simulations suggest that the impact of carbon dioxide and aerosol emission reductions is actually a temporary enhancement in warming rate. However, our results demonstrate that even large emission reductions applied for a short duration have only a small and likely undetectable impact.}, author = {Fyfe, J C and Kharin, V V and Swart, N and Flato, G M and Sigmond, M and Gillett, N P}, doi = {10.1126/sciadv.abf7133}, journal = {Science Advances}, number = {10}, pages = {eabf7133}, publisher = {American Association for the Advancement of Science}, title = {{Quantifying the influence of short-term emission reductions on climate}}, url = {https://advances.sciencemag.org/content/7/10/eabf7133}, volume = {7}, year = {2021} } @article{adgeo-45-105-2018, author = {G{\'{o}}mez-Sanabria, A and H{\"{o}}glund-Isaksson, L and Rafaj, P and Sch{\"{o}}pp, W}, doi = {10.5194/adgeo-45-105-2018}, journal = {Advances in Geosciences}, pages = {105--113}, title = {{Carbon in global waste and wastewater flows – its potential as energy source under alternative future waste management regimes}}, url = {https://www.adv-geosci.net/45/105/2018/}, volume = {45}, year = {2018} } @article{Gabric2013, abstract = {The sea-to-air flux of the biogenic sulfur (S) compound dimethylsulfide (DMS) is thought to constitute an important radiative impact on climate, especially in remote marine areas. Previous biogeochemical modelling analyses simulate medium to large changes in the sea-to-air flux of DMS in polar regions under warming scenarios. Here we assess the global radiative impact of such a prescribed change in DMS flux on contemporary climate using a low-resolution atmospheric general circulation model. This impact operates through the atmospheric oxidation of DMS to radiatively-active sulfate aerosols, which are known to both reflect incoming short-wave radiation and to affect the microphysical properties of clouds, for example, through an increase in cloud albedo. We use an atmospheric GCM with incorporated sulfur cycle, coupled to a mixed-layer ('q-flux') ocean, to estimate the climatic response to a prescribed meridionally-variable change in zonal DMS flux, as simulated in a previous modelling analysis. We compare baseline sulfur emissions (contemporary anthropogenic S and contemporary DMS sea-to-air flux), with contemporary anthropogenic S and a perturbed DMS flux. Our results indicate that the global mean DMS vertically integrated concentration increases by about 41 per cent. The relative increase in DMS annual emission is around 17 per cent in 70-80°N, although the most significant increase is in 50-70°S, up to 70 per cent. However, concentrations of atmospheric SO2 and SO42- increase by only about eight per cent. The oxidation of DMS by OH increases by about 20 per cent. Oxidation of SO2 to SO 42 by H2O2 increases seven per cent. The oxidation of SO2 by O3 increases around six per cent. Overall sulfur emissions increase globally by around 4.6 per cent. Global mean aerosol optical depth (AOD) increases by 3.5 per cent. Global mean surface temperature decreases by 0.6 K. There is a notable difference between the impacts in the southern and northern hemispheres. In general, most processes and chemical species related to the sulfur cycle show a larger increase in the southern hemisphere, except SO2 and the oxidation of DMS by NO 3. The global mean direct radiative forcing due to the DMS change is -0.05 Wm-2 with total forcing (direct + indirect effects) of -0.48 Wm-2. This perturbation on DMS flux leads to a mean surface temperature decrease in the southern hemisphere of around 0.8 K, compared with a decrease of 0.4 K in the northern hemisphere.}, author = {Gabric, Albert J. and Qu, Bo and Rotstayn, Leon and Shephard, Jill M.}, doi = {10.22499/2.6303.002}, issn = {1836716X}, journal = {Australian Meteorological and Oceanographic Journal}, number = {3}, pages = {365--376}, publisher = {Australian Bureau of Meteorology}, title = {{Global simulations of the impact on contemporary climate of a perturbation to the sea-to-air flux of dimethylsulfide}}, volume = {63}, year = {2013} } @article{Gallardo2018, abstract = {Worldwide, urbanization constitutes a major and growing driver of global change and a distinctive feature of the Anthropocene. Thus, urban development paths present opportunities for technological and societal transformations towards energy efficiency and decarbonization, with benefits for both greenhouse gas (GHG) and air pollution mitigation. This requires a better understanding of the intertwined dynamics of urban energy and land use, emissions, demographics, governance, and societal and biophysical processes. In this study, we address several characteristics of urbanization in Santiago (33.5°S, 70.5°W, 500 m a.s.l.), the capital city of Chile. Specifically, we focus on the multiple links between mobility and air quality, describe the evolution of these two aspects over the past 30 years, and review the role scientific knowledge has played in policy-making. We show evidence of how technological measures (e.g., fuel quality, three-way catalytic converters, diesel particle filters) have been successful in decreasing coarse mode aerosol (PM10) concentrations in Santiago despite increasing urbanization (e.g., population, motorization, urban sprawl). However, we also show that such measures will likely be insufficient if behavioral changes do not achieve an increase in the use of public transportation. Our investigation seeks to inform urban development in the Anthropocene, and our results may be useful for other developing countries, particularly in Latin America and the Caribbean where more than 80{\%} of the population is urban.}, author = {Gallardo, Laura and Barraza, Francisco and Ceballos, Andr{\'{e}}s and Galleguillos, Mauricio and Huneeus, Nicol{\'{a}}s and Lambert, Fabrice and Ibarra, Cecilia and Munizaga, Marcela and O'Ryan, Ra{\'{u}}l and Osses, Mauricio and Tolvett, Sebasti{\'{a}}n and Urquiza, Anah{\'{i}} and V{\'{e}}liz, Karina D.}, doi = {10.1525/elementa.293}, isbn = {2325-1026}, issn = {23251026}, journal = {Elementa: Science of the Anthropocene}, keywords = {Air quality,Chile,Climate mitigation,Mobility,Policy-science interface,Urbanization}, number = {1}, pages = {38}, title = {{Evolution of air quality in Santiago: The role of mobility and lessons from the science–policy interface}}, volume = {6}, year = {2018} } @article{Galmarini2017, abstract = {We present an overview of the coordinated global numerical modelling experiments performed during 2012-2016 by the Task Force on Hemispheric Transport of Air Pollution (TF HTAP), the regional experiments by the Air Quality Model Evaluation International Initiative (AQMEII) over Europe and North America, and the Model Intercomparison Study for Asia (MICS-Asia). To improve model estimates of the impacts of intercontinental transport of air pollution on climate, ecosystems, and human health and to answer a set of policy-relevant questions, these three initiatives performed emission perturbation modelling experiments consistent across the global, hemispheric, and continental/ regional scales. In all three initiatives, model results are extensively compared against monitoring data for a range of variables (meteorological, trace gas concentrations, and aerosol mass and composition) from different measurement platforms (ground measurements, vertical profiles, airborne measurements) collected from a number of sources. Approximately 10 to 25 modelling groups have contributed to each initiative, and model results have been managed centrally through three data hubs maintained by each initiative. Given the organizational complexity of bringing together these three initiatives to address a common set of policyrelevant questions, this publication provides the motivation for the modelling activity, the rationale for specific choices made in the model experiments, and an overview of the organizational structures for both the modelling and the measurements used and analysed in a number of modelling studies in this special issue.}, author = {Galmarini, Stefano and Koffi, Brigitte and Solazzo, Efisio and Keating, Terry and Hogrefe, Christian and Schulz, Michael and Benedictow, Anna and {Jurgen Griesfeller}, Jan and Janssens-Maenhout, Greet and Carmichael, Greg and Fu, Joshua and Dentener, Frank}, doi = {10.5194/acp-17-1543-2017}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {2}, pages = {1543--1555}, title = {{Technical note: Coordination and harmonization of the multi-scale, multi-model activities HTAP2, AQMEII3, and MICS-Asia3: Simulations, emission inventories, boundary conditions, and model output formats}}, volume = {17}, year = {2017} } @article{Gao2018a, abstract = {Topic 3 of the Model Inter-Comparison Study for Asia (MICS-Asia) Phase III examines how online coupled air quality models perform in simulating high aerosol pollution in the North China Plain region during wintertime haze events and evaluates the importance of aerosol radiative and microphysical feedbacks. A comprehensive overview of the MICS-Asia III Topic 3 study design, including descriptions of participating models and model inputs, the experimental designs, and results of model evaluation, are presented. Six modeling groups from China, Korea and the United States submitted results from seven applications of online coupled chemistry–meteorology models. Results are compared to meteorology and air quality measurements, including data from the Campaign on Atmospheric Aerosol Research Network of China (CARE-China) and the Acid Deposition Monitoring Network in East Asia (EANET). The correlation coefficients between the multi-model ensemble mean and the CARE-China observed near-surface air pollutants range from 0.51 to 0.94 (0.51 for ozone and 0.94 for PM2.5) for January 2010. However, large discrepancies exist between simulated aerosol chemical compositions from different models. The coefficient of variation (SD divided by the mean) can reach above 1.3 for sulfate in Beijing and above 1.6 for nitrate and organic aerosols in coastal regions, indicating that these compositions are less consistent from different models. During clean periods, simulated aerosol optical depths (AODs) from different models are similar, but peak values differ during severe haze events, which can be explained by the differences in simulated inorganic aerosol concentrations and the hygroscopic growth efficiency (affected by varied relative humidity). These differences in composition and AOD suggest that future models can be improved by including new heterogeneous or aqueous pathways for sulfate and nitrate formation under hazy conditions, a secondary organic aerosol (SOA) formation chemical mechanism with new volatile organic compound (VOCs) precursors, yield data and approaches, and a more detailed evaluation of the dependence of aerosol optical properties on size distribution and mixing state. It was also found that using the ensemble mean of the models produced the best prediction skill. While this has been shown for other conditions (for example, the prediction of high-ozone events in the US (McKeen et al., 2005)), this is to our knowledge the first time it has been shown for heavy haze events.}, author = {Gao, Meng and Han, Zhiwei and Liu, Zirui and Li, Meng and Xin, Jinyuan and Tao, Zhining and Li, Jiawei and Kang, Jeong Eon and Huang, Kan and Dong, Xinyi and Zhuang, Bingliang and Li, Shu and Ge, Baozhu and Wu, Qizhong and Cheng, Yafang and Wang, Yuesi and Lee, Hyo Jung and Kim, Cheol Hee and Fu, Joshua S. and Wang, Tijian and Chin, Mian and Woo, Jung Hun and Zhang, Qiang and Wang, Zifa and Carmichael, Gregory R.}, doi = {10.5194/acp-18-4859-2018}, isbn = {1680-7324}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {7}, pages = {4859--4884}, title = {{Air quality and climate change, Topic 3 of the Model Inter-Comparison Study for Asia Phase III (MICS-Asia III) – Part 1: Overview and model evaluation}}, volume = {18}, year = {2018} } @article{Garcia-Menendez2017, abstract = {Abstract Climate change can impact air quality by altering the atmospheric conditions that determine pollutant concentrations. Over large regions of the U.S., projected changes in climate are expected to favor formation of ground-level ozone and aggravate associated health effects. However, modeling studies exploring air quality-climate interactions have often overlooked the role of natural variability, a major source of uncertainty in projections. Here we use the largest ensemble simulation of climate-induced changes in air quality generated to date to assess its influence on estimates of climate change impacts on U.S. ozone. We find that natural variability can significantly alter the robustness of projections of the future climate's effect on ozone pollution. In this study, a 15?year simulation length minimum is required to identify a distinct anthropogenic-forced signal. Therefore, we suggest that studies assessing air quality impacts use multidecadal simulations or initial condition ensembles. With natural variability, impacts attributable to climate may be difficult to discern before midcentury or under stabilization scenarios.}, annote = {doi: 10.1002/2016GL071565}, author = {Garcia-Menendez, Fernando and Monier, Erwan and Selin, Noelle E}, doi = {10.1002/2016GL071565}, issn = {0094-8276}, journal = {Geophysical Research Letters}, keywords = {air pollution,climate change impacts,model projections,natural variability,ozone}, month = {mar}, number = {6}, pages = {2911--2921}, publisher = {Wiley-Blackwell}, title = {{The role of natural variability in projections of climate change impacts on U.S. ozone pollution}}, url = {https://doi.org/10.1002/2016GL071565}, volume = {44}, year = {2017} } @article{Garrido-Perez2019, abstract = {We have examined the joint impact of daily maximum temperature and air stagnation on observed maximum daily 8-h running average (MDA8) and hourly near-surface ozone (O3) over eight regions of Europe for the summer period 1998–2015. The percentage of stagnant area in a region is a better predictor of summer MDA8 O3 in central/southern Europe (correlation coefficient R = 0.50–0.70) than in the north (R = 0.06–0.39). The correlations of MDA8 O3 with temperature are higher than with stagnation for most regions, and the impact of stagnation on those correlations is region-dependent. MDA8 O3 mixing ratios consistently increase over central/southern Europe under stagnant conditions, but this has not been found for some temperature ranges in the north. Under non-stagnant situations and relatively high temperatures (20–25 °C), southerly advection often brings aged air masses from more polluted areas to the receptor regions in the north. Furthermore, the occurrence of stagnation tends to amplify the ozone diurnal cycles in the center/south of the continent, yielding lower nighttime and higher daytime mixing ratios than on non-stagnant days, again with a less clear effect in the north. Changes in planetary boundary layer height, accumulation of ozone and precursors, and subsequent photochemical production during stagnant days are the presumed underlying mechanisms for the amplification of the diurnal cycles. The results from this study prove that the effects of stagnation on summer ozone are regionally dependent across Europe. Consequently, climate model projections of increases in stagnation should not directly be translated into degraded air quality without a proper assessment of the regional impacts.}, author = {Garrido-Perez, Jose M. and Ord{\'{o}}{\~{n}}ez, Carlos and Garc{\'{i}}a-Herrera, Ricardo and Schnell, Jordan L.}, doi = {10.1016/j.atmosenv.2019.117062}, issn = {13522310}, journal = {Atmospheric Environment}, keywords = {Air pollution,Air quality,Meteorology,Ozone,Stagnation}, month = {dec}, pages = {117062}, title = {{The differing impact of air stagnation on summer ozone across Europe}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1352231019307010}, volume = {219}, year = {2019} } @article{Gasparini2016, abstract = {The net warming effect of cirrus clouds has driven part of the geoengineering research toward the idea of decreasing their occurrence frequency by seeding them with efficient ice nucleating particles. We study responses of cirrus clouds to simplified global seeding strategies in terms of their radiative fluxes with the help of the ECHAM-HAM general circulation model. Our cirrus scheme takes into account the competition between homogeneous and heterogeneous freezing, preexisting ice crystals, and the full spectrum of updraft velocities. While we find that the cirrus cloud radiative effect evaluated from our model is positive and large enough (5.7 W/m2) to confirm their geoengineering potential, none of the seeding strategies achieves a significant cooling due to complex microphysical mechanisms limiting their climatic responses. After globally uniform seeding is applied, we observe an increase in cirrus cloud cover, a decrease in ice crystal number concentration, and a decrease in ice crystal radius. An analysis of their respective radiative contributions points to the ice crystal radius decrease as the main factor limiting seeding effectiveness.}, author = {Gasparini, Bla{\v{z}} and Lohmann, Ulrike}, doi = {10.1002/2015JD024666}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {may}, number = {9}, pages = {4877--4893}, title = {{Why cirrus cloud seeding cannot substantially cool the planet}}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2015JD024666}, volume = {121}, year = {2016} } @article{Gasparini2020, author = {Gasparini, Bla{\v{z}} and McGraw, Zachary and Storelvmo, Trude and Lohmann, Ulrike}, doi = {10.1088/1748-9326/ab71a3}, issn = {1748-9326}, journal = {Environmental Research Letters}, month = {apr}, number = {5}, pages = {054002}, publisher = {IOP Publishing}, title = {{To what extent can cirrus cloud seeding counteract global warming?}}, url = {https://iopscience.iop.org/article/10.1088/1748-9326/ab71a3}, volume = {15}, year = {2020} } @article{Gaubert2017, abstract = {Abstract Understanding changes in the burden and growth rate of atmospheric methane (CH4) has been the focus of several recent studies but still lacks scientific consensus. Here we investigate the role of decreasing anthropogenic carbon monoxide (CO) emissions since 2002 on hydroxyl radical (OH) sinks and tropospheric CH4 loss. We quantify this impact by contrasting two model simulations for 2002?2013: (1) a Measurement of the Pollution in the Troposphere (MOPITT) CO reanalysis and (2) a Control-Run without CO assimilation. These simulations are performed with the Community Atmosphere Model with Chemistry of the Community Earth System Model fully coupled chemistry climate model with prescribed CH4 surface concentrations. The assimilation of MOPITT observations constrains the global CO burden, which significantly decreased over this period by {\~{}}20{\%}. We find that this decrease results to (a) increase in CO chemical production, (b) higher CH4 oxidation by OH, and (c) {\~{}}8{\%} shorter CH4 lifetime. We elucidate this coupling by a surrogate mechanism for CO-OH-CH4 that is quantified from the full chemistry simulations.}, author = {Gaubert, B. and Worden, H. M. and Arellano, A. F.J. and Emmons, L. K. and Tilmes, S. and Barr{\'{e}}, J. and {Martinez Alonso}, S. and Vitt, F. and Anderson, J. L. and Alkemade, F. and Houweling, S. and Edwards, D. P.}, doi = {10.1002/2017GL074987}, isbn = {0094-8276}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {air pollution,chemistry climate modeling,data assimilation,global chemistry transport model,tropospheric composition}, number = {19}, pages = {9985--9995}, title = {{Chemical Feedback From Decreasing Carbon Monoxide Emissions}}, volume = {44}, year = {2017} } @article{Gaudel2018a, abstract = {The Tropospheric Ozone Assessment Report (TOAR) is an activity of the International Global Atmospheric Chemistry Project. This paper is a component of the report, focusing on the present-day distribution and trends of tropospheric ozone relevant to climate and global atmospheric chemistry model evaluation. Utilizing the TOAR surface ozone database, several figures present the global distribution and trends of daytime average ozone at 2702 non-urban monitoring sites, highlighting the regions and seasons of the world with the greatest ozone levels. Similarly, ozonesonde and commercial aircraft observations reveal ozone's distribution throughout the depth of the free troposphere. Long-term surface observations are limited in their global spatial coverage, but data from remote locations indicate that ozone in the 21st century is greater than during the 1970s and 1980s. While some remote sites and many sites in the heavily polluted regions of East Asia show ozone increases since 2000, many others show decreases and there is no clear global pattern for surface ozone changes since 2000. Two new satellite products provide detailed views of ozone in the lower troposphere across East Asia and Europe, revealing the full spatial extent of the spring and summer ozone enhancements across eastern China that cannot be assessed from limited surface observations. Sufficient data are now available (ozonesondes, satellite, aircraft) across the tropics from South America eastwards to the western Pacific Ocean, to indicate a likely tropospheric column ozone increase since the 1990s. The 2014–2016 mean tropospheric ozone burden (TOB) between 60˚N–60˚S from five satellite products is 300 Tg ± 4{\%}. While this agreement is excellent, the products differ in their quantification of TOB trends and further work is required to reconcile the differences. Satellites can now estimate ozone's global long-wave radiative effect, but evaluation is difficult due to limited in situ observations where the radiative effect is greatest.}, author = {Gaudel, A. and Cooper, O. R. and Ancellet, G. and Barret, B. and Boynard, A. and Burrows, J. P. and Clerbaux, C. and Coheur, P.-F. and Cuesta, J. and Cuevas, E. and Doniki, S. and Dufour, G. and Ebojie, F. and Foret, G. and Garcia, O. and Granados-Mu{\~{n}}oz, M. J. and Hannigan, J. W. and Hase, F. and Hassler, B. and Huang, G. and Hurtmans, D. and Jaffe, D. and Jones, N. and Kalabokas, P. and Kerridge, B. and Kulawik, S. and Latter, B. and Leblanc, T. and {Le Flochmo{\"{e}}n}, E. and Lin, W. and Liu, J. and Liu, X. and Mahieu, E. and McClure-Begley, A. and Neu, J. L. and Osman, M. and Palm, M. and Petetin, H. and Petropavlovskikh, I. and Querel, R. and Rahpoe, N. and Rozanov, A. and Schultz, M. G. and Schwab, J. and Siddans, R. and Smale, D. and Steinbacher, M. and Tanimoto, H. and Tarasick, D. W. and Thouret, V. and Thompson, A. M. and Trickl, T. and Weatherhead, E. and Wespes, C. and Worden, H. M. and Vigouroux, C. and Xu, X. and Zeng, G. and Ziemke, J. and Helmig, Detlev and Lewis, Alastair}, doi = {10.1525/elementa.291}, issn = {2325-1026}, journal = {Elementa: Science of the Anthropocene}, keywords = {Global tropospheric ozone burden,Ozone trends,Tropospheric composition and chemistry,ground-level ozone,tropospheric ozone}, number = {1}, pages = {39}, title = {{Tropospheric Ozone Assessment Report: Present-day distribution and trends of tropospheric ozone relevant to climate and global atmospheric chemistry model evaluation}}, url = {http://www.elementascience.org/articles/10.1525/elementa.291/}, volume = {6}, year = {2018} } @article{Gaudeleaba8272, abstract = {Tropospheric ozone is an important greenhouse gas, is detrimental to human health and crop and ecosystem productivity, and controls the oxidizing capacity of the troposphere. Because of its high spatial and temporal variability and limited observations, quantifying net tropospheric ozone changes across the Northern Hemisphere on time scales of two decades had not been possible. Here, we show, using newly available observations from an extensive commercial aircraft monitoring network, that tropospheric ozone has increased above 11 regions of the Northern Hemisphere since the mid-1990s, consistent with the OMI/MLS satellite product. The net result of shifting anthropogenic ozone precursor emissions has led to an increase of ozone and its radiative forcing above all 11 study regions of the Northern Hemisphere, despite NOx emission reductions at midlatitudes.}, author = {Gaudel, Audrey and Cooper, Owen R and Chang, Kai-Lan and Bourgeois, Ilann and Ziemke, Jerry R and Strode, Sarah A and Oman, Luke D and Sellitto, Pasquale and N{\'{e}}d{\'{e}}lec, Philippe and Blot, Romain and Thouret, Val{\'{e}}rie and Granier, Claire}, doi = {10.1126/sciadv.aba8272}, journal = {Science Advances}, number = {34}, pages = {eaba8272}, publisher = {American Association for the Advancement of Science}, title = {{Aircraft observations since the 1990s reveal increases of tropospheric ozone at multiple locations across the Northern Hemisphere}}, url = {https://advances.sciencemag.org/content/6/34/eaba8272}, volume = {6}, year = {2020} } @article{Ge2018, abstract = {Ammonia plays a key role in the neutralization of atmospheric acids such as sulfate and nitrates. A few in situ observations have supported the theory that gas-phase NH 3 concentrations should decrease sharply with altitude and be extremely low in the upper troposphere and lower stratosphere (UTLS). This theory, however, seems inconsistent with recent satellite measurements and is also not supported by the aircraft data showing highly or fully neutralized sulfate aerosol particles by ammonium in the UTLS in many parts of the world. Here we reveal the contributions of deep convective clouds to NH 3 in the UTLS by using integrated cross-scale modeling, which includes molecular dynamic simulations, a global chemistry transport model, and satellite and aircraft measurements. We show that the NH 3 dissolved in liquid cloud droplets is prone to being released into the UTLS upon freezing during deep convection. Because NH 3 emission is not regulated in most countries and its future increase is likely persistent from agricultural growth and the warmer climate, the effect of NH 3 on composition and phase of aerosol particles in the UTLS can be significant, which in turn can affect cirrus cloud formation, radiation, and the budgets of NOx and O 3 .}, author = {Ge, Cui and Zhu, Chongqin and Francisco, Joseph S. and Zeng, Xiao Cheng and Wang, Jun}, doi = {10.1073/pnas.1719949115}, issn = {10916490}, journal = {Proceedings of the National Academy of Sciences}, keywords = {Ammonia,Deep convection,Freezing clouds,Global model,Molecular dynamics simulation}, month = {may}, number = {24}, pages = {6147--6152}, publisher = {Proceedings of the National Academy of Sciences}, title = {{A molecular perspective for global modeling of upper atmospheric NH3 from freezing clouds}}, volume = {115}, year = {2018} } @article{Geddes2016, abstract = {BACKGROUND: Air pollution is associated with morbidity and premature mortality. Satellite remote sensing provides globally consistent decadal-scale observations of ambient nitrogen dioxide (NO(2)) pollution. OBJECTIVE: We determined global population-weighted annual mean NO(2) concentrations from 1996 through 2012. METHODS: We used observations of NO(2) tropospheric column densities from three satellite instruments in combination with chemical transport modeling to produce a global 17-year record of ground-level NO(2) at 0.1° × 0.1° resolution. We calculated linear trends in population-weighted annual mean NO(2) (PWM(NO2)) concentrations in different regions around the world. RESULTS: We found that PWM(NO2) in high-income North America (Canada and the United States) decreased more steeply than in any other region, having declined at a rate of –4.7{\%}/year [95{\%} confidence interval (CI): –5.3, –4.1]. PWM(NO2) decreased in western Europe at a rate of –2.5{\%}/year (95{\%} CI: –3.0, –2.1). The highest PWM(NO2) occurred in high-income Asia Pacific (predominantly Japan and South Korea) in 1996, with a subsequent decrease of –2.1{\%}/year (95{\%} CI: –2.7, –1.5). In contrast, PWM(NO2) almost tripled in East Asia (China, North Korea, and Taiwan) at a rate of 6.7{\%}/year (95{\%} CI: 6.0, 7.3). The satellite-derived estimates of trends in ground-level NO(2) were consistent with regional trends inferred from data obtained from ground-station monitoring networks in North America (within 0.7{\%}/year) and Europe (within 0.3{\%}/year). Our rankings of regional average NO(2) and long-term trends differed from the satellite-derived estimates of fine particulate matter reported elsewhere, demonstrating the utility of both indicators to describe changing pollutant mixtures. CONCLUSIONS: Long-term trends in satellite-derived ambient NO(2) provide new information about changing global exposure to ambient air pollution. Our estimates are publicly available at http://fizz.phys.dal.ca/{\~{}}atmos/martin/?page{\_}id=232. CITATION: Geddes JA, Martin RV, Boys BL, van Donkelaar A. 2016. Long-term trends worldwide in ambient NO(2) concentrations inferred from satellite observations. Environ Health Perspect 124:281–289; http://dx.doi.org/10.1289/ehp.1409567}, annote = {ehp.1409567[PII] 26241114[pmid] Environ Health Perspect}, author = {Geddes, Jeffrey A and Martin, Randall V and Boys, Brian L and van Donkelaar, Aaron}, doi = {10.1289/ehp.1409567}, isbn = {0091-6765 1552-9924}, journal = {Environmental Health Perspectives}, number = {3}, pages = {281--289}, publisher = {National Institute of Environmental Health Sciences}, title = {{Long-Term Trends Worldwide in Ambient NO2 Concentrations Inferred from Satellite Observations}}, url = {http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4786989/}, volume = {124}, year = {2016} } @article{Genard-Zielinski2018, author = {Genard-Zielinski, Anne-Cyrielle and Boissard, Christophe and Orme{\~{n}}o, Elena and Lathi{\`{e}}re, Juliette and Reiter, Ilja M. and Wortham, Henri and Orts, Jean-Philippe and Temime-Roussel, Brice and Guenet, Bertrand and Bartsch, Svenja and Gauquelin, Thierry and Fernandez, Catherine}, doi = {10.5194/bg-15-4711-2018}, issn = {1726-4189}, journal = {Biogeosciences}, month = {aug}, number = {15}, pages = {4711--4730}, title = {{Seasonal variations of Quercus pubescens isoprene emissions from an in natura forest under drought stress and sensitivity to future climate change in the Mediterranean area}}, url = {https://bg.copernicus.org/articles/15/4711/2018/}, volume = {15}, year = {2018} } @article{Geng2014, abstract = {Nitrogen stable isotope ratio ($\delta$15N) in Greenland snow nitrate and in North American remote lake sediments has decreased gradually beginning as early as ∼1850 Christian Era. This decrease was attributed to increasing atmospheric deposition of anthropogenic nitrate, reflecting an anthropogenic impact on the global nitrogen cycle, and the impact was thought to be amplified ∼1970. However, our subannually resolved ice core records of $\delta$15N and major ions (e.g., NO3-, SO 42-) over the last ∼200 y show that the decrease in $\delta$15N is not always associated with increasing NO 3- concentrations, and the decreasing trend actually leveled off ∼1970. Correlation of $\delta$15N with H+, NO3-, and HNO3 concentrations, combined with nitrogen isotope fractionation models, suggests that the $\delta$15N decrease from ∼1850-1970 was mainly caused by an anthropogenic-driven increase in atmospheric acidity through alteration of the gas-particle partitioning of atmospheric nitrate. The concentrations of NO3- and SO42- also leveled off ∼1970, reflecting the effect of air pollution mitigation strategies in North America on anthropogenic NOx and SO2 emissions. The consequent atmospheric acidity change, as reflected in the ice core record of H+ concentrations, is likely responsible for the leveling off of $\delta$15N ∼1970, which, together with the leveling off of NO3- concentrations, suggests a regionalmitigation of anthropogenic impact on the nitrogen cycle. Our results highlight the importance of atmospheric processes in controlling $\delta$15N of nitrate and should be considered when using $\delta$15N as a source indicator to study atmospheric flux of nitrate to land surface/ecosystems.}, author = {Geng, Lei and Alexander, Becky and Cole-Dai, Jihong and Steig, Eric J. and Savarino, Jo{\"{e}}l and Sofen, Eric D. and Schauer, Andrew J.}, doi = {10.1073/pnas.1319441111}, issn = {10916490}, journal = {Proceedings of the National Academy of Sciences}, keywords = {Acid deposition,Clean air act,Fossil fuel emissions,Industrial,Proxy}, month = {apr}, number = {16}, pages = {5808--5812}, title = {{Nitrogen isotopes in ice core nitrate linked to anthropogenic atmospheric acidity change}}, volume = {111}, year = {2014} } @article{doi:10.1175/JCLI-D-12-00195.1, abstract = { AbstractThis is the first part of a series of two articles analyzing the global thermal properties of atmosphere–ocean coupled general circulation models (AOGCMs) within the framework of a two-layer energy-balance model (EBM). In this part, the general analytical solution of the system is given and two idealized climate change scenarios, one with a step forcing and one with a linear forcing, are discussed. These solutions give a didactic description of the contributions from the equilibrium response and of the fast and slow transient responses during a climate transition. Based on these analytical solutions, a simple and physically based procedure to calibrate the two-layer model parameters using an AOGCM step-forcing experiment is introduced. Using this procedure, the global thermal properties of 16 AOGCMs participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) are determined. It is shown that, for a given AOGCM, the EBM tuned with only the abrupt 4×CO2 experiment is able to reproduce with a very good accuracy the temperature evolution in both a step-forcing and a linear-forcing experiment. The role of the upper-ocean and deep-ocean heat uptakes in the fast and slow responses is also discussed. One of the main weaknesses of the simple EBM discussed in this part is its ability to represent the evolution of the top-of-the-atmosphere radiative imbalance in the transient regime. This issue is addressed in Part II by taking into account the efficacy factor of deep-ocean heat uptake. }, author = {Geoffroy, O and Saint-Martin, D and Olivi{\'{e}}, D J L and Voldoire, A and Bellon, G and Tyt{\'{e}}ca, S}, doi = {10.1175/JCLI-D-12-00195.1}, journal = {Journal of Climate}, number = {6}, pages = {1841--1857}, title = {{Transient Climate Response in a Two-Layer Energy-Balance Model. Part I: Analytical Solution and Parameter Calibration Using CMIP5 AOGCM Experiments}}, url = {https://doi.org/10.1175/JCLI-D-12-00195.1}, volume = {26}, year = {2013} } @article{Georgoulias2019, abstract = {In this work, a 21-year global dataset from four different satellite sensors with a mid-morning overpass (GOME/ERS-2, SCIAMACHY/ENVISAT, GOME- 2/Metop-A, and GOME-2/Metop-B) is compiled to study the long-term tropospheric NO2 patterns and trends. The Global Ozone Monitoring Experiment (GOME) and GOME-2 data are corrected relative to the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) data to produce a self-consistent dataset that covers the period April 1996September 2017. The highest tropospheric NO2 concentrations are seen over urban, industrialized, and highly populated areas and over ship tracks in the oceans. Tropospheric NO2 has generally decreased during the last 2 decades over the industrialized and highly populated regions of the western world (a total decrease of the order of 49{\%} over the US, the Netherlands, and the UK; 36{\%} over Italy and Japan; and 32{\%} over Germany and France) and increased over developing regions (a total increase of 160{\%} over China and 33{\%} over India). It is suggested here that linear trends cannot be used efficiently worldwide for such long periods. Tropospheric NO2 is very sensitive to socioeconomic changes (e.g., environmental protection policies, economic recession, warfare, etc.) which may cause either short-term changes or even a reversal of the trends. The application of a method capable of detecting the year when a reversal of trends happened shows that tropospheric NO2 concentrations switched from positive to negative trends and vice versa over several regions around the globe. A country-level analysis revealed clusters of countries that exhibit similar positive-to-negative or negative-topositive trend reversals, while 29 out of a total of 64 examined megacities and large urban agglomerations experienced a trend reversal at some point within the last 2 decades.}, author = {Georgoulias, Aristeidis K. and {Van Der}, Ronald A.J. and Stammes, Piet and {Folkert Boersma}, K. and Eskes, Henk J.}, doi = {10.5194/acp-19-6269-2019}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {9}, pages = {6269--6294}, publisher = {Copernicus Publications}, title = {{Trends and trend reversal detection in 2 decades of tropospheric NO2 satellite observations}}, volume = {19}, year = {2019} } @article{https://doi.org/10.1029/2020GL091805, abstract = {Abstract The COVID-19 pandemic led to dramatic changes in economic activity in 2020. We use estimates of emission changes for 2020 in two Earth System Models (ESMs) to simulate the impacts of the COVID-19 economic changes. Ensembles of nudged simulations are used to separate small signals from meteorological variability. Reductions in aerosol and precursor emissions, chiefly black carbon and sulfate (SO4), led to reductions in total anthropogenic aerosol cooling through aerosol-cloud interactions. The average overall Effective Radiative Forcing (ERF) peaks at +0.29 ± 0.15 Wm−2 in spring 2020. Changes in cloud properties are smaller than observed changes during 2020. Impacts of these changes on regional land surface temperature range up to +0.3 K. The peak impact of these aerosol changes on global surface temperature is very small (+0.03 K). However, the aerosol changes are the largest contribution to radiative forcing and temperature changes as a result of COVID-19 affected emissions, larger than ozone, CO2 and contrail effects.}, annote = {e2020GL091805 2020GL091805}, author = {Gettelman, A and Lamboll, R and Bardeen, C G and Forster, P M and Watson-Parris, D}, doi = {https://doi.org/10.1029/2020GL091805}, journal = {Geophysical Research Letters}, keywords = {COVID-19,aerosol,climate}, number = {3}, pages = {e2020GL091805}, title = {{Climate Impacts of COVID-19 Induced Emission Changes}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL091805}, volume = {48}, year = {2021} } @article{Ghan2013, abstract = {Abstract. Estimating anthropogenic aerosol effects on the planetary energy balance through the aerosol influence on clouds using the difference in cloud radiative forcing from simulations with and without anthropogenic emissions produces estimates that are positively biased. A more representative method is suggested using the difference in cloud radiative forcing calculated as a diagnostic with aerosol scattering and absorption neglected. The method also yields an aerosol radiative forcing decomposition that includes a term quantifying the impact of changes in surface albedo. The method requires only two additional diagnostic calculations: the whole-sky and clear-sky top-of-atmosphere radiative flux with aerosol scattering and absorption neglected.}, author = {Ghan, S. J.}, doi = {10.5194/acp-13-9971-2013}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {oct}, number = {19}, pages = {9971--9974}, title = {{Technical Note: Estimating aerosol effects on cloud radiative forcing}}, url = {https://acp.copernicus.org/articles/13/9971/2013/}, volume = {13}, year = {2013} } @article{gmd-2018-266, abstract = {Abstract. We present a suite of nine scenarios of future emissions trajectories of anthropogenic sources, a key deliverable of the ScenarioMIP experiment within CMIP6. Integrated Assessment Model results for 14 different emissions species and 13 emissions sectors are provided for each scenario with consistent transitions from the historical data used in CMIP6 to future trajectories using automated harmonization before being downscaled to provide higher emission source spatial detail. We find that the scenarios span a wide range of end-of-century radiative forcing values, thus making this set of scenarios ideal for exploring a variety of warming pathways. The set of scenarios are bounded on the low end by a 1.9{\&}thinsp;W{\&}thinsp;m-2 scenario, ideal for analyzing a world with end-of-century temperatures well below 2{\&}thinsp;{\&}deg;C, and on the high-end by a 8.5{\&}thinsp;W{\&}thinsp;m-2 scenario, resulting in an increase in warming of nearly 5{\&}thinsp;{\&}deg;C over pre-industrial levels. Between these two extremes, scenarios are provided such that differences between forcing outcomes provide statistically significant regional temperature outcomes to maximize their usefulness for downstream experiments within CMIP6. A wide range of scenario data products are provided for the CMIP6 scientific community including global, regional, and gridded emissions datasets.}, author = {Gidden, Matthew J. and Riahi, Keywan and Smith, Steven J. and Fujimori, Shinichiro and Luderer, Gunnar and Kriegler, Elmar and {Van Vuuren}, Detlef P. and {Van Den Berg}, Maarten and Feng, Leyang and Klein, David and Calvin, Katherine and Doelman, Jonathan C. and Frank, Stefan and Fricko, Oliver and Harmsen, Mathijs and Hasegawa, Tomoko and Havlik, Petr and Hilaire, J{\'{e}}r{\^{o}}me and Hoesly, Rachel and Horing, Jill and Popp, Alexander and Stehfest, Elke and Takahashi, Kiyoshi}, doi = {10.5194/gmd-12-1443-2019}, issn = {19919603}, journal = {Geoscientific Model Development}, number = {4}, pages = {1443--1475}, title = {{Global emissions pathways under different socioeconomic scenarios for use in CMIP6: A dataset of harmonized emissions trajectories through the end of the century}}, url = {https://www.geosci-model-dev-discuss.net/gmd-2018-266/}, volume = {12}, year = {2019} } @article{doi:10.1029/2012RG000388, abstract = {Our understanding of the global dust cycle is limited by a dearth of information about dust sources, especially small-scale features which could account for a large fraction of global emissions. Here we present a global-scale high-resolution (0.1°) mapping of sources based on Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue estimates of dust optical depth in conjunction with other data sets including land use. We ascribe dust sources to natural and anthropogenic (primarily agricultural) origins, calculate their respective contributions to emissions, and extensively compare these products against literature. Natural dust sources globally account for 75{\%} of emissions; anthropogenic sources account for 25{\%}. North Africa accounts for 55{\%} of global dust emissions with only 8{\%} being anthropogenic, mostly from the Sahel. Elsewhere, anthropogenic dust emissions can be much higher (75{\%} in Australia). Hydrologic dust sources (e.g., ephemeral water bodies) account for 31{\%} worldwide; 15{\%} of them are natural while 85{\%} are anthropogenic. Globally, 20{\%} of emissions are from vegetated surfaces, primarily desert shrublands and agricultural lands. Since anthropogenic dust sources are associated with land use and ephemeral water bodies, both in turn linked to the hydrological cycle, their emissions are affected by climate variability. Such changes in dust emissions can impact climate, air quality, and human health. Improved dust emission estimates will require a better mapping of threshold wind velocities, vegetation dynamics, and surface conditions (soil moisture and land use) especially in the sensitive regions identified here, as well as improved ability to address small-scale convective processes producing dust via cold pool (haboob) events frequent in monsoon regimes.}, author = {Ginoux, Paul and Prospero, Joseph M and Gill, Thomas E and Hsu, N Christina and Zhao, Ming}, doi = {10.1029/2012RG000388}, journal = {Reviews of Geophysics}, keywords = {aerosols,anthropogenic,dust sources,remote sensing}, number = {3}, pages = {RG3005}, title = {{Global-scale attribution of anthropogenic and natural dust sources and their emission rates based on MODIS Deep Blue aerosol products}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2012RG000388}, volume = {50}, year = {2012} } @article{C1EM10240K, abstract = {Aerosol particle samples (PM10) were collected at urban, industrial and rural sites located in Rio de Janeiro, Brazil, between October 2008 and September 2009. Aerosol samples for each site were analyzed for total and soluble metals, water-soluble ions, carboxylic acids, and water-soluble organic carbon (WSOC). The results showed that the mean PM10 concentrations were 34 $\mu$g m−3; 47 $\mu$g m−3 and 71 $\mu$g m−3 at the rural,urban and industrial sites, respectively. An increase in the average concentration of these particles due to air stagnation was observed during the period from May to September for all sites, and an increase in hospitalization for respiratory problems was also reported. On average, the anions species represented 4 to 14{\%} of total content, while cations species corresponded to 1 to 11{\%} and 7.5{\%} for WSOC. The overall metal content at the industrial site was nearly the double that at the rural site. The concentrations of the studied species are influenced mainly by site location and the specific characteristics present at each site. However, higher concentrations of some species were observed on particular dates and were probably due to biomass burning and African dust events. The acid/aqueous percentiles showed that the most efficiently extracted metals from the aqueous phase were V and Ni (40{\%}), while Al and Fe represented a lower percentage ({\textless}3{\%}). Analysis of the aqueous fraction provides important information about the bioavailability of metals that is associated with the inflammatory process in the lungs.}, author = {Gioda, Adriana and Amaral, Beatriz Silva and Monteiro, Isabela Luizi Gon{\c{c}}alves and Saint'Pierre, Tatiana Dillenburg}, doi = {10.1039/c1em10240k}, issn = {1464-0325}, journal = {Journal of Environmental Monitoring}, number = {8}, pages = {2134}, publisher = {The Royal Society of Chemistry}, title = {{Chemical composition, sources, solubility, and transport of aerosol trace elements in a tropical region}}, url = {http://dx.doi.org/10.1039/C1EM10240K http://xlink.rsc.org/?DOI=c1em10240k}, volume = {13}, year = {2011} } @article{Gkatzelis2021, author = {Gkatzelis, GI and Gilman, J.B. and Brown, S.S. and Eskes, H and Gomes, A.R. and Lange, A.C. and McDonald, B.C. and Peischl, J. and Petzold, A. and Thompson, C.R. and Kiendler-Schar, A.}, doi = {10.1525/elementa.2021.00176}, journal = {Elementa: Science of the Anthropocene}, number = {1}, pages = {00176}, title = {{The global impacts of COVID-19 lockdowns on urban air quality: a critical review and recommendations}}, url = {https://doi.org/10.1525/elementa.2021.00176}, volume = {9}, year = {2021} } @article{Gliß2021, abstract = {Abstract. Within the framework of the AeroCom (Aerosol Comparisons between Observations and Models) initiative, the state-of-the-art modelling of aerosol optical properties is assessed from 14 global models participating in the phase III control experiment (AP3). The models are similar to CMIP6/AerChemMIP Earth System Models (ESMs) and provide a robust multi-model ensemble. Inter-model spread of aerosol species lifetimes and emissions appears to be similar to that of mass extinction coefficients (MECs), suggesting that aerosol optical depth (AOD) uncertainties are associated with a broad spectrum of parameterised aerosol processes. Total AOD is approximately the same as in AeroCom phase I (AP1) simulations. However, we find a 50 {\%} decrease in the optical depth (OD) of black carbon (BC), attributable to a combination of decreased emissions and lifetimes. Relative contributions from sea salt (SS) and dust (DU) have shifted from being approximately equal in AP1 to SS contributing about 2∕3 of the natural AOD in AP3. This shift is linked with a decrease in DU mass burden, a lower DU MEC, and a slight decrease in DU lifetime, suggesting coarser DU particle sizes in AP3 compared to AP1. Relative to observations, the AP3 ensemble median and most of the participating models underestimate all aerosol optical properties investigated, that is, total AOD as well as fine and coarse AOD (AODf, AODc), {\AA}ngstr{\"{o}}m exponent (AE), dry surface scattering (SCdry), and absorption (ACdry) coefficients. Compared to AERONET, the models underestimate total AOD by ca. 21 {\%} ± 20 {\%} (as inferred from the ensemble median and interquartile range). Against satellite data, the ensemble AOD biases range from −37 {\%} (MODIS-Terra) to −16 {\%} (MERGED-FMI, a multi-satellite AOD product), which we explain by differences between individual satellites and AERONET measurements themselves. Correlation coefficients (R) between model and observation AOD records are generally high (R{\textgreater}0.75), suggesting that the models are capable of capturing spatio-temporal variations in AOD. We find a much larger underestimate in coarse AODc (∼ −45 {\%} ± 25 {\%}) than in fine AODf (∼ −15 {\%} ± 25 {\%}) with slightly increased inter-model spread compared to total AOD. These results indicate problems in the modelling of DU and SS. The AODc bias is likely due to missing DU over continental land masses (particularly over the United States, SE Asia, and S. America), while marine AERONET sites and the AATSR SU satellite data suggest more moderate oceanic biases in AODc. Column AEs are underestimated by about 10 {\%} ± 16 {\%}. For situations in which measurements show AE {\textgreater} 2, models underestimate AERONET AE by ca. 35 {\%}. In contrast, all models (but one) exhibit large overestimates in AE when coarse aerosol dominates (bias ca. +140 {\%} if observed AE}, author = {Gli{\ss}, Jonas and Mortier, Augustin and Schulz, Michael and Andrews, Elisabeth and Balkanski, Yves and Bauer, Susanne E and Benedictow, Anna M K and Bian, Huisheng and Checa-Garcia, Ramiro and Chin, Mian and Ginoux, Paul and Griesfeller, Jan J and Heckel, Andreas and Kipling, Zak and Kirkev{\aa}g, Alf and Kokkola, Harri and Laj, Paolo and {Le Sager}, Philippe and Lund, Marianne Tronstad and {Lund Myhre}, Cathrine and Matsui, Hitoshi and Myhre, Gunnar and Neubauer, David and van Noije, Twan and North, Peter and Olivi{\'{e}}, Dirk J L and R{\'{e}}my, Samuel and Sogacheva, Larisa and Takemura, Toshihiko and Tsigaridis, Kostas and Tsyro, Svetlana G}, doi = {10.5194/acp-21-87-2021}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jan}, number = {1}, pages = {87--128}, publisher = {Copernicus Publications}, title = {{AeroCom phase III multi-model evaluation of the aerosol life cycle and optical properties using ground- and space-based remote sensing as well as surface in situ observations}}, url = {https://acp.copernicus.org/articles/21/87/2021/}, volume = {21}, year = {2021} } @article{Gonzalez-Abraham2015, abstract = {Abstract. To understand more fully the effects of global changes on ambient concentrations of ozone and particulate matter with aerodynamic diameter smaller than 2.5 $\mu$m (PM2.5) in the United States (US), we conducted a comprehensive modeling effort to evaluate explicitly the effects of changes in climate, biogenic emissions, land use and global/regional anthropogenic emissions on ozone and PM2.5 concentrations and composition. Results from the ECHAM5 global climate model driven with the A1B emission scenario from the Intergovernmental Panel on Climate Change (IPCC) were downscaled using the Weather Research and Forecasting (WRF) model to provide regional meteorological fields. We developed air quality simulations using the Community Multiscale Air Quality Model (CMAQ) chemical transport model for two nested domains with 220 and 36 km horizontal grid cell resolution for a semi-hemispheric domain and a continental United States (US) domain, respectively. The semi-hemispheric domain was used to evaluate the impact of projected global emissions changes on US air quality. WRF meteorological fields were used to calculate current (2000s) and future (2050s) biogenic emissions using the Model of Emissions of Gases and Aerosols from Nature (MEGAN). For the semi-hemispheric domain CMAQ simulations, present-day global emissions inventories were used and projected to the 2050s based on the IPCC A1B scenario. Regional anthropogenic emissions were obtained from the US Environmental Protection Agency National Emission Inventory 2002 (EPA NEI2002) and projected to the future using the MARKet ALlocation (MARKAL) energy system model assuming a business as usual scenario that extends current decade emission regulations through 2050. Our results suggest that daily maximum 8 h average ozone (DM8O) concentrations will increase in a range between 2 to 12 parts per billion (ppb) across most of the continental US. The highest increase occurs in the South, Central and Midwest regions of the US due to increases in temperature, enhanced biogenic emissions and changes in land use. The model predicts an average increase of 1–6 ppb in DM8O due to projected increase in global emissions of ozone precursors. The effects of these factors are only partially offset by reductions in DM8O associated with decreasing US anthropogenic emissions. Increases in PM2.5 levels between 4 and 10 $\mu$g m−3 in the Northeast, Southeast, Midwest and South regions are mostly a result of increase in primary anthropogenic particulate matter (PM), enhanced biogenic emissions and land use changes. Changes in boundary conditions shift the composition but do not alter overall simulated PM2.5 mass concentrations.}, author = {Gonzalez-Abraham, R. and Chung, S. H. and Avise, J. and Lamb, B. and Salath{\'{e}}, E. P. and Nolte, C. G. and Loughlin, D. and Guenther, A. and Wiedinmyer, C. and Duhl, T. and Zhang, Y. and Streets, D. G.}, doi = {10.5194/acp-15-12645-2015}, isbn = {1680-7375}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {nov}, number = {21}, pages = {12645--12665}, title = {{The effects of global change upon United States air quality}}, url = {https://www.atmos-chem-phys.net/15/12645/2015/}, volume = {15}, year = {2015} } @article{Gratz2015, abstract = {We report trends in springtime ozone (O3) and carbon monoxide (CO) at the Mt. Bachelor Observatory (MBO) in central Oregon, U.S.A. from 2004 to 2013. Over the 10-year period the median and 95th percentile springtime O3increased by 0.76 ± 0.61 ppbv yr-1(1.7 ± 1.4{\%} yr-1) and 0.87 ± 0.73 ppbv yr-1(1.5 ± 1.2{\%} yr-1), respectively. These trends are consistent with reported positive trends in springtime O3in the western U.S. In contrast, median CO decreased by -3.1 ± 2.4 ppbv yr-1(-1.9 ± 1.4{\%} yr-1), which is highly similar to springtime North Pacific surface flask measurements from 2004 to 2012. While a 10-year record is relatively short to evaluate long-term variability, we incorporate transport model analysis and contextualize our measurements with reported northern mid-latitude trends over similar time frames to investigate the causes of increasing O3and decreasing CO at MBO. We performed cluster analysis of 10-day HYSPLIT back-trajectories from MBO and examined O3and CO trends within each cluster. Significant positive O3trends were associated with high-altitude, rapid transport from East Asia. Significant negative CO trends were most associated with transport from the North Pacific and Siberia, as well as from East Asia. The rise in springtime O3is likely associated with increasing O3precursor emissions in Asia and long-range transport to the western U.S. The decline in springtime CO appears linked to decreasing Northern Hemisphere background CO, largely due to anthropogenic emissions reductions in Europe and North America, and also to a recently reported decline in total CO output from China caused by more efficient combustion. These springtime O3and CO trends suggest that hydroxyl radical (OH) mixing ratios in the North Pacific may have increased over the study period.}, author = {Gratz, L. E. and Jaffe, D. A. and Hee, J. R.}, doi = {10.1016/j.atmosenv.2014.05.076}, isbn = {1352-2310}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Asian long-range transport,Carbon monoxide,Long-term trends,Ozone,Trajectory cluster analysis,Western U.S.}, pages = {323--330}, title = {{Causes of increasing ozone and decreasing carbon monoxide in springtime at the Mt. Bachelor Observatory from 2004 to 2013}}, volume = {109}, year = {2015} } @article{Grewe2001, abstract = {Year-long measurements of NOxand ozone performed during the NOXAR project are compared to results from the ECHAM4.L39(DLR)/CHEM (E39/C) and GISS coupled chemistry-climate models. The measurements were taken on flights between Europe and the eastern United States and between Europe and the Far East in the latitude range 40-65°N. Our comparison concentrates on the upper troposphere and reveals strong longitudinal variations in seasonal mean NOxof more than 200pptv, which both models are able to reproduce qualitatively. Vertical profiles show maximum NOxvalues 2-3km below the tropopause ('E-shape') with a strong seasonal cycle. E39/C simulates a maximum located at the tropopause and with a reasonable seasonal cycle. The GISS model reproduces the seasonal cycle but not the profile's shape due to its coarser vertical resolution. A comparison of NOxfrequency distributions reveals that both models are capable of reproducing the observed variability, except that E39/C shows no very high NOxmixing ratios.Both models show that lightning and surface NOxemissions contribute the most to the seasonal cycle of NOxat tropopause altitudes. The impact of lightning in the upper troposphere does not vary strongly with altitude, whereas the impact of surface emissions decreases with altitude. Among all sources, lightning contributes the most to the variability of NOxin the upper troposphere in northern mid-latitudes during summer. Copyright {\textcopyright} 2001 Elsevier Science Ltd.}, author = {Grewe, V. and Brunner, D. and Dameris, M. and Grenfell, J. L. and Hein, R. and Shindell, D. and Staehelin, J.}, doi = {10.1016/S1352-2310(01)00134-0}, isbn = {1352-2310}, issn = {13522310}, journal = {Atmospheric Environment}, keywords = {GCM,Lightning NOx,NOXAR,Upper troposphere NOxand ozone}, number = {20}, pages = {3421--3433}, title = {{Origin and variability of upper tropospheric nitrogen oxides and ozone at northern mid-latitudes}}, volume = {35}, year = {2001} } @article{Grewe2019, author = {Grewe, Volker and Matthes, Sigrun and Dahlmann, Katrin}, doi = {10.1088/1748-9326/ab5dd7}, issn = {1748-9326}, journal = {Environmental Research Letters}, number = {12}, pages = {121003}, publisher = {IOP Publishing}, title = {{The contribution of aviation NOx emissions to climate change: are we ignoring methodological flaws?}}, url = {http://dx.doi.org/10.1088/1748-9326/ab5dd7}, volume = {14}, year = {2019} } @article{acp-2019-1216, abstract = {Abstract. The evolution of tropospheric ozone from 1850 to 2100 has been studied using data from Phase 6 of the Coupled Model Intercomparison Project (CMIP6). We evaluate long-term changes using coupled atmosphere–ocean chemistry–climate models, focusing on the CMIP Historical and ScenarioMIP ssp370 experiments, for which detailed tropospheric-ozone diagnostics were archived. The model ensemble has been evaluated against a suite of surface, sonde and satellite observations of the past several decades and found to reproduce well the salient spatial, seasonal and decadal variability and trends. The multi-model mean tropospheric-ozone burden increases from 247 ± 36 Tg in 1850 to a mean value of 356 ± 31 Tg for the period 2005–2014, an increase of 44 {\%}. Modelled present-day values agree well with previous determinations (ACCENT: 336 ± 27 Tg; Atmospheric Chemistry and Climate Model Intercomparison Project, ACCMIP: 337 ± 23 Tg; Tropospheric Ozone Assessment Report, TOAR: 340 ± 34 Tg). In the ssp370 experiments, the ozone burden increases to 416 ± 35 Tg by 2100. The ozone budget has been examined over the same period using lumped ozone production (PO3) and loss (LO3) diagnostics. Both ozone production and chemical loss terms increase steadily over the period 1850 to 2100, with net chemical production (PO3-LO3) reaching a maximum around the year 2000. The residual term, which contains contributions from stratosphere–troposphere transport reaches a minimum around the same time before recovering in the 21st century, while dry deposition increases steadily over the period 1850–2100. Differences between the model residual terms are explained in terms of variation in tropopause height and stratospheric ozone burden.}, author = {Griffiths, Paul T and Murray, Lee T and Zeng, Guang and Shin, Youngsub Matthew and Abraham, N. Luke and Archibald, Alexander T and Deushi, Makoto and Emmons, Louisa K and Galbally, Ian E. and Hassler, Birgit and Horowitz, Larry W and Keeble, James and Liu, Jane and Moeini, Omid and Naik, Vaishali and O'Connor, Fiona M and Oshima, Naga and Tarasick, David and Tilmes, Simone and Turnock, Steven T and Wild, Oliver and Young, Paul J and Zanis, Prodromos}, doi = {10.5194/acp-21-4187-2021}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {5}, pages = {4187--4218}, title = {{Tropospheric ozone in CMIP6 simulations}}, url = {https://acp.copernicus.org/articles/21/4187/2021/}, volume = {21}, year = {2021} } @misc{Grythe2014, abstract = {Sea-spray aerosols (SSA) are an important part of the climate system because of their effects on the global radiative budget-both directly as scatterers and absorbers of solar and terrestrial radiation, and indirectly as cloud condensation nuclei (CCN) influencing cloud formation, lifetime, and precipitation. In terms of their global mass, SSA have the largest uncertainty of all aerosols. In this study we review 21 SSA source functions from the literature, several of which are used in current climate models. In addition, we propose a∼new function. Even excluding outliers, the global annual SSA mass produced spans roughly 3-70 Pg yr-1 for the different source functions, for particles with dry diameter Dp10 $\mu$m, with relatively little interannual variability for a given function. The FLEXPART Lagrangian particle dispersion model was run in backward mode for a large global set of observed SSA concentrations, comprised of several station networks and ship cruise measurement campaigns. FLEXPART backward calculations produce gridded emission sensitivity fields, which can subsequently be multiplied with gridded SSA production fluxes in order to obtain modeled SSA concentrations. This allowed us to efficiently and simultaneously evaluate all 21 source functions against the measurements. Another advantage of this method is that source-region information on wind speed and sea surface temperatures (SSTs) could be stored and used for improving the SSA source function parameterizations. The best source functions reproduced as much as 70{\%} of the observed SSA concentration variability at several stations, which is comparable with "state of the art" aerosol models. The main driver of SSA production is wind, and we found that the best fit to the observation data could be obtained when the SSA production is proportional to U103.5, where U10 is the source region averaged 10 m wind speed. A strong influence of SST on SSA production, with higher temperatures leading to higher production, could be detected as well, although the underlying physical mechanisms of the SST influence remains unclear. Our new source function with wind speed and temperature dependence gives a global SSA production for particles smaller than Dp 10 $\mu$m of 9 Pg yr-1, and is the best fit to the observed concentrations. {\textcopyright} 2014 Auhtor(s).}, author = {Grythe, H. and Str{\"{o}}m, J. and Krejci, R. and Quinn, P. and Stohl, A.}, booktitle = {Atmospheric Chemistry and Physics}, doi = {10.5194/acp-14-1277-2014}, issn = {16807316}, number = {3}, pages = {1277--1297}, title = {{A review of sea-spray aerosol source functions using a large global set of sea salt aerosol concentration measurements}}, volume = {14}, year = {2014} } @article{Gschrey2011, abstract = {Emissions of fluorinated greenhouse gases (GHGs) (hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphurhexafluoride (SF6)) have increased significantly in recent years and are estimated to rise further. Banks and emissions of HFCs, PFCs and SF6 in the year 2050 are projected per sector in a business-as-usual scenario. The total global emissions of fluorinated GHGs will amount to 4 GT CO2 eq. by 2050 if no mitigation measures are taken. The contribution of F-gases to global warming will increase from approx. 1.3{\%} (2004) to 7.9{\%} of projected total anthropogenic CO2 emissions in this business-as-usual scenario in 2050. For significant reductions in future emissions of Kyoto F-gases, additional efforts from both developed and developing countries are needed.}, author = {Gschrey, Barbara and Schwarz, Winfried and Elsner, Cornelia and Engelhardt, Rolf}, doi = {10.1080/20430779.2011.579352}, issn = {2043-0779}, journal = {Greenhouse Gas Measurement and Management}, number = {2}, pages = {85--92}, title = {{High increase of global F-gas emissions until 2050}}, volume = {1}, year = {2011} } @article{gmd-5-1471-2012, abstract = {The Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1) is a modeling framework for estimating fluxes of biogenic compounds between terrestrial ecosystems and the atmosphere using simple mechanistic algorithms to account for the major known processes controlling biogenic emissions. It is available as an offline code and has also been coupled into land surface and atmospheric chemistry models. MEGAN2.1 is an update from the previous versions including MEGAN2.0, which was described for isoprene emissions by Guenther et al. (2006) and MEGAN2.02, which was described for monoterpene and sesquiterpene emissions by Sakulyanontvittaya et al. (2008). Isoprene comprises about half of the total global biogenic volatile organic compound (BVOC) emission of 1 Pg (1000 Tg or 1015 g) estimated using MEGAN2.1. Methanol, ethanol, acetaldehyde, acetone, $\alpha$-pinene, $\beta$-pinene, t-$\beta$-ocimene, limonene, ethene, and propene together contribute another 30{\%} of the MEGAN2.1 estimated emission. An additional 20 compounds (mostly terpenoids) are associated with the MEGAN2.1 estimates of another 17{\%} of the total emission with the remaining 3{\%} distributed among {\textgreater}100 compounds. Emissions of 41 monoterpenes and 32 sesquiterpenes together comprise about 15{\%} and 3{\%}, respectively, of the estimated total global BVOC emission. Tropical trees cover about 18{\%} of the global land surface and are estimated to be responsible for ∼80{\%} of terpenoid emissions and ∼50{\%} of other VOC emissions. Other trees cover about the same area but are estimated to contribute only about 10{\%} of total emissions. The magnitude of the emissions estimated with MEGAN2.1 are within the range of estimates reported using other approaches and much of the differences between reported values can be attributed to land cover and meteorological driving variables. The offline version of MEGAN2.1 source code and driving variables is available from http://bai.acd.ucar.edu/ MEGAN/ and the version integrated into the Community Land Model version 4 (CLM4) can be downloaded from http://www.cesm.ucar.edu/. {\textcopyright} Author(s) 2012.}, author = {Guenther, A. B. and Jiang, X. and Heald, C. L. and Sakulyanontvittaya, T. and Duhl, T. and Emmons, L. K. and Wang, X.}, doi = {10.5194/gmd-5-1471-2012}, issn = {1991959X}, journal = {Geoscientific Model Development}, number = {6}, pages = {1471--1492}, title = {{The model of emissions of gases and aerosols from nature version 2.1 (MEGAN2.1): An extended and updated framework for modeling biogenic emissions}}, url = {https://www.geosci-model-dev.net/5/1471/2012/}, volume = {5}, year = {2012} } @article{Guo2018a, abstract = {In some regions, reducing aerosol ammonium nitrate (NH4NO3) concentrations may substantially improve air quality. This can be accomplished by reductions in precursor emissions, such as nitrogen oxides (NO) to lower nitric acid (HNO3) that partitions to the aerosol, or reductions in ammonia (NH3) to lower particle pH and keep HNO3 in the gas phase. Using the ISORROPIA-II thermodynamic aerosol model and detailed observational data sets, we explore the sensitivity of aerosol NH4NO3 to gas-phase NH3 and NOx controls for a number of contrasting locations, including Europe, the United States, and China. NOx control is always effective, whereas the aerosol response to NH3 control is highly nonlinear and only becomes effective at a thermodynamic sweet spot. The analysis provides a conceptual framework and fundamental evaluation on the relative value of NOx versus NH3 control and demonstrates the relevance of pH as an air quality parameter. We find that, regardless of the locations examined, it is only when ambient particle pH drops below an approximate critical value of 3 (slightly higher in warm and slightly lower in cold seasons) that NH3 reduction leads to an effective response in PM2.5 mass. The required amount of NH3 reduction to reach the critical pH and efficiently decrease NH4NO3 at different sites is assessed. Owing to the linkage between NH3 emissions and agricultural productivity, the substantial NH3 reduction required in some locations may not be feasible. Finally, controlling NH3 emissions to increase aerosol acidity and evaporate NH4NO3 will have other effects, beyond reduction of PM2.5 NH4NO3, such as increasing aerosol toxicity and potentially altering the deposition patterns of nitrogen and trace nutrients.}, author = {Guo, Hongyu and Otjes, Rene and Schlag, Patrick and Kiendler-Scharr, Astrid and Nenes, Athanasios and Weber, Rodney J.}, doi = {10.5194/acp-18-12241-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {aug}, number = {16}, pages = {12241--12256}, publisher = {Copernicus Publications}, title = {{Effectiveness of ammonia reduction on control of fine particle nitrate}}, volume = {18}, year = {2018} } @article{Guo2014, author = {Guo, Song and Hu, Min and Zamora, Misti L and Peng, Jianfei and Shang, Dongjie and Zheng, Jing and Du, Zhuofei and Wu, Zhijun and Shao, Min and Zeng, Limin and Molina, Mario J and Zhang, Renyi}, doi = {10.1073/pnas.1419604111}, journal = {Proceedings of the National Academy of Sciences}, month = {nov}, number = {49}, pages = {17373--17378}, publisher = {Proceedings of the National Academy of Sciences}, title = {{Elucidating severe urban haze formation in China}}, volume = {111}, year = {2014} } @article{Guo2016a, abstract = {Particle pH is a critical but poorly constrained quantity that affects many aerosol processes and properties, including aerosol composition, concentrations, and toxicity. We assess PM1 pH as a function of geographical location and altitude, focusing on the northeastern U.S., based on aircraft measurements from the Wintertime Investigation of Transport, Emissions, and Reactivity campaign (1 February to 15 March 2015). Particle pH and water were predicted with the ISORROPIA-II thermodynamic model and validated by comparing predicted to observed partitioning of inorganic nitrate between the gas and particle phases. Good agreement was found for relative humidity (RH) above 40{\%}; at lower RH observed particle nitrate was higher than predicted, possibly due to organic-inorganic phase separations or nitrate measurement uncertainties associated with low concentrations (nitrate{\textless}1 µgm-3). Including refractory ions in the pH calculations did not improve model predictions, suggesting they were externally mixed with PM1 sulfate, nitrate, and ammonium. Sample line volatilization artifacts were found to be minimal. Overall, particle pH for altitudes up to 5000m ranged between -0.51 and 1.9 (10th and 90th percentiles) with a study mean of 0.77 ± 0.96, similar to those reported for the southeastern U.S. and eastern Mediterranean. This expansive aircraft data set is used to investigate causes in variability in pH and pH-dependent aerosol components, such as PM1 nitrate, over a wide range of temperatures (-21 to 19°C), RH (20 to 95{\%}), inorganic gas, and particle concentrations and also provides further evidence that particles with low pH are ubiquitous.}, author = {Guo, Hongyu and Sullivan, Amy P. and Campuzano‐Jost, Pedro and Schroder, Jason C. and Lopez‐Hilfiker, Felipe D. and Dibb, Jack E. and Jimenez, Jose L. and Thornton, Joel A. and Brown, Steven S. and Nenes, Athanasios and Weber, Rodney J.}, doi = {10.1002/2016JD025311}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {sep}, number = {17}, pages = {10355--10376}, title = {{Fine particle pH and the partitioning of nitric acid during winter in the northeastern United States}}, url = {https://onlinelibrary.wiley.com/doi/10.1002/2016JD025311}, volume = {121}, year = {2016} } @article{Guttikunda2014, abstract = {The global burden of disease study estimated 695,000 premature deaths in 2010 due to continued exposure to outdoor particulate matter and ozone pollution for India. By 2030, the expected growth in many of the sectors (industries, residential, transportation, power generation, and construction) will result in an increase in pollution related health impacts for most cities. The available information on urban air pollution, their sources, and the potential of various interventions to control pollution, should help us propose a cleaner path to 2030. In this paper, we present an overview of the emission sources and control options for better air quality in Indian cities, with a particular focus on interventions like urban public transportation facilities; travel demand management; emission regulations for power plants; clean technology for brick kilns; management of road dust; and waste management to control open waste burning. Also included is a broader discussion on key institutional measures, like public awareness and scientific studies, necessary for building an effective air quality management plan in Indian cities.}, author = {Guttikunda, Sarath K and Goel, Rahul and Pant, Pallavi}, doi = {10.1016/j.atmosenv.2014.07.006}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Brick kilns,Emissions control,Health impacts,Power plants,Vehicular emissions}, pages = {501--510}, title = {{Nature of air pollution, emission sources, and management in the Indian cities}}, url = {https://www.sciencedirect.com/science/article/pii/S1352231014005275}, volume = {95}, year = {2014} } @article{Hoglund-Isaksson2017, abstract = {Hydrofluorocarbons (HFCs) are synthetically produced compounds primarily used for cooling purposes and with strong global warming properties. In this paper, we analyze the global abatement costs for achieving the substantial reductions in HFC consumption agreed in the Kigali Amendment (KA) of the Montreal Protocol from October 2016. We estimate that compliance with the KA is expected to remove 39 Pg CO2eq or 61{\%} of global baseline HFC emissions over the entire period 2018–2050. The marginal cost of meeting the KA targets is expected to remain below 60 €/t CO2eq throughout the period in all world regions except for developed regions where legislation to control HFC emissions has already been in place since a few years. For the latter regions, the required HFC consumption reduction is expected to come at a marginal cost increasing steadily to between 90 and 118 €/t CO2eq in 2050. Depending on the expected rate of technological development and the extent to which envisaged electricity savings can be realized, compliance with KA is estimated attainable at a global cost ranging from a net cost-saving of 240 billion € to a net cost of 350 billion € over the entire period 2018 to 2050 and with future global electricity-savings estimated at between 0.2{\%} and 0.7{\%} of expected future electricity consumption.}, author = {H{\"{o}}glund-Isaksson, Lena and Purohit, Pallav and Amann, Markus and Bertok, Imrich and Rafaj, Peter and Sch{\"{o}}pp, Wolfgang and Borken-Kleefeld, Jens}, doi = {10.1016/j.envsci.2017.05.006}, issn = {18736416}, journal = {Environmental Science {\&} Policy}, keywords = {Abatement cost,Energy efficiency co-benefits,Greenhouse gases,Hydrofluorocarbons,Kigali amendment,Montreal protocol}, pages = {138--147}, title = {{Cost estimates of the Kigali Amendment to phase-down hydrofluorocarbons}}, url = {http://www.sciencedirect.com/science/article/pii/S146290111730120X}, volume = {75}, year = {2017} } @article{acp-12-9079-2012, author = {H{\"{o}}glund-Isaksson, L}, doi = {10.5194/acp-12-9079-2012}, journal = {Atmospheric Chemistry and Physics}, number = {19}, pages = {9079--9096}, title = {{Global anthropogenic methane emissions 2005–2030: technical mitigation potentials and costs}}, url = {https://www.atmos-chem-phys.net/12/9079/2012/}, volume = {12}, year = {2012} } @article{Hoglund-Isaksson2020, author = {H{\"{o}}glund-Isaksson, Lena and G{\'{o}}mez-Sanabria, Adriana and Klimont, Zbigniew and Rafaj, Peter and Sch{\"{o}}pp, Wolfgang}, doi = {10.1088/2515-7620/ab7457}, issn = {2515-7620}, journal = {Environmental Research Communications}, month = {feb}, number = {2}, pages = {025004}, title = {{Technical potentials and costs for reducing global anthropogenic methane emissions in the 2050 timeframe – results from the GAINS model}}, url = {https://doi.org/10.1088/2515-7620/ab7457 https://iopscience.iop.org/article/10.1088/2515-7620/ab7457}, volume = {2}, year = {2020} } @article{Hopfner2016, abstract = {Ammonia (NH3) has been detected in the upper troposphere by the analysis of averaged MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) infrared limb-emission spectra. We have found enhanced amounts of NH3 within the region of the Asian summer monsoon at 12-15 km altitude. Three-monthly, 10° longitude × 10° latitude average profiles reaching maximum mixing ratios of around 30 pptv in this altitude range have been retrieved, with a vertical resolution of 3-8 km and estimated errors of about 5 pptv. These observations show that loss processes during transport from the boundary layer to the upper troposphere within the Asian monsoon do not deplete the air entirely of NH3. Thus, ammonia might contribute to the so-called Asian tropopause aerosol layer by the formation of ammonium aerosol particles. On a global scale, outside the monsoon area and during different seasons, we could not detect enhanced values of NH3 above the actual detection limit of about 3-5 pptv. This upper bound helps to constrain global model simulations.}, author = {H{\"{o}}pfner, Michael and Volkamer, Rainer and Grabowski, Udo and Grutter, Michel and Orphal, Johannes and Stiller, Gabriele and {Von Clarmann}, Thomas and Wetzel, Gerald}, doi = {10.5194/acp-16-14357-2016}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {nov}, number = {22}, pages = {14357--14369}, publisher = {Copernicus Publications}, title = {{First detection of ammonia (NH3) in the Asian summer monsoon upper troposphere}}, volume = {16}, year = {2016} } @article{Hopfner2019nature, abstract = {The rise of ammonia emissions in Asia is predicted to increase radiative cooling and air pollution by forming ammonium nitrate particles in the lower troposphere. There is, however, a severe lack of knowledge about ammonia and ammoniated aerosol particles in the upper troposphere and their possible effects on the formation of clouds. Here we employ satellite observations and high-altitude aircraft measurements, combined with atmospheric trajectory simulations and cloud-chamber experiments, to demonstrate the presence of ammonium nitrate particles and also track the source of the ammonia that forms into the particles. We found that during the Asian monsoon period, solid ammonium nitrate particles are surprisingly ubiquitous in the upper troposphere from the Eastern Mediterranean to the Western Pacific—even as early as in 1997. We show that this ammonium nitrate aerosol layer is fed by convection that transports large amounts of ammonia from surface sources into the upper troposphere. Impurities of ammonium sulfate allow the crystallization of ammonium nitrate even in the conditions, such as a high relative humidity, that prevail in the upper troposphere. Solid ammonium nitrate particles in the upper troposphere play a hitherto neglected role in ice cloud formation and aerosol indirect radiative forcing.}, author = {H{\"{o}}pfner, Michael and Ungermann, J{\"{o}}rn and Borrmann, Stephan and Wagner, Robert and Spang, Reinhold and Riese, Martin and Stiller, Gabriele and Appel, Oliver and Batenburg, Anneke M. and Bucci, Silvia and Cairo, Francesco and Dragoneas, Antonis and Friedl-Vallon, Felix and H{\"{u}}nig, Andreas and Johansson, S{\"{o}}ren and Krasauskas, Lukas and Legras, Bernard and Leisner, Thomas and Mahnke, Christoph and M{\"{o}}hler, Ottmar and Molleker, Sergej and M{\"{u}}ller, Rolf and Neubert, Tom and Orphal, Johannes and Preusse, Peter and Rex, Markus and Saathoff, Harald and Stroh, Fred and Weigel, Ralf and Wohltmann, Ingo}, doi = {10.1038/s41561-019-0385-8}, isbn = {1752-0908}, issn = {17520908}, journal = {Nature Geoscience}, number = {8}, pages = {608--612}, title = {{Ammonium nitrate particles formed in upper troposphere from ground ammonia sources during Asian monsoons}}, url = {https://doi.org/10.1038/s41561-019-0385-8}, volume = {12}, year = {2019} } @article{Haines2017b, abstract = {The post-2015 development agenda is dominated by a set of Sustainable Development Goals (SDGs) that arose from the 2012 Rio+20 United Nations Conference on Sustainable Development. The 17 goals and 169 targets address diverse and intersecting aspects of human and environmental needs and challenges. Achieving the SDGs by 2030 requires implementing coordinated and concerted strategies and actions that minimize potential trade-offs and conflicts and maximize synergies to contribute to multiple SDGs. Measures to mitigate emissions of short-lived climate pollutants are an example of actions that contribute to multiple outcomes relevant to development. This Perspective highlights the interlinkages between these pollutants and the SDGs, and shows that implementing emissions reduction measures can contribute to achieving many of the SDGs.}, author = {Haines, Andy and Amann, Markus and Borgford-Parnell, Nathan and Leonard, Sunday and Kuylenstierna, Johan and Shindell, Drew}, doi = {10.1038/s41558-017-0012-x}, isbn = {1758-678X}, issn = {17586798}, journal = {Nature Climate Change}, month = {dec}, number = {12}, pages = {863--869}, title = {{Short-lived climate pollutant mitigation and the Sustainable Development Goals}}, url = {http://www.nature.com/articles/s41558-017-0012-x}, volume = {7}, year = {2017} } @article{acp-18-8097-2018, abstract = {Observations of aerosol scattering and absorption offer valuable information about aerosol composition. We apply a simulation of the Ultraviolet Aerosol Index (UVAI), a method of detecting aerosol absorption from satellite observations, to interpret UVAI values observed by the Ozone Monitoring Instrument (OMI) from 2005 to 2015 to understand global trends in aerosol composition. We conduct our simulation using the vector radiative transfer model VLIDORT with aerosol fields from the global chemical transport model GEOS-Chem. We examine the 2005–2015 trends in individual aerosol species from GEOS-Chem and apply these trends to the UVAI simulation to calculate the change in simulated UVAI due to the trends in individual aerosol species. We find that global trends in the UVAI are largely explained by trends in absorption by mineral dust, absorption by brown carbon, and scattering by secondary inorganic aerosol. Trends in absorption by mineral dust dominate the simulated UVAI trends over North Africa, the Middle East, East Asia, and Australia. The UVAI simulation resolves observed negative UVAI trends well over Australia, but underestimates positive UVAI trends over North Africa and Central Asia near the Aral Sea and underestimates negative UVAI trends over East Asia. We find evidence of an increasing dust source from the desiccating Aral Sea that may not be well represented by the current generation of models. Trends in absorption by brown carbon dominate the simulated UVAI trends over biomass burning regions. The UVAI simulation reproduces observed negative trends over central South America and West Africa, but underestimates observed UVAI trends over boreal forests. Trends in scattering by secondary inorganic aerosol dominate the simulated UVAI trends over the eastern United States and eastern India. The UVAI simulation slightly overestimates the observed positive UVAI trends over the eastern United States and underestimates the observed negative UVAI trends over India. Quantitative simulation of the OMI UVAI offers new insight into global trends in aerosol composition.}, author = {Hammer, M S and Martin, R V and Li, C and Torres, O and Manning, M and Boys, B L}, doi = {10.5194/acp-18-8097-2018}, journal = {Atmospheric Chemistry and Physics}, number = {11}, pages = {8097--8112}, title = {{Insight into global trends in aerosol composition from 2005 to 2015 inferred from the OMI Ultraviolet Aerosol Index}}, url = {https://www.atmos-chem-phys.net/18/8097/2018/}, volume = {18}, year = {2018} } @article{Hand2013, abstract = {The rural/remote IMPROVE network (Interagency Monitoring of Protected Visual Environments) and the Environmental Protection Agency's urban Chemical Speciation Network have measured PM 2.5 organic (OC) and elemental carbon (EC) since 1989 and 2000, respectively. We aggregated OC and EC data from 2007 to 2010 at over 300 sites from both networks in order to characterize the spatial and seasonal patterns in rural and urban carbonaceous aerosols. The spatial extent of OC and EC was more regional in the eastern United States relative to more localized concentrations in the West. The highest urban impacts of OC and EC relative to background concentrations occurred in the West during fall and winter. Urban and rural carbonaceous aerosols experienced a large (although opposite) range in seasonality in the West compared to a much lower seasonal variability in the East. Long-term (1990–2010) trend analyses indicated a widespread decrease in rural TC (TC = OC + EC) across the country, with positive, though insignificant, trends in the summer and fall in the West. Short-term trends indicated that urban and rural TC concentrations have both decreased since 2000, with the strongest and more spatially homogeneous urban and rural trends in the West relative to the East.}, author = {Hand, J. L. and Schichtel, B. A. and Malm, W. C. and Frank, N. H.}, doi = {10.1155/2013/367674}, issn = {1687-9309}, journal = {Advances in Meteorology}, pages = {1--13}, title = {{Spatial and Temporal Trends in PM2.5 Organic and Elemental Carbon across the United States}}, url = {http://www.hindawi.com/journals/amete/2013/367674/}, volume = {2013}, year = {2013} } @article{HAND2012107, abstract = {Trends in wintertime particulate sulfate ion and nitrate ion concentrations were computed for 2000–2010 using data from remote and rural sites across the United States from the Interagency Monitoring of Protected Visual Environments (IMPROVE) program. Several sites in the northern and central Great Plains had increasing sulfate and nitrate ion concentrations in December at the rate of over 5{\%} yr−1. The positive trends are in contrast to the decreasing national annual trends in nitrogen oxides (NOx) and sulfur dioxide (SO2) emissions as reported by the Environmental Protection Agency. Increasing trends in particulate nitrate and sulfate ion concentrations have important implications for air pollution mitigation strategies, considering concentrations at these sites counter the reductions in emissions from controlled sources across the United States.}, author = {Hand, J L and Gebhart, K A and Schichtel, B A and Malm, W C}, doi = {https://doi.org/10.1016/j.atmosenv.2012.03.050}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Aerosol trends,Great Plains,Rural aerosols}, pages = {107--110}, title = {{Increasing trends in wintertime particulate sulfate and nitrate ion concentrations in the Great Plains of the United States (2000–2010)}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231012002919}, volume = {55}, year = {2012} } @article{Hantson2017, abstract = {Plants emit large quantities of isoprene and monoterpenes, the main components of global biogenic volatile organic compound (BVOC) emissions. BVOCs have an important impact on the atmospheric composition of methane, and of short-lived radiative forcing agents (e.g. ozone, aerosols etc.). It is therefore necessary to know how isoprene and monoterpene emissions have changed over the past and how future changes in climate, land-use and other factors will impact them. Here we present emission estimates of isoprene and monoterpenes over the period 1901–2 100 based on the dynamic global vegetation model LPJ-GUESS, including the effects of all known important drivers. We find that both isoprene and monoterpene emissions at the beginning of the 20th century were higher than at present. While anthropogenic land-use change largely drives the global decreasing trend for isoprene over the 20th century, changes in natural vegetation composition caused a decreasing trend for monoterpene emissions. Future global isoprene and monoterpene emissions depend strongly on the climate and land-use scenarios considered. Over the 21st century, global isoprene emissions are simulated to either remain stable (RCP 4.5), or decrease further (RCP 8.5), with important differences depending on the underlying land-use scenario. Future monoterpene emissions are expected to continue their present decreasing trend for all scenarios, possibly stabilizing from 2050 onwards (RCP 4.5). These results demonstrate the importance to take both natural vegetation dynamics and anthropogenic changes in land-use into account when estimating past and future BVOC emissions. They also indicate that a future global increase in BVOC emissions is improbable.}, author = {Hantson, Stijn and Knorr, Wolfgang and Schurgers, Guy and Pugh, Thomas A M and Arneth, Almut}, doi = {https://doi.org/10.1016/j.atmosenv.2017.02.010}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {BVOC,Isoprene,Land use,Monoterpenes}, pages = {35--45}, title = {{Global isoprene and monoterpene emissions under changing climate, vegetation, CO2 and land use}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231017300808}, volume = {155}, year = {2017} } @article{Harmsen2015, abstract = {This study aims to create insight in how Integrated Assessment Models (IAMs) perform in describing the climate forcing by non-CO2 gases and aerosols. The simple climate models (SCMs) included in IAMs have been run with the same prescribed anthropogenic emission pathways and compared to analyses with complex earth system models (ESMs) in terms of concentration and radiative forcing levels. In our comparison, particular attention was given to the short-lived forcers' climate effects. In general, SCMs show forcing levels within the expert model ranges. However, the more simple SCMs seem to underestimate forcing differences between baseline and mitigation scenarios because of omission of ozone, black carbon and/or indirect methane forcing effects. Above all, results also show that among IAMs there is a significant spread (0.74 W/m2 in 2100) in non-CO2 forcing projections for a 2.6 W/m2 mitigation scenario, mainly due to uncertainties in the indirect effects of aerosols. This has large implications for determining optimal mitigation strategies among IAMs with regard to required CO2 forcing targets and policy costs.}, author = {Harmsen, Mathijs J. H. M. and van Vuuren, Detlef P and van den Berg, Maarten and Hof, Andries F and Hope, Chris and Krey, Volker and Lamarque, Jean-Francois and Marcucci, Adriana and Shindell, Drew T and Schaeffer, Michiel}, doi = {10.1007/s10584-015-1485-0}, isbn = {0165-0009}, issn = {0165-0009}, journal = {Climatic Change}, month = {dec}, number = {4}, pages = {565--582}, title = {{How well do integrated assessment models represent non-CO2 radiative forcing?}}, url = {http://link.springer.com/10.1007/s10584-015-1485-0}, volume = {133}, year = {2015} } @article{Harmsen2019a, abstract = {Several studies have shown that the greenhouse gas reduction resulting from the current nationally determined contributions (NDCs) will not be enough to meet the overall targets of the Paris Climate Agreement. It has been suggested that more ambition mitigations of short-lived climate forcer (SLCF) emissions could potentially be a way to reduce the risk of overshooting the 1.5 or 2 °C target in a cost-effective way. In this study, we employ eight state-of-the-art integrated assessment models (IAMs) to examine the global temperature effects of ambitious reductions of methane, black and organic carbon, and hydrofluorocarbon emissions. The SLCFs measures considered are found to add significantly to the effect of the NDCs on short-term global mean temperature (GMT) (in the year 2040: − 0.03 to − 0.15 °C) and on reducing the short-term rate-of-change (by − 2 to 15{\%}), but only a small effect on reducing the maximum temperature change before 2100. This, because later in the century under assumed ambitious climate policy, SLCF mitigation is maximized, either directly or indirectly due to changes in the energy system. All three SLCF groups can contribute to achieving GMT changes.}, author = {Harmsen, Mathijs J.H.M. and Fricko, Oliver and Hilaire, J{\'{e}}r{\^{o}}me and van Vuuren, Detlef P. and Drouet, Laurent and Durand-Lasserve, Olivier and Fujimori, Shinichiro and Keramidas, Kimon and Klimont, Zbigniew and Luderer, Gunnar and {Aleluia Reis}, Lara and Riahi, Keywan and Sano, Fuminori and Smith, Steven J.}, doi = {10.1007/s10584-019-02436-3}, issn = {0165-0009}, journal = {Climatic Change}, month = {dec}, number = {3}, pages = {1443--1461}, title = {{Taking some heat off the NDCs? The limited potential of additional short-lived climate forcers' mitigation}}, url = {https://doi.org/10.1007/s10584-019-02436-3 http://link.springer.com/10.1007/s10584-019-02436-3}, volume = {163}, year = {2020} } @article{Harmsen2020, abstract = {Mitigation of black carbon (BC) aerosol emissions can potentially contribute to both reducing air pollution and climate change, although mixed results have been reported regarding the latter. A detailed quantification of the synergy between global air quality and climate policy is still lacking. This study contributes with an integrated assessment model-based scenario analysis of BC-focused mitigation strategies aimed at maximizing air quality and climate benefits. The impacts of these policy strategies have been examined under different socio-economic conditions, climate ambitions, and BC mitigation strategies. The study finds that measures targeting BC emissions (including reduction of co-emitted organic carbon, sulfur dioxide, and nitrogen dioxides) result in significant decline in premature mortality due to ambient air pollution, in the order of 4 to 12 million avoided deaths between 2015 and 2030. Under certain circumstances, BC mitigation can also reduce climate change, i.e., mainly by lowering BC emissions in the residential sector and in high BC emission scenarios. Still, the effect of BC mitigation on global mean temperature is found to be modest at best (with a maximum short-term GMT decrease of 0.02 °C in 2030) and could even lead to warming (with a maximum increase of 0.05 °C in case of a health-focused strategy, where all aerosols are strongly reduced). At the same time, strong climate policy would improve air quality (the opposite relation) through reduced fossil fuel use, leading to an estimated 2 to 5 million avoided deaths in the period up to2030. By combining both air quality and climate goals, net health benefits can be maximized.}, author = {Harmsen, Mathijs J H M and van Dorst, Pim and van Vuuren, Detlef P and van den Berg, Maarten and {Van Dingenen}, Rita and Klimont, Zbigniew}, doi = {10.1007/s10584-020-02800-8}, issn = {1573-1480}, journal = {Climatic Change}, number = {3}, pages = {1519--1538}, title = {{Co-benefits of black carbon mitigation for climate and air quality}}, url = {https://doi.org/10.1007/s10584-020-02800-8}, volume = {163}, year = {2020} } @incollection{Hartmann2013a, author = {Hartmann, Dennis L. and {Klein Tank}, Albert M.G. and Rusticucci, Matilde and Alexander, Lisa V. and Br{\"{o}}nnimann, Stefan and Charabi, Yassine Abdul Rahman and Dentener, Frank J. and Dlugokencky, Edward J. and Easterling, David R. and Kaplan, Alexey and Soden, Brian J. and Thorne, Peter W. and Wild, Martin and Zhai, Panmao}, booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change}, chapter = {7}, doi = {10.1017/CBO9781107415324.008}, editor = {Stocker, T F and Qin, D and Plattner, G.-K. and Tignor, M and Allen, S K and Boschung, J and Nauels, A and Xia, Y and Bex, V and Midgley, P M}, isbn = {9781107661820}, pages = {159--254}, publisher = {Cambridge University Press}, title = {{Observations: Atmosphere and Surface}}, url = {https://www.ipcc.ch/report/ar5/wg1}, year = {2013} } @article{Hastings1288, abstract = {A strong, unambiguous negative trend is found in the nitrogen isotopic composition ($\delta$15N) of nitrate over the industrial period, on the basis of a 100-meter ice core from Summit, Greenland. This record indicates that ice-core nitrate reflects changes in nitrogen oxide (NOx) source emissions and that anthropogenic emissions of NOx have resulted in a 12 per mil decline in $\delta$15N of atmospheric nitrate from preindustrial values to present. Variations in the isotopic composition of nitrate may affect the interpretation of other records of environmental change that are affected by atmospheric nitrate.}, author = {Hastings, M G and Jarvis, J C and Steig, E J}, doi = {10.1126/science.1170510}, issn = {0036-8075}, journal = {Science}, number = {5932}, pages = {1288}, publisher = {American Association for the Advancement of Science}, title = {{Anthropogenic Impacts on Nitrogen Isotopes of Ice-Core Nitrate}}, url = {http://science.sciencemag.org/content/324/5932/1288}, volume = {324}, year = {2009} } @article{Hauglustaine2014, abstract = {The ammonia cycle and nitrate particle formation are introduced into the LMDz-INCA (Laboratoire de M{\'{e}}t{\'{e}}orologie Dynamique, version 4-INteraction with Chemistry and Aerosols, version 3) global model. An important aspect of this new model is that both fine nitrate particle formation in the accumulation mode and coarse nitrate forming on existing dust and sea-salt particles are considered. The model simulates distributions of nitrates and related species in agreement with previous studies and observations. The calculated present-day total nitrate direct radiative forcing since the pre-industrial is-'0.056 W m-2. This forcing corresponds to 18{\%} of the sulfate forcing. Fine particles largely dominate the nitrate forcing, representing close to 90{\%} of this value. The model has been used to investigate the future changes in nitrates and direct radiative forcing of climate based on snapshot simulations for the four representative concentration pathway (RCP) scenarios and for the 2030, 2050, and 2100 time horizons. Due to a decrease in fossil fuel emissions in the future, the concentration of most of the species involved in the nitrate-ammonium-sulfate system drop by 2100 except for ammonia, which originates from agricultural practices and for which emissions significantly increase in the future. Despite the decrease of nitrate surface levels in Europe and North America, the global burden of accumulation mode nitrates increases by up to a factor of 2.6 in 2100. This increase in ammonium nitrate in the future arises despite decreasing NOx emissions due to increased availability of ammonia to form ammonium nitrate. The total aerosol direct forcing decreases from its present-day value of-'0.234 W m-2 to a range of-'0.070 to-'0.130 Wm-2 in 2100 based on the considered scenario. The direct forcing decreases for all aerosols except for nitrates, for which the direct negative forcing increases to a range of-'0.060 to-'0.115 Wm-2 in 2100. Including nitrates in the radiative forcing calculations increases the total direct forcing of aerosols by a factor of 1.3 in 2000, by a factor of 1.7-2.6 in 2030, by 1.9-4.8 in 2050, and by 6.4-8.6 in 2100. These results show that the agricultural emissions of ammonia will play a key role in the future mitigation of climate change, with nitrates becoming the dominant contributor to the anthropogenic aerosol optical depth during the second half of the 21st century and significantly increasing the calculated aerosol direct forcing. This significant increase in the influence that nitrate exerts on climate in the future will at the same time affect regional air quality and nitrogen deposition to the ecosystem.}, author = {Hauglustaine, D. A. and Balkanski, Y. and Schulz, M.}, doi = {10.5194/acp-14-11031-2014}, isbn = {1680-7375}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {20}, pages = {11031--11063}, publisher = {Copernicus Publications}, title = {{A global model simulation of present and future nitrate aerosols and their direct radiative forcing of climate}}, volume = {14}, year = {2014} } @article{He2018166, abstract = {This study investigates the future U.S. PM2.5pollution under multiple emissions scenarios, climate states, and long-range transport (LRT) effects using the regional Community Multi-scale Air Quality (CMAQ) model integrated with a regional climate model. CMAQ with fixed chemical lateral boundary conditions (LBCs) successfully reproduces the present-day PM2.5pollution and its major species in rural and suburban areas, but has some discrepancies in urban areas such as the Los Angeles Basin, where detailed emissions and meteorology conditions cannot be resolved by the 30 km grid. Its performance is slightly worsened when using dynamic chemical LBCs from global chemical transport model (CTM) simulations, which provide cleaner conditions into the CMAQ lateral boundaries. Under future Intergovernmental Panel on Climate Change (IPCC) emission scenarios, CMAQ projects large PM2.5reductions (∼40{\%} for A1B and ∼20{\%} for A1Fi scenario) in the eastern United States, but slight to moderate increases (∼5{\%} for A1B and ∼10{\%} for A1Fi) in the western United States. The projected increases are particularly large (up to 30{\%}) near the Mexico-U.S. border, suggesting that Mexico is a major source for future U.S. PM2.5pollution. The effect from climate change alone is estimated to increase PM2.5levels ubiquitously (∼5{\%} for both A1B and A1Fi) over the United States, except for a small decrease in the Houston, Texas area, where anthropogenic non-methane volatile organic compounds (NMVOCs) emissions dominate. This climate penalty, however, is substantially smaller than effects of emissions change, especially in the eastern United States. Future PM2.5pollution is affected substantially (up to −20{\%}) by changes in SO2emissions and moderately (3–5{\%}) by changes in NOxand NH3emissions. The long-range transport (LRT) effects, which are estimated by comparing CMAQ simulations with fixed and dynamic LBCs, are regional dependent, causing up to 10–20{\%} decrease over the western United States in future summertime PM2.5pollution. Therefore, it is important to consider the relative contributions of emissions scenarios, climate conditions, and LRT to the major PM2.5components in future U.S. air quality regulation.}, annote = {cited By 0}, author = {He, Hao and Liang, Xin Zhong and Wuebbles, Donald J.}, doi = {10.1016/j.atmosenv.2018.02.020}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Future projections,PM2.5species,Regional modeling,Sensitivity}, pages = {166--176}, title = {{Effects of emissions change, climate change and long-range transport on regional modeling of future U.S. particulate matter pollution and speciation}}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042173638{\&}doi=10.1016{\%}2Fj.atmosenv.2018.02.020{\&}partnerID=40{\&}md5=ff74930bc776b116f98fdc32faa9c3f7}, volume = {179}, year = {2018} } @article{Heald2014, abstract = {The direct radiative effect (DRE) of aerosols, which is the instantaneous radiative impact of all atmospheric particles on the Earth's energy balance, is sometimes confused with the direct radiative forcing (DRF), which is the change in DRE from pre-industrial to present-day (not including climate feedbacks). In this study we couple a global chemical transport model (GEOS-Chem) with a radiative transfer model (RRTMG) to contrast these concepts. We estimate a global mean all-sky aerosol DRF of -0.36 Wm(-2) and a DRE of -1.83 Wm(-2) for 2010. Therefore, natural sources of aerosol (here including fire) affect the global energy balance over four times more than do present-day anthropogenic aerosols. If global anthropogenic emissions of aerosols and their precursors continue to decline as projected in recent scenarios due to effective pollution emission controls, the DRF will shrink (-0.22 Wm(-2) for 2100). Secondary metrics, like DRE, that quantify temporal changes in both natural and anthropogenic aerosol burdens are therefore needed to quantify the total effect of aerosols on climate.}, annote = {Estimates of DRE (anthro+natural) and DRF for aerosols -- section 6.5}, author = {Heald, C L and Ridley, D A and Kroll, J H and Barrett, S R H and Cady-Pereira, K E and Alvarado, M J and Holmes, C D}, doi = {10.5194/acp-14-5513-2014}, issn = {1680-7316}, journal = {Atmospheric Chemistry and Physics}, number = {11}, pages = {5513--5527}, title = {{Contrasting the direct radiative effect and direct radiative forcing of aerosols}}, type = {Article}, volume = {14}, year = {2014} } @article{doi:10.1021/cr500446g, annote = {PMID: 25839909}, author = {Heald, Colette L. and Spracklen, Dominick V.}, doi = {10.1021/cr500446g}, issn = {15206890}, journal = {Chemical Reviews}, number = {10}, pages = {4476--4496}, title = {{Land Use Change Impacts on Air Quality and Climate}}, url = {https://doi.org/10.1021/cr500446g}, volume = {115}, year = {2015} } @article{acp-16-14997-2016, abstract = {Anthropogenic land use change (LUC) since preindustrial (1850) has altered the vegetation distribution and density around the world. We use a global model (GEOS-Chem) to assess the attendant changes in surface air quality and the direct radiative forcing (DRF). We focus our analysis on secondary particulate matter and tropospheric ozone formation. The general trend of expansion of managed ecosystems (croplands and pasturelands) at the expense of natural ecosystems has led to an 11 {\%} decline in global mean biogenic volatile organic compound emissions. Concomitant growth in agricultural activity has more than doubled ammonia emissions and increased emissions of nitrogen oxides from soils by more than 50 {\%}. Conversion to croplands has also led to a widespread increase in ozone dry deposition velocity. Together these changes in biosphere–atmosphere exchange have led to a 14 {\%} global mean increase in biogenic secondary organic aerosol (BSOA) surface concentrations, a doubling of surface aerosol nitrate concentrations, and local changes in surface ozone of up to 8.5 ppb. We assess a global mean LUC-DRF of +0.017, −0.071, and −0.01 W m−2 for BSOA, nitrate, and tropospheric ozone, respectively. We conclude that the DRF and the perturbations in surface air quality associated with LUC (and the associated changes in agricultural emissions) are substantial and should be considered alongside changes in anthropogenic emissions and climate feedbacks in chemistry–climate studies.}, author = {Heald, Colette L. and Geddes, Jeffrey A.}, doi = {10.5194/acp-16-14997-2016}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {dec}, number = {23}, pages = {14997--15010}, title = {{The impact of historical land use change from 1850 to 2000 on secondary particulate matter and ozone}}, url = {https://www.atmos-chem-phys.net/16/14997/2016/}, volume = {16}, year = {2016} } @article{Heinze2019, abstract = {Earth system models (ESMs) are key tools for providing climate projections under different scenarios of human-induced forcing. ESMs include a large number of additional processes and feedbacks such as biogeochemical cycles that traditional physical climate models do not consider. Yet, some processes such as cloud dynamics and ecosystem functional response still have fairly high uncertainties. In this article, we present an overview of climate feedbacks for Earth system components currently included in state-of-the-art ESMs and discuss the challenges to evaluate and quantify them. Uncertainties in feedback quantification arise from the interdependencies of biogeochemical matter fluxes and physical properties, the spatial and temporal heterogeneity of processes, and the lack of long-term continuous observational data to constrain them. We present an outlook for promising approaches that can help to quantify and to constrain the large number of feedbacks in ESMs in the future. The target group for this article includes generalists with a background in natural sciences and an interest in climate change as well as experts working in interdisciplinary climate research (researchers, lecturers, and students). This study updates and significantly expands upon the last comprehensive overview of climate feedbacks in ESMs, which was produced 15 years ago (NRC, 2003).}, author = {Heinze, Christoph and Eyring, Veronika and Friedlingstein, Pierre and Jones, Colin and Balkanski, Yves and Collins, William and Fichefet, Thierry and Gao, Shuang and Hall, Alex and Ivanova, Detelina and Knorr, Wolfgang and Knutti, Reto and L{\"{o}}w, Alexander and Ponater, Michael and Schultz, Martin and Schulz, Michael and Siebesma, Pier and Teixeira, Joao and Tselioudis, George and Vancoppenolle, Martin}, doi = {10.5194/esd-10-379-2019}, issn = {21904987}, journal = {Earth System Dynamics}, month = {jul}, number = {3}, pages = {379--452}, publisher = {Copernicus Publications}, title = {{ESD Reviews: Climate feedbacks in the Earth system and prospects for their evaluation}}, volume = {10}, year = {2019} } @article{Hess2015a, abstract = {Despite the need to understand the impact of changes in emissions and climate on tropospheric ozone, the attribution of tropospheric interannual ozone variability to specific processes has proven difficult. Here, we analyze the stratospheric contribution to tropospheric ozone variability and trends from 1953 to 2005 in the Northern Hemisphere (NH) mid-latitudes using four ensemble simulations of the free running (FR) Whole Atmosphere Community Climate Model (WACCM). The simulations are externally forced with observed time-varying (1) sea-surface temperatures (SSTs), (2) greenhouse gases (GHGs), (3) ozone depleting substances (ODS), (4) quasi-biennial oscillation (QBO), (5) solar variability (SV) and (6) stratospheric sulfate surface area density (SAD). A detailed representation of stratospheric chemistry is simulated, including the ozone loss due to volcanic eruptions and polar stratospheric clouds. In the troposphere, ozone production is represented by CH{\textless}sub{\textgreater}4{\textless}/sub{\textgreater}–NO{\textless}sub{\textgreater}x{\textless}/sub{\textgreater} smog chemistry, where surface chemical emissions remain interannually constant. Despite the simplicity of its tropospheric chemistry, at many NH measurement locations, the interannual ozone variability in the FR WACCM simulations is significantly correlated with the measured interannual variability. This suggests the importance of the external forcing applied in these simulations in driving interannual ozone variability. The variability and trend in the simulated 1953–2005 tropospheric ozone from 30 to 90° N at background surface measurement sites, 500 hPa measurement sites and in the area average are largely explained on interannual timescales by changes in the 30–90° N area averaged flux of ozone across the 100 hPa surface and changes in tropospheric methane concentrations. The average sensitivity of tropospheric ozone to methane (percent change in ozone to a percent change in methane) from 30 to 90° N is 0.17 at 500 hPa and 0.21 at the surface; the average sensitivity of tropospheric ozone to the 100 hPa ozone flux (percent change in ozone to a percent change in the ozone flux) from 30 to 90° N is 0.19 at 500 hPa and 0.11 at the surface. The 30–90° N simulated downward residual velocity at 100 hPa increased by 15{\%} between 1953 and 2005. However, the impact of this on the 30–90° N 100 hPa ozone flux is modulated by the long-term changes in stratospheric ozone. The ozone flux decreases from 1965 to 1990 due to stratospheric ozone depletion, but increases again by approximately 7{\%} from 1990 to 2005. The first empirical orthogonal function of interannual ozone variability explains from 40{\%} (at the surface) to over 80{\%} (at 150 hPa) of the simulated ozone interannual variability from 30 to 90° N. This identified mode of ozone variability shows strong stratosphere–troposphere coupling, demonstrating the importance of the stratosphere in an attribution of tropospheric ozone variability. The simulations, with no change in emissions, capture almost 50{\%} of the measured ozone change during the 1990s at a variety of locations. This suggests that a large portion of the measured change is not due to changes in emissions, but can be traced to changes in large-scale modes of ozone variability. This emphasizes the difficulty in the attribution of ozone changes, and the importance of natural variability in understanding the trends and variability of ozone. We find little relation between the El Ni{\~{n}}o–Southern Oscillation (ENSO) index and large-scale tropospheric ozone variability over the long-term record.}, author = {Hess, P. and Kinnison, D. and Tang, Q.}, doi = {10.5194/acp-15-2341-2015}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {5}, pages = {2341--2365}, title = {{Ensemble simulations of the role of the stratosphere in the attribution of northern extratropical tropospheric ozone variability}}, url = {https://www.atmos-chem-phys.net/15/2341/2015/}, volume = {15}, year = {2015} } @incollection{Hock2019, author = {Hock, R. and Rasul, G. and Adler, C. and C{\'{a}}ceres, B. and Gruber, S. and Hirabayashi, Y. and Jackson, M. and K{\"{a}}{\"{a}}b, A. and Kang, S. and Kutuzov, S. and Milner, A. and Molau, U. and Morin, S. and Orlove, B. and Steltzer, H.}, booktitle = {IPCC Special Report on the Ocean and Cryosphere in a Changing Climate}, chapter = {2}, doi = {https://www.ipcc.ch/srocc/chapter/chapter-2}, editor = {Pörtner, H.-O. and Roberts, D.C. and Masson-Delmotte, V. and Zhai, P. and Tignor, M. and Poloczanska, E. and Mintenbeck, K. and Alegría, A. and Nicolai, M. and Okem, A. and Petzold, J. and Rama, B. and Weyer, N.M.}, pages = {131--202}, publisher = {In Press}, title = {{High Mountain Areas}}, url = {https://www.ipcc.ch/srocc/chapter/chapter-2}, year = {2019} } @article{Hodgson2018, author = {Hodgson, Amy K. and Morgan, William T. and O'Shea, Sebastian and Bauguitte, St{\'{e}}phane and Allan, James D. and Darbyshire, Eoghan and Flynn, Michael J. and Liu, Dantong and Lee, James and Johnson, Ben and Haywood, Jim M. and Longo, Karla M. and Artaxo, Paulo E. and Coe, Hugh}, doi = {10.5194/acp-18-5619-2018}, file = {::}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {apr}, number = {8}, pages = {5619--5638}, title = {{Near-field emission profiling of tropical forest and Cerrado fires in Brazil during SAMBBA 2012}}, url = {https://acp.copernicus.org/articles/18/5619/2018/}, volume = {18}, year = {2018} } @article{Hodzic2020a, author = {Hodzic, Alma and Campuzano-Jost, Pedro and Bian, Huisheng and Chin, Mian and Colarco, Peter R and Day, Douglas A and Froyd, Karl D and Heinold, Bernd and Jo, Duseong S and Katich, Joseph M and Kodros, John K and Nault, Benjamin A and Pierce, Jeffrey R and Ray, Eric and Schacht, Jacob and Schill, Gregory P and Schroder, Jason C and Schwarz, Joshua P and Sueper, Donna T and Tegen, Ina and Tilmes, Simone and Tsigaridis, Kostas and Yu, Pengfei and Jimenez, Jose L}, doi = {10.5194/acp-20-4607-2020}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {apr}, number = {8}, pages = {4607--4635}, publisher = {Copernicus Publications}, title = {{Characterization of organic aerosol across the global remote troposphere: a comparison of ATom measurements and global chemistry models}}, url = {https://acp.copernicus.org/articles/20/4607/2020/}, volume = {20}, year = {2020} } @article{Hodzic2016a, abstract = {Abstract. Recent laboratory studies suggest that secondary organic aerosol (SOA) formation rates are higher than assumed in current models. There is also evidence that SOA removal by dry and wet deposition occurs more efficiently than some current models suggest and that photolysis and heterogeneous oxidation may be important (but currently ignored) SOA sinks. Here, we have updated the global GEOS-Chem model to include this new information on formation (i.e., wall-corrected yields and emissions of semi-volatile and intermediate volatility organic compounds) and on removal processes (photolysis and heterogeneous oxidation). We compare simulated SOA from various model configurations against ground, aircraft and satellite measurements to assess the extent to which these improved representations of SOA formation and removal processes are consistent with observed characteristics of the SOA distribution. The updated model presents a more dynamic picture of the life cycle of atmospheric SOA, with production rates 3.9 times higher and sinks a factor of 3.6 more efficient than in the base model. In particular, the updated model predicts larger SOA concentrations in the boundary layer and lower concentrations in the upper troposphere, leading to better agreement with surface and aircraft measurements of organic aerosol compared to the base model. Our analysis thus suggests that the long-standing discrepancy in model predictions of the vertical SOA distribution can now be resolved, at least in part, by a stronger source and stronger sinks leading to a shorter lifetime. The predicted global SOA burden in the updated model is 0.88 Tg and the corresponding direct radiative effect at top of the atmosphere is −0.33 W m−2, which is comparable to recent model estimates constrained by observations. The updated model predicts a population-weighed global mean surface SOA concentration that is a factor of 2 higher than in the base model, suggesting the need for a reanalysis of the contribution of SOA to PM pollution-related human health effects. The potential importance of our estimates highlights the need for more extensive field and laboratory studies focused on characterizing organic aerosol removal mechanisms and rates.}, author = {Hodzic, Alma and Kasibhatla, Prasad S and Jo, Duseong S and Cappa, Christopher D and Jimenez, Jose L and Madronich, Sasha and Park, Rokjin J}, doi = {10.5194/acp-16-7917-2016}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jun}, number = {12}, pages = {7917--7941}, publisher = {Copernicus Publications}, title = {{Rethinking the global secondary organic aerosol (SOA) budget: stronger production, faster removal, shorter lifetime}}, url = {https://acp.copernicus.org/articles/16/7917/2016/}, volume = {16}, year = {2016} } @article{Hoesly2018a, abstract = {We present a new data set of annual historical (1750–2014) anthropogenic chemically reactive gases (CO, CH4, NH3, NOx, SO2, NMVOCs), carbonaceous aerosols (black carbon – BC, and organic carbon – OC), and CO2 developed with the Community Emissions Data System (CEDS). We improve upon existing inventories with a more consistent and reproducible methodology applied to all emission species, updated emission factors, and recent estimates through 2014. The data system relies on existing energy consumption data sets and regional and country-specific inventories to produce trends over recent decades. All emission species are consistently estimated using the same activity data over all time periods. Emissions are provided on an annual basis at the level of country and sector and gridded with monthly seasonality. These estimates are comparable to, but generally slightly higher than, existing global inventories. Emissions over the most recent years are more uncertain, particularly in low- and middle-income regions where country-specific emission inventories are less available. Future work will involve refining and updating these emission estimates, estimating emissions' uncertainty, and publication of the system as open-source software.}, author = {Hoesly, Rachel M. and Smith, Steven J. and Feng, Leyang and Klimont, Zbigniew and Janssens-Maenhout, Greet and Pitkanen, Tyler and Seibert, Jonathan J. and Vu, Linh and Andres, Robert J. and Bolt, Ryan M. and Bond, Tami C. and Dawidowski, Laura and Kholod, Nazar and Kurokawa, June Ichi and Li, Meng and Liu, Liang and Lu, Zifeng and Moura, Maria C.P. and O'Rourke, Patrick R. and Zhang, Qiang}, doi = {10.5194/gmd-11-369-2018}, isbn = {1991-962X}, issn = {19919603}, journal = {Geoscientific Model Development}, number = {1}, pages = {369--408}, title = {{Historical (1750–2014) anthropogenic emissions of reactive gases and aerosols from the Community Emissions Data System (CEDS)}}, url = {https://www.geosci-model-dev.net/11/369/2018/}, volume = {11}, year = {2018} } @misc{Hoesly2019_CEDS, abstract = {The Community Emissions Data System (CEDS) produces consistent estimates of global air emissions species over the industrial era (1750 - present). The system is written in R and uses open-source data (with the exception of the IEA energy statistics which must be purchased from IEA). CEDS is publicly available through an Open Source License.}, author = {Hoesly, Rachel and O'Rourke, Patrick and Braun, Caleb and Feng, Leyang and Smith, Steven J. and Pitkanen, Tyler and Seibert, Jonathan J. and Vu, Linh and Muwan, Presley and Bolt, Ryan and Goldstein, Ben and Kholod, Nazar}, doi = {10.5281/zenodo.3592073}, publisher = {Zenodo}, title = {{Community Emissions Data System (Version Dec-23-2019)}}, url = {http://www.globalchange.umd.edu/ceds/ https://github.com/JGCRI/CEDS/tree/Ded-23-2019}, urldate = {2019-12-23}, year = {2019} } @article{Hofzumahaus2009, abstract = {The degradation of trace gases and pollutants in the troposphere is dominated by their reaction with hydroxyl radicals (OH). The importance of OH rests on its high reactivity, its ubiquitous photochemical production in the sunlit atmosphere, and most importantly on its regeneration in the oxidation chain of the trace gases. In the current understanding, the recycling of OH proceeds through HO2 reacting with NO, thereby forming ozone. A recent field campaign in the Pearl River Delta, China, quantified tropospheric OH and HO2 concentrations and turnover rates by direct measurements. We report that concentrations of OH were three to five times greater than expected, and we propose the existence of a pathway for the regeneration of OH independent of NO, which amplifies the degradation of pollutants without producing ozone.}, author = {Hofzumahaus, Andreas and Rohrer, Franz and Lu, Keding and Bohn, Birger and Brauers, Theo and Chang, C.-C. and Fuchs, Hendrik and Holland, Frank and Kita, Kazuyuki and Kondo, Yutaka and Li, Xin and Lou, Shengrong and Shao, Min and Zeng, Limin and Wahner, Andreas and Zhang, Yuanhang}, doi = {10.1126/science.1164566}, issn = {0036-8075}, journal = {Science}, month = {jun}, number = {5935}, pages = {1702--1704}, pmid = {19498111}, publisher = {American Association for the Advancement of Science}, title = {{Amplified Trace Gas Removal in the Troposphere}}, url = {https://www.sciencemag.org/lookup/doi/10.1126/science.1164566}, volume = {324}, year = {2009} } @article{Hollaway2017, abstract = {We use an Earth System model (HadGEM2-ES) to investigate the sensitivity of midnineteenth century tropospheric ozone to vegetation distribution and atmospheric chemistry-vegetation interaction processes. We conduct model experiments to isolate the response of midnineteenth century tropospheric ozone to vegetation cover changes between the 1860s and present day and to CO2-induced changes in isoprene emissions and dry deposition over the same period. Changes in vegetation distribution and CO2 suppression of isoprene emissions between midnineteenth century and present day lead to decreases in global isoprene emissions of 19{\%} and 21{\%}, respectively. This results in increases in surface ozone over the continents of up to 2 ppbv and of 2-6 ppbv in the tropical upper troposphere. The effects of CO2 increases on suppression of isoprene emissions and suppression of dry deposition to vegetation are small compared with the effects of vegetation cover change. Accounting for present-day climate in addition to present-day vegetation cover and atmospheric CO2 concentrations leads to increases in surface ozone concentrations of up to 5 ppbv over the entire northern hemisphere (NH) and of up to 8 ppbv in the NH free troposphere, compared with a midnineteenth century control simulation. Ozone changes are dominated by the following: (1) the role of isoprene as an ozone sink in the low NOx midnineteenth century atmosphere and (2) the redistribution of NOx to remote regions and the free troposphere via PAN (peroxyacetyl nitrate) formed from isoprene oxidation. We estimate a tropospheric ozone radiative forcing of 0.264 W m-2 and a sensitivity in ozone radiative forcing to midnineteenth century to present-day vegetation cover change of -0.012 W m-2.}, annote = {doi: 10.1002/2016JD025462}, author = {Hollaway, M. J. and Arnold, S. R. and Collins, W. J. and Folberth, G. and Rap, A.}, doi = {10.1002/2016JD025462}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {ozone,pre-industrial,radiative forcing,vegetation}, month = {feb}, number = {4}, pages = {2452--2473}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Sensitivity of midnineteenth century tropospheric ozone to atmospheric chemistry‐vegetation interactions}}, url = {https://doi.org/10.1002/2016JD025462 https://onlinelibrary.wiley.com/doi/abs/10.1002/2016JD025462}, volume = {122}, year = {2017} } @article{Holmes2013a, abstract = {Accurate prediction of future methane abundances following a climate scenario requires understanding the lifetime changes driven by anthropogenic emissions, meteorological factors, and chemistry-climate feedbacks. Uncertainty in any of these influences or the underlying processes implies uncertainty in future abundance and radiative forcing. We simulate methane lifetime in three chemical transport models (CTMs)-UCI CTM, GEOS-Chem, and Oslo CTM3-over the period 1997-2009 and compare the models' year-to-year variability against constraints from global methyl chloroform observations. Using sensitivity tests, we find that temperature, water vapor, stratospheric ozone column, biomass burning and lightning NOx are the dominant sources of interannual changes in methane lifetime in all three models. We also evaluate each model's response to forcings that have impacts on decadal time scales, such as methane feedback, and anthropogenic emissions. In general, these different CTMs show similar sensitivities to the driving variables. We construct a parametric model that reproduces most of the interannual variability of each CTM and use it to predict methane lifetime from 1980 through 2100 following a specified emissions and climate scenario (RCP 8.5). The parametric model propagates uncertainties through all steps and provides a foundation for predicting methane abundances in any climate scenario. Our sensitivity tests also enable a new estimate of the methane global warming potential (GWP), accounting for stratospheric ozone effects, including those mediated by water vapor. We estimate the 100-yr GWP to be 32, which is 25{\%} larger than past assessments. {\textcopyright} 2013 Author(s).}, author = {Holmes, C. D. and Prather, M. J. and S{\o}vde, O. A. and Myhre, G.}, doi = {10.5194/acp-13-285-2013}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, month = {jan}, number = {1}, pages = {285--302}, publisher = {Copernicus Publications}, title = {{Future methane, hydroxyl, and their uncertainties: Key climate and emission parameters for future predictions}}, volume = {13}, year = {2013} } @article{Holmes2018, abstract = {The atmospheric methane (CH4) chemical feedback is a key process for understanding the behavior of atmospheric CH4 and its environmental impact. This work reviews how the feedback is defined and used, then examines the meteorological, chemical, and emission factors that control the feedback strength. Geographical and temporal variations in the feedback are described and explained by HOx (HOx = OH + HO2) production and partitioning. Different CH4 boundary conditions used by models, however, make no meaningful difference to the feedback calculation. The strength of the CH4 feedback depends on atmospheric composition, particularly the atmospheric CH4 burden, and is therefore not constant. Sensitivity tests show that the feedback depends very weakly on temperature, insolation, water vapor, and emissions of NO. While the feedback strength has likely remained within 10{\%} of its present value over the industrial era and likely will over the twenty-first century, neglecting these changes biases our understanding of CH4 impacts. Most environmental consequences per kg of CH4 emissions, including its global warming potential (GWP), scale with the perturbation time, which may have grown as much as 40{\%} over the industrial era and continues to rise.}, author = {Holmes, Christopher D.}, doi = {10.1002/2017MS001196}, isbn = {1942-2466}, issn = {19422466}, journal = {Journal of Advances in Modeling Earth Systems}, keywords = {feedback,methane,oxidants}, number = {4}, pages = {1087--1099}, title = {{Methane Feedback on Atmospheric Chemistry: Methods, Models, and Mechanisms}}, volume = {10}, year = {2018} } @article{Hong2019, abstract = {In recent years, air pollution has caused more than 1 million deaths per year in China, making it a major focus of public health efforts. However, future climate change may exacerbate such human health impacts by increasing the frequency and duration of weather conditions that enhance air pollution exposure. Here, we use a combination of climate, air quality, and epidemiological models to assess future air pollution deaths in a changing climate under Representative Concentration Pathway 4.5 (RCP4.5). We find that, assuming pollution emissions and population are held constant at current levels, climate change would adversely affect future air quality for {\textgreater}85{\%} of China's population (∼55{\%} of land area) by the middle of the century, and would increase by 3{\%} and 4{\%} the population-weighted average concentrations of fine particulate matter (PM2.5) and ozone, respectively. As a result, we estimate an additional 12,100 and 8,900 Chinese (95{\%} confidence interval: 10,300 to 13,800 and 2,300 to 14,700, respectively) will die per year from PM2.5 and ozone exposure, respectively. The important underlying climate mechanisms are changes in extreme conditions such as atmospheric stagnation and heat waves (contributing 39{\%} and 6{\%}, respectively, to the increase in mortality). Additionally, greater vulnerability of China's aging population will further increase the estimated deaths from PM2.5 and ozone in 2050 by factors of 1 and 3, respectively. Our results indicate that climate change and more intense extremes are likely to increase the risk of severe pollution events in China. Managing air quality in China in a changing climate will thus become more challenging.}, author = {Hong, Chaopeng and Zhang, Qiang and Zhang, Yang and Davis, Steven J. and Tong, Dan and Zheng, Yixuan and Liu, Zhu and Guan, Dabo and He, Kebin and Schellnhuber, Hans Joachim}, doi = {10.1073/pnas.1812881116}, issn = {10916490}, journal = {Proceedings of the National Academy of Sciences}, keywords = {Air quality,China,Climate change,Extreme event,Health}, month = {aug}, number = {35}, pages = {17193--17200}, title = {{Impacts of climate change on future air quality and human health in China}}, url = {http://www.pnas.org/content/116/35/17193.abstract}, volume = {116}, year = {2019} } @article{Hopcroft2017, abstract = {Atmospheric methane (CH 4) varied with climate during the Quaternary, rising from a concentration of 375 p.p.b.v. during the last glacial maximum (LGM) 21,000 years ago, to 680 p.p.b.v. at the beginning of the industrial revolution. However, the causes of this increase remain unclear; proposed hypotheses rely on fluctuations in either the magnitude of CH 4 sources or CH 4 atmospheric lifetime, or both. Here we use an Earth System model to provide a comprehensive assessment of these competing hypotheses, including estimates of uncertainty. We show that in this model, the global LGM CH 4 source was reduced by 28-46{\%}, and the lifetime increased by 2-8{\%}, with a best-estimate LGM CH 4 concentration of 463-480 p.p.b.v. Simulating the observed LGM concentration requires a 46-49{\%} reduction in sources, indicating that we cannot reconcile the observed amplitude. This highlights the need for better understanding of the effects of low CO 2 and cooler climate on wetlands and other natural CH 4 sources.}, author = {Hopcroft, Peter O. and Valdes, Paul J. and O'Connor, Fiona M. and Kaplan, Jed O. and Beerling, David J.}, doi = {10.1038/ncomms14383}, issn = {20411723}, journal = {Nature Communications}, month = {feb}, pages = {14383}, publisher = {The Author(s)}, title = {{Understanding the glacial methane cycle}}, url = {http://dx.doi.org/10.1038/ncomms14383 http://10.0.4.14/ncomms14383 https://www.nature.com/articles/ncomms14383{\#}supplementary-information}, volume = {8}, year = {2017} } @article{Horowitz2020, abstract = {Abstract We describe the baseline model configuration and simulation characteristics of the Geophysical Fluid Dynamics Laboratory (GFDL)'s Atmosphere Model version 4.1 (AM4.1), which builds on developments at GFDL over 2013?2018 for coupled carbon-chemistry-climate simulation as part of the sixth phase of the Coupled Model Intercomparison Project. In contrast with GFDL's AM4.0 development effort, which focused on physical and aerosol interactions and which is used as the atmospheric component of CM4.0, AM4.1 focuses on comprehensiveness of Earth system interactions. Key features of this model include doubled horizontal resolution of the atmosphere ({\~{}}200 to {\~{}}100 km) with revised dynamics and physics from GFDL's previous-generation AM3 atmospheric chemistry-climate model. AM4.1 features improved representation of atmospheric chemical composition, including aerosol and aerosol precursor emissions, key land-atmosphere interactions, comprehensive land-atmosphere-ocean cycling of dust and iron, and interactive ocean-atmosphere cycling of reactive nitrogen. AM4.1 provides vast improvements in fidelity over AM3, captures most of AM4.0's baseline simulations characteristics, and notably improves on AM4.0 in the representation of aerosols over the Southern Ocean, India, and China?even with its interactive chemistry representation?and in its manifestation of sudden stratospheric warmings in the coldest months. Distributions of reactive nitrogen and sulfur species, carbon monoxide, and ozone are all substantially improved over AM3. Fidelity concerns include degradation of upper atmosphere equatorial winds and of aerosols in some regions.}, annote = {https://doi.org/10.1029/2019MS002032}, author = {Horowitz, Larry W and Naik, Vaishali and Paulot, Fabien and Ginoux, Paul A and Dunne, John P and Mao, Jingqiu and Schnell, Jordan and Chen, Xi and He, Jian and John, Jasmin G and Lin, Meiyun and Lin, Pu and Malyshev, Sergey and Paynter, David and Shevliakova, Elena and Zhao, Ming}, doi = {https://doi.org/10.1029/2019MS002032}, issn = {1942-2466}, journal = {Journal of Advances in Modeling Earth Systems}, keywords = {Earth system model,aerosols,atmospheric chemistry,chemistry-climate model,ozone}, month = {oct}, number = {10}, pages = {e2019MS002032}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{The GFDL Global Atmospheric Chemistry–Climate Model AM4.1: Model Description and Simulation Characteristics}}, url = {https://doi.org/10.1029/2019MS002032}, volume = {12}, year = {2020} } @article{Hoshika2015, annote = {NULL}, author = {Hoshika, Yasutomo and Katata, Genki and Deushi, Makoto and Watanabe, Makoto and Koike, Takayoshi and Paoletti, Elena}, doi = {10.1038/srep09871}, issn = {2045-2322}, journal = {Scientific Reports}, month = {sep}, number = {1}, pages = {9871}, title = {{Ozone-induced stomatal sluggishness changes carbon and water balance of temperate deciduous forests}}, url = {http://www.nature.com/articles/srep09871}, volume = {5}, year = {2015} } @article{ISI:000350770900014, abstract = {Halogens released from long-lived anthropogenic substances, such as chlorofluorocarbons, are the principal cause of recent depletion of stratospheric ozone, a greenhouse gas(1-3). Recent observations show that very short-lived substances, with lifetimes generally under six months, are also an important source of stratospheric halogens(4,5). Short-lived bromine substances are produced naturally by seaweed and phytoplankton, whereas short-lived chlorine substances are primarily anthropogenic. Here we used a chemical transport model to quantify the depletion of ozone in the lower stratosphere from short-lived halogen substances, and a radiative transfer model to quantify the radiative effects of that ozone depletion. According to our simulations, ozone loss from short-lived substances had a radiative effect nearly half that from long-lived halocarbons in 2011 and, since pre-industrial times, has contributed a total of about -0.02 W m(-2) to global radiative forcing. We find natural short-lived bromine substances exert a 3.6 times larger ozone radiative effect than long-lived halocarbons, normalized by halogen content, and show atmospheric levels of dichloromethane, a short-lived chlorine substance not controlled by the Montreal Protocol, are rapidly increasing. We conclude that potential further significant increases in the atmospheric abundance of short-lived halogen substances, through changing natural processes(6-8) or continued anthropogenic emissions(9), could be important for future climate.}, annote = {RF from depletion of stratospheric ozone by short-lived halogens -- section 6.5}, author = {Hossaini, R and Chipperfield, M P and Montzka, S A and Rap, A and Dhomse, S and Feng, W}, doi = {10.1038/NGEO2363}, issn = {1752-0894}, journal = {Nature Geoscience}, month = {mar}, number = {3}, pages = {186--190}, title = {{Efficiency of short-lived halogens at influencing climate through depletion of stratospheric ozone}}, type = {Article}, volume = {8}, year = {2015} } @article{Hossaini2017, abstract = {It is well established that anthropogenic chlorine-containing chemicals contribute to ozone layer depletion. The successful implementation of the Montreal Protocol has led to reductions in the atmospheric concentration of many ozone-depleting gases, such as chlorofluorocarbons. As a consequence, stratospheric chlorine levels are declining and ozone is projected to return to levels observed pre-1980 later this century. However, recent observations show the atmospheric concentration of dichloromethane—an ozone-depleting gas not controlled by the Montreal Protocol—is increasing rapidly. Using atmospheric model simulations, we show that although currently modest, the impact of dichloromethane on ozone has increased markedly in recent years and if these increases continue into the future, the return of Antarctic ozone to pre-1980 levels could be substantially delayed. Sustained growth in dichloromethane would therefore offset some of the gains achieved by the Montreal Protocol, further delaying recovery of Earth's ozone layer.}, author = {Hossaini, Ryan and Chipperfield, Martyn P and Montzka, Stephen A and Leeson, Amber A and Dhomse, Sandip S and Pyle, John A}, doi = {10.1038/ncomms15962}, journal = {Nature Communications}, month = {jun}, pages = {15962}, publisher = {The Author(s)}, title = {{The increasing threat to stratospheric ozone from dichloromethane}}, url = {http://dx.doi.org/10.1038/ncomms15962 http://10.0.4.14/ncomms15962 https://www.nature.com/articles/ncomms15962{\#}supplementary-information}, volume = {8}, year = {2017} } @article{Hou20188173, abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Wet deposition driven by precipitation is an important sink for atmospheric aerosols and soluble gases. We investigate the sensitivity of atmospheric aerosol lifetimes to precipitation intensity and frequency in the context of global climate change. Our sensitivity model simulations, through some simplified perturbations to precipitation in the GEOS-Chem model, show that the removal efficiency and hence the atmospheric lifetime of aerosols have significantly higher sensitivities to precipitation frequencies than to precipitation intensities, indicating that the same amount of precipitation may lead to different removal efficiencies of atmospheric aerosols. Combining the long-term trends of precipitation patterns for various regions with the sensitivities of atmospheric aerosol lifetimes to various precipitation characteristics allows us to examine the potential impacts of precipitation changes on atmospheric aerosols. Analyses based on an observational dataset show that precipitation frequencies in some regions have decreased in the past 14 years, which might increase the atmospheric aerosol lifetimes in those regions. Similar analyses based on multiple reanalysis meteorological datasets indicate that the changes of precipitation intensity and frequency over the past 30 years can lead to perturbations in the atmospheric aerosol lifetimes by 10{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%} or higher at the regional scale.{\textless}/p{\textgreater}{\textless}/p{\textgreater}}, annote = {cited By 0}, author = {Hou, Pei and Wu, Shiliang and McCarty, Jessica L. and Gao, Yang}, doi = {10.5194/acp-18-8173-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {11}, pages = {8173--8182}, title = {{Sensitivity of atmospheric aerosol scavenging to precipitation intensity and frequency in the context of global climate change}}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048557272{\&}doi=10.5194{\%}2Facp-18-8173-2018{\&}partnerID=40{\&}md5=dd1d20b2656c624d4d9fe783569bc2e4}, volume = {18}, year = {2018} } @article{Hou2016, annote = {cited By 8}, author = {Hou, Pei and Wu, Shiliang}, doi = {10.1038/srep23792}, issn = {2045-2322}, journal = {Scientific Reports}, month = {apr}, number = {1}, pages = {23792}, title = {{Long-term Changes in Extreme Air Pollution Meteorology and the Implications for Air Quality}}, url = {http://www.nature.com/articles/srep23792}, volume = {6}, year = {2016} } @article{Huang2015, abstract = {Development of reliable source emission inventories is particularly needed to advance the understanding of the origin of Arctic haze using chemical transport modeling. This study develops a regional anthropogenic black carbon (BC) emission inventory for the Russian Federation, the largest country by land area in the Arctic Council. Activity data from combination of local Russia information and international resources, emission factors based on either Russian documents or adjusted values for local conditions, and other emission source data are used to approximate the BC emissions. Emissions are gridded at a resolution of 0.1° × 0.1° and developed into a monthly temporal profile. Total anthropogenic BC emission of Russia in 2010 is estimated to be around 224 Gg. Gas flaring, a commonly ignored black carbon source, contributes a significant fraction of 36.2{\%} to Russia's total anthropogenic BC emissions. Other sectors, i.e., residential, transportation, industry, and power plants, contribute 25.0{\%}, 20.3{\%}, 13.1{\%}, and 5.4{\%}, respectively. Three major BC hot spot regions are identified: the European part of Russia, the southern central part of Russia where human population densities are relatively high, and the Urals Federal District where Russia's major oil and gas fields are located but with sparse human population. BC simulations are conducted using the hemispheric version of Community Multi-scale Air Quality Model with emission inputs from a global emission database EDGAR (Emissions Database for Global Atmospheric Research)-HTAPv2 (Hemispheric Transport of Air Pollution) and EDGAR-HTAPv2 with its Russian part replaced by the newly developed Russian BC emissions, respectively. The simulation using the new Russian BC emission inventory could improve 30–65{\%} of absorption aerosol optical depth measured at the AERONET sites in Russia throughout the whole year as compared to that using the default HTAPv2 emissions. At the four ground monitoring sites (Zeppelin, Barrow, Alert, and Tiksi) in the Arctic Circle, surface BC simulations are improved the most during the Arctic haze periods (October–March). The poor performance of Arctic BC simulations in previous studies may be partly ascribed to the Russian BC emissions built on out-of-date and/or missing information, which could result in biases to both emission rates and the spatial distribution of emissions. This study highlights that the impact of Russian emissions on the Arctic haze has likely been underestimated, and its role in the Arctic climate system needs to be reassessed. The Russian black carbon emission source data generated in this study can be obtained via http://abci.ornl.gov/download.shtml or http://acs.engr.utk.edu/Data.php.}, author = {Huang, Kan and Fu, Joshua S and Prikhodko, Vitaly Y and Storey, John M and Romanov, Alexander and Hodson, Elke L and Cresko, Joe and Morozova, Irina and Ignatieva, Yulia and Cabaniss, John}, doi = {10.1002/2015JD023358}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {Aerosols and particles,Arctic,Arctic region,Emissions,Model verification and validation,Russia,black carbon,numerical simulation}, month = {nov}, number = {21}, pages = {11306--11333}, title = {{Russian anthropogenic black carbon: Emission reconstruction and Arctic black carbon simulation}}, url = {http://dx.doi.org/10.1002/2015JD023358 http://doi.wiley.com/10.1002/2015JD023358}, volume = {120}, year = {2015} } @article{Huang2016, author = {Huang, Kan and Fu, Joshua S}, doi = {10.1038/sdata.2016.104}, issn = {2052-4463}, journal = {Scientific Data}, month = {dec}, number = {1}, pages = {160104}, title = {{A global gas flaring black carbon emission rate dataset from 1994 to 2012}}, url = {http://dx.doi.org/10.1038/sdata.2016.104 http://www.nature.com/articles/sdata2016104}, volume = {3}, year = {2016} } @article{Huang2013, abstract = {Abstract. Carbonaceous aerosols including organic carbon and black carbon have significant implications for both climate and air quality. In the current global climate or chemical transport models, a fixed hydrophobic-to-hydrophilic conversion lifetime for carbonaceous aerosol ($\tau$) is generally assumed, which is usually around one day. We have implemented a new detailed aging scheme for carbonaceous aerosols in a chemical transport model (GEOS-Chem) to account for both the chemical oxidation and the physical condensation-coagulation effects, where $\tau$ is affected by local atmospheric environment including atmospheric concentrations of water vapor, ozone, hydroxyl radical and sulfuric acid. The updated $\tau$ exhibits large spatial and temporal variations with the global average (up to 11 km altitude) calculated to be 2.6 days. The chemical aging effects are found to be strongest over the tropical regions driven by the low ozone concentrations and high humidity there. The $\tau$ resulted from chemical aging generally decreases with altitude due to increases in ozone concentration and decreases in humidity. The condensation-coagulation effects are found to be most important for the high-latitude areas, in particular the polar regions, where the $\tau$ values are calculated to be up to 15 days. When both the chemical aging and condensation-coagulation effects are considered, the total atmospheric burdens and global average lifetimes of BC, black carbon, (OC, organic carbon) are calculated to increase by 9{\%} (3{\%}) compared to the control simulation, with considerable enhancements of BC and OC concentrations in the Southern Hemisphere. Model evaluations against data from multiple datasets show that the updated aging scheme improves model simulations of carbonaceous aerosols for some regions, especially for the remote areas in the Northern Hemisphere. The improvement helps explain the persistent low model bias for carbonaceous aerosols in the Northern Hemisphere reported in literature. Further model sensitivity simulations focusing on the continental outflow of carbonaceous aerosols demonstrate that previous studies using the old aging scheme could have significantly underestimated the intercontinental transport of carbonaceous aerosols.}, author = {Huang, Y. and Wu, S. and Dubey, M. K. and French, N. H F}, doi = {10.5194/acp-13-6329-2013}, isbn = {1680-7316}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jul}, number = {13}, pages = {6329--6343}, pmid = {24174929}, title = {{Impact of aging mechanism on model simulated carbonaceous aerosols}}, url = {https://acp.copernicus.org/articles/13/6329/2013/}, volume = {13}, year = {2013} } @article{Huang2018, abstract = {We apply the NCAR CAM5-Chem global aerosol{\&}ndash;climate model to quantify the net global radiative effects of black and organic carbon aerosols from global and Indian solid fuel cookstove emissions for the year 2010. Our updated assessment accounts for the direct radiative effects, changes to cloud albedo and lifetime (aerosol indirect effect, AIE), impacts on clouds via the vertical temperature profile (semi-direct effect, SDE), and changes in the surface albedo of snow and ice (surface albedo effect). In addition, we provide the first estimate of household solid fuel black carbon emission effects on ice clouds. Anthropogenic emissions are from the IIASA GAINS ECLIPSE V5a inventory. A global dataset of black carbon (BC) and organic aerosol (OA) measurements from surface sites and aerosol optical depth (AOD) from AERONET is used to evaluate the model skill. Compared with observations, the model successfully reproduces the spatial patterns of atmospheric BC and OA concentrations, and agrees with measurements to within a factor of 2. Globally, the simulated AOD agrees well with observations, with normalized mean bias close to zero. However, the model tends to underestimate AOD over India and China by {\~{}}{\&}thinsp;19{\&}thinsp;{\%} but overestimate it over Africa by {\~{}}{\&}thinsp;25{\&}thinsp;{\%}. Without BC serving as ice nuclei (IN), global and Indian solid fuel cookstove aerosol emissions have a net cooling impact on global climate of {\&}minus;141{\&}thinsp;{\&}plusmn;{\&}thinsp;4{\&}thinsp;mW{\&}thinsp;m{\&}minus;2 and {\&}minus;12{\&}thinsp;{\&}plusmn;{\&}thinsp;4{\&}thinsp;mW{\&}thinsp;m{\&}minus;2, respectively. The net radiative impacts are dominated by the AIE and SDE mechanisms, which originate from enhanced cloud condensation nuclei concentrations for the formation of liquid and mixed-phase clouds, and a suppression of convective transport of water vapor from the lower troposphere to the upper troposphere/lower stratosphere that in turn leads to reduced ice cloud formation. When BC is allowed to behave as a source of IN, the net global climate impacts of the global and Indian solid fuel cookstove emissions range from {\&}minus;260 to +135{\&}thinsp;mW{\&}thinsp;m{\&}minus;2 and {\&}minus;33 to +24{\&}thinsp;mW{\&}thinsp;m{\&}minus;2, with globally averaged values {\&}minus;51{\&}thinsp;{\&}plusmn;{\&}thinsp;210 and 0.3{\&}thinsp;{\&}plusmn;{\&}thinsp;29{\&}thinsp;mW{\&}thinsp;m{\&}minus;2 respectively. The uncertainty range is calculated from sensitivity simulations that alter the maximum freezing efficiency of BC across a plausible range: 0.01, 0.05 and 0.1. BC{\&}ndash;ice cloud interactions lead to substantial increases in high cloud (}, author = {Huang, Yaoxian and Unger, Nadine and Storelvmo, Trude and Harper, Kandice and Zheng, Yiqi and Heyes, Chris}, doi = {10.5194/acp-18-5219-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {8}, pages = {5219--5233}, title = {{Global radiative effects of solid fuel cookstove aerosol emissions}}, volume = {18}, year = {2018} } @article{Huang2020, author = {Huang, Yaoxian and Unger, Nadine and Harper, Kandice and Heyes, Chris}, doi = {10.1029/2019GH000240}, issn = {2471-1403}, journal = {GeoHealth}, month = {mar}, number = {3}, pages = {e2019GH000240}, title = {{Global Climate and Human Health Effects of the Gasoline and Diesel Vehicle Fleets}}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019GH000240}, volume = {4}, year = {2020} } @article{cite-key, abstract = {Investigation of the chemical nature and sources of particulate matter at urban locations in four Chinese cities during a severe haze pollution event finds that the event was driven to a large extent by secondary aerosol formation.}, author = {Huang, Ru-Jin and Zhang, Yanlin and Bozzetti, Carlo and Ho, Kin-Fai and Cao, Jun-Ji and Han, Yongming and Daellenbach, Kaspar R and Slowik, Jay G and Platt, Stephen M and Canonaco, Francesco and Zotter, Peter and Wolf, Robert and Pieber, Simone M and Bruns, Emily A and Crippa, Monica and Ciarelli, Giancarlo and Piazzalunga, Andrea and Schwikowski, Margit and Abbaszade, G{\"{u}}lcin and Schnelle-Kreis, J{\"{u}}rgen and Zimmermann, Ralf and An, Zhisheng and Szidat, S{\"{o}}nke and Baltensperger, Urs and Haddad, Imad El and Pr{\'{e}}v{\^{o}}t, Andr{\'{e}}S. H}, doi = {10.1038/nature13774}, isbn = {1476-4687}, journal = {Nature}, number = {7521}, pages = {218--222}, title = {{High secondary aerosol contribution to particulate pollution during haze events in China}}, url = {https://doi.org/10.1038/nature13774}, volume = {514}, year = {2014} } @article{Huang2020, abstract = {To control the spread of the 2019 novel coronavirus (COVID-19), China imposed nationwide restrictions on the movement of its population (lockdown) after the Chinese New Year of 2020, leading to large reductions in economic activities and associated emissions. Despite such large decreases in primary pollution, there were nonetheless several periods of heavy haze pollution in eastern China, raising questions about the well-established relationship between human activities and air quality. Here, using comprehensive measurements and modeling, we show that the haze during the COVID lockdown was driven by enhancements of secondary pollution. In particular, large decreases in NOx emissions from transportation increased ozone and nighttime NO3 radical formation, and these increases in atmospheric oxidizing capacity in turn facilitated the formation of secondary particulate matter. Our results, afforded by the tragic natural experiment of the COVID-19 pandemic, indicate that haze mitigation depends upon a coordinated and balanced strategy for controlling multiple pollutants.}, author = {Huang, Xin and Ding, Aijun and Gao, Jian and Zheng, Bo and Zhou, Derong and Qi, Ximeng and Tang, Rong and Wang, Jiaping and Ren, Chuanhua and Nie, Wei and Chi, Xuguang and Xu, Zheng and Chen, Liangduo and Li, Yuanyuan and Che, Fei and Pang, Nini and Wang, Haikun and Tong, Dan and Qin, Wei and Cheng, Wei and Liu, Weijing and Fu, Qingyan and Liu, Baoxian and Chai, Fahe and Davis, Steven J and Zhang, Qiang and He, Kebin}, doi = {10.1093/nsr/nwaa137}, issn = {2095-5138}, journal = {National Science Review}, keywords = {COVID-19,emission reduction,haze pollution,ozone,secondary pollution}, month = {feb}, number = {2}, pages = {nwaa137}, publisher = {Oxford University Press (OUP)}, title = {{Enhanced secondary pollution offset reduction of primary emissions during COVID-19 lockdown in China}}, url = {https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwaa137/5859289 https://academic.oup.com/nsr/article/doi/10.1093/nsr/nwaa137/5859289}, volume = {8}, year = {2021} } @article{Hudman2012, abstract = {Abstract. Soils have been identified as a major source ({\~{}}15{\%}) of global nitrogen oxide (NOx) emissions. Parameterizations of soil NOx emissions (SNOx) commonly used in the current generation of chemical transport models were designed to capture mean seasonal behaviour. These parameterizations do not, however, respond quantitatively to the meteorological triggers that are observed to result in pulsed SNOx. Here we present a new parameterization of SNOx implemented within a global chemical transport model (GEOS-Chem). The parameterization represents available nitrogen (N) in soils using biome specific emission factors, online wet- and dry-deposition of N, and fertilizer and manure N derived from a spatially explicit dataset, distributed using seasonality derived from data obtained by the Moderate Resolution Imaging Spectrometer. Moreover, it represents the functional form of emissions derived from point measurements and ecosystem scale experiments including pulsing following soil wetting by rain or irrigation, and emissions that are a smooth function of soil moisture as well as temperature between 0 and 30 °C. This parameterization yields global above-soil SNOx of 10.7 Tg N yr−1, including 1.8 Tg N yr−1 from fertilizer N input (1.5{\%} of applied N) and 0.5 Tg N yr−1 from atmospheric N deposition. Over the United States (US) Great Plains region, SNOx are predicted to comprise 15–40{\%} of the tropospheric NO2 column and increase column variability by a factor of 2–4 during the summer months due to chemical fertilizer application and warm temperatures. SNOx enhancements of 50–80{\%} of the simulated NO2 column are predicted over the African Sahel during the monsoon onset (April–June). In this region the day-to-day variability of column NO2 is increased by a factor of 5 due to pulsed-N emissions. We evaluate the model by comparison with observations of NO2 column density from the Ozone Monitoring Instrument (OMI). We find that the model is able to reproduce the observed interannual variability of NO2 (induced by pulsed-N emissions) over the US Great Plains. We also show that the OMI mean (median) NO2 observed during the overpass following first rainfall over the Sahel is 49{\%} (23{\%}) higher than in the five days preceding. The measured NO2 on the day after rainfall is still 23{\%} (5{\%}) higher, providing a direct measure of the pulse's decay time of 1–2 days. This is consistent with the pulsing representation used in our parameterization and much shorter than 5–14 day pulse decay length used in current models.}, author = {Hudman, R. C. and Moore, N. E. and Mebust, A. K. and Martin, R. V. and Russell, A. R. and Valin, L. C. and Cohen, R. C.}, doi = {10.5194/acp-12-7779-2012}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, keywords = {pzanis}, month = {aug}, number = {16}, pages = {7779--7795}, title = {{Steps towards a mechanistic model of global soil nitric oxide emissions: implementation and space based-constraints}}, url = {https://www.atmos-chem-phys.net/12/7779/2012/}, volume = {12}, year = {2012} } @article{Iizuka2017, abstract = {The Southeastern Greenland Dome (SE-Dome) has both a high elevation and a high accumulation rate (1.01 m we yr−1), which are suitable properties for reconstructing past environmental changes with a high time resolution. For this study, we measured the major ion fluxes in a 90 m ice core drilled from the SE-Dome region in 2015 and present the records of annual ion fluxes from 1957 to 2014. From 1970 to 2010, the trend of nonsea-salt (nss) SO42− flux decreases, whereas that for NH4+ increases, tracking well with the anthropogenic SOx and NH3 emissions mainly from North America. The result suggests that these fluxes reflect histories of the anthropogenic SOx and NH3 emissions. In contrast, the decadal trend of NO3− flux differs from the decreasing trend of anthropogenic NOx emissions. Although the cause of this discrepancy remains unclear, it may be related to changes in particle formation processes and chemical scavenging rates caused by an increase in sea salt and dust and/or a decrease in nssSO42−. We also find a high average NO3− flux (1.13 mmol m−2 yr−1) in the ice core, which suggests a negligible effect from postdepositional NO3− loss. Thus, the SE-Dome region is an excellent location for reconstructing nitrate fluxes. Over a decadal time scale, our NO3− flux record is similar to those from other ice cores in Greenland high-elevation sites, suggesting that NO3− concentration records from these ice cores are reliable.}, author = {Iizuka, Yoshinori and Uemura, Ryu and Fujita, Koji and Hattori, Shohei and Seki, Osamu and Miyamoto, Chihiro and Suzuki, Toshitaka and Yoshida, Naohiro and Motoyama, Hideaki and Matoba, Sumito}, doi = {10.1002/2017JD026733}, issn = {21698996}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {Greenland,anthropogenic emission,ice core,nitrate,postdepositional effect,sulfate}, number = {1}, pages = {574--589}, title = {{A 60 Year Record of Atmospheric Aerosol Depositions Preserved in a High-Accumulation Dome Ice Core, Southeast Greenland}}, volume = {123}, year = {2018} } @article{Im2012164, abstract = {The impact of ambient temperature on the levels and chemical composition of aerosols over the Eastern Mediterranean in July 2004 is investigated using the WRF/CMAQ model system coupled with the MEGAN biogenic emissions model. CMAQ is able to capture the observed mean aerosol concentrations over the studied period. Non-sea-salt sulfate (nss-SO 42-) is calculated to be the major aerosol component contributing by 63{\%}, 16{\%} and 40{\%} to the fine (PM 2.5), coarse (PM 2.5-10) and total particulate matter mass (PM 10), respectively. PM 2.5 to PM 10 mass ratios reach more than 80{\%} over the large urban agglomerations but decrease to 45{\%} at downwind locations suggesting coagulation and condensation on coarse particles. Higher temperatures increase biogenic emissions, enhance spatially-averaged biogenic secondary organic aerosol (SOA, by 0.01±0.00$\mu$gm -3K -1) and nitrate (NO 3-) aerosol concentrations (by0.02±0.02$\mu$gm -3K -1). They reduce nss-SO 42- (by-0.04±0.07$\mu$gm -3K -1), induced by significant reduction in the cloud cover (90{\%} K -1) and subsequent aqueous-phase production. The PM 2.5 concentrations show a very small positive response to temperature changes, increasing by 0.003±0.042$\mu$gm -3K -1 (0.04{\%} K -1) due to the compensation of organic carbon increases by nss-SO 42- reductions. Locally, larger changes are computed, with nss-SO 42- and NO 3- in fine aerosols reduced by up to 0.62$\mu$gm -3K -1 and 0.80$\mu$gm -3K -1, respectively. Increases as high as 0.097$\mu$gm -3K -1 and 0.034$\mu$gm -3K -1 are calculated for organic and elemental carbon, respectively. Results show that changes in temperature modify not only the aerosol mass but also its chemical composition. {\textcopyright} 2011 Elsevier Ltd.}, annote = {cited By 25}, author = {Im, Ulas and Markakis, Kostas and Ko{\c{c}}ak, Mustafa and Gerasopoulos, Evangelos and Daskalakis, Nikos and Mihalopoulos, Nikolaos and Poupkou, Anastasia and Kindap, Tayfun and Unal, Alper and Kanakidou, Maria}, doi = {10.1016/j.atmosenv.2011.12.044}, issn = {13522310}, journal = {Atmospheric Environment}, keywords = {Aerosol chemical composition,Eastern Mediterranean,Megacity,Temperature change}, month = {apr}, pages = {164--173}, title = {{Summertime aerosol chemical composition in the Eastern Mediterranean and its sensitivity to temperature}}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84856679237{\&}doi=10.1016{\%}2Fj.atmosenv.2011.12.044{\&}partnerID=40{\&}md5=a63cf6f539025519832d0409ab1e87f1 https://linkinghub.elsevier.com/retrieve/pii/S1352231011013318}, volume = {50}, year = {2012} } @incollection{IMO2016a, address = {London, UK}, author = {IMO}, booktitle = {MARPOL Annex VI}, isbn = {978-93-801-16588}, publisher = {International Maritime Organization (IMO)}, series = {MEPC 70/18/Add.1}, title = {{Effective Date of Implementation of the Fuel Oil Standard in Regulation 14.1.3 of MARPOL Annex VI. Annex 6. Resolution MEPC. 280(70) (Adopted on 28 October 2016)}}, url = {https://wwwcdn.imo.org/localresources/en/OurWork/Environment/Documents/280(70).pdf}, year = {2016} } @article{Inness2019, abstract = {Abstract. The Copernicus Atmosphere Monitoring Service (CAMS) reanalysis is the latest global reanalysis dataset of atmospheric composition produced by the European Centre for Medium-Range Weather Forecasts (ECMWF), consisting of three-dimensional time-consistent atmospheric composition fields, including aerosols and chemical species. The dataset currently covers the period 2003–2016 and will be extended in the future by adding 1 year each year. A reanalysis for greenhouse gases is being produced separately. The CAMS reanalysis builds on the experience gained during the production of the earlier Monitoring Atmospheric Composition and Climate (MACC) reanalysis and CAMS interim reanalysis. Satellite retrievals of total column CO; tropospheric column NO2; aerosol optical depth (AOD); and total column, partial column and profile ozone retrievals were assimilated for the CAMS reanalysis with ECMWF's Integrated Forecasting System. The new reanalysis has an increased horizontal resolution of about 80{\&}thinsp;km and provides more chemical species at a better temporal resolution (3-hourly analysis fields, 3-hourly forecast fields and hourly surface forecast fields) than the previously produced CAMS interim reanalysis. The CAMS reanalysis has smaller biases compared with most of the independent ozone, carbon monoxide, nitrogen dioxide and aerosol optical depth observations used for validation in this paper than the previous two reanalyses and is much improved and more consistent in time, especially compared to the MACC reanalysis. The CAMS reanalysis is a dataset that can be used to compute climatologies, study trends, evaluate models, benchmark other reanalyses or serve as boundary conditions for regional models for past periods. ]]{\textgreater}}, author = {Inness, Antje and Ades, Melanie and Agust{\'{i}}-Panareda, Anna and Barr{\'{e}}, J{\'{e}}r{\^{o}}me and Benedictow, Anna and Blechschmidt, Anne-Marlene and Dominguez, Juan Jose and Engelen, Richard and Eskes, Henk and Flemming, Johannes and Huijnen, Vincent and Jones, Luke and Kipling, Zak and Massart, Sebastien and Parrington, Mark and Peuch, Vincent-Henri and Razinger, Miha and Remy, Samuel and Schulz, Michael and Suttie, Martin}, doi = {10.5194/acp-19-3515-2019}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {6}, pages = {3515--3556}, title = {{The CAMS reanalysis of atmospheric composition}}, url = {https://www.atmos-chem-phys.net/19/3515/2019/}, volume = {19}, year = {2019} } @techreport{hock2019SROCC_ch2, author = {IPCC}, doi = {https://www.ipcc.ch/report/srocc/}, editor = {Pörtner, H.-O. and Roberts, D.C. and Masson-Delmotte, V. and Zhai, P. and Tignor, M. and Poloczanska, E. and Mintenbeck, K. and Alegría, A. and Nicolai, M. and Okem, A. and Petzold, J. and Rama, B. and Weyer, N.M.}, pages = {755}, publisher = {In Press}, title = {{IPCC Special Report on the Ocean and Cryosphere in a Changing Climate}}, url = {https://www.ipcc.ch/report/srocc/}, year = {2019} } @techreport{IPCC2019SRCCL, author = {IPCC}, doi = {https://www.ipcc.ch/srccl}, editor = {Shukla, P.R. and Skea, J. and Buendia, E. Calvo and Masson-Delmotte, V. and P{\"{o}}rtner, H.-O. and Roberts, D. C. and Zhai, P. and Slade, R. and Connors, S. and van Diemen, R. and Ferrat, M. and Haughey, E. and Luz, S. and Neogi, S. and Pathak, M. and Petzold, J. and Pereira, J. Portugal and Vyas, P. and Huntley, E. and Kissick, K. and Belkacemi, M. and Malley, J.}, pages = {896}, publisher = {In Press}, title = {{Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems}}, url = {https://www.ipcc.ch/srccl}, year = {2019} } @article{Irie2016, abstract = {Long-term (2005-2015) tropospheric nitrogen dioxide (NO2) column data recorded by the satellite-borne Ozone Monitoring Instrument (OMI) in East Asia were analyzed to investigate annual trends on an national basis and their potential causes. We found an evident decrease of 6{\%} year(-1) in the NO2 level over China after 2011. The grid-basis trend analysis implies that the rapid decrease occurred on a provincial or larger spatial scale and was likely due to a nationwide action such as the widespread use of denitrification units. In Japan and South Korea, a turnaround indicating an increase was observed after 2013 and 2012, respectively. As a consequence, the tropospheric NO2 pollution level in East Asia was found to be recovered to the 5-year-ago level in 2015.}, annote = {Times Cited: 13 Kyushu, RIAM/F-4018-2015; Itahashi, Syuichi/F-5684-2014 Kyushu, RIAM/0000-0002-3518-444X; Itahashi, Syuichi/0000-0001-7567-7831 0 13}, author = {Irie, Hitoshi and Muto, Takuya and Itahashi, Syuichi and Kurokawa, Jun-Ichi and Uno, Itsushi}, doi = {10.2151/sola.2016-035}, isbn = {1349-6476}, journal = {SOLA}, pages = {170--174}, title = {{Turnaround of Tropospheric Nitrogen Dioxide Pollution Trends in China, Japan, and South Korea}}, volume = {12}, year = {2016} } @article{Jackson2016, abstract = {Proposals to geoengineer Earth's climate by cirrus cloud thinning (CCT) potentially offer advantages over solar radiation management schemes: amplified cooling of the Arctic and smaller perturbations to global mean precipitation in particular. Using an idealized climate model implementation of CCT in which ice particle fall speeds were increased 2×, 4×, and 8× we examine the relationships between effective radiative forcing (ERF) at the top of atmosphere, near-surface temperature, and the response of the hydrological cycle. ERF was nonlinear with fall speed change and driven by the trade-off between opposing positive shortwave and negative longwave radiative forcings. ERF was-2.0Wm-2 for both 4× and 8× fall speeds. Global mean temperature decreased linearly with ERF, while Arctic temperature reductions were amplified compared with the global mean change. The change in global mean precipitation involved a rapid adjustment ({\~{}} 1{\%}/Wm2), which was linear with the change in the net atmospheric energy balance, and a feedback response ({\~{}}2{\%}/°C). Global mean precipitation and evaporation increased strongly in the first year of CCT. Intensification of the hydrological cycle was promoted by intensification of the vertical overturning circulation of the atmosphere, changes in boundary layer climate favorable for evaporation, and increased energy available at the surface for evaporation (from increased net shortwave radiation and reduced subsurface storage of heat). Such intensification of the hydrological cycle is a significant side effect to the cooling of climate by CCT. Any accompanying negative cirrus cloud feedback response would implicitly increase the costs and complexity of CCT deployment.}, author = {Jackson, L. S. and Crook, J. A. and Forster, P. M.}, doi = {10.1002/2015JD024304}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {jun}, number = {12}, pages = {6822--6840}, title = {{An intensified hydrological cycle in the simulation of geoengineering by cirrus cloud thinning using ice crystal fall speed changes}}, url = {http://doi.wiley.com/10.1002/2015JD024304}, volume = {121}, year = {2016} } @article{Jakob2016, abstract = {Evaluating the trade-offs between the risks related to climate change, climate change mitigation as well as co-benefits requires an integrated scenarios approach to sustainable development. We outline a conceptual multi-objective framework to assess climate policies that takes into account climate impacts, mitigation costs, water and food availability, technological risks of nuclear energy and carbon capture and sequestration as well as co-benefits of reducing local air pollution and increasing energy security. This framework is then employed as an example to different climate change mitigation scenarios generated with integrated assessment models. Even though some scenarios encompass considerable challenges for sustainability, no scenario performs better or worse than others in all dimensions, pointing to trade-offs between different dimensions of sustainable development. For this reason, we argue that these trade-offs need to be evaluated in a process of public deliberation that includes all relevant social actors.}, author = {Jakob, Michael and Steckel, Jan Christoph}, doi = {10.1088/1748-9326/11/10/104010}, issn = {1748-9326}, journal = {Environmental Research Letters}, number = {10}, pages = {104010}, publisher = {IOP Publishing}, title = {{Implications of climate change mitigation for sustainable development}}, url = {http://dx.doi.org/10.1088/1748-9326/11/10/104010}, volume = {11}, year = {2016} } @article{essd-2018-164, author = {Janssens-Maenhout, Greet and Crippa, Monica and Guizzardi, Diego and Muntean, Marilena and Schaaf, Edwin and Dentener, Frank and Bergamaschi, Peter and Pagliari, Valerio and Olivier, Jos G. J. and Peters, Jeroen A. H. W. and van Aardenne, John A. and Monni, Suvi and Doering, Ulrike and Petrescu, A. M. Roxana and Solazzo, Efisio and Oreggioni, Gabriel D.}, doi = {10.5194/essd-11-959-2019}, issn = {1866-3516}, journal = {Earth System Science Data}, month = {jul}, number = {3}, pages = {959--1002}, title = {{EDGAR v4.3.2 Global Atlas of the three major greenhouse gas emissions for the period 1970–2012}}, url = {https://essd.copernicus.org/articles/11/959/2019/}, volume = {11}, year = {2019} } @article{Jardine2016, abstract = {Abstract Tropical forests absorb large amounts of atmospheric CO2 through photosynthesis but elevated temperatures suppress this absorption and promote monoterpene emissions. Using 13CO2 labeling, here we show that monoterpene emissions from tropical leaves derive from recent photosynthesis and demonstrate distinct temperature optima for five groups (Groups 1?5), potentially corresponding to different enzymatic temperature-dependent reaction mechanisms within ?-ocimene synthases. As diurnal and seasonal leaf temperatures increased during the Amazonian 2015 El Ni{\~{n}}o event, leaf and landscape monoterpene emissions showed strong linear enrichments of ?-ocimenes (+4.4{\%}?°C?1) at the expense of other monoterpene isomers. The observed inverse temperature response of $\alpha$-pinene (?0.8{\%}?°C?1), typically assumed to be the dominant monoterpene with moderate reactivity, was not accurately simulated by current global emission models. Given that ?-ocimenes are highly reactive with respect to both atmospheric and biological oxidants, the results suggest that highly reactive ?-ocimenes may play important roles in the thermotolerance of photosynthesis by functioning as effective antioxidants within plants and as efficient atmospheric precursors of secondary organic aerosols. Thus, monoterpene composition may represent a new sensitive ?thermometer? of leaf oxidative stress and atmospheric reactivity, and therefore a new tool in future studies of warming impacts on tropical biosphere-atmosphere carbon-cycle feedbacks.}, annote = {doi: 10.1111/pce.12879}, author = {Jardine, Kolby J and Jardine, Angela B and Holm, Jennifer A and Lombardozzi, Danica L and Negron-Juarez, Robinson I and Martin, Scot T and Beller, Harry R and Gimenez, Bruno O and Higuchi, Niro and Chambers, Jeffrey Q}, doi = {10.1111/pce.12879}, issn = {0140-7791}, journal = {Plant, Cell {\&} Environment}, keywords = {13CO2 labeling,El Ni{\~{n}}o,TPS synthase,drought,heat,photosynthesis: carbon reactions,secondary organic aerosols,volatile emissions}, month = {dec}, number = {3}, pages = {441--452}, publisher = {Wiley/Blackwell (10.1111)}, title = {{Monoterpene ‘thermometer' of tropical forest-atmosphere response to climate warming}}, url = {https://doi.org/10.1111/pce.12879}, volume = {40}, year = {2016} } @incollection{JiaG.2019_SRCCL, author = {Jia, G. and Shevliakova, E. and Artaxo, P. and {N. De Noblet-Ducoudr{\'{e}}} and Houghton, R. and House, J. and Kitajima, K. and Lennard, C. and Popp, A. and Sirin, A. and Sukumar, R. and Verchot, L.}, booktitle = {Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems}, chapter = {2}, doi = {https://www.ipcc.ch/srccl/chapter/chapter-2}, editor = {Shukla, P.R. and Skea, J. and Buendia, E. Calvo and Masson-Delmotte, V. and P{\"{o}}rtner, H.-O. and Roberts, D.C. and Zhai, P. and Slade, R. and Connors, S. and van Diemen, R. and Ferrat, M. and Haughey, E. and Luz, S. and Neogi, S. and Pathak, M. and Petzold, J. and {Portugal Pereira}, J. and {P. Vyas}, E. Huntley and Kissick, K. and Belkacemi, M. and Malley, J.}, pages = {131--247}, publisher = {In Press}, title = {{Land–climate interactions}}, url = {https://www.ipcc.ch/srccl/chapter/chapter-2}, year = {2019} } @article{Jiang2017, abstract = {The new scenario process for climate change research includes the creation of Shared Socioeconomic Pathways (SSPs) describing alternative societal development trends over the coming decades. Urbanization is a key aspect of development that is relevant to studies of mitigation, adaptation, and impacts. Incorporating urbanization into the SSPs requires a consistent set of global urbanization projections that cover long time horizons and span a full range of uncertainty. Existing urbanization projections do not meet these needs, in particular providing only a single scenario over the next few decades, a period during which urbanization is likely to be highly dynamic in many countries. We present here a new, long-term, global set of urbanization projections at country level that cover a plausible range of uncertainty. We create SSP-specific projections by choosing urbanization outcomes consistent with each SSP narrative. Results show that the world continues to urbanize in each of the SSPs but outcomes differ widely across them, with urbanization reaching 60{\%}, 79{\%}, and 92{\%} by the end of century in SSP3, SSP2, and SSP1/SSP4/SSP5, respectively. The degree of convergence in urbanization across countries also differs substantially, with largely convergent outcomes by the end of the century in SSP1 and SSP5 and persistent diversity in SSP3. This set of global, country-specific projections produces urbanization pathways that are typical of regions in different stages of urbanization and development levels, and can be extended to further elaborate assumptions about the styles of urban growth and spatial distributions of urban people and land cover occurring in each SSP.}, author = {Jiang, Leiwen and O'Neill, Brian C.}, doi = {10.1016/J.GLOENVCHA.2015.03.008}, issn = {0959-3780}, journal = {Global Environmental Change}, month = {jan}, pages = {193--199}, publisher = {Pergamon}, title = {{Global urbanization projections for the Shared Socioeconomic Pathways}}, url = {https://www.sciencedirect.com/science/article/pii/S0959378015000394}, volume = {42}, year = {2017} } @article{Jiang2013a, abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} We investigate projected 2000–2050 changes in concentrations of aerosols in China and the associated transboundary aerosol transport by using the chemical transport model GEOS-Chem driven by the Goddard Institute for Space Studies (GISS) general circulation model (GCM) 3 at 4° × 5° resolution. Future changes in climate and emissions projected by the IPCC A1B scenario are imposed separately and together through sensitivity simulations. Accounting for sulfate, nitrate, ammonium, black carbon (BC), and organic carbon (OC) aerosols, concentrations of individual aerosol species change by −1.5 to +0.8 $\mu$g m{\textless}sup{\textgreater}−3{\textless}/sup{\textgreater}, and PM{\textless}sub{\textgreater}2.5{\textless}/sub{\textgreater} levels are projected to change by about 10–20{\%} in eastern China as a result of 2000–2050 change in climate alone. With future changes in anthropogenic emissions alone, concentrations of sulfate, BC, and OC are simulated to decrease because of assumed reductions in emissions, and those of nitrate are predicted to increase because of higher NO{\textless}sub{\textgreater}x{\textless}/sub{\textgreater} emissions combined with decreases in sulfate. The net result is a predicted reduction of seasonal mean PM{\textless}sub{\textgreater}2.5{\textless}/sub{\textgreater} concentrations in eastern China by 1–8 $\mu$g m{\textless}sup{\textgreater}−3{\textless}/sup{\textgreater} (or 10–40{\%}) over 2000–2050. It is noted that current emission inventories for BC and OC over China are judged to be inadequate at present. Transboundary fluxes of different aerosol species show different sensitivities to future changes in climate and emissions. The annual outflow of PM{\textless}sub{\textgreater}2.5{\textless}/sub{\textgreater} from eastern China to the western Pacific is estimated to change by −7.0{\%}, −0.7{\%}, and −9.0{\%} over 2000–2050 owing to climate change alone, changes in emissions alone, and changes in both climate and emissions, respectively. The fluxes of nitrate and ammonium aerosols from Europe and Central Asia into western China increase over 2000–2050 in response to projected changes in emissions, leading to a 10.5{\%} increase in annual inflow of PM{\textless}sub{\textgreater}2.5{\textless}/sub{\textgreater} to western China with future changes in both emissions and climate. Fluxes of BC and OC from South Asia to China in spring contribute a large fraction of the annual inflow of PM{\textless}sub{\textgreater}2.5{\textless}/sub{\textgreater}. The annual inflow of PM{\textless}sub{\textgreater}2.5{\textless}/sub{\textgreater} from South Asia and Southeast Asia to China is estimated to change by −8{\%}, +281{\%}, and +227{\%} over 2000–2050 owing to climate change alone, changes in emissions alone, and changes in both climate and emissions, respectively. While the 4° × 5° spatial resolution is a limitation of the present study, the direction of predicted changes in aerosol levels and transboundary fluxes still provides valuable insight into future air quality.{\textless}/p{\textgreater}{\textless}/p{\textgreater}}, author = {Jiang, H. and Liao, H. and Pye, H. O. T. and Wu, S. and Mickley, L. J. and Seinfeld, J. H. and Zhang, X. Y.}, doi = {10.5194/acp-13-7937-2013}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {aug}, number = {16}, pages = {7937--7960}, title = {{Projected effect of 2000–2050 changes in climate and emissions on aerosol levels in China and associated transboundary transport}}, url = {https://www.atmos-chem-phys.net/13/7937/2013/}, volume = {13}, year = {2013} } @article{Jiang2017a, abstract = {Long-term measurements from satellites and surface stations have demonstrated a decreasing trend of tropospheric carbon monoxide (CO) in the Northern Hemisphere over the past decade. Likely explanations for this decrease include changes in anthropogenic, fires, and/or biogenic emissions or changes in the primary chemical sink hydroxyl radical (OH). Using remotely sensed CO measurements from the Measurement of Pollution in the Troposphere (MOPITT) satellite instrument, in situ methyl chloroform (MCF) measurements from the World Data Centre for Greenhouse Gases (WDCGG) and the adjoint of the GEOS-Chem model, we estimate the change in global CO emissions from 2001 to 2015. We show that the loss rate of MCF varied by 0.2{\%} in the past 15 years, indicating that changes in global OH distributions do not explain the recent decrease in CO. Our two-step inversion approach for estimating CO emissions is intended to mitigate the effect of bias errors in the MOPITT data as well as model errors in transport and chemistry, which are the primary factors contributing to the uncertainties when quantifying CO emissions using these remotely sensed data. Our results confirm that the decreasing trend of tropospheric CO in the Northern Hemisphere is due to decreasing CO emissions from anthropogenic and biomass burning sources. In particular, we find decreasing CO emissions from the United States and China in the past 15 years, and unchanged anthropogenic CO emissions from Europe since 2008. We find decreasing trends of biomass burning CO emissions from boreal North America, boreal Asia and South America, but little change over Africa. In contrast to prior results, we find that a positive trend in CO emissions is likely for India and southeast Asia.}, annote = {Times Cited: 8 Chem, GEOS/C-5595-2014 0 8 1680-7324}, author = {Jiang, Zhe and Worden, John R and Worden, Helen and Deeter, Merritt and Jones, Dylan B A and Arellano, Avelino F and Henze, Daven K}, doi = {10.5194/acp-17-4565-2017}, isbn = {1680-7316}, journal = {Atmospheric Chemistry and Physics}, number = {7}, pages = {4565--4583}, title = {{A 15-year record of CO emissions constrained by MOPITT CO observations}}, volume = {17}, year = {2017} } @article{Jiang2018b, abstract = {Ground and satellite observations show that air pollution regulations in the United States (US) have resulted in substantial reductions in emissions and corresponding improvements in air quality over the last several decades. However, large uncertainties remain in evaluating how recent regulations affect different emission sectors and pollutant trends. Here we show a significant slowdown in decreasing US emissions of nitrogen oxides (NO x ) and carbon monoxide (CO) for 2011–2015 using satellite and surface measurements. This observed slowdown in emission reductions is significantly different from the trend expected using US Environmental Protection Agency (EPA) bottom-up inventories and impedes compliance with local and federal agency air-quality goals. We find that the difference between observations and EPA's NO x emission estimates could be explained by: ( i ) growing relative contributions of industrial, area, and off-road sources, ( ii ) decreasing relative contributions of on-road gasoline, and ( iii ) slower than expected decreases in on-road diesel emissions.}, author = {Jiang, Zhe and McDonald, Brian C. and Worden, Helen and Worden, John R. and Miyazaki, Kazuyuki and Qu, Zhen and Henze, Daven K. and Jones, Dylan B. A. and Arellano, Avelino F. and Fischer, Emily V. and Zhu, Liye and Boersma, K. Folkert}, doi = {10.1073/pnas.1801191115}, isbn = {1801191115}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, keywords = {Decadal scale variation,Emission regulations,Nitrogen oxides,decadal scale variation,emission regulations,nitrogen oxides}, month = {may}, number = {20}, pages = {5099--5104}, pmid = {29712822}, publisher = {National Academy of Sciences}, title = {{Unexpected slowdown of US pollutant emission reduction in the past decade}}, url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1801191115}, volume = {115}, year = {2018} } @article{Jiao2014a, abstract = {Though many global aerosols models prognose surface deposition, only a few models have been used to directly simulate the radiative effect from black carbon (BC) deposition to snow and sea ice. Here, we apply aerosol deposition fields from 25 models contributing to two phases of the Aerosol Comparisons between Observations and Models (AeroCom) project to simulate and evaluate within-snow BC concentrations and radiative effect in the Arctic. We accomplish this by driving the offline land and sea ice components of the Community Earth System Model with different deposition fields and meteorological conditions from 2004 to 2009, during which an extensive field campaign of BC measurements in Arctic snow occurred. We find that models generally underestimate BC concentrations in snow in northern Russia and Norway, while overestimating BC amounts elsewhere in the Arctic. Although simulated BC distributions in snow are poorly correlated with measurements, mean values are reasonable. The multi-model mean (range) bias in BC concentrations, sampled over the same grid cells, snow depths, and months of measurements, are -4.4 (-13.2 to + 10.7) ng g(-1) for an earlier phase of AeroCom models (phase I), and + 4.1 (-13.0 to + 21.4) ng g(-1) for a more recent phase of AeroCom models (phase II), compared to the observational mean of 19.2 ng g(-1). Factors determining model BC concentrations in Arctic snow include Arctic BC emissions, transport of extra-Arctic aerosols, precipitation, deposition efficiency of aerosols within the Arctic, and meltwater removal of particles in snow. Sensitivity studies show that the model-measurement evaluation is only weakly affected by meltwater scavenging efficiency because most measurements were conducted in non-melting snow. The Arctic (60-90 degrees N) atmospheric residence time for BC in phase II models ranges from 3.7 to 23.2 days, implying large inter-model variation in local BC deposition efficiency. Combined with the fact that most Arctic BC deposition originates from extra-Arctic emissions, these results suggest that aerosol removal processes are a leading source of variation in model performance. The multi-model mean (full range) of Arctic radiative effect from BC in snow is 0.15 (0.07-0.25) W m(-2) and 0.18 (0.06-0.28) W m(-2) in phase I and phase II models, respectively. After correcting for model biases relative to observed BC concentrations in different regions of the Arctic, we obtain a multi-model mean Arctic radiative effect of 0.17W m(-2) for the combined AeroCom ensembles. Finally, there is a high correlation between modeled BC concentrations sampled over the observational sites and the Arctic as a whole, indicating that the field campaign provided a reasonable sample of the Arctic.}, address = {BAHNHOFSALLEE 1E, GOTTINGEN, 37081, GERMANY}, author = {Jiao, C. and Flanner, M. G. and Balkanski, Y. and Bauer, S. E. and Bellouin, N. and Berntsen, T. K. and Bian, H. and Carslaw, K. S. and Chin, M. and {De Luca}, N. and Diehl, T. and Ghan, S. J. and Iversen, T. and Kirkev{\"{a}}g, A. and Koch, D. and Liu, X. and Mann, G. W. and Penner, J. E. and Pitari, G. and Schulz, M. and {Seland {\O}.} and Skeie, R. B. and Steenrod, S. D. and Stier, P. and Takemura, T. and Tsigaridis, K. and {Van Noije}, T. and Yun, Y. and Zhang, K.}, doi = {10.5194/acp-14-2399-2014}, isbn = {1680-7324}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, number = {5}, pages = {2399--2417}, publisher = {COPERNICUS GESELLSCHAFT MBH}, title = {{An AeroCom assessment of black carbon in Arctic snow and sea ice}}, type = {Article}, volume = {14}, year = {2014} } @article{Jing2017, abstract = {This paper investigates the relationship between ground-level ozone (O3) and temperature in the Midwestern U.S. during the period 1990–2015. From 1990 to 2015, the overall trend of 95th percentile temperature showed an increase of 0.04 K yr−1, while summertime 95th percentile O3 concentrations in the Midwest decreased at an average rate of 0.7 ppb yr−1 largely because NO2 concentrations decreased by more than 50{\%}. The ozone-climate penalty, defined as the slope of O3 change with increasing temperature ($\Delta$O3/$\Delta$T), was by average 0.43 ppb K−1 less in 1999–2007 than in 1990–1998, indicating the early success of NOx emission controls. However, the slope did not continue to decrease in 2008–2015 despite further NOx emission reductions, and it increased more rapidly with increasing temperature ($\Delta$2O3/$\Delta$T2) by 0.03–0.09 ppb K−2 in most urban areas of the Midwest. This was accompanied by more frequent dry tropical (DT) weather in the Midwest since 2008. We find that O3 in DT weather was 12 ppb and 17 ppb higher than in non-DT weather in rural and urban areas, respectively. Furthermore, the 2008–2015 period experienced 8{\%} more surface air stagnation days than in 1990–1998. This demonstrates that, in addition to the impact of warmer temperatures, the ozone-climate penalty could be aggravated by altered weather conditions under climate change. It will be challenging for Midwestern cities to attain the National Ambient Air Quality Standard for O3 if such conditions persist in the future, and future air quality improvements may require even greater efforts to reduce both NOx and VOC emissions in the Midwest.}, author = {Jing, Ping and Lu, Zifeng and Steiner, Allison L.}, doi = {10.1016/j.atmosenv.2017.09.038}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Midwestern U.S.,NOx and VOC emission control,Ozone-climate penalty,Temperature dependence of O3}, month = {dec}, pages = {130--142}, publisher = {Pergamon}, title = {{The ozone–climate penalty in the Midwestern U.S.}}, url = {https://www.sciencedirect.com/science/article/pii/S1352231017306374?via{\%}3Dihub}, volume = {170}, year = {2017} } @article{Jo2016, abstract = {Recent observations suggest that a certain fraction of organic carbon (OC) aerosol effectively absorbs solar radiation, which is also known as brown carbon (BrC) aerosol. Despite much observational evidence of its presence, very few global modelling studies have been conducted because of poor understanding of global BrC emissions. Here we present an explicit global simulation of BrC in a global 3-D chemical transport model (GEOS-Chem), including global BrC emission estimates from primary (3.9 ± 1.7 and 3.0 ± 1.3 TgC yr-1 from biomass burning and biofuel) and secondary (5.7 TgC yr-1 from aromatic oxidation) sources. We evaluate the model by comparing the results with observed absorption by water-soluble OC in surface air in the United States, and with single scattering albedo observations at Aerosol Robotic Network (AERONET) sites all over the globe. The model successfully reproduces the seasonal variations of observed light absorption by water-soluble OC, but underestimates the magnitudes, especially in regions with high secondary source contributions. Our global simulations show that BrC accounts for 21 {\%} of the global mean surface OC concentration, which is typically assumed to be scattering. We find that the global direct radiative effect of BrC is nearly zero at the top of the atmosphere, and consequently decreases the direct radiative cooling effect of OC by 16 {\%}. In addition, the BrC absorption leads to a general reduction of NO2 photolysis rates, whose maximum decreases occur in Asia up to-8 {\%} (-17 {\%}) on an annual (spring) mean basis. The resulting decreases of annual (spring) mean surface ozone concentrations are up to-6 {\%} (-13 {\%}) in Asia, indicating a non-negligible effect of BrC on photochemistry in this region.}, author = {Jo, Duseong S. and Park, Rokjin J. and Lee, Seungun and Kim, Sang Woo and Zhang, Xiaolu}, doi = {10.5194/acp-16-3413-2016}, isbn = {1680-7375}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {5}, pages = {3413--3432}, title = {{A global simulation of brown carbon: Implications for photochemistry and direct radiative effect}}, url = {https://www.atmos-chem-phys.net/16/3413/2016/}, volume = {16}, year = {2016} } @article{John2012, abstract = {With a more-than-doubling in the atmospheric abundance of the potent greenhouse gas methane (CH4) since preindustrial times, and indications of renewed growth following a leveling off in recent years, questions arise as to future trends and resulting climate and public health impacts from continued growth without mitigation. Changes in atmospheric methane lifetime are determined by factors which regulate the abundance of OH, the primary methane removal mechanism, including changes in CH4 itself. We investigate the role of emissions of short-lived species and climate in determining the evolution of methane lifetime against loss by tropospheric OH, (tau(CH4{\_}OH)), in a suite of historical (1860-2005) and future Representative Concentration Pathway (RCP) simulations (2006-2100), conducted with the Geophysical Fluid Dynamics Laboratory (GFDL) fully coupled chemistry-climate model (CM3). From preindustrial to present, CM3 simulates an overall 5{\%} increase in tau(CH4{\_}OH) due to a doubling of the methane burden which offsets coincident increases in nitrogen oxide (NOx) emissions. Over the last two decades, however, the tau(CH4{\_}OH) declines steadily, coinciding with the most rapid climate warming and observed slow-down in CH4 growth rates, reflecting a possible negative feedback through the CH4 sink. Sensitivity simulations with CM3 suggest that the aerosol indirect effect (aerosol-cloud interactions) plays a significant role in cooling the CM3 climate. The projected decline in aerosols under all RCPs contributes to climate warming over the 21st century, which influences the future evolution of OH concentration and tau(CH4{\_}OH). Projected changes in tau(CH4{\_}OH) from 2006 to 2100 range from -13{\%} to +4{\%}. The only projected increase occurs in the most extreme warming case (RCP8.5) due to the near-doubling of the CH4 abundance, reflecting a positive feedback on the climate system. The largest decrease occurs in the RCP4.5 scenario due to changes in short-lived climate forcing agents which reinforce climate warming and enhance OH. This decrease is more-than-halved in a sensitivity simulation in which only well-mixed greenhouse gas radiative forcing changes along the RCP4.5 scenario (5{\%} vs. 13{\%}).}, annote = {Times Cited: 34 John, Jasmin/F-8194-2012; Horowitz, Larry/D-8048-2014; Dunne, John/F-8086-2012; Naik, Vaishali/A-4938-2013 John, Jasmin/0000-0003-2696-277X; Horowitz, Larry/0000-0002-5886-3314; Dunne, John/0000-0002-8794-0489; Naik, Vaishali/0000-0002-2254-1700 0 35 1680-7324}, author = {John, J G and Fiore, A M and Naik, V and Horowitz, L W and Dunne, J P}, doi = {10.5194/acp-12-12021-2012}, isbn = {1680-7316}, journal = {Atmospheric Chemistry and Physics}, number = {24}, pages = {12021--12036}, title = {{Climate versus emission drivers of methane lifetime against loss by tropospheric OH from 1860–2100}}, volume = {12}, year = {2012} } @article{Jones2003, author = {Jones, Chris D.}, doi = {10.1029/2003GL016867}, issn = {0094-8276}, journal = {Geophysical Research Letters}, number = {9}, pages = {1479}, title = {{Strong carbon cycle feedbacks in a climate model with interactive CO2 and sulphate aerosols}}, url = {http://doi.wiley.com/10.1029/2003GL016867}, volume = {30}, year = {2003} } @article{Jones2012, abstract = {The radiative impact and climate effects of geoengineering using sea-spray aerosols have been investigated in the HadGEM2-ES Earth system model using a fully prognostic treatment of the sea-spray aerosols and also including their direct radiative effect. Two different emission patterns were considered, one to maximise the direct effect in clear skies, the other to maximise the indirect effects of the sea-spray on low clouds; in both cases the emissions were limited to 10{\%} of the ocean area. While the direct effect was found to be significant, the indirect effects on clouds were much more effective in reducing global mean temperature as well as having less of an impact on global mean precipitation per unit temperature reduction. The impact on the distribution of precipitation was found to be similar in character, but less in degree, to that simulated by a previous study using a much simpler treatment of this geoengineering process. {\textcopyright} 2012 Author(s).}, author = {Jones, A. and Haywood, J. M.}, doi = {10.5194/acp-12-10887-2012}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, title = {{Sea-spray geoengineering in the HadGEM2-ES earth-system model: Radiative impact and climate response}}, year = {2012} } @article{Jones2016, abstract = {Abstract. In this paper, we examine the potential climatic effects of geoengineering by sulfate, black carbon and titania injection against a baseline RCP8.5 scenario. We use the HadGEM2-CCS model to simulate scenarios in which the top-of-the-atmosphere radiative imbalance due to rising greenhouse gas concentrations is offset by sufficient aerosol injection throughout the 2020–2100 period. We find that the global-mean temperature is effectively maintained at historical levels for the entirety of the period for all three aerosol-injection scenarios, though there is a wide range of side-effects which are discussed in detail. The most prominent conclusion is that although the BC injection rate necessary to produce an equivalent global mean temperature response is much lower, the severity of stratospheric temperature changes ({\textgreater} +70 °C) and precipitation impacts effectively exclude BC from being a viable option for geoengineering. Additionally, while it has been suggested that titania would be an effective particle because of its high scattering efficiency, it also efficiently absorbs solar ultraviolet radiation producing a significant stratospheric warming ({\textgreater} +20 °C). As injection rates and climatic impacts for titania are close to those for sulfate, there appears to be little benefit in terms of climatic influence of using titania when compared to the injection of sulfur dioxide, which has the added benefit of being well-modeled through extensive research that has been carried out on naturally occurring explosive volcanic eruptions.}, author = {Jones, Anthony C. and Haywood, James M. and Jones, Andy}, doi = {10.5194/acp-16-2843-2016}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {5}, pages = {2843--2862}, title = {{Climatic impacts of stratospheric geoengineering with sulfate, black carbon and titania injection}}, url = {https://acp.copernicus.org/articles/16/2843/2016/}, volume = {16}, year = {2016} } @article{Jones2011, abstract = {We examine the climate impact of geoengineering via two different methods, namely, stratospheric SO2 injection and increasing reflectivity of marine stratocumulus clouds. Although both methods appear capable, in principle, of counteracting the global mean warming due to increases in greenhouse gas concentrations, significant changes in regional climate still result. The extent of this regional climate change appears linked to the location and degree of inhomogeneity of the radiative flux perturbations produced by each geoengineering method. {\textcopyright} 2010.}, author = {Jones, Andy and Haywood, Jim and Boucher, Olivier}, doi = {10.1002/asl.291}, issn = {1530261X}, journal = {Atmospheric Science Letters}, keywords = {Climate change,Geoengineering,Regional climate}, month = {apr}, number = {2}, pages = {176--183}, title = {{A comparison of the climate impacts of geoengineering by stratospheric SO2 injection and by brightening of marine stratocumulus cloud}}, url = {https://onlinelibrary.wiley.com/doi/10.1002/asl.291}, volume = {12}, year = {2011} } @article{Jonson2017, abstract = {Diesel cars have been emitting four to seven times more NOx in on-road driving than in type approval tests. These 'excess emissions' are a consequence of deliberate design of the vehicle's after-Treatment system, as investigations during the 'Dieselgate' scandal have revealed. Here we calculate health and environmental impacts of these excess NOx emissions in all European countries for the year 2013. We use national emissions reported officially under the UNECE Convention for Long-range Transport of Atmospheric Pollutants and employ the EMEP MSC-W Chemistry Transport Model and the GAINS Integrated Assessment Model to determine atmospheric concentrations and resulting impacts. We compare with impacts from hypothetical emissions where light duty diesel vehicles are assumed to emit only as much as their respective type approval limit value or as little as petrol cars of the same age. Excess NO2 concentrations can also have direct health impacts, but these overlap with the impacts from particulate matter (PM) and are not included here. We estimate that almost 10 000 premature deaths from PM2.5 and ozone in the adult population (age {\textgreater}30 years) can be attributed to the NOx emissions from diesel cars and light commercial vehicles in EU28 plus Norway and Switzerland in 2013. About 50{\%} of these could have been avoided if diesel limits had been achieved also in on-road driving; and had diesel cars emitted as little NOx as petrol cars, 80{\%} of these premature deaths could have been avoided. Ecosystem eutrophication impacts (critical load exceedances) from the same diesel vehicles would also have been reduced at similar rates as for the health effects.}, author = {Jonson, J. E. and Borken-Kleefeld, J. and Simpson, D. and Ny{\'{i}}ri, A. and Posch, M. and Heyes, C.}, doi = {10.1088/1748-9326/aa8850}, issn = {17489326}, journal = {Environmental Research Letters}, keywords = {air pollution,diesel cars,eutrophication,health}, month = {sep}, number = {9}, pages = {94017}, title = {{Impact of excess NOx emissions from diesel cars on air quality, public health and eutrophication in Europe}}, url = {http://stacks.iop.org/1748-9326/12/i=9/a=094017?key=crossref.db2121654c33c0baf7a0d50d05cb0aff http://iopscience.iop.org/article/10.1088/1748-9326/aa8850/pdf}, volume = {12}, year = {2017} } @article{acp-20-11399-2020, author = {Jonson, J E and Gauss, M and Schulz, M and Jalkanen, J.-P. and Fagerli, H}, doi = {10.5194/acp-20-11399-2020}, journal = {Atmospheric Chemistry and Physics}, number = {19}, pages = {11399--11422}, title = {{Effects of global ship emissions on European air pollution levels}}, url = {https://acp.copernicus.org/articles/20/11399/2020/}, volume = {20}, year = {2020} } @article{Kaltsonoudis2016, abstract = {Abstract. During the summer of 2012 volatile organic compounds (VOCs) were monitored by proton transfer reaction mass spectrometry (PTR-MS) in urban sites, in Athens and Patras, two of the largest cities in Greece. Also, during the winter of 2013, PTR-MS measurements were conducted in the center of the city of Athens. Positive matrix factorization (PMF) was applied to the VOC measurements to gain insights about their sources. In summer most of the measured VOCs were due to biogenic and traffic emissions. Isoprene, monoterpenes, and several oxygenated VOCs (oVOCs) originated mainly from vegetation either directly or as oxidation products. Isoprene average concentrations in Patras and Athens were 1 and 0.7 ppb respectively, while the monoterpene concentrations were 0.3 and 0.9 ppb respectively. Traffic was the main source of aromatic compounds during summer. For Patras and Athens the average concentrations of benzene were 0.1 and 0.2 ppb, of toluene 0.3 and 0.8 ppb, and of the xylenes 0.3 and 0.7 ppb respectively. Winter measurements in Athens revealed that biomass burning used for residential heating was a major VOC source contributing both aromatic VOCs and biogenic compounds such as monoterpenes. Several episodes related to biomass burning were identified and emission ratios (ERs) and emission factors (EFs) were estimated.}, author = {Kaltsonoudis, Christos and Kostenidou, Evangelia and Florou, Kalliopi and Psichoudaki, Magda and Pandis, Spyros N.}, doi = {10.5194/acp-16-14825-2016}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {nov}, number = {23}, pages = {14825--14842}, title = {{Temporal variability and sources of VOCs in urban areas of the eastern Mediterranean}}, url = {https://acp.copernicus.org/articles/16/14825/2016/}, volume = {16}, year = {2016} } @article{Kanakidou2018, abstract = {Atmospheric aerosols have complex and variable compositions and properties. While scientific interest is centered on the health and climatic effects of atmospheric aerosols, insufficient attention is given to their involvement in multiphase chemistry that alters their contribution as carriers of nutrients in ecosystems. However, there is experimental proof that the nutrient equilibria of both land and marine ecosystems have been disturbed during the Anthropocene period. This review study first summarizes our current understanding of aerosol chemical processing in the atmosphere as relevant to biogeochemical cycles. Then it binds together results of recent modeling studies based on laboratory and field experiments, focusing on the organic and dust components of aerosols that account for multiphase chemistry, aerosol ageing in the atmosphere, nutrient (N, P, Fe) emissions, atmospheric transport, transformation and deposition. The human-driven contribution to atmospheric deposition of these nutrients, derived by global simulations using past and future anthropogenic emissions of pollutants, is put into perspective with regard to potential changes in nutrient limitations and biodiversity. Atmospheric deposition of nutrients has been suggested to result in human-induced ecosystem limitations with regard to specific nutrients. Such modifications favor the development of certain species against others and affect the overall functioning of ecosystems. Organic forms of nutrients are found to contribute to the atmospheric deposition of the nutrients N, P and Fe by 20{\%}-40{\%}, 35{\%}-45{\%} and 7{\%}-18{\%}, respectively. These have the potential to be key components of the biogeochemical cycles since there is initial proof of their bioavailability to ecosystems. Bioaerosols have been found to make a significant contribution to atmospheric sources of N and P, indicating potentially significant interactions between terrestrial and marine ecosystems. These results deserve further experimental and modeling studies to reduce uncertainties and understand the feedbacks induced by atmospheric deposition of nutrients to ecosystems.}, author = {Kanakidou, Maria and Myriokefalitakis, Stelios and Tsigaridis, Kostas}, doi = {10.1088/1748-9326/aabcdb}, issn = {17489326}, journal = {Environmental Research Letters}, keywords = {Fe,P,atmospheric acidity,biogeochemical cycles of N,dust,multiphase chemistry,organics}, month = {jun}, number = {6}, pages = {063004}, title = {{Aerosols in atmospheric chemistry and biogeochemical cycles of nutrients}}, url = {http://stacks.iop.org/1748-9326/13/i=6/a=063004?key=crossref.9eb33b239f3fa53f0afc0a813d5536d7}, volume = {13}, year = {2018} } @article{Kanaya2020, author = {Kanaya, Yugo and Yamaji, Kazuyo and Miyakawa, Takuma and Taketani, Fumikazu and Zhu, Chunmao and Choi, Yongjoo and Komazaki, Yuichi and Ikeda, Kohei and Kondo, Yutaka and Klimont, Zbigniew}, doi = {10.5194/acp-20-6339-2020}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jun}, number = {11}, pages = {6339--6356}, title = {{Rapid reduction in black carbon emissions from China: evidence from 2009–2019 observations on Fukue Island, Japan}}, url = {https://doi.org/10.5194/acp-20-6339-2020 https://acp.copernicus.org/articles/20/6339/2020/}, volume = {20}, year = {2020} } @article{Kang2002, abstract = {An NH{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}+{\textless}/sup{\textgreater} record covering the period A.D. 1845-1997 was reconstructed using an 80.4 m ice core from East Rongbuk Glacier at an elevation of 6450 m on the northern slope of Mount Everest. Variations in NH{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}+{\textless}/sup{\textgreater} are characterized by a dramatic increase since the 1950s. The highest NH{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}+{\textless}/sup{\textgreater} concentrations occur in the 1980s. They are about twofold more than those in the first half of twentieth century. Empirical orthogonal function (EOF) analysis on the eight major ion (Na{\textless}sup{\textgreater}+{\textless}/sup{\textgreater}, K{\textless}sup{\textgreater}+{\textless}/sup{\textgreater}, Mg{\textless}sup{\textgreater}2+{\textless}/sup{\textgreater}, NH{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}+{\textless}/sup{\textgreater}, Ca{\textless}sup{\textgreater}2+{\textless}/sup{\textgreater}, NO{\textless}inf{\textgreater}3{\textless}/inf{\textgreater}{\textless}sup{\textgreater}-{\textless}/sup{\textgreater}, SO{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}2-{\textless}/sup{\textgreater} and Cl{\textless}sup{\textgreater}-{\textless}/sup{\textgreater}) series from this core indicates that NH{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}+{\textless}/sup{\textgreater} is loaded mainly on EOF3 (60{\%} of NH{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}+{\textless}/sup{\textgreater} variance), suggesting that NH{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}+{\textless}/sup{\textgreater} has a unique signature. Instrumental sea level pressure (SLP) and regional temperatures are used to explore the relationship between NH{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}+{\textless}/sup{\textgreater} variations and both atmospheric circulation and natural source strength over Asia. Higher NH{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}+{\textless}/sup{\textgreater} concentrations are associated with an enhanced winter Mongolian High and a deepened summer Mongolian Low. A positive relationship also exists between NH{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}+{\textless}/sup{\textgreater} concentrations and regional temperature changes of the GIS Box 36 (Indian subcontinent), indicating that an increase in temperature may contribute to the strengthening of natural ammonia emissions (e.g., from plants and soils). A close positive correlation between NH{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}+{\textless}/sup{\textgreater} and acidic species (SO{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}2-{\textless}/sup{\textgreater} plus NO{\textless}inf{\textgreater}3{\textless}/inf{\textgreater}{\textless}sup{\textgreater}-{\textless}/sup{\textgreater}) concentrations suggests that a portion of the increase in NH{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}+{\textless}/sup{\textgreater} concentrations could be contributed by enhanced atmospheric acidification. Anthropogenic ammonia emissions from enhanced agricultural activities and energy consumption over Asia in concert with population increase since the 1950s appear also to be a significant factor in the dramatic increase of NH{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}{\textless}sup{\textgreater}+{\textless}/sup{\textgreater} concentrations during the last few decades. Copyright 2002 by the American Geophysical Union.}, author = {Kang, Shichang and Mayewski, Paul A. and Qin, Dahe and Yan, Yuping and Zhang, Dongqi and Hou, Shugui and Ren, Jiawen}, doi = {10.1029/2001JD001413}, issn = {01480227}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {Atmospheric ammonia,Ice core records,Mount everest}, month = {nov}, number = {D21}, pages = {ACL 13--1--ACL 13--9}, publisher = {Wiley-Blackwell}, title = {{Twentieth century increase of atmospheric ammonia recorded in Mount Everest ice core}}, url = {http://doi.wiley.com/10.1029/2001JD001413}, volume = {107}, year = {2002} } @article{Karset2018, author = {Karset, Inger Helene Hafsahl and Berntsen, Terje Koren and Storelvmo, Trude and Alterskj{\ae}r, Kari and Grini, Alf and Olivi{\'{e}}, Dirk and Kirkev{\aa}g, Alf and Seland, {\O}yvind and Iversen, Trond and Schulz, Michael}, doi = {10.5194/acp-18-7669-2018}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jun}, number = {10}, pages = {7669--7690}, publisher = {Copernicus Publications}, title = {{Strong impacts on aerosol indirect effects from historical oxidant changes}}, url = {https://acp.copernicus.org/articles/18/7669/2018/ https://acp.copernicus.org/articles/18/7669/2018/acp-18-7669-2018.pdf}, volume = {18}, year = {2018} } @article{Kasoar2016a, abstract = {We use the HadGEM3-GA4, CESM1, and GISS ModelE2 climate models to investigate the global and regional aerosol burden, radiative flux, and surface temperature responses to removing anthropogenic sulfur dioxide (SO2) emissions from China. We find that the models differ by up to a factor of six in the simulated change in aerosol optical depth (AOD) and shortwave radiative flux over China that results from reduced sulfate aerosol, leading to a large range of magnitudes in the regional and global temperature responses. Two of the three models simulate a near-ubiquitous hemispheric warming due to the regional SO2 removal, with similarities in the local and remote pattern of response, but overall with a substantially different magnitude. The third model simulates almost no significant temperature response. We attribute the discrepancies in the response to a combination of substantial differences in the chemical conversion of SO2 to sulfate, translation of sulfate mass into AOD, and differences in the radiative forcing efficiency of sulfate aerosol in the models. The model with the strongest response (HadGEM3-GA4) compares best with observations of AOD regionally, however the other two models compare similarly (albeit poorly) and still disagree substantially in their simulated climate response, indicating that total AOD observations are far from sufficient to determine which model response is more plausible. Our results highlight that there remains a large uncertainty in the representation of both aerosol chemistry as well as direct and indirect aerosol radiative effects in current climate models, and reinforces that caution must be applied when interpreting the results of single-model studies of aerosol influences on climate. Model studies that implicate aerosols in climate responses should ideally explore a range of radiative forcing strengths representative of this uncertainty, in addition to thoroughly evaluating the models used against observations.}, author = {Kasoar, Matthew and Voulgarakis, Apostolos and Lamarque, Jean Fran{\c{c}}ois and Shindell, Drew T. and Bellouin, Nicolas and Faluvegi, Greg and Tsigaridis, Kostas}, doi = {10.5194/acp-16-9785-2016}, isbn = {1680-7375}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {aug}, number = {15}, pages = {9785--9804}, title = {{Regional and global temperature response to anthropogenic SO2 emissions from China in three climate models}}, url = {https://www.atmos-chem-phys.net/16/9785/2016/}, volume = {16}, year = {2016} } @article{Kasoar2018, abstract = {Anthropogenic aerosol forcing is spatially heterogeneous, mostly localised around industrialised regions like North America, Europe, East and South Asia. Emission reductions in each of these regions will force the climate in different locations, which could have diverse impacts on regional and global climate. Here, we show that removing sulphur dioxide (SO2) emissions from any of these northern-hemisphere regions in a global composition-climate model results in significant warming across the hemisphere, regardless of the emission region. Although the temperature response to these regionally localised forcings varies considerably in magnitude depending on the emission region, it shows a preferred spatial pattern independent of the location of the forcing. Using empirical orthogonal function analysis, we show that the structure of the response is tied to existing modes of internal climate variability in the model. This has implications for assessing impacts of emission reduction policies, and our understanding of how climate responds to heterogeneous forcings.}, author = {Kasoar, Matthew and Shawki, Dilshad and Voulgarakis, Apostolos}, doi = {10.1038/s41612-018-0022-z}, issn = {2397-3722}, journal = {npj Climate and Atmospheric Science}, month = {dec}, number = {1}, pages = {12}, title = {{Similar spatial patterns of global climate response to aerosols from different regions}}, url = {http://www.nature.com/articles/s41612-018-0022-z}, volume = {1}, year = {2018} } @article{Keeble2019, author = {Keeble, James and Hassler, Birgit and Banerjee, Antara and Checa-Garcia, Ramiro and Chiodo, Gabriel and Davis, Sean and Eyring, Veronika and Griffiths, Paul T. and Morgenstern, Olaf and Nowack, Peer and Zeng, Guang and Zhang, Jiankai and Bodeker, Greg and Burrows, Susannah and Cameron-Smith, Philip and Cugnet, David and Danek, Christopher and Deushi, Makoto and Horowitz, Larry W. and Kubin, Anne and Li, Lijuan and Lohmann, Gerrit and Michou, Martine and Mills, Michael J. and Nabat, Pierre and Olivi{\'{e}}, Dirk and Park, Sungsu and Seland, {\O}yvind and Stoll, Jens and Wieners, Karl-Hermann and Wu, Tongwen}, doi = {10.5194/acp-21-5015-2021}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {6}, pages = {5015--5061}, title = {{Evaluating stratospheric ozone and water vapour changes in CMIP6 models from 1850 to 2100}}, url = {https://acp.copernicus.org/articles/21/5015/2021/}, volume = {21}, year = {2021} } @article{Kekonen2005, abstract = {We present a high-resolution record of water-soluble ion chemistry from a 121 m ice core spanning about 800 years. The core is well dated to 2/3 depth using cycle counting and reference horizons and a simple but close fitting model for the lower 1/3 of the core. This core suffers from modest seasonal melt, and so we present concentration data in decadal running means to minimize percolation effects. Sea-salt ions (Na+, Cl-, Mg 2+, and K+) account for more than 70{\%} of all ions. In general, sea-salt ion concentrations are rather variable and have no clear association with climatic variations. Sulfate, with 74{\%} being from non-sea-salt sources, has higher concentrations than seen on Vestfonna ice cap but lower than in Ny-{\AA}lesund aerosols, suggesting central Spitsbergen receives more marine (westerly) air masses than Ny-{\AA}lesund but more sulfate enriched (easterly) air masses than Nordaustlandet. Clear anthropogenic impacts are found for sulfate, nitrate, and ammonium (and probably excess chloride) after the mid twentieth century, with sulfate showing a significant rise by the end of the nineteenth century. Sulfate and methanesulfonate concentrations correlate well during the twentieth century, and it is clear that most of the preindustrial sulfate is of biogenic origin. Terrestrial component (Ca 2+) has the highest concentrations in the coldest part of the Little Ice Age, suggesting more windy conditions, transporting local terrestrial dust to the ice cap. All ion concentrations decrease at the end of the twentieth century, which reflects loss of ions by runoff, with non-sea-salt magnesium being particularly sensitive to melting. Copyright 2005 by the American Geophysical Union.}, author = {Kekonen, Teija and Moore, John and Per{\"{a}}m{\"{a}}ki, Paavo and Mulvaney, Robert and Isaksson, Elisabeth and Pohjola, Veijo and van de Wal, Roderik S. W.}, doi = {10.1029/2004JD005223}, issn = {0148-0227}, journal = {Journal of Geophysical Research: Atmospheres}, month = {apr}, number = {D7}, pages = {D07304}, publisher = {Wiley-Blackwell}, title = {{The 800 year long ion record from the Lomonosovfonna (Svalbard) ice core}}, url = {http://doi.wiley.com/10.1029/2004JD005223}, volume = {110}, year = {2005} } @article{ISI:000439357900001, abstract = {The body of literature on ambient air pollution suggests that atmospheric stagnation events trigger high levels of air pollution. In this paper we use fifteen years (2000-2014) of summertime in situ air quality measurements together with meteorological reanalysis data to examine the temporal correlation of pollutants with the Air Stagnation Index (ASI) on daily timescales. We find that while the direction of the relationship between the ASI and summertime PM2.5 and O-3 ranges from near-zero to positive throughout regions comprising the contiguous United States (US), the strength of the relationship is very weak (e.g. in the Northeast the correlation coefficient between the ASI and PM2.5 is 0.09). Moreover, similar to our analysis of the correlation of day-to-day variations of the ASI and pollutants, the percentage of co-occurring extreme pollution and stagnation events is small (e.g. days with a high coverage of stagnation only co-occur with extreme pollution events about one-third of the time in the Northeast). The southern US is an exception to our overall findings as the strength of the relationship between the ASI and pollution is stronger and the percentage of co-occurring events is higher compared with other regions. The results of this study suggest a reevaluation of the ASI as an index to assess meteorological and climatic impacts to air quality.}, author = {Kerr, Gaige Hunter and Waugh, Darryn W}, doi = {10.1088/1748-9326/aad2e2}, issn = {1748-9326}, journal = {Environmental Research Letters}, month = {jul}, number = {8}, pages = {084001}, title = {{Connections between summer air pollution and stagnation}}, url = {http://stacks.iop.org/1748-9326/13/i=8/a=084001?key=crossref.95e9ab6587bba77b207cefe51e4c5c7b}, volume = {13}, year = {2018} } @article{acp-16-11267-2016, abstract = {Black carbon (BC) is a significant climate forcer with a particularly pronounced forcing effect in polar regions, like the Russian Arctic. Diesel combustion is a major global source of BC emissions, accounting for 25{\&}ndash;30 {\%} of all BC emissions. The demand for diesel is growing in Russia, but Russian diesel emissions are poorly understood. This paper presents a detailed inventory of Russian BC emissions from diesel sources. Drawing on a complete Russian vehicle registry with detailed information about vehicle types and emission standards, this paper analyzes BC emissions from diesel on-road vehicles. We use the COPERT emission model with Russia-specific emission factors for all types of on-road vehicles. On-road diesel vehicles emitted 21 Gg of BC in 2014; heavy-duty trucks account for 70 {\%} of the on-road BC emissions, while cars represent only 4 {\%} (light commercial vehicles and buses account for the remainder). Using Russian activity data and fuel-based emission factors, the paper also presents BC emissions from diesel locomotives and ships, off-road engines in industry, construction and agriculture, and from diesel generators. The study also factors in the role of superemitters in BC emissions from diesel on-road vehicles and off-road sources. The total emissions from diesel sources in Russia are estimated to be 48 Gg of BC and 16 Gg of OC in 2014. Off-road diesel sources emitted 57 {\%} of all diesel BC in Russia.}, author = {Kholod, Nazar and Evans, Meredydd and Kuklinski, Teresa}, doi = {10.5194/acp-16-11267-2016}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {17}, pages = {11267--11281}, title = {{Russia's black carbon emissions: Focus on diesel sources}}, url = {https://www.atmos-chem-phys.net/16/11267/2016/}, volume = {16}, year = {2016} } @article{Kirkby2011, author = {Kirkby, Jasper and Curtius, Joachim and Almeida, Joao and Dunne, Eimear and Duplissy, Jonathan and Ehrhart, Sebastian and Franchin, Alessandro and Gagne, Stephanie and Ickes, Luisa and Kurten, Andreas and Kupc, Agnieszka and Metzger, Axel and Riccobono, Francesco and Rondo, Linda and Schobesberger, Siegfried and Tsagkogeorgas, Georgios and Wimmer, Daniela and Amorim, Antonio and Bianchi, Federico and Breitenlechner, Martin and David, Andre and Dommen, Josef and Downard, Andrew and Ehn, Mikael and Flagan, Richard C and Haider, Stefan and Hansel, Armin and Hauser, Daniel and Jud, Werner and Junninen, Heikki and Kreissl, Fabian and Kvashin, Alexander and Laaksonen, Ari and Lehtipalo, Katrianne and Lima, Jorge and Lovejoy, Edward R and Makhmutov, Vladimir and Mathot, Serge and Mikkila, Jyri and Minginette, Pierre and Mogo, Sandra and Nieminen, Tuomo and Onnela, Antti and Pereira, Paulo and Petaja, Tuukka and Schnitzhofer, Ralf and Seinfeld, John H and Sipila, Mikko and Stozhkov, Yuri and Stratmann, Frank and Tome, Antonio and Vanhanen, Joonas and Viisanen, Yrjo and Vrtala, Aron and Wagner, Paul E and Walther, Hansueli and Weingartner, Ernest and Wex, Heike and Winkler, Paul M and Carslaw, Kenneth S and Worsnop, Douglas R and Baltensperger, Urs and Kulmala, Markku}, doi = {10.1038/nature10343}, isbn = {0028-0836}, journal = {Nature}, number = {7361}, pages = {429--433}, publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.}, title = {{Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation}}, volume = {476}, year = {2011} } @article{Kirkevag2018, abstract = {Abstract. We document model updates and present and discuss modeling and validation results from a further developed production-tagged aerosol module, OsloAero5.3, for use in Earth system models. The aerosol module has in this study been implemented and applied in CAM5.3-Oslo. This model is based on CAM5.3–CESM1.2 and its own predecessor model version CAM4-Oslo. OsloAero5.3 has improved treatment of emissions, aerosol chemistry, particle life cycle, and aerosol–cloud interactions compared to its predecessor OsloAero4.0 in CAM4-Oslo. The main new features consist of improved aerosol sources; the module now explicitly accounts for aerosol particle nucleation and secondary organic aerosol production, with new emissions schemes also for sea salt, dimethyl sulfide (DMS), and marine primary organics. Mineral dust emissions are updated as well, adopting the formulation of CESM1.2. The improved model representation of aerosol–cloud interactions now resolves heterogeneous ice nucleation based on black carbon (BC) and mineral dust calculated by the model and treats the activation of cloud condensation nuclei (CCN) as in CAM5.3. Compared to OsloAero4.0 in CAM4-Oslo, the black carbon (BC) mass concentrations are less excessive aloft, with a better fit to observations. Near-surface mass concentrations of BC and sea salt aerosols are also less biased, while sulfate and mineral dust are slightly more biased. Although appearing quite similar for CAM5.3-Oslo and CAM4-Oslo, the validation results for organic matter (OM) are inconclusive, since both of the respective versions of OsloAero are equipped with a limited number of OM tracers for the sake of computational efficiency. Any information about the assumed mass ratios of OM to organic carbon (OC) for different types of OM sources is lost in the transport module. Assuming that observed OC concentrations scaled by 1.4 are representative for the modeled OM concentrations, CAM5.3-Oslo with OsloAero5.3 is slightly inferior for the very sparsely available observation data. Comparing clear-sky column-integrated optical properties with data from ground-based remote sensing, we find a negative bias in optical depth globally; however, it is not as strong as in CAM4-Oslo, but has positive biases in some areas typically dominated by mineral dust emissions. Aerosol absorption has a larger negative bias than the optical depth globally. This is reflected in a lower positive bias in areas where mineral dust is the main contributor to absorption. Globally, the low bias in absorption is smaller than in CAM4-Oslo. The {\AA}ngstr{\"{o}}m parameter exhibits small biases both globally and regionally, suggesting that the aerosol particle sizes are reasonably well represented. Cloud-top droplet number concentrations over oceans are generally underestimated compared to satellite retrievals, but seem to be overestimated downwind of major emissions of dust and biomass burning sources. Finally, we find small changes in direct radiative forcing at the top of the atmosphere, while the cloud radiative forcing due to anthropogenic aerosols is now more negative than in CAM4-Oslo, being on the strong side compared to the multi-model estimate in IPCC AR5. Although not all validation results in this study show improvement for the present CAM5.3-Oslo version, the extended and updated aerosol module OsloAero5.3 is more advanced and applicable than its predecessor OsloAero4.0, as it includes new parameterizations that more readily facilitate sensitivity and process studies and use in climate and Earth system model studies in general.}, author = {Kirkev{\aa}g, Alf and Grini, Alf and Olivi{\'{e}}, Dirk and Seland, {\O}yvind and Alterskj{\ae}r, Kari and Hummel, Matthias and Karset, Inger H H and Lewinschal, Anna and Liu, Xiaohong and Makkonen, Risto and Bethke, Ingo and Griesfeller, Jan and Schulz, Michael and Iversen, Trond}, doi = {10.5194/gmd-11-3945-2018}, issn = {1991-9603}, journal = {Geoscientific Model Development}, month = {oct}, number = {10}, pages = {3945--3982}, publisher = {Copernicus Publications}, title = {{A production-tagged aerosol module for Earth system models, OsloAero5.3 – extensions and updates for CAM5.3-Oslo}}, url = {https://gmd.copernicus.org/articles/11/3945/2018/}, volume = {11}, year = {2018} } @incollection{Kirtman2013, address = {Cambridge, United Kingdom and New York, USA}, author = {Kirtman, B. and Power, S.B. and Adedoyin, J.A. and Boer, G.J. and Bojariu, R. and Camilloni, I. and Doblas-Reyes, F.J. and Fiore, A.M. and Kimoto, M. and Meehl, G.A. and Prather, M. and Sarr, A. and Sch{\"{a}}r, C. and Sutton, R. and van Oldenborgh, G.J. and Vecchi, G. and Wang, H.J.}, booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change}, doi = {10.1017/CBO9781107415324.023}, editor = {Stocker, T.F. and Qin, D. and Plattner, G.-K. and Tignor, M. and Allen, S.K. and Boschung, J. and Nauels, A. and Xia, Y. and Bex, V. and Midgley, P.M.}, isbn = {9781107661820}, keywords = {atmospheric circulation,cryosphere,decadal prediction,near-term climate,near-term temperature,ocean,radiative forcing of climate,water cycle}, pages = {953--1028}, publisher = {Cambridge University Press}, title = {{Near-term Climate Change: Projections and Predictability}}, url = {https://www.ipcc.ch/report/ar5/wg1}, year = {2013} } @article{Kleinschmitt2018, author = {Kleinschmitt, Christoph and Boucher, Olivier and Platt, Ulrich}, doi = {10.5194/acp-18-2769-2018}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {feb}, number = {4}, pages = {2769--2786}, title = {{Sensitivity of the radiative forcing by stratospheric sulfur geoengineering to the amount and strategy of the SO2 injection studied with the LMDZ-S3A model}}, url = {https://acp.copernicus.org/articles/18/2769/2018/}, volume = {18}, year = {2018} } @incollection{Klimont2017, address = {Nairobi, Kenya}, author = {Klimont, Z and Shindell, D and Borgford-Parnell, N and {H{\"{o}}glund Isaksson}, L and Kallbekken, S and Kuylenstierna, J C I and Molina, L T and Srivastava, L and Tao, S and Venkataraman, C}, booktitle = {The Emissions Gap Report 2017}, doi = {https://www.unep.org/resources/emissions-gap-report-2017}, isbn = {978-92-807-3673-1}, pages = {48--57}, publisher = {United Nations Environment Programme (UNEP)}, title = {{Bridging the gap – The role of short-lived climate pollutants}}, url = {https://www.unep.org/resources/emissions-gap-report-2017}, year = {2017} } @incollection{Klimont2015, address = {Dordrecht, The Netherlands}, author = {Klimont, Z and Winiwarter, W}, booktitle = {Costs of Ammonia Abatement and the Climate Co-Benefits}, doi = {10.1007/978-94-017-9722-1_9}, edition = {1}, editor = {Reis, S and Howard, C and Sutton, M A}, pages = {233--261}, publisher = {Springer}, title = {{Estimating Costs and Potential for Reduction of Ammonia Emissions from Agriculture in the GAINS Model}}, url = {http://www.springer.com/gp/book/9789401797214}, year = {2015} } @article{Klimont2017a, abstract = {This paper presents a comprehensive assessment of historical (1990-2010) global anthropogenic particulate matter (PM) emissions including the consistent and harmonized calculation of mass-based size distribution (PM1, PM2. 5, PM10), as well as primary carbonaceous aerosols including black carbon (BC) and organic carbon (OC). The estimates were developed with the integrated assessment model GAINS, where source-and region-specific technology characteristics are explicitly included. This assessment includes a number of previously unaccounted or often misallocated emission sources, i.e. kerosene lamps, gas flaring, diesel generators, refuse burning; some of them were reported in the past for selected regions or in the context of a particular pollutant or sector but not included as part of a total estimate. Spatially, emissions were calculated for 172 source regions (as well as international shipping), presented for 25 global regions, and allocated to 0.5°ĝ€ × ĝ€0.5° longitude-latitude grids. No independent estimates of emissions from forest fires and savannah burning are provided and neither windblown dust nor unpaved roads emissions are included. We estimate that global emissions of PM have not changed significantly between 1990 and 2010, showing a strong decoupling from the global increase in energy consumption and, consequently, CO2 emissions, but there are significantly different regional trends, with a particularly strong increase in East Asia and Africa and a strong decline in Europe, North America, and the Pacific region. This in turn resulted in important changes in the spatial pattern of PM burden, e.g. European, North American, and Pacific contributions to global emissions dropped from nearly 30ĝ€{\%} in 1990 to well below 15ĝ€{\%} in 2010, while Asia's contribution grew from just over 50ĝ€{\%} to nearly two-Thirds of the global total in 2010. For all PM species considered, Asian sources represented over 60ĝ€{\%} of the global anthropogenic total, and residential combustion was the most important sector, contributing about 60ĝ€{\%} for BC and OC, 45ĝ€{\%} for PM2. 5, and less than 40ĝ€{\%} for PM10, where large combustion sources and industrial processes are equally important. Global anthropogenic emissions of BC were estimated at about 6.6 and 7.2ĝ€Tg in 2000 and 2010, respectively, and represent about 15ĝ€{\%} of PM2. 5 but for some sources reach nearly 50ĝ€{\%}, i.e. for the transport sector. Our global BC numbers are higher than previously published owing primarily to the inclusion of new sources. This PM estimate fills the gap in emission data and emission source characterization required in air quality and climate modelling studies and health impact assessments at a regional and global level, as it includes both carbonaceous and non-carbonaceous constituents of primary particulate matter emissions. The developed emission dataset has been used in several regional and global atmospheric transport and climate model simulations within the ECLIPSE (Evaluating the Climate and Air Quality Impacts of Short-Lived Pollutants) project and beyond, serves better parameterization of the global integrated assessment models with respect to representation of black carbon and organic carbon emissions, and built a basis for recently published global particulate number estimates.}, author = {Klimont, Zbigniew and Kupiainen, Kaarle and Heyes, Chris and Purohit, Pallav and Cofala, Janusz and Rafaj, Peter and Borken-Kleefeld, Jens and Sch{\"{o}}pp, Wolfgang}, doi = {10.5194/acp-17-8681-2017}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {14}, pages = {8681--8723}, title = {{Global anthropogenic emissions of particulate matter including black carbon}}, volume = {17}, year = {2017} } @article{Kloster2007, abstract = {A global coupled ocean-atmosphere modeling system is applied in a transient climate simulation to study the response to global warming of Dimethylsulfide (DMS) in the ocean, the DMS flux to the atmosphere, and the resulting DMS concentrations in the atmosphere. The DMS production and consumption processes in the ocean are linked to plankton dynamics simulated in the marine biogeochemistry model HAMOCC5.1, embedded in an ocean general circulation model (MPI-OM). The atmospheric model ECHAM5 is extended by the microphysical aerosol model HAM, treating the sulfur chemistry in the atmosphere and the evolution of microphysically interacting internally and externally mixed aerosol populations. For future conditions (2000?2100) we assume greenhouse gas concentrations, aerosol and aerosol precursor emissions according to the SRES A1B scenario. We analyzed the results in terms of simulated changes between the period 1861?1890 and 2061?2090. For the global annual mean DMS sea surface concentration and the DMS flux we found a reduction by 10{\%}. The DMS burden in the atmosphere is reduced by only 3{\%}, owing to a longer lifetime of DMS in the atmosphere in a warmer climate (+7{\%}). Regionally the response and the underlying mechanisms are quite inhomogeneous. The largest reduction in the DMS sea surface concentration is simulated in the Southern Ocean (?40{\%}) caused by an increase in the summer mixed layer depth, leading to less favorable light conditions for phytoplankton growth. In the mid and low latitudes DMS sea surface concentrations are predominantly reduced due to nutrient limitation of the phytoplankton growth through higher ocean stratification and less transport of nutrients into the surface layers.}, author = {Kloster, S and Six, K D and Feichter, J and Maier-Reimer, E and Roeckner, E and Wetzel, P and Stier, P and Esch, M}, doi = {10.1029/2006JG000224}, issn = {0148-0227}, journal = {Journal of Geophysical Research: Biogeosciences}, month = {sep}, number = {G3}, pages = {G03005}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Response of dimethylsulfide (DMS) in the ocean and atmosphere to global warming}}, volume = {112}, year = {2007} } @article{Kodros2015, abstract = {Aerosol emissions from biofuel combustion impact both health and climate; however, while reducing emissions through improvements to combustion technologies will improve health, the net effect on climate is largely unconstrained. In this study, we examine sensitivities in global aerosol concentration, direct radiative climate effect, and cloud-albedo aerosol indirect climate effect to uncertainties in biofuel emission factors, optical mixing state, and model nucleation and background secondary organic aerosol (SOA). We use the Goddard Earth Observing System global chemical-transport model (GEOS-Chem) with TwO Moment Aerosol Sectional (TOMAS) microphysics. The emission factors include amount, composition, size, and hygroscopicity, as well as optical mixing-state properties. We also evaluate emissions from domestic coal use, which is not biofuel but is also frequently emitted from homes. We estimate the direct radiative effect assuming different mixing states (homogeneous, core-shell, and external) with and without absorptive organic aerosol (brown carbon). We find the global-mean direct radiative effect of biofuel emissions ranges from −0.02 to +0.06 W m−2 across all simulation/mixing-state combinations with regional effects in source regions ranging from −0.2 to +0.8 W m−2. The global-mean cloud-albedo aerosol indirect effect (AIE) ranges from +0.01 to −0.02 W m−2 with regional effects in source regions ranging from −1.0 to −0.05 W m−2. The direct radiative effect is strongly dependent on uncertainties in emissions mass, composition, emissions aerosol size distributions, and assumed optical mixing state, while the indirect effect is dependent on the emissions mass, emissions aerosol size distribution, and the choice of model nucleation and secondary organic aerosol schemes. The sign and magnitude of these effects have a strong regional dependence. We conclude that the climate effects of biofuel aerosols are largely unconstrained, and the overall sign of the aerosol effects is unclear due to uncertainties in model inputs. This uncertainty limits our ability to introduce mitigation strategies aimed at reducing biofuel black carbon emissions in order to counter warming effects from greenhouse gases. To better understand the climate impact of particle emissions from biofuel combustion, we recommend field/laboratory measurements to narrow constraints on (1) emissions mass, (2) emission size distribution, (3) mixing state, and (4) ratio of black carbon to orga{\ldots}}, author = {Kodros, J. K. and Scott, C. E. and Farina, S. C. and Lee, Y. H. and L'Orange, C. and Volckens, J. and Pierce, J. R.}, doi = {10.5194/acp-15-8577-2015}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {15}, pages = {8577--8596}, title = {{Uncertainties in global aerosols and climate effects due to biofuel emissions}}, volume = {15}, year = {2015} } @article{Kok2018, abstract = {Feedbacks between the global dust cycle and the climate system might have amplified past climate changes. Yet, it remains unclear what role the dust-climate feedback will play in future anthropogenic climate change. Here, we estimate the direct dust-climate feedback, arising from changes in the dust direct radiative effect (DRE), using a simple theoretical framework that combines constraints on the dust DRE with a series of climate model results. We find that the direct dust-climate feedback is likely in the range of -0.04 to +0.02 Wm -2 K-1, such that it could account for a substantial fraction of the total aerosol feedbacks in the climate system. On a regional scale, the direct dust-climate feedback is enhanced by approximately an order of magnitude close to major source regions. This suggests that it could play an important role in shaping the future climates of Northern Africa, the Sahel, the Mediterranean region, the Middle East, and Central Asia.}, author = {Kok, Jasper F. and Ward, Daniel S. and Mahowald, Natalie M. and Evan, Amato T.}, doi = {10.1038/s41467-017-02620-y}, issn = {20411723}, journal = {Nature Communications}, number = {1}, pages = {241}, publisher = {Nature Publishing Group}, title = {{Global and regional importance of the direct dust-climate feedback}}, volume = {9}, year = {2018} } @article{Kok2012, abstract = {The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This paper presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices. We also discuss the physics of wind-blown sand and dune formation on Venus and Titan. {\textcopyright} 2012 IOP Publishing Ltd.}, author = {Kok, Jasper F. and Parteli, Eric J.R. and Michaels, Timothy I. and Karam, Diana Bou}, doi = {10.1088/0034-4885/75/10/106901}, issn = {00344885}, journal = {Reports on Progress in Physics}, number = {10}, pages = {106901}, pmid = {22982806}, title = {{The physics of wind-blown sand and dust}}, volume = {75}, year = {2012} } @article{Kok2014, abstract = {Simulations of the dust cycle and its interactions with the changing Earth system are hindered by the empirical nature of dust emission parameterizations in weather and climate models. Here we take a step towards improving dust cycle simulations by using a combination of theory and numerical simulations to derive a physically based dust emission parameterization. Our parameterization is straightforward to implement into large-scale models, as it depends only on the wind friction velocity and the soil's threshold friction velocity. Moreover, it accounts for two processes missing from most existing parameterizations: a soil's increased ability to produce dust under saltation bombardment as it becomes more erodible, and the increased scaling of the dust flux with wind speed as a soil becomes less erodible. Our treatment of both these processes is supported by a compilation of quality-controlled vertical dust flux measurements. Furthermore, our scheme reproduces this measurement compilation with substantially less error than the existing dust flux parameterizations we were able to compare against. A critical insight from both our theory and the measurement compilation is that dust fluxes are substantially more sensitive to the soil's threshold friction velocity than most current schemes account for.}, author = {Kok, J. F. and Mahowald, N. M. and Fratini, G. and Gillies, J. A. and Ishizuka, M. and Leys, J. F. and Mikami, M. and Park, M. S. and Park, S. U. and {Van Pelt}, R. S. and Zobeck, T. M.}, doi = {10.5194/acp-14-13023-2014}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {dec}, number = {23}, pages = {13023--13041}, publisher = {Copernicus Publications}, title = {{An improved dust emission model – Part 1: Model description and comparison against measurements}}, volume = {14}, year = {2014} } @article{Kok2017, abstract = {Desert dust aerosols affect Earth's global energy balance through direct interactions with radiation, and through indirect interactions with clouds and ecosystems. But the magnitudes of these effects are so uncertain that it remains unclear whether atmospheric dust has a net warming or cooling effect on global climate. Consequently, it is still uncertain whether large changes in atmospheric dust loading over the past century have slowed or accelerated anthropogenic climate change, or what the effects of potential future changes in dust loading will be. Here we present an analysis of the size and abundance of dust aerosols to constrain the direct radiative effect of dust. Using observational data on dust abundance, in situ measurements of dust optical properties and size distribution, and climate and atmospheric chemical transport model simulations of dust lifetime, we find that the dust found in the atmosphere is substantially coarser than represented in current global climate models. As coarse dust warms the climate, the global dust direct radiative effect is likely to be less cooling than the ∼−0.4 W m−2 estimated by models in a current global aerosol model ensemble. Instead, we constrain the dust direct radiative effect to a range between −0.48 and +0.20 W m−2, which includes the possibility that dust causes a net warming of the planet.}, author = {Kok, Jasper F and Ridley, David A and Zhou, Qing and Miller, Ron L and Zhao, Chun and Heald, Colette L and Ward, Daniel S and Albani, Samuel and Haustein, Karsten}, doi = {10.1038/ngeo2912}, issn = {1752-0908}, journal = {Nature Geoscience}, number = {4}, pages = {274--278}, title = {{Smaller desert dust cooling effect estimated from analysis of dust size and abundance}}, url = {https://doi.org/10.1038/ngeo2912}, volume = {10}, year = {2017} } @article{Koshak2014a, abstract = {Recent improvements to the NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) and its application to the Community Multiscale Air Quality (CMAQ) modeling system are discussed. The LNOM analyzes Lightning Mapping Array (LMA) and National Lightning Detection Network™ (NLDN) data to estimate the raw (i.e., unmixed and otherwise environmentally unmodified) vertical profile of lightning NOx(=NO+NO2) production. The latest LNOM estimates of mean lightning channel length, the lightning 10-m segment altitude distribution, and the vertical profile of lightning NOxproduction are obtained. The primary improvement to the LNOM is the inclusion of non-return stroke lightning NOxproduction due to: hot core stepped and dart leaders, stepped leader corona sheath, K-changes, continuing currents, and M-components. The impact of including LNOM-estimates of lightning NOxfor an August 2006 run of CMAQ is discussed. An estimate of global annual lightning NOxproduction is also provided using the NASA satellite global lightning climatology. {\textcopyright} 2013 Elsevier B.V.}, author = {Koshak, William and Peterson, Harold and Biazar, Arastoo and Khan, Maudood and Wang, Lihua}, doi = {10.1016/j.atmosres.2012.12.015}, isbn = {0169-8095}, issn = {01698095}, journal = {Atmospheric Research}, keywords = {Lightning,Lightning climatology,Lightning mapping,Lightning physics,Nitrogen oxide}, pages = {363--369}, title = {{The NASA Lightning Nitrogen Oxides Model (LNOM): Application to air quality modeling}}, volume = {135-136}, year = {2014} } @article{Kremser2016, abstract = {Abstract Interest in stratospheric aerosol and its role in climate have increased over the last decade due to the observed increase in stratospheric aerosol since 2000 and the potential for changes in the sulfur cycle induced by climate change. This review provides an overview about the advances in stratospheric aerosol research since the last comprehensive assessment of stratospheric aerosol was published in 2006. A crucial development since 2006 is the substantial improvement in the agreement between in situ and space-based inferences of stratospheric aerosol properties during volcanically quiescent periods. Furthermore, new measurement systems and techniques, both in situ and space based, have been developed for measuring physical aerosol properties with greater accuracy and for characterizing aerosol composition. However, these changes induce challenges to constructing a long-term stratospheric aerosol climatology. Currently, changes in stratospheric aerosol levels less than 20{\%} cannot be confidently quantified. The volcanic signals tend to mask any nonvolcanically driven change, making them difficult to understand. While the role of carbonyl sulfide as a substantial and relatively constant source of stratospheric sulfur has been confirmed by new observations and model simulations, large uncertainties remain with respect to the contribution from anthropogenic sulfur dioxide emissions. New evidence has been provided that stratospheric aerosol can also contain small amounts of nonsulfate matter such as black carbon and organics. Chemistry-climate models have substantially increased in quantity and sophistication. In many models the implementation of stratospheric aerosol processes is coupled to radiation and/or stratospheric chemistry modules to account for relevant feedback processes.}, author = {Kremser, Stefanie and Thomason, Larry W and von Hobe, Marc and Hermann, Markus and Deshler, Terry and Timmreck, Claudia and Toohey, Matthew and Stenke, Andrea and Schwarz, Joshua P and Weigel, Ralf and Fueglistaler, Stephan and Prata, Fred J and Vernier, Jean-Paul and Schlager, Hans and Barnes, John E and Antu{\~{n}}a-Marrero, Juan-Carlos and Fairlie, Duncan and Palm, Mathias and Mahieu, Emmanuel and Notholt, Justus and Rex, Markus and Bingen, Christine and Vanhellemont, Filip and Bourassa, Adam and Plane, John M C and Klocke, Daniel and Carn, Simon A and Clarisse, Lieven and Trickl, Thomas and Neely, Ryan and James, Alexander D and Rieger, Landon and Wilson, James C and Meland, Brian}, doi = {10.1002/2015RG000511}, issn = {8755-1209}, journal = {Reviews of Geophysics}, month = {jun}, number = {2}, pages = {278--335}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Stratospheric aerosol – Observations, processes, and impact on climate}}, volume = {54}, year = {2016} } @article{Kristiansen2016, abstract = {Aerosols have important impacts on air quality and climate, but the processes affecting their removal from the atmosphere are not fully understood and are poorly constrained by observations. This makes modelled aerosol lifetimes uncertain. In this study, we make use of an observational constraint on aerosol lifetimes provided by radionuclide measurements and investigate the causes of differences within a set of global models. During the Fukushima Dai-Ichi nuclear power plant accident of March 2011, the radioactive isotopes cesium-137 (137Cs) and xenon-133 (133Xe) were released in large quantities. Cesium attached to particles in the ambient air, approximately according to their available aerosol surface area. 137Cs size distribution measurements taken close to the power plant suggested that accumulationmode (AM) sulfate aerosols were the main carriers of cesium. Hence, 137Cs can be used as a proxy tracer for the AM sulfate aerosol's fate in the atmosphere. In contrast, the noble gas 133Xe behaves almost like a passive transport tracer. Global surface measurements of the two radioactive isotopes taken over several months after the release allow the derivation of a lifetime of the carrier aerosol. We compare this to the lifetimes simulated by 19 different atmospheric transport models initialized with identical emissions of 137Cs that were assigned to an aerosol tracer with each model's default properties of AM sulfate, and 133Xe emissions that were assigned to a passive tracer. We investigate to what extent the modelled sulfate tracer can reproduce the measurements, especially with respect to the observed loss of aerosol mass with time. Modelled 137Cs and 133Xe concentrations sampled at the same location and times as station measurements allow a direct comparison between measured and modelled aerosol lifetime. The e-folding lifetime $\tau$e, calculated from station measurement data taken between 2 and 9 weeks after the start of the emissions, is 14.3 days (95{\%} confidence interval 13.1-15.7 days). The equivalent modelled $\tau$e lifetimes have a large spread, varying between 4.8 and 26.7 days with a model median of 9.4±2.3 days, indicating too fast a removal in most models. Because sufficient measurement data were only available from about 2 weeks after the release, the estimated lifetimes apply to aerosols that have undergone long-range transport, i.e. not for freshly emitted aerosol. However, modelled instantaneous lifetimes show that the initial removal in the first 2 weeks was quicker (lifetimes between 1 and 5 days) due to the emissions occurring at low altitudes and co-location of the fresh plume with strong precipitation. Deviations between measured and modelled aerosol lifetimes are largest for the northernmost stations and at later time periods, suggesting that models do not transport enough of the aerosol towards the Arctic. The models underestimate passive tracer (133Xe) concentrations in the Arctic as well but to a smaller extent than for the aerosol (137Cs) tracer. This indicates that in addition to too fast an aerosol removal in the models, errors in simulated atmospheric transport towards the Arctic in most models also contribute to the underestimation of the Arctic aerosol concentrations.}, author = {Kristiansen, N. I. and Stohl, A. and Olivi{\'{e}}, D. J.L. and Croft, B. and S{\o}vde, O. A. and Klein, H. and Christoudias, T. and Kunkel, D. and Leadbetter, S. J. and Lee, Y. H. and Zhang, K. and Tsigaridis, K. and Bergman, T. and Evangeliou, N. and Wang, H. and Ma, P. L. and Easter, R. C. and Rasch, P. J. and Liu, X. and Pitari, G. and {Di Genova}, G. and Zhao, S. Y. and Balkanski, Y. and Bauer, S. E. and Faluvegi, G. S. and Kokkola, H. and Martin, R. V. and Pierce, J. R. and Schulz, M. and Shindell, D. and Tost, H. and Zhang, H.}, doi = {10.5194/acp-16-3525-2016}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {5}, pages = {3525--3561}, title = {{Evaluation of observed and modelled aerosol lifetimes using radioactive tracers of opportunity and an ensemble of 19 global models}}, volume = {16}, year = {2016} } @article{Kristjansson2015, abstract = {Recent multimodel studies have shown that if one attempts to cancel increasing CO2 concentrations by reducing absorbed solar radiation, the hydrological cycle will weaken if global temperature is kept unchanged. Using a global climate model, we investigate the hydrological cycle response to "cirrus cloud thinning (CCT)," which is a proposed climate engineering technique that seeks to enhance outgoing longwave radiation. Investigations of the "fast response" in experiments with fixed sea surface temperatures reveal that CCT causes a significant enhancement of the latent heat flux and precipitation. This is due to enhanced radiative cooling of the troposphere, which is opposite to the effect of increased CO2 concentrations. By combining CCT with CO2 increase in multidecadal simulations with a slab ocean, we demonstrate a systematic enhancement of the hydrological cycle due to CCT. This leads to enhanced moisture availability in low-latitude land regions and a strengthening of the Indian monsoon.}, author = {Kristj{\'{a}}nsson, J{\'{o}}n Egill and Muri, Helene and Schmidt, Hauke}, doi = {10.1002/2015GL066795}, issn = {0094-8276}, journal = {Geophysical Research Letters}, keywords = {cirrus clouds,climate engineering,hydrological cycle}, month = {dec}, number = {24}, pages = {10807--10815}, title = {{The hydrological cycle response to cirrus cloud thinning}}, url = {https://onlinelibrary.wiley.com/doi/10.1002/2015GL066795}, volume = {42}, year = {2015} } @article{Kroll2020, author = {Kroll, Jesse H and Heald, Colette L and Cappa, Christopher D and Farmer, Delphine K and Fry, Juliane L and Murphy, Jennifer G and Steiner, Allison L}, doi = {10.1038/s41557-020-0535-z}, issn = {1755-4330}, journal = {Nature Chemistry}, month = {sep}, number = {9}, pages = {777--779}, title = {{The complex chemical effects of COVID-19 shutdowns on air quality}}, url = {http://www.nature.com/articles/s41557-020-0535-z}, volume = {12}, year = {2020} } @article{Krotkov2016a, abstract = {The Ozone Monitoring Instrument (OMI) onboard NASA's Aura satellite has been providing global observations of the ozone layer and key atmospheric pollutant gases, such as nitrogen dioxide (NO2) and sulfur dioxide (SO2), since October 2004. The data products from the same instrument provide consistent spatial and temporal coverage and permit the study of anthropogenic and natural emissions on local-to-global scales. In this paper we examine changes in SO2 and NO2 over some of the world's most polluted industrialized regions during the first decade of OMI observations. In terms of regional pollution changes, we see both upward and downward trends, sometimes in opposite directions for NO2 and SO2, for the different study areas. The trends are, for the most part, associated with economic and/or technological changes in energy use, as well as regional regulatory policies. Over the eastern US, both NO2 and SO2 levels decreased dramatically from 2005 to 2014, by more than 40 and 80 {\%}, respectively, as a result of both technological improvements and stricter regulations of emissions. OMI confirmed large reductions in SO2 over eastern Europe's largest coal power plants after installation of flue gas desulfurization devices. The North China Plain has the world's most severe SO2 pollution, but a decreasing trend has been observed since 2011, with about a 50 {\%} reduction in 2012–2014, due to an economic slowdown and government efforts to restrain emissions from the power and industrial sectors. In contrast, India's SO2 and NO2 levels from coal power plants and smelters are growing at a fast pace, increasing by more than 100 and 50 {\%}, respectively, from 2005 to 2014. Several SO2 hot spots observed over the Persian Gulf are probably related to oil and gas operations and indicate a possible underestimation of emissions from these sources in bottom-up emission inventories. Overall, OMI observations have proved to be very valuable in documenting rapid changes in air quality over different parts of the world during the last decade. The baseline established during the first 10 years of OMI is indispensable for the interpretation of air quality measurements from current and future satellite atmospheric composition missions.}, annote = {ACP}, author = {Krotkov, Nickolay A. and McLinden, Chris A. and Li, Can and Lamsal, Lok N. and Celarier, Edward A. and Marchenko, Sergey V. and Swartz, William H. and Bucsela, Eric J. and Joiner, Joanna and Duncan, Bryan N. and {Folkert Boersma}, K. and {Pepijn Veefkind}, J. and Levelt, Pieternel F. and Fioletov, Vitali E. and Dickerson, Russell R. and He, Hao and Lu, Zifeng and Streets, David G.}, doi = {10.5194/acp-16-4605-2016}, isbn = {1680-7324}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {7}, pages = {4605--4629}, publisher = {Copernicus Publications}, title = {{Aura OMI observations of regional SO2 and NO2 pollution changes from 2005 to 2015}}, url = {https://www.atmos-chem-phys.net/16/4605/2016/}, volume = {16}, year = {2016} } @article{Krzyzanowski2008, abstract = {Based on a systematic review of literature on adverse health effects of air pollution, the World Health Organization has updated its Air Quality Guidelines in 2005. The current update is intended to be relevant and applicable worldwide and takes into consideration large regional inequalities in exposures to air pollution. It recommends guideline levels for particulate matter, ozone, nitrogen dioxide and sulfur dioxide, as well as the set of interim targets for these pollutants' concentrations, encouraging gradual improvement of air quality and reduction of health impacts of the pollution.}, author = {Krzyzanowski, Michal and Cohen, Aaron}, doi = {10.1007/s11869-008-0008-9}, issn = {1873-9326}, journal = {Air Quality, Atmosphere {\&} Health}, number = {1}, pages = {7--13}, title = {{Update of WHO air quality guidelines}}, url = {https://doi.org/10.1007/s11869-008-0008-9}, volume = {1}, year = {2008} } @article{Kulmala2004, abstract = {The possible connections between the carbon balance of ecosystems and aerosol-cloud-climate interactions play a significant role in climate change studies. Carbon dioxide is a greenhouse gas, whereas the net effect of atmospheric aerosols is to cool the climate. Here, we investigated the connection between forest-atmosphere carbon exchange and aerosol dynamics in the continental boundary layer by means of multiannual data sets of particle formation and growth rates, of CO2 fluxes, and of monoterpene concentrations in a Scots pine forest in southern Finland. We suggest a new, interesting link and a potentially important feedback among forest ecosystem functioning, aerosols, and climate: Considering that globally increasing temperatures and CO2 fertilization are likely to lead to increased photosynthesis and forest growth, an increase in forest biomass would increase emissions of non-methane biogenic volatile organic compounds and thereby enhance organic aerosol production. This feedback mechanism couples the climate effect of CO2 with that of aerosols in a novel way.}, author = {Kulmala, M. and Suni, T. and Lehtinen, K. E. J. and {Dal Maso}, M. and Boy, M. and Reissell, A. and Rannik, {\"{U}}. and Aalto, P. and Keronen, P. and Hakola, H. and B{\"{a}}ck, J. and Hoffmann, T. and Vesala, T. and Hari, P.}, doi = {10.5194/acp-4-557-2004}, isbn = {1680-7324}, issn = {1680-7316}, journal = {Atmospheric Chemistry and Physics}, number = {2}, pages = {557--562}, publisher = {Copernicus Publications}, title = {{A new feedback mechanism linking forests, aerosols, and climate}}, volume = {4}, year = {2004} } @article{Kumar2013, abstract = {Abstract. In situ measurements of carbon monoxide (CO) and ozone (O3) at the Pico Mountain Observatory (PMO) located in the Azores, Portugal, are analyzed together with results from an atmospheric chemical transport model (GEOS-Chem) and satellite remote sensing data (AIRS (Atmospheric Infrared Sounder) for CO, and TES (Tropospheric Emission Spectrometer) for O3) to examine the evolution of free-troposphere CO and O3 over the North Atlantic for 2001–2011. GEOS-Chem captured the seasonal cycles for CO and O3 well but significantly underestimated the mixing ratios of CO, particularly in spring. Statistically significant (using a significance level of 0.05) decreasing trends were found for both CO and O3 based on harmonic regression analysis of the measurement data. The best estimates of the possible trends for CO and O3 measurements are −0.31 ± 0.30 (2-$\sigma$) ppbv yr−1 and −0.21 ± 0.11 (2-$\sigma$) ppbv yr−1, respectively. Similar decreasing trends for both species were obtained with GEOS-Chem simulation results. The most important factor contributing to the decreases in CO and O3 at PMO over the past decade is the decline in anthropogenic emissions from North America, which more than compensate for the impacts from increasing Asian emissions. It is likely that climate change in the past decade has also affected the intercontinental transport of O3.}, author = {Kumar, A. and Wu, S. and Weise, M. F. and Honrath, R. and Owen, R. C. and Helmig, D. and Kramer, L. and {Val Martin}, M. and Li, Q.}, doi = {10.5194/acp-13-12537-2013}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {dec}, number = {24}, pages = {12537--12547}, title = {{Free-troposphere ozone and carbon monoxide over the North Atlantic for 2001–2011}}, url = {https://acp.copernicus.org/articles/13/12537/2013/}, volume = {13}, year = {2013} } @article{Kuprov2014, author = {Kuprov, Roman and Eatough, Delbert J and Cruickshank, Tyler and Olson, Neal and Cropper, Paul M and Hansen, Jaron C}, doi = {10.1080/10962247.2014.903878}, journal = {Journal of the Air {\&} Waste Management Association}, month = {jul}, number = {8}, pages = {957--969}, publisher = {Informa {\{}UK{\}} Limited}, title = {{Composition and secondary formation of fine particulate matter in the Salt Lake Valley: Winter 2009}}, volume = {64}, year = {2014} } @article{Kutzner2018, abstract = {Lately, black carbon (BC) has received significant attention due to its climate-warming properties and adverse health effects. Nevertheless, long-term observations in urban areas are scarce, most likely because BC monitoring is not required by environmental legislation. This, however, handicaps the evaluation of air quality models which can be used to assess the effectiveness of policy measures which aim to reduce BC concentrations. Here, we present a new dataset of atmospheric BC measurements from Germany constructed from over six million measurements at over 170 stations. Data covering the period between 1994 and 2014 were collected from twelve German Federal States and the Federal Environment Agency, quality checked and harmonized into a database with comprehensive metadata. The final data in original time resolution are available for download (https://doi.org/10.1594/PANGAEA.881173). Though assembled in a consistent way, the dataset is characterized by differences in (a) measurement methodologies for determining evolved carbon and optical absorption, (b) covered time periods, and (c) temporal resolutions that ranged from half hourly to measurements every 6th day. Usage and interpretation of this dataset thus requires a careful consideration of these differences. Our analysis focuses on 2009, the year with the largest data coverage with one single methodology, as well as on the relative changes in long-term trends over ten years. For 2009, we find that BC concentrations at traffic sites were at least twice as high as at urban background, industrial and rural sites. Weekly cycles are most prominent at traffic stations, however, the presence of differences in concentrations during the week and on weekends at other station types suggests that traffic plays an important role throughout the full network. Generally higher concentrations and weaker weekly cycles during the winter months point towards the influence of other sources such as domestic heating. Regarding the long-term trends, advanced statistical techniques allow us to account for instrumentation changes and to separate seasonal and long-term changes in our dataset. Analysis shows a downward trend in BC at nearly all locations and in all conditions, with a high level of confidence for the period of 2005-2014. In depth analysis indicates that background BC is decreasing slowly, while the occurrences of high concentrations are decreasing more rapidly. In summary, legislation - both in Europe and locally - to reduce particulate emissions and indirectly BC appear to be working, based on this analysis. Adverse human health and climate impacts are likely to be diminished because of the improvements in air quality.}, author = {Kutzner, Rebecca D. and von Schneidemesser, Erika and Kuik, Friderike and Quedenau, J{\"{o}}rn and Weatherhead, Elizabeth C. and Schmale, Julia}, doi = {10.1016/j.atmosenv.2018.04.039}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Air pollution,Black carbon,Germany,Long-term monitoring,Policy measures,Trend analysis}, month = {jul}, pages = {41--52}, publisher = {Elsevier Ltd}, title = {{Long-term monitoring of black carbon across Germany}}, volume = {185}, year = {2018} } @article{Kuzu2020, abstract = {In this study, black carbon (BC), particulate matter (PM), nitrogen oxides (NOx), and sulphur dioxide (SO2) were monitored between May 2019 and February 2020. During this sampling period, size-segregated particle samples were collected by a high-volume cascade impactor, once a week. Elemental carbon (EC) and organic carbon (OC) were investigated on the size-segregated particles. The study was carried out at Esenler district of Istanbul. Main sources in the vicinity of the sampling area are Central Coach Station of Istanbul, residential buildings, small-scale industrial facilities, and O-1 and O-2 highway connection. The average BC concentration was 2763 ± 1974 ng/m3. PM10 and PM2.5 concentrations were 38.2 ± 17.4 and 21.5 ± 12.4 $\mu$g/m3, respectively. BC comprised 12.8{\%} and 7.2{\%} of PM2.5 and PM10, respectively. Diurnal variation of BC had a similar trend with NO2 concentrations, which showed peak concentrations during rush hours. BC had high Pearson correlation coefficients with NO, NO2, and PM2.5. The geographical position of possible emission sources was estimated through conditional probability function. The Central Coach Station of Istanbul had the highest geographical possibility for BC sources. EC and OC exhibited bimodal size distribution. The coarse mode peak was at 0.95–1.5-$\mu$m size bin for OC, whilst it was at 1.5–3-$\mu$m size bin for EC. Since EC and BC exhibit the same origin with different measurement principles, we concluded that resuspension of road dust also contributed ambient BC concentrations.}, author = {Kuzu, S Levent and Yavuz, Elif and Aky{\"{u}}z, Ezgi and Saral, Arslan and Akkoyunlu, B{\"{u}}lent Oktay and {\"{O}}zdemir, H{\"{u}}seyin and Demir, G{\"{o}}ksel and {\"{U}}nal, Alper}, doi = {10.1007/s11869-020-00839-1}, issn = {1873-9326}, journal = {Air Quality, Atmosphere {\&} Health}, number = {7}, pages = {827--837}, title = {{Black carbon and size-segregated elemental carbon, organic carbon compositions in a megacity: a case study for Istanbul}}, url = {https://doi.org/10.1007/s11869-020-00839-1}, volume = {13}, year = {2020} } @article{Laakso2017, abstract = {Stratospheric sulfur injections have often been suggested as a cost-effective geoengineering method to prevent or slow down global warming. In geoengineering studies, these injections are commonly targeted to the Equator, where the yearly mean intensity of the solar radiation is the highest and from where the aerosols disperse globally due to the Brewer–Dobson Circulation. However, compensating for greenhouse gas-induced zonal warming by reducing solar radiation would require a relatively larger radiative forcing to the mid- and high latitudes and a lower forcing to the low latitudes than what is achieved by continuous equatorial injections. In this study we employ alternative aerosol injection scenarios to investigate if the resulting radiative forcing can be targeted to be zonally more uniform without decreasing the global the mean radiative forcing of stratospheric sulfur geoengineering. We used a global aerosol–climate model together with an Earth system model to study the radiative and climate effects of stratospheric sulfur injection scenarios with different injection areas. According to our simulations, varying the SO2 injection area seasonally would result in a similar global mean cooling effect as injecting SO2 to the Equator, but with a more uniform zonal distribution of shortwave radiative forcing. Compared to the case of equatorial injections, in the seasonally varying injection scenario where the maximum sulfur production from injected SO2 followed the maximum of solar radiation, the shortwave radiative forcing decreased by 27 {\%} over the Equator (the latitudes between 20° N and 20° S) and increased by 15 {\%} over higher latitudes. Compared to the continuous injections to the Equator, in summer months the radiative forcing was increased by 17 and 14 {\%} and in winter months decreased by 14 and 16 {\%} in Northern and Southern hemispheres, respectively. However, these forcings do not translate into as large changes in temperatures. The changes in forcing would only lead to 0.05 K warmer winters and 0.05 K cooler summers in the Northern Hemisphere, which is roughly 3 {\%} of the cooling resulting from solar radiation management scenarios studied here.}, author = {Laakso, Anton and Korhonen, Hannele and Romakkaniemi, Sami and Kokkola, Harri}, doi = {10.5194/acp-17-6957-2017}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jun}, number = {11}, pages = {6957--6974}, title = {{Radiative and climate effects of stratospheric sulfur geoengineering using seasonally varying injection areas}}, url = {https://acp.copernicus.org/articles/17/6957/2017/}, volume = {17}, year = {2017} } @article{Lacressonnii¿re2017, abstract = {In the framework of the IMPACT2C project, we have evaluated the future European particulate matter concentrations under the influence of climate change and anthropogenic emission reductions. To do so, 30-year simulations for present and future scenarios were performed with an ensemble of four regional Chemical Transport Models. +2 °C scenarios were issued from different regional climate simulations belonging to the CORDEX experiment (RCP4.5 scenario). Comparing present day simulations to observations shows that these simulations meet the requested quality criteria even if some biases do exist. Also, we showed that using regional climate models instead of meteorological reanalysis was not critical for the quality of our simulations. Present day as well as future scenarios show the large variability between models associated with different meteorology and process parameterizations. Future projections of PM concentrations show a large reduction of PM10 and PM2.5 concentrations in a +2 °C climate over the European continent (especially over Benelux), which can be mostly attributed to emission reduction policies. Under a current legislation scenario, annual PM10 could be reduced by between 1.8 and 2.9 $\mu$g m−3(14.1–20.4{\%}). If maximum technologically feasible emission reductions were implemented, further reductions of 1.4–1.9 $\mu$g m−3(18.6–20.9{\%}) are highlighted. Changes due to a +2 °C warming, in isolation from emission changes, are in general much weaker (−1.1 to +0.4 $\mu$g m−3,-0.3 to +5.1{\%} for annual PM10 averaged over the European domain). Even if large differences exist between models, we have determined that the decrease of PM over Europe associated with emission reduction is a robust result. The patterns of PM changes resulting from climate change (for example the increase of PM over Spain and southern France and the decrease of PM10 over eastern Europe) are also robustly predicted even if its amplitude remains weak compared to changes associated with emission reductions.}, author = {Lacressonni{\`{e}}re, Gwendoline and Watson, Laura and Gauss, Michael and Engardt, Magnuz and Andersson, Camilla and Beekmann, Matthias and Colette, Augustin and Foret, Gilles and Josse, B{\'{e}}atrice and Mar{\'{e}}cal, Virginie and Nyiri, Agnes and Siour, Guillaume and Sobolowski, Stefan and Vautard, Robert}, doi = {10.1016/j.atmosenv.2017.01.037}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Air quality,Chemical transport models,Climate change,IMPACT2C project,Particulate matter}, pages = {129--140}, title = {{Particulate matter air pollution in Europe in a +2 °C warming world}}, volume = {154}, year = {2017} } @article{ISI:000375683200011, abstract = {A 2-degree global warming is likely to affect the production, deposition, and transport of air pollutants, leading to impacts on air quality and health. In the present study we use an ensemble of four regional chemistry-transport models, driven by meteorological data from different climate models, to assess such changes and their uncertainties for PM2.5 and SOMO35. Changes and uncertainties are compared to the inter-model variability. We find that the impact of regional climate change on PM2.5, averaged over the model ensemble, ranges from −0.5 $\mu$g.m−3 to +1.3 $\mu$g.m−3 over Europe. It mainly results from changes in natural and biogenic emissions, such as desert dust, sea salt and biogenic VOCs. Statistically significant decreases in PM2.5 are found over southwestern Russia and Ukraine as well as an increase over Southern Spain. Modeled changes in summer ozone levels range from −1.7 to 1.6 ppbv. We find a smaller ensemble-mean evolution of SOMO35 as compared to inter-model variability. We also investigate the uncertainty due to inter-decadal variability and find that 10-year periods may not be sufficient to allow the detection of statistically significant change signals.}, author = {Lacressonni{\`{e}}re, Gwendoline and Foret, Gilles and Beekmann, Matthias and Siour, Guillaume and Engardt, Magnuz and Gauss, Michael and Watson, Laura and Andersson, Camilla and Colette, Augustin and Josse, B{\'{e}}atrice and Mar{\'{e}}cal, Virginie and Nyiri, Agnes and Vautard, Robert}, doi = {10.1007/s10584-016-1619-z}, issn = {15731480}, journal = {Climatic Change}, number = {2}, pages = {309--324}, title = {{Impacts of regional climate change on air quality projections and associated uncertainties}}, url = {https://doi.org/10.1007/s10584-016-1619-z}, volume = {136}, year = {2016} } @article{Laj2020a, abstract = {Aerosol particles are essential constituents of the Earth's atmosphere, impacting the earth radiation balance directly by scattering and absorbing solar radiation, and indirectly by acting as cloud condensation nuclei. In contrast to most greenhouse gases, aerosol particles have short atmospheric residence times, resulting in a highly heterogeneous distribution in space and time. There is a clear need to document this variability at regional scale through observations involving, in particular, the in situ near-surface segment of the atmospheric observation system. This paper will provide the widest effort so far to document variability of climate-relevant in situ aerosol properties (namely wavelength dependent particle light scattering and absorption coefficients, particle number concentration and particle number size distribution) from all sites connected to the Global Atmosphere Watch network. High-quality data from almost 90 stations worldwide have been collected and controlled for quality and are reported for a reference year in 2017, providing a very extended and robust view of the variability of these variables worldwide. The range of variability observed worldwide for light scattering and absorption coefficients, single-scattering albedo, and particle number concentration are presented together with preliminary information on their long-term trends and comparison with model simulation for the different stations. The scope of the present paper is also to provide the necessary suite of information, including data provision procedures, quality control and analysis, data policy, and usage of the ground-based aerosol measurement network. It delivers to users of the World Data Centre on Aerosol, the required confidence in data products in the form of a fully characterized value chain, including uncertainty estimation and requirements for contributing to the global climate monitoring system.}, author = {Laj, Paolo and Bigi, Alessandro and Rose, Clemence and Andrews, Elisabeth and {Lund Myhre}, Cathrine and {Collaud Coen}, Martine and Lin, Yong and Wiedensohler, Alfred and Schulz, Michael and {A. Ogren}, John and Fiebig, Markus and Gli{\ss}, Jonas and Mortier, Augustin and Pandolfi, Marco and Pet{\"{a}}ja, Tuukka and Kim, Sang Woo and Aas, Wenche and Putaud, Jean Philippe and Mayol-Bracero, Olga and Keywood, Melita and Labrador, Lorenzo and Aalto, Pasi and Ahlberg, Erik and {Alados Arboledas}, Lucas and Alastuey, Andres and Andrade, Marcos and Artinano, Begona and Ausmeel, Stina and Arsov, Todor and Asmi, Eija and Backman, John and Baltensperger, Urs and Bastian, Susanne and Bath, Olaf and {Paul Beukes}, Johan and {T. Brem}, Benjamin and Bukowiecki, Nicolas and Conil, Sebastien and Couret, Cedric and Day, Derek and Dayantolis, Wan and Degorska, Anna and Eleftheriadis, Konstantinos and Fetfatzis, Prodromos and Favez, Olivier and Flentje, Harald and {I. Gini}, Maria and Gregori{\v{c}}, Asta and Gysel-Beer, Martin and {Gannet Hallar}, A. and Hand, Jenny and Hoffer, Andras and Hueglin, Christoph and {K. Hooda}, Rakesh and Hyv{\"{a}}rinen, Antti and Kalapov, Ivo and Kalivitis, Nikos and Kasper-Giebl, Anne and {Eun Kim}, Jeong and Kouvarakis, Giorgos and Kranjc, Irena and Krejci, Radovan and Kulmala, Markku and Labuschagne, Casper and Lee, Hae Jung and Lihavainen, Heikki and Lin, Neng Huei and L{\"{o}}schau, Gunter and Luoma, Krista and Marinoni, Angela and {Martins Dos Santos}, Sebastiao and Meinhardt, Frank and Merkel, Maik and Metzger, Jean Marc and Mihalopoulos, Nikolaos and {Anh Nguyen}, Nhat and Ondracek, Jakub and P{\'{e}}rez, Noemi and {Rita Perrone}, Maria and Pichon, Jean Marc and Picard, David and Pichon, Jean Marc and Pont, Veronique and Prats, Natalia and Prenni, Anthony and Reisen, Fabienne and Romano, Salvatore and Sellegri, Karine and Sharma, Sangeeta and Schauer, Gerhard and Sheridan, Patrick and {Patrick Sherman}, James and Sch{\"{u}}tze, Maik and Schwerin, Andreas and Sohmer, Ralf and Sorribas, Mar and Steinbacher, Martin and Sun, Junying and Titos, Gloria and Toczko, Barbara and Tuch, Thomas and Tulet, Pierre and Tunved, Peter and Vakkari, Ville and Velarde, Fernando and Velasquez, Patricio and Villani, Paolo and Vratolis, Sterios and Wang, Sheng Hsiang and Weinhold, Kay and Weller, Rolf and Yela, Margarita and Yus-Diez, Jesus and Zdimal, Vladimir and Zieger, Paul and Zikova, Nadezda}, doi = {10.5194/amt-13-4353-2020}, issn = {18678548}, journal = {Atmospheric Measurement Techniques}, month = {aug}, number = {8}, pages = {4353--4392}, publisher = {Copernicus GmbH}, title = {{A global analysis of climate-relevant aerosol properties retrieved from the network of Global Atmosphere Watch (GAW) near-surface observatories}}, url = {https://amt.copernicus.org/articles/13/4353/2020/}, volume = {13}, year = {2020} } @article{Lamarque2013, abstract = {Abstract. The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) consists of a series of time slice experiments targeting the long-term changes in atmospheric composition between 1850 and 2100, with the goal of documenting composition changes and the associated radiative forcing. In this overview paper, we introduce the ACCMIP activity, the various simulations performed (with a requested set of 14) and the associated model output. The 16 ACCMIP models have a wide range of horizontal and vertical resolutions, vertical extent, chemistry schemes and interaction with radiation and clouds. While anthropogenic and biomass burning emissions were specified for all time slices in the ACCMIP protocol, it is found that the natural emissions are responsible for a significant range across models, mostly in the case of ozone precursors. The analysis of selected present-day climate diagnostics (precipitation, temperature, specific humidity and zonal wind) reveals biases consistent with state-of-the-art climate models. The model-to-model comparison of changes in temperature, specific humidity and zonal wind between 1850 and 2000 and between 2000 and 2100 indicates mostly consistent results. However, models that are clear outliers are different enough from the other models to significantly affect their simulation of atmospheric chemistry.}, author = {Lamarque, J.-F. and Shindell, D. T. and Josse, B. and Young, P. J. and Cionni, I. and Eyring, V. and Bergmann, D. and Cameron-Smith, P. and Collins, W. J. and Doherty, R. and Dalsoren, S. and Faluvegi, G. and Folberth, G. and Ghan, S. J. and Horowitz, L. W. and Lee, Y. H. and MacKenzie, I. A. and Nagashima, T. and Naik, V. and Plummer, D. and Righi, M. and Rumbold, S. T. and Schulz, M. and Skeie, R. B. and Stevenson, D. S. and Strode, S. and Sudo, K. and Szopa, S. and Voulgarakis, A. and Zeng, G.}, doi = {10.5194/gmd-6-179-2013}, isbn = {1991-9603}, issn = {1991-9603}, journal = {Geoscientific Model Development}, month = {feb}, number = {1}, pages = {179--206}, title = {{The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): overview and description of models, simulations and climate diagnostics}}, url = {https://gmd.copernicus.org/articles/6/179/2013/}, volume = {6}, year = {2013} } @article{Lamarque2013a, abstract = {We present multi-model global datasets of nitrogen and sulfate deposition covering time periods from 1850 to 2100, calculated within the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The computed deposition fluxes are compared to surface wet deposition and ice core measurements. We use a new dataset of wet deposition for 2000–2002 based on critical assessment of the quality of existing regional network data. We show that for present day (year 2000 ACCMIP time slice), the ACCMIP results perform similarly to previously published multi-model assessments. For this time slice, we find a multi-model mean deposition of approximately 50 Tg(N) yr−1 from nitrogen oxide emissions, 60 Tg(N) yr−1 from ammonia emissions, and 83 Tg(S) yr−1 from sulfur emissions. The analysis of changes between 1980 and 2000 indicates significant differences between model and measurements over the United States but less so over Europe. This difference points towards a potential misrepresentation of 1980 NH3 emissions over North America. Based on ice core records, the 1850 deposition fluxes agree well with Greenland ice cores, but the change between 1850 and 2000 seems to be overestimated in the Northern Hemisphere for both nitrogen and sulfur species. Using the Representative Concentration Pathways (RCPs) to define the projected climate and atmospheric chemistry related emissions and concentrations, we find large regional nitrogen deposition increases in 2100 in Latin America, Africa and parts of Asia under some of the scenarios considered. Increases in South Asia are especially large, and are seen in all scenarios, with 2100 values more than double their 2000 counterpart in some scenarios and reaching {\textgreater} 1300 mg(N) m−2 yr−1 averaged over regional to continental-scale regions in RCP 2.6 and 8.5, {\~{}} 30–50{\%} larger than the values in any region currently (circa 2000). However, sulfur deposition rates in 2100 are in all regions lower than in 2000 in all the RCPs. The new ACCMIP multi-model deposition dataset provides state-of-the-science, consistent and evaluated time slice (spanning 1850–2100) global gridded deposition fields for use in a wide range of climate and ecological studies.}, author = {Lamarque, J.-F. and Dentener, F. and McConnell, J. and Ro, C.-U. and Shaw, M. and Vet, R. and Bergmann, D. and Cameron-Smith, P. and Dalsoren, S. and Doherty, R. and Faluvegi, G. and Ghan, S. J. and Josse, B. and Lee, Y. H. and MacKenzie, I. A. and Plummer, D. and Shindell, D. T. and Skeie, R. B. and Stevenson, D. S. and Strode, S. and Zeng, G. and Curran, M. and Dahl-Jensen, D. and Das, S. and Fritzsche, D. and Nolan, M.}, doi = {10.5194/acp-13-7997-2013}, isbn = {1680-7324}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {aug}, number = {16}, pages = {7997--8018}, publisher = {Copernicus Publications}, title = {{Multi-model mean nitrogen and sulfur deposition from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): evaluation of historical and projected future changes}}, url = {https://acp.copernicus.org/articles/13/7997/2013/}, volume = {13}, year = {2013} } @article{acp-10-7017-2010, abstract = {Abstract. We present and discuss a new dataset of gridded emissions covering the historical period (1850–2000) in decadal increments at a horizontal resolution of 0.5° in latitude and longitude. The primary purpose of this inventory is to provide consistent gridded emissions of reactive gases and aerosols for use in chemistry model simulations needed by climate models for the Climate Model Intercomparison Program {\#}5 (CMIP5) in support of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment report (AR5). Our best estimate for the year 2000 inventory represents a combination of existing regional and global inventories to capture the best information available at this point; 40 regions and 12 sectors are used to combine the various sources. The historical reconstruction of each emitted compound, for each region and sector, is then forced to agree with our 2000 estimate, ensuring continuity between past and 2000 emissions. Simulations from two chemistry-climate models are used to test the ability of the emission dataset described here to capture long-term changes in atmospheric ozone, carbon monoxide and aerosol distributions. The simulated long-term change in the Northern mid-latitudes surface and mid-troposphere ozone is not quite as rapid as observed. However, stations outside this latitude band show much better agreement in both present-day and long-term trend. The model simulations indicate that the concentration of carbon monoxide is underestimated at the Mace Head station; however, the long-term trend over the limited observational period seems to be reasonably well captured. The simulated sulfate and black carbon deposition over Greenland is in very good agreement with the ice-core observations spanning the simulation period. Finally, aerosol optical depth and additional aerosol diagnostics are shown to be in good agreement with previously published estimates and observations.}, author = {Lamarque, J.-F. and Bond, T. C. and Eyring, V. and Granier, C. and Heil, A. and Klimont, Z. and Lee, D. and Liousse, C. and Mieville, A. and Owen, B. and Schultz, M. G. and Shindell, D. and Smith, S. J. and Stehfest, E. and {Van Aardenne}, J. and Cooper, O. R. and Kainuma, M. and Mahowald, N. and McConnell, J. R. and Naik, V. and Riahi, K. and van Vuuren, D. P.}, doi = {10.5194/acp-10-7017-2010}, file = {::}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {aug}, number = {15}, pages = {7017--7039}, title = {{Historical (1850–2000) gridded anthropogenic and biomass burning emissions of reactive gases and aerosols: methodology and application}}, url = {https://www.atmos-chem-phys.net/10/7017/2010/ https://acp.copernicus.org/articles/10/7017/2010/}, volume = {10}, year = {2010} } @article{Lamsal2015, author = {Lamsal, Lok N and Duncan, Bryan N and Yoshida, Yasuko and Krotkov, Nickolay A and Pickering, Kenneth E and Streets, David G and Lu, Zifeng}, doi = {https://doi.org/10.1016/j.atmosenv.2015.03.055}, isbn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Air quality,Aura OMI,Nitrogen dioxide,Trend,Troposphere}, pages = {130--143}, title = {{U.S. NO2 trends (2005–2013): EPA Air Quality System (AQS) data versus improved observations from the Ozone Monitoring Instrument (OMI)}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231015002794}, volume = {110}, year = {2015} } @article{Lana2011, abstract = {The potentially significant role of the biogenic trace gas dimethylsulfide (DMS) in determining the Earth's radiation budget makes it necessary to accurately reproduce seawater DMS distribution and quantify its global flux across the sea/air interface. Following a threefold increase of data (from 15,000 to over 47,000) in the global surface ocean DMS database over the last decade, new global monthly climatologies of surface ocean DMS concentration and sea-to-air emission flux are presented as updates of those constructed 10 years ago. Interpolation/extrapolation techniques were applied to project the discrete concentration data onto a first guess field based on Longhurst's biogeographic provinces. Further objective analysis allowed us to obtain the final monthly maps. The new climatology projects DMS concentrations typically in the range of 1?7 nM, with higher levels occurring in the high latitudes, and with a general trend toward increasing concentration in summer. The increased size and distribution of the observations in the DMS database have produced in the new climatology substantially lower DMS concentrations in the polar latitudes and generally higher DMS concentrations in regions that were severely undersampled 10 years ago, such as the southern Indian Ocean. Using the new DMS concentration climatology in conjunction with state-of-the-art parameterizations for the sea/air gas transfer velocity and climatological wind fields, we estimate that 28.1 (17.6?34.4) Tg of sulfur are transferred from the oceans into the atmosphere annually in the form of DMS. This represents a global emission increase of 17{\%} with respect to the equivalent calculation using the previous climatology. This new DMS climatology represents a valuable tool for atmospheric chemistry, climate, and Earth System models.}, annote = {doi: 10.1029/2010GB003850}, author = {Lana, A and Bell, T G and Sim{\'{o}}, R and Vallina, S M and Ballabrera-Poy, J and Kettle, A J and Dachs, J and Bopp, L and Saltzman, E S and Stefels, J and Johnson, J E and Liss, P S}, doi = {10.1029/2010GB003850}, issn = {0886-6236}, journal = {Global Biogeochemical Cycles}, keywords = {dimethylsulfide,global DMS emission flux,ocean DMS climatology}, month = {mar}, number = {1}, pages = {GB1004}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{An updated climatology of surface dimethlysulfide concentrations and emission fluxes in the global ocean}}, url = {https://doi.org/10.1029/2010GB003850}, volume = {25}, year = {2011} } @article{Landry2015a, abstract = {Changes in the current fire regime would directly affect carbon cycling, land–atmosphere exchanges, and atmospheric composition, and could therefore modulate the ongoing climate warming. We used a coupled climate–carbon model to quantify the effect of major changes in non-deforestation fires on the global carbon cycle and temperature, from 2015 to 2300. When considering only CO2 fire emissions, the impacts from changes in fire frequency were limited for the global carbon cycle, and almost negligible for the global atmospheric surface temperature. The net fire emissions were only a fraction of the CO2 directly emitted during combustion due to vegetation regrowth and climate–CO2 feedbacks, and the albedo increases caused by changes in vegetation cover countered the effect of increased atmospheric CO2 on global temperature. When employing a simplified approach based on global-mean radiative forcings in order to estimate the impact of non-CO2 fire emissions, the effect of increased fire frequency on global temperature depended critically on the uncertain net aerosol forcing. Despite this major uncertainty, our results overall do not support the hypothesis of a strong positive climate–fire feedback for the coming centuries.}, author = {Landry, Jean-S{\'{e}}bastien and Matthews, H Damon and Ramankutty, Navin}, doi = {10.1007/s10584-015-1461-8}, issn = {1573-1480}, journal = {Climatic Change}, number = {2}, pages = {179--192}, title = {{A global assessment of the carbon cycle and temperature responses to major changes in future fire regime}}, volume = {133}, year = {2015} } @article{Languille2020, abstract = {Wood burning is widely used for domestic heating and has been identified as a ubiquitous pollution source in urban areas, especially during cold months. The present study is based on a three and a half winter months field campaign in the Paris region measuring Volatile Organic Compounds (VOCs) by Proton Transfer Reaction Mass Spectrometry (PTR-MS) in addition to Black Carbon (BC). Several VOCs were identified as strongly wood burning-influenced (e.g., acetic acid, furfural), or traffic-influenced (e.g., toluene, C8-aromatics). Methylbutenone, benzenediol and butandione were identified for the first time as wood burning-related in ambient air. A Positive Matrix Factorization (PMF) analysis highlighted that wood burning is the most important source of VOCs during the winter season. (47{\%}). Traffic was found to account for about 22{\%} of the measured VOCs during the same period, whereas solvent use plus background accounted altogether for the remaining fraction. The comparison with the regional emission inventory showed good consistency for benzene and xylenes but revisions of the inventory should be considered for several VOCs such as acetic acid, C9-aromatics and methanol. Finally, complementary measurements acquired simultaneously at other sites in {\^{I}}le-de-France (the Paris region) enabled evaluation of spatial variabilities. The influence of traffic emissions on investigated pollutants displayed a clear negative gradient from roadside to suburban stations, whereas wood burning pollution was found to be fairly homogeneous over the region.}, author = {Languille, Baptiste and Gros, Val{\'{e}}rie and Petit, Jean-Eudes and Honor{\'{e}}, C{\'{e}}cile and Baudic, Alexia and Perrussel, Olivier and Foret, Gilles and Michoud, Vincent and Truong, Fran{\c{c}}ois and Bonnaire, Nicolas and Sarda-Est{\`{e}}ve, Roland and Delmotte, Marc and Feron, Ana{\"{i}}s and Maisonneuve, Franck and Gaimoz, C{\'{e}}cile and Formenti, Paola and Kotthaus, Simone and Haeffelin, Martial and Favez, Olivier}, doi = {10.1016/j.scitotenv.2019.135055}, issn = {00489697}, journal = {Science of The Total Environment}, month = {apr}, pages = {135055}, pmid = {31810669}, title = {{Wood burning: A major source of Volatile Organic Compounds during wintertime in the Paris region}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0048969719350478}, volume = {711}, year = {2020} } @article{Latham2008, abstract = {An assessment is made herein of the proposal that controlled global cooling sufficient to balance global warming resulting from increasing atmospheric CO2 concentrations might be achieved by seeding low-level, extensive maritime clouds with seawater particles that act as cloud condensation nuclei, thereby activating new droplets and increasing cloud albedo (and possibly longevity). This paper focuses on scientific and meteorological aspects of the scheme. Associated technological issues are addressed in a companion paper. Analytical calculations, cloud modelling and (particularly) GCM computations suggest that, if outstanding questions are satisfactorily resolved, the controllable, globally averaged negative forcing resulting from deployment of this scheme might be sufficient to balance the positive forcing associated with a doubling of CO2 concentration. This statement is supported quantitatively by recent observational evidence from three disparate sources. We conclude that this technique could thus be adequate to hold the Earth's temperature constant for many decades. More work-especially assessments of possible meteorological and climatological ramifications-is required on several components of the scheme, which possesses the advantages that (i) it is ecologically benign-the only raw materials being wind and seawater, (ii) the degree of cooling could be controlled, and (iii) if unforeseen adverse effects occur, the system could be immediately switched off, with the forcing returning to normal within a few days (although the response would take a much longer time). {\textcopyright} 2008 The Royal Society.}, author = {Latham, John and Rasch, Philip and Chen, Chih Chieh and Kettles, Laura and Gadian, Alan and Gettelman, Andrew and Morrison, Hugh and Bower, Keith and Choularton, Tom}, doi = {10.1098/rsta.2008.0137}, issn = {1364503X}, journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences}, keywords = {Cloud albedo,Global cooling,Negative forcing,Seeding maritime clouds}, number = {1882}, pages = {3969--3987}, title = {{Global temperature stabilization via controlled albedo enhancement of low-level maritime clouds}}, volume = {366}, year = {2008} } @article{doi:10.1029/2009GB003548, abstract = {We describe the development and analysis of a global model based on Model of Emissions of Gases and Aerosols from Nature (MEGAN) (Guenther et al., 2006) for estimating isoprene emissions from terrestrial vegetation. The sensitivity of calculated isoprene emissions to descriptors including leaf age, soil moisture, atmospheric CO2 concentration, and regional variability of emission factors is analyzed. The validity of the results is evaluated by comparison with compilations of published field-based canopy-scale observations. Calculated isoprene emissions reproduce above-canopy flux measurements and the site-to-site variability across a wide range of latitudes, with the model explaining 60{\%} of the variance. Although the model underestimates isoprene emissions, especially in northern latitude localities, this disagreement is significantly corrected when regional variability of emission factors for particular plant functional types is considered (r2 = 0.78). At the global scale, we estimate a terrestrial biosphere isoprene flux of 413 TgC yr−1 using the present-day climate, atmospheric CO2 concentration, and vegetation distribution, and this compares with other published estimates from global modeling studies of 402 to 660 TgC yr−1. The validated model was used to calculate changes in isoprene emissions in response to atmospheric CO2 increase, climate change, and land use change during the 20th century (1901–2002). Changes in all of these factors are found to impact significantly on isoprene emissions over the course of the 20th century. Between 1901 and 2002, we estimate that at the global scale, climate change was responsible for a 7{\%} increase in isoprene emissions, and rising atmospheric CO2 caused a 21{\%} reduction. However, by the end of the 20th century (2002), anthropogenic cropland expansion has the largest impact reducing isoprene emissions by 15{\%}. Overall, these factors combined to cause a 24{\%} decrease in global isoprene emissions during the 20th century. It remains to be determined whether predicted 21st century warming and increased use of isoprene-emitting crops for biofuels (e.g., oil palm) will more than offset any future CO2 suppression of isoprene emission rates.}, author = {Lathi{\`{e}}re, J and Hewitt, C N and Beerling, D J}, doi = {10.1029/2009GB003548}, journal = {Global Biogeochemical Cycles}, keywords = {biogenic emissions,global change,isoprene}, number = {1}, pages = {GB1004}, title = {{Sensitivity of isoprene emissions from the terrestrial biosphere to 20th century changes in atmospheric CO2 concentration, climate, and land use}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2009GB003548}, volume = {24}, year = {2010} } @article{Lauer2007, abstract = {Abstract. International shipping contributes significantly to the fuel consumption of all transport related activities. Specific emissions of pollutants such as sulfur dioxide (SO2) per kg of fuel emitted are higher than for road transport or aviation. Besides gaseous pollutants, ships also emit various types of particulate matter. The aerosol impacts the Earth's radiation budget directly by scattering and absorbing the solar and thermal radiation and indirectly by changing cloud properties. Here we use ECHAM5/MESSy1-MADE, a global climate model with detailed aerosol and cloud microphysics to study the climate impacts of international shipping. The simulations show that emissions from ships significantly increase the cloud droplet number concentration of low marine water clouds by up to 5{\%} to 30{\%} depending on the ship emission inventory and the geographic region. Whereas the cloud liquid water content remains nearly unchanged in these simulations, effective radii of cloud droplets decrease, leading to cloud optical thickness increase of up to 5–10{\%}. The sensitivity of the results is estimated by using three different emission inventories for present-day conditions. The sensitivity analysis reveals that shipping contributes to 2.3{\%} to 3.6{\%} of the total sulfate burden and 0.4{\%} to 1.4{\%} to the total black carbon burden in the year 2000 on the global mean. In addition to changes in aerosol chemical composition, shipping increases the aerosol number concentration, e.g. up to 25{\%} in the size range of the accumulation mode (typically {\textgreater}0.1 $\mu$m) over the Atlantic. The total aerosol optical thickness over the Indian Ocean, the Gulf of Mexico and the Northeastern Pacific increases by up to 8–10{\%} depending on the emission inventory. Changes in aerosol optical thickness caused by shipping induced modification of aerosol particle number concentration and chemical composition lead to a change in the shortwave radiation budget at the top of the atmosphere (ToA) under clear-sky condition of about −0.014 W/m² to −0.038 W/m² for a global annual average. The corresponding all-sky direct aerosol forcing ranges between −0.011 W/m² and −0.013 W/m². The indirect aerosol effect of ships on climate is found to be far larger than previously estimated. An indirect radiative effect of −0.19 W/m² to −0.60 W/m² (a change in the atmospheric shortwave radiative flux at ToA) is calculated here, contributing 17{\%} to 39{\%} of the total indirect effect of anthropogenic aerosols. This contribution is high because ship emissions are released in regions with frequent low marine clouds in an otherwise clean environment. In addition, the potential impact of particulate matter on the radiation budget is larger over the dark ocean surface than over polluted regions over land.}, author = {Lauer, A. and Eyring, V. and Hendricks, J. and J{\"{o}}ckel, P. and Lohmann, U.}, doi = {10.5194/acp-7-5061-2007}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {oct}, number = {19}, pages = {5061--5079}, title = {{Global model simulations of the impact of ocean-going ships on aerosols, clouds, and the radiation budget}}, url = {https://acp.copernicus.org/articles/7/5061/2007/}, volume = {7}, year = {2007} } @article{Lauwaet2014, abstract = {{\textless}p{\textgreater}Abstract. Belgium is one of the areas within Europe experiencing the highest levels of air pollution. A high-resolution (3 km) modelling experiment is employed to provide guidance to policymakers about expected air quality changes in the near future (2026–2035). The regional air quality model AURORA (Air quality modelling in Urban Regions using an Optimal Resolution Approach), driven by output from a regional climate model, is used to simulate several 10-year time slices to investigate the impact of climatic changes and different emission scenarios on near-surface O3 concentrations, one of the key indices for air quality. Evaluation of the model against measurements from 34 observation stations shows that the AURORA model is capable of reproducing 10-year mean concentrations, daily cycles and spatial patterns. The results for the Representative Concentration Pathways (RCP)4.5 emission scenario indicate that the mean surface O3 concentrations are expected to increase significantly in the near future due to less O3 titration by reduced NOx emissions. Applying an alternative emission scenario for Europe is found to have only a minor impact on the overall concentrations, which are dominated by the background changes. Climate change alone has a much smaller effect on the near-surface O3 concentrations over Belgium than the projected emission changes. The very high horizontal resolution that is used in this study results in much improved spatial correlations and simulated peak concentrations compared to a standard 25 km simulation. An analysis of the number of peak episodes during summer revealed that the emission reductions in RCP4.5 result in a 25{\%} decrease of these peak episodes.{\textless}/p{\textgreater}}, author = {Lauwaet, D. and Viaene, P. and Brisson, E. and van Lipzig, N.P.M. and van Noije, T. and Strunk, A. and {Van Looy}, S. and Veldeman, N. and Blyth, L. and {De Ridder}, K. and Janssen, S.}, doi = {10.5194/acp-14-5893-2014}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jun}, number = {12}, pages = {5893--5904}, title = {{The effect of climate change and emission scenarios on ozone concentrations over Belgium: a high-resolution model study for policy support}}, url = {https://acp.copernicus.org/articles/14/5893/2014/}, volume = {14}, year = {2014} } @article{Lawrence2018, abstract = {Current mitigation efforts and existing future commitments are inadequate to accomplish the Paris Agreement temperature goals. In light of this, research and debate are intensifying on the possibilities of additionally employing proposed climate geoengineering technologies, either through atmospheric carbon dioxide removal or farther-reaching interventions altering the Earth's radiative energy budget. Although research indicates that several techniques may eventually have the physical potential to contribute to limiting climate change, all are in early stages of development, involve substantial uncertainties and risks, and raise ethical and governance dilemmas. Based on present knowledge, climate geoengineering techniques cannot be relied on to significantly contribute to meeting the Paris Agreement temperature goals.}, author = {Lawrence, Mark G. and Sch{\"{a}}fer, Stefan and Muri, Helene and Scott, Vivian and Oschlies, Andreas and Vaughan, Naomi E. and Boucher, Olivier and Schmidt, Hauke and Haywood, Jim and Scheffran, J{\"{u}}rgen}, doi = {10.1038/s41467-018-05938-3}, issn = {2041-1723}, journal = {Nature Communications}, month = {dec}, number = {1}, pages = {3734}, title = {{Evaluating climate geoengineering proposals in the context of the Paris Agreement temperature goals}}, url = {http://www.nature.com/articles/s41467-018-05938-3}, volume = {9}, year = {2018} } @article{Le2020, abstract = {The absence of motor vehicle traffic and suspended manufacturing during the coronavirus disease 2019 (COVID-19) pandemic in China enabled assessment of the efficiency of air pollution mitigation. Up to 90{\%} reduction of certain emissions during the city-lockdown period can be identified from satellite and ground-based observations. Unexpectedly, extreme particulate matter levels simultaneously occurred in northern China. Our synergistic observation analyses and model simulations show that anomalously high humidity promoted aerosol heterogeneous chemistry, along with stagnant airflow and uninterrupted emissions from power plants and petrochemical facilities, contributing to severe haze formation. Also, because of nonlinear production chemistry and titration of ozone in winter, reduced nitrogen oxides resulted in ozone enhancement in urban areas, further increasing the atmospheric oxidizing capacity and facilitating secondary aerosol formation.}, author = {Le, Tianhao and Wang, Yuan and Liu, Lang and Yang, Jiani and Yung, Yuk L and Li, Guohui and Seinfeld, John H}, doi = {10.1126/science.abb7431}, issn = {10959203}, journal = {Science}, month = {aug}, number = {6504}, pages = {702--706}, pmid = {32554754}, publisher = {American Association for the Advancement of Science}, title = {{Unexpected air pollution with marked emission reductions during the COVID-19 outbreak in China}}, url = {http://science.sciencemag.org/}, volume = {369}, year = {2020} } @article{LeQuere2020, abstract = {Government policies during the COVID-19 pandemic have drastically altered patterns of energy demand around the world. Many international borders were closed and populations were confined to their homes, which reduced transport and changed consumption patterns. Here we compile government policies and activity data to estimate the decrease in CO2 emissions during forced confinements. Daily global CO2 emissions decreased by –17{\%} (–11 to –25{\%} for ±1{\$}\sigma{\$}) by early April 2020 compared with the mean 2019 levels, just under half from changes in surface transport. At their peak, emissions in individual countries decreased by –26{\%} on average. The impact on 2020 annual emissions depends on the duration of the confinement, with a low estimate of –4{\%} (–2 to –7{\%}) if prepandemic conditions return by mid-June, and a high estimate of –7{\%} (–3 to –13{\%}) if some restrictions remain worldwide until the end of 2020. Government actions and economic incentives postcrisis will likely influence the global CO2 emissions path for decades.}, author = {{Le Qu{\'{e}}r{\'{e}}}, Corinne and Jackson, Robert B and Jones, Matthew W and Smith, Adam J P and Abernethy, Sam and Andrew, Robbie M and De-Gol, Anthony J and Willis, David R and Shan, Yuli and Canadell, Josep G and Friedlingstein, Pierre and Creutzig, Felix and Peters, Glen P}, doi = {10.1038/s41558-020-0797-x}, journal = {Nature Climate Change}, month = {jul}, number = {7}, pages = {647--653}, publisher = {Nature Research}, title = {{Temporary reduction in daily global CO2 emissions during the COVID-19 forced confinement}}, volume = {10}, year = {2020} } @article{Lee2016a, abstract = {We have investigated how future air quality and climate change are influenced by the US air quality regulations that existed or were proposed in 2013 and a hypothetical climate mitigation policy that aims to reduce 2050 CO2 emissions to be 50 {\%} below 2005 emissions. Using the NASA GISS ModelE2 general circulation model, we look at the impacts for year 2030 and 2055. The US energy-sector emissions are from the GLIMPSE project (GEOS-Chem LIDORT Integrated with MARKAL (MARKet ALlocation) for the Purpose of Scenario Exploration), and other US emissions data sets and the rest of the world emissions data sets are based on the RCP4.5 scenario. The US air quality regulations are projected to have a strong beneficial impact on US air quality and public health in year 2030 and 2055 but result in positive radiative forcing. Under this scenario, no more emission constraints are added after 2020, and the impacts on air quality and climate change are similar between year 2030 and 2055. Surface particulate matter with a diameter smaller than 2.5 µm (PM2.5) is reduced by ∼ 2 µg m−3 on average over the USA, and surface ozone by ∼ 8 ppbv. The improved air quality prevents about 91 400 premature deaths in the USA, mainly due to the PM2.5 reduction (∼ 74 200 lives saved). The air quality regulations reduce the light-reflecting aerosols (i.e., sulfate and organic matter) more than the light-absorbing species (i.e., black carbon and ozone), leading to a strong positive radiative forcing (RF) over the USA by both aerosols' direct and indirect forcing: the total RF is ∼ 0.04 W m−2 over the globe, and ∼ 0.8 W m−2 over the USA. Under the hypothetical climate policy, a future CO2 emissions cut is achieved in part by relying less on coal, and thus SO2 emissions are noticeably reduced. This provides air quality co-benefits, but it could lead to potential climate disbenefits over the USA. In 2055, the US mean total RF is +0.22 W m−2 due to positive aerosol direct and indirect forcing, while the global mean total RF is −0.06 W m−2 due to the dominant negative CO2 RF (instantaneous RF). To achieve a regional-scale climate benefit via a climate policy, it is critical (1) to have multinational efforts to reduce greenhouse gas (GHG) emissions and (2) to simultaneously target emission reduction of light-absorbing species (e.g., BC and O3) on top of long-lived species. The latter is very desirable as the resulting climate benefit occurs faster and provides co-benefits to air quality and public health.}, author = {Lee, Yunha and Shindell, Drew T. and Faluvegi, Greg and Pinder, Rob W.}, doi = {10.5194/acp-16-5323-2016}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {8}, pages = {5323--5342}, title = {{Potential impact of a US climate policy and air quality regulations on future air quality and climate change}}, volume = {16}, year = {2016} } @article{Lee2013, abstract = {As part of the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), we evaluate the historical black carbon (BC) aerosols simulated by 8 ACCMIP models against observations including 12 ice core records, long-term surface mass concentrations, and recent Arctic BC snowpack measurements. We also estimate BC albedo forcing by performing additional simulations using offline models with prescribed meteorology from 1996–2000. We evaluate the vertical profile of BC snow concentrations from these offline simulations using the recent BC snowpack measurements. Despite using the same BC emissions, the global BC burden differs by approximately a factor of 3 among models due to differences in aerosol removal parameterizations and simulated meteorology: 34 Gg to 103 Gg in 1850 and 82 Gg to 315 Gg in 2000. However, the global BC burden from preindustrial to present-day increases by 2.5–3 times with little variation among models, roughly matching the 2.5-fold increase in total BC emissions during the same period. We find a large divergence among models at both Northern Hemisphere (NH) and Southern Hemisphere (SH) high latitude regions for BC burden and at SH high latitude regions for deposition fluxes. The ACCMIP simulations match the observed BC surface mass concentrations well in Europe and North America except at Ispra. However, the models fail to predict the Arctic BC seasonality due to severe underestimations during winter and spring. The simulated vertically resolved BC snow concentrations are, on average, within a factor of 2–3 of the BC snowpack measurements except for Greenland and the Arctic Ocean. For the ice core evaluation, models tend to adequately capture both the observed temporal trends and the magnitudes at Greenland sites. However, models fail to predict the decreasing trend of BC depositions/ice core concentrations from the 1950s to the 1970s in most Tibetan Plateau ice cores. The distinct temporal trend at the Tibetan Plateau ice cores indicates a strong influence from Western Europe, but the modeled BC increases in that period are consistent with the emission changes in Eastern Europe, the Middle East, South and East Asia. At the Alps site, the simulated BC suggests a strong influence from Europe, which agrees with the Alps ice core observations. At Zuoqiupu on the Tibetan Plateau, models successfully simulate the higher BC concentrations observed during the non-monsoon season compared to the monsoon season but overpredict BC in both seasons. Despite a large divergence in BC deposition at two Antarctic ice core sites, some models with a BC lifetime of less than 7 days are able to capture the observed concentrations. In 2000 relative to 1850, globally and annually averaged BC surface albedo forcing from the offline simulations ranges from 0.014 to 0.019 W m−2 among the ACCMIP models. Comparing offline and online BC albedo forcings computed by some of the same models, we find that the global annual mean can vary by up to a factor of two because of different aerosol models or different BC-snow parameterizations and snow cover. The spatial distributions of the offline BC albedo forcing in 2000 show especially high BC forcing (i.e., over 0.1 W m−2) over Manchuria, Karakoram, and most of the Former USSR. Models predict the highest global annual mean BC forcing in 1980 rather than 2000, mostly driven by the high fossil fuel and biofuel emissions in the Former USSR in 1980.}, author = {Lee, Y. H. and Lamarque, J. F. and Flanner, M. G. and Jiao, C. and Shindell, D. T. and Berntsen, T. and Bisiaux, M. M. and Cao, J. and Collins, W. J. and Curran, M. and Edwards, R. and Faluvegi, G. and Ghan, S. and Horowitz, Lw and McConnell, J. R. and Ming, J. and Myhre, G. and Nagashima, T. and Naik, V. and Rumbold, S. T. and Skeie, R. B. and Sudo, K. and Takemura, T. and Thevenon, F. and Xu, B. and Yoon, J. H.}, doi = {10.5194/acp-13-2607-2013}, isbn = {1326072013}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {5}, pages = {2607--2634}, title = {{Evaluation of preindustrial to present-day black carbon and its albedo forcing from Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)}}, volume = {13}, year = {2013} } @article{Lee2020, author = {Lee, D.S. and Fahey, D.W. and Skowron, A. and Allen, M.R. and Burkhardt, U. and Chen, Q. and Doherty, S.J. and Freeman, S. and Forster, P.M. and Fuglestvedt, J. and Gettelman, A. and {De Le{\'{o}}n}, R.R. and Lim, L.L. and Lund, M.T. and Millar, R.J. and Owen, B. and Penner, J.E. and Pitari, G. and Prather, M.J. and Sausen, R. and Wilcox, L.J.}, doi = {10.1016/j.atmosenv.2020.117834}, issn = {13522310}, journal = {Atmospheric Environment}, month = {jan}, pages = {117834}, title = {{The contribution of global aviation to anthropogenic climate forcing for 2000 to 2018}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1352231020305689}, volume = {244}, year = {2021} } @article{Lehtipalo2018, abstract = {A major fraction of atmospheric aerosol particles, which affect both air quality and climate, form from gaseous precursors in the atmosphere. Highly oxygenated organic molecules (HOMs), formed by oxidation of biogenic volatile organic compounds, are known to participate in particle formation and growth. However, it is not well understood how they interact with atmospheric pollutants, such as nitrogen oxides (NOx) and sulfur oxides (SOx) from fossil fuel combustion, as well as ammonia (NH3) from livestock and fertilizers. Here, we show how NOx suppresses particle formation, while HOMs, sulfuric acid, and NH3 have a synergistic enhancing effect on particle formation. We postulate a novel mechanism, involving HOMs, sulfuric acid, and ammonia, which is able to closely reproduce observations of particle formation and growth in daytime boreal forest and similar environments. The findings elucidate the complex interactions between biogenic and anthropogenic vapors in the atmospheric aerosol system.}, author = {Lehtipalo, Katrianne and Yan, Chao and Dada, Lubna and Bianchi, Federico and Xiao, Mao and Wagner, Robert and Stolzenburg, Dominik and Ahonen, Lauri R and Amorim, Antonio and Baccarini, Andrea and Bauer, Paulus S and Baumgartner, Bernhard and Bergen, Anton and Bernhammer, Anne-Kathrin and Breitenlechner, Martin and Brilke, Sophia and Buchholz, Angela and Mazon, Stephany Buenrostro and Chen, Dexian and Chen, Xuemeng and Dias, Antonio and Dommen, Josef and Draper, Danielle C and Duplissy, Jonathan and Ehn, Mikael and Finkenzeller, Henning and Fischer, Lukas and Frege, Carla and Fuchs, Claudia and Garmash, Olga and Gordon, Hamish and Hakala, Jani and He, Xucheng and Heikkinen, Liine and Heinritzi, Martin and Helm, Johanna C and Hofbauer, Victoria and Hoyle, Christopher R and Jokinen, Tuija and Kangasluoma, Juha and Kerminen, Veli-Matti and Kim, Changhyuk and Kirkby, Jasper and Kontkanen, Jenni and K{\"{u}}rten, Andreas and Lawler, Michael J and Mai, Huajun and Mathot, Serge and Mauldin, Roy L and Molteni, Ugo and Nichman, Leonid and Nie, Wei and Nieminen, Tuomo and Ojdanic, Andrea and Onnela, Antti and Passananti, Monica and Pet{\"{a}}j{\"{a}}, Tuukka and Piel, Felix and Pospisilova, Veronika and Qu{\'{e}}l{\'{e}}ver, Lauriane L J and Rissanen, Matti P and Rose, Cl{\'{e}}mence and Sarnela, Nina and Schallhart, Simon and Schuchmann, Simone and Sengupta, Kamalika and Simon, Mario and Sipil{\"{a}}, Mikko and Tauber, Christian and Tom{\'{e}}, Ant{\'{o}}nio and Tr{\"{o}}stl, Jasmin and V{\"{a}}is{\"{a}}nen, Olli and Vogel, Alexander L and Volkamer, Rainer and Wagner, Andrea C and Wang, Mingyi and Weitz, Lena and Wimmer, Daniela and Ye, Penglin and Ylisirni{\"{o}}, Arttu and Zha, Qiaozhi and Carslaw, Kenneth S and Curtius, Joachim and Donahue, Neil M and Flagan, Richard C and Hansel, Armin and Riipinen, Ilona and Virtanen, Annele and Winkler, Paul M and Baltensperger, Urs and Kulmala, Markku and Worsnop, Douglas R}, doi = {10.1126/sciadv.aau5363}, file = {::}, journal = {Science Advances}, month = {dec}, number = {12}, pages = {eaau5363}, title = {{Multicomponent new particle formation from sulfuric acid, ammonia, and biogenic vapors}}, url = {http://advances.sciencemag.org/content/4/12/eaau5363.abstract}, volume = {4}, year = {2018} } @article{Lelieveld20141937, annote = {cited By 29}, author = {Lelieveld, J and Hadjinicolaou, P and Kostopoulou, E and Giannakopoulos, C and Pozzer, A and Tanarhte, M and Tyrlis, E}, doi = {10.1007/s10113-013-0444-4}, journal = {Regional Environmental Change}, number = {5}, pages = {1937--1949}, title = {{Model projected heat extremes and air pollution in the eastern Mediterranean and Middle East in the twenty-first century}}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84907698799{\&}doi=10.1007{\%}2Fs10113-013-0444-4{\&}partnerID=40{\&}md5=81d477e329d67fbf446e5c80063ab6a3}, volume = {14}, year = {2014} } @article{Lelieveld2015a, abstract = {Nitrogen oxides, released from fossil fuel use and other combustion processes, affect air quality and climate. From the mid-1990s onward, nitrogen dioxide (NO2) has been monitored from space, and since 2004 with relatively high spatial resolution by the Ozone Monitoring Instrument. Strong upward NO2 trends have been observed over South and East Asia and the Middle East, in particular over major cities. We show, however, that a combination of air quality control and political factors, including economical crisis and armed conflict, has drastically altered the emission landscape of nitrogen oxides in the Middle East. Large changes, including trend reversals, have occurred since about 2010 that could not have been predicted and therefore are at odds with emission scenarios used in projections of air pollution and climate change in the early 21st century.}, author = {Lelieveld, Jos and Beirle, Steffen and H{\"{o}}rmann, Christoph and Stenchikov, Georgiy and Wagner, Thomas}, doi = {10.1126/sciadv.1500498}, journal = {Science Advances}, number = {7}, pages = {e1500498}, title = {{Abrupt recent trend changes in atmospheric nitrogen dioxide over the Middle East}}, url = {http://advances.sciencemag.org/content/1/7/e1500498.abstract}, volume = {1}, year = {2015} } @article{Lelieveld2016, abstract = {The self-cleaning or oxidation capacity of the atmosphere is principally controlled by hydroxyl (OH) radicals in the troposphere. Hydroxyl has primary (P) and secondary (S) sources, the former mainly through the photodissociation of ozone, the latter through OH recycling in radical reaction chains. We used the recent Mainz Organics Mechanism (MOM) to advance volatile organic carbon (VOC) chemistry in the general circulation model EMAC (ECHAM/MESSy Atmospheric Chemistry) and show that S is larger than previously assumed. By including emissions of a large number of primary VOC, and accounting for their complete breakdown and intermediate products, MOM is mass-conserving and calculates substantially higher OH reactivity from VOC oxidation compared to predecessor models. Whereas previously P and S were found to be of similar magnitude, the present work indicates that S may be twice as large, mostly due to OH recycling in the free troposphere. Further, we find that nighttime OH formation may be significant in the polluted subtropical boundary layer in summer. With a mean OH recycling probability of about 67 {\%}, global OH is buffered and not sensitive to perturbations by natural or anthropogenic emission changes. Complementary primary and secondary OH formation mechanisms in pristine and polluted environments in the continental and marine troposphere, connected through long-range transport of O3, can maintain stable global OH levels.}, annote = {Times Cited: 33 Gromov, Sergey/G-1224-2013; Taraborrelli, Domenico/O-8668-2015; Pozzer, Andrea/L-4872-2013; Lelieveld, Johannes/A-1986-2013 Gromov, Sergey/0000-0002-2542-3005; Taraborrelli, Domenico/0000-0003-2213-6307; Pozzer, Andrea/0000-0003-2440-6104; Lelieveld, Johannes/0000-0001-6307-3846 0 33 1680-7324}, author = {Lelieveld, Jos and Gromov, Sergey and Pozzer, Andrea and Taraborrelli, Domenico}, doi = {10.5194/acp-16-12477-2016}, isbn = {1680-7316}, journal = {Atmospheric Chemistry and Physics}, number = {19}, pages = {12477--12493}, title = {{Global tropospheric hydroxyl distribution, budget and reactivity}}, volume = {16}, year = {2016} } @article{lelieveld2017clean, abstract = {In atmospheric chemistry, interactions between air pollution, the biosphere and human health, often through reaction mixtures from both natural and anthropogenic sources, are of growing interest. Massive pollution emissions in the Anthropocene have transformed atmospheric composition to the extent that biogeochemical cycles, air quality and climate have changed globally and partly profoundly. It is estimated that mortality attributable to outdoor air pollution amounts to 4.33 million individuals per year, associated with 123 million years of life lost. Worldwide, air pollution is the major environmental risk factor to human health, and strict air quality standards have the potential to strongly reduce morbidity and mortality. Preserving clean air should be considered a human right, and is fundamental to many sustainable development goals of the United Nations, such as good health, climate action, sustainable cities, clean energy, and protecting life on land and in the water. It would be appropriate to adopt “clean air” as a sustainable development goal.}, author = {Lelieveld, Jos}, doi = {10.1039/c7fd90032e}, issn = {1359-6640}, journal = {Faraday Discussions}, pages = {693--703}, publisher = {The Royal Society of Chemistry}, title = {{Clean air in the Anthropocene}}, volume = {200}, year = {2017} } @article{Lelieveld2019, abstract = {Anthropogenic greenhouse gases and aerosols are associated with climate change and human health risks. We used a global model to estimate the climate and public health outcomes attributable to fossil fuel use, indicating the potential benefits of a phaseout. We show that it can avoid an excess mortality rate of 3.61 (2.96–4.21) million per year from outdoor air pollution worldwide. This could be up to 5.55 (4.52–6.52) million per year by additionally controlling nonfossil anthropogenic sources. Globally, fossil-fuel-related emissions account for about 65{\%} of the excess mortality, and 70{\%} of the climate cooling by anthropogenic aerosols. The chemical influence of air pollution on aeolian dust contributes to the aerosol cooling. Because aerosols affect the hydrologic cycle, removing the anthropogenic emissions in the model increases rainfall by 10–70{\%} over densely populated regions in India and 10–30{\%} over northern China, and by 10–40{\%} over Central America, West Africa, and the drought-prone Sahel, thus contributing to water and food security. Since aerosols mask the anthropogenic rise in global temperature, removing fossil-fuel-generated particles liberates 0.51(±0.03) °C and all pollution particles 0.73(±0.03) °C warming, reaching around 2 °C over North America and Northeast Asia. The steep temperature increase from removing aerosols can be moderated to about 0.36(±0.06) °C globally by the simultaneous reduction of tropospheric ozone and methane. We conclude that a rapid phaseout of fossil-fuel-related emissions and major reductions of other anthropogenic sources are needed to save millions of lives, restore aerosol-perturbed rainfall patterns, and limit global warming to 2 °C.}, author = {Lelieveld, J and Klingm{\"{u}}ller, K and Pozzer, A and Burnett, R T and Haines, A and Ramanathan, V}, doi = {10.1073/pnas.1819989116}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, month = {apr}, number = {15}, pages = {7192--7197}, title = {{Effects of fossil fuel and total anthropogenic emission removal on public health and climate}}, url = {http://www.pnas.org/content/early/2019/03/19/1819989116.abstract http://www.pnas.org/lookup/doi/10.1073/pnas.1819989116}, volume = {116}, year = {2019} } @article{Lelieveld2015b, abstract = {Assessment of the global burden of disease is based on epidemiological cohort studies that connect premature mortality to a wide range of causes, including the long-term health impacts of ozone and fine particulate matter with a diameter smaller than 2.5 micrometres (PM2.5). It has proved difficult to quantify premature mortality related to air pollution, notably in regions where air quality is not monitored, and also because the toxicity of particles from various sources may vary. Here we use a global atmospheric chemistry model to investigate the link between premature mortality and seven emission source categories in urban and rural environments. In accord with the global burden of disease for 2010 (ref. 5), we calculate that outdoor air pollution, mostly by PM2.5, leads to 3.3 (95 per cent confidence interval 1.61-4.81) million premature deaths per year worldwide, predominantly in Asia. We primarily assume that all particles are equally toxic, but also include a sensitivity study that accounts for differential toxicity. We find that emissions from residential energy use such as heating and cooking, prevalent in India and China, have the largest impact on premature mortality globally, being even more dominant if carbonaceous particles are assumed to be most toxic. Whereas in much of the USA and in a few other countries emissions from traffic and power generation are important, in eastern USA, Europe, Russia and East Asia agricultural emissions make the largest relative contribution to PM2.5, with the estimate of overall health impact depending on assumptions regarding particle toxicity. Model projections based on a business-as-usual emission scenario indicate that the contribution of outdoor air pollution to premature mortality could double by 2050.}, author = {Lelieveld, J. and Evans, J. S. and Fnais, M. and Giannadaki, D. and Pozzer, A.}, doi = {10.1038/nature15371}, file = {::}, issn = {14764687}, journal = {Nature}, month = {sep}, number = {7569}, pages = {367--371}, title = {{The contribution of outdoor air pollution sources to premature mortality on a global scale}}, url = {http://www.nature.com/doifinder/10.1038/nature15371}, volume = {525}, year = {2015} } @article{Lemaire20162559, abstract = {Because of its sensitivity to unfavorable weather patterns, air pollution is sensitive to climate change so that, in the future, a climate penalty could jeopardize the expected efficiency of air pollution mitigation measures. A common method to assess the impact of climate on air quality consists in implementing chemistry-transport models forced by climate projections. However, the computing cost of such methods requires optimizing ensemble exploration techniques. By using a training data set from a deterministic projection of climate and air quality over Europe, we identified the main meteorological drivers of air quality for eight regions in Europe and developed statistical models that could be used to predict air pollutant concentrations. The evolution of the key climate variables driving either particulate or gaseous pollution allows selecting the members of the EuroCordex ensemble of regional climate projections that should be used in priority for future air quality projections (CanESM2/RCA4; CNRM-CM5-LR/RCA4 and CSIRO-Mk3-6-0/RCA4 and MPI-ESM-LR/CCLM following the EuroCordex terminology). After having tested the validity of the statistical model in predictive mode, we can provide ranges of uncertainty attributed to the spread of the regional climate projection ensemble by the end of the century (2071-2100) for the RCP8.5. In the three regions where the statistical model of the impact of climate change on PM2.5 offers satisfactory performances, we find a climate benefit (a decrease of PM2.5 concentrations under future climate) of -1.08 (±0.21), -1.03 (±0.32), -0.83 (±0.14) $\mu$g m-3, for respectively Eastern Europe, Mid-Europe and Northern Italy. In the British-Irish Isles, Scandinavia, France, the Iberian Peninsula and the Mediterranean, the statistical model is not considered skillful enough to draw any conclusion for PM2.5. In Eastern Europe, France, the Iberian Peninsula, Mid-Europe and Northern Italy, the statistical model of the impact of climate change on ozone was considered satisfactory and it confirms the climate penalty bearing upon ozone of 10.51 (±3.06), 11.70 (±3.63), 11.53 (±1.55), 9.86 (±4.41), 4.82 (±1.79) $\mu$g m-3, respectively. In the British-Irish Isles, Scandinavia and the Mediterranean, the skill of the statistical model was not considered robust enough to draw any conclusion for ozone pollution.}, annote = {cited By 2}, author = {Lemaire, Vincent E.P. and Colette, Augustin and Menut, Laurent}, doi = {10.5194/acp-16-2559-2016}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {4}, pages = {2559--2574}, title = {{Using statistical models to explore ensemble uncertainty in climate impact studies: The example of air pollution in Europe}}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960171955{\&}doi=10.5194{\%}2Facp-16-2559-2016{\&}partnerID=40{\&}md5=600401aba0b304cec74b7c4cc52d2494}, volume = {16}, year = {2016} } @article{Lewinschal2019, abstract = {Short-lived anthropogenic climate forcers (SLCFs), such as sulfate aerosols, affect both climate and air quality. Despite being short-lived, these forcers do not affect temperatures only locally; regions far away from the emission sources are also affected. Climate metrics are often used in a policy context to compare the climate impact of different anthropogenic forcing agents. These metrics typically relate a forcing change in a certain region with a temperature change in another region and thus often require a separate model to convert emission changes to radiative forcing (RF) changes. In this study, we used a coupled Earth system model, NorESM (Norwegian Earth System Model), to calculate emission-to-temperature-response metrics for sulfur dioxide (SO2) emission changes in four different policy-relevant regions: Europe (EU), North America (NA), East Asia (EA) and South Asia (SA). We first increased the SO2 emissions in each individual region by an amount giving approximately the same global average radiative forcing change (-0.45Wm-2). The global mean temperature change per unit sulfur emission compared to the control experiment was independent of emission region and equal to ∼0.006 K(TgSyr-1)-1. On a regional scale, the Arctic showed the largest temperature response in all experiments. The second largest temperature change occurred in the region of the imposed emission increase, except when South Asian emissions were changed; in this experiment, the temperature response was approximately the same in South Asia and East Asia. We also examined the non-linearity of the temperature response by removing all anthropogenic SO2 emissions over Europe in one experiment. In this case, the temperature response (both global and regional) was twice that in the corresponding experiment with a European emission increase. This non-linearity in the temperature response is one of many uncertainties associated with the use of simplified climate metrics.}, author = {Lewinschal, Anna and Ekman, Annica M.L. and Hansson, Hans Christen and Sand, Maria and Berntsen, Terje K. and Langner, Joakim}, doi = {10.5194/acp-19-2385-2019}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {feb}, number = {4}, pages = {2385--2403}, title = {{Local and remote temperature response of regional SO2 emissions}}, url = {https://www.atmos-chem-phys.net/19/2385/2019/}, volume = {19}, year = {2019} } @article{li2016pnas_a, abstract = {Rapid development of agriculture and fossil fuel combustion greatly increased US reactive nitrogen emissions to the atmosphere in the second half of the 20th century, resulting in excess nitrogen deposition to natural ecosystems. Recent efforts to lower nitrogen oxides emissions have substantially decreased nitrate wet deposition. Levels of wet ammonium deposition, by contrast, have increased in many regions. Together these changes have altered the balance between oxidized and reduced nitrogen deposition. Across most of the United States, wet deposition has transitioned from being nitrate-dominated in the 1980s to ammonium-dominated in recent years. Ammonia has historically not been routinely measured because there are no specific regulatory requirements for its measurement. Recent expansion in ammonia observations, however, along with ongoing measurements of nitric acid and fine particle ammonium and nitrate, permit new insight into the balance of oxidized and reduced nitrogen in the total (wet + dry) US nitrogen deposition budget. Observations from 37 sites reveal that reduced nitrogen contributes, on average, ∼65{\%} of the total inorganic nitrogen deposition budget. Dry deposition of ammonia plays an especially key role in nitrogen deposition, contributing from 19{\%} to 65{\%} in different regions. Future progress toward reducing US nitrogen deposition will be increasingly difficult without a reduction in ammonia emissions.}, author = {Li, Yi and Schichtel, Bret A. and Walker, John T. and Schwede, Donna B. and Chen, Xi and Lehmann, Christopher M.B. and Puchalski, Melissa A. and Gay, David A. and Collett, Jeffrey L.}, doi = {10.1073/pnas.1525736113}, issn = {10916490}, journal = {Proceedings of the National Academy of Sciences}, keywords = {Agriculture,Ammonia,Dry deposition,Nitrogen oxides,Wet deposition}, month = {may}, number = {21}, pages = {5874--5879}, pmid = {27162336}, title = {{Increasing importance of deposition of reduced nitrogen in the United States}}, url = {http://www.pnas.org/content/early/2016/05/04/1525736113}, volume = {113}, year = {2016} } @article{Li2019, abstract = {Non-methane volatile organic compounds (NMVOCs) are important ozone and secondary organic aerosol precursors and play important roles in tropospheric chemistry. In this work, we estimated the total and speciated NMVOC emissions from China's anthropogenic sources during 1990-2017 by using a bottom-up emission inventory framework and investigated the main drivers behind the trends. We found that anthropogenic NMVOC emissions in China have been increasing continuously since 1990 due to the dramatic growth in activity rates and absence of effective control measures. We estimated that anthropogenic NMVOC emissions in China increased from 9.76Tg in 1990 to 28.5Tg in 2017, mainly driven by the persistent growth from the industry sector and solvent use. Meanwhile, emissions from the residential and transportation sectors declined after 2005, partly offsetting the total emission increase. During 1990-2017, mass-based emissions of alkanes, alkenes, alkynes, aromatics, oxygenated volatile organic compounds (OVOCs) and other species increased by 274{\%}, 88{\%}, 4{\%}, 387{\%}, 91{\%} and 231{\%}, respectively. Following the growth in total NMVOC emissions, the corresponding ozone formation potential (OFP) increased from 38.2Tg of O3 in 1990 to 99.7Tg of O3 in 2017. We estimated that aromatics accounted for the largest share (43{\%}) of the total OFP, followed by alkenes (37{\%}) and OVOCs (10{\%}). Growth in China's NMVOC emissions was mainly driven by the transportation sector before 2000, while industry and solvent use dominated the emission growth during 2000-2010. Since 2010, although emissions from the industry sector and solvent use kept growing, strict control measures on transportation and fuel transition in residential stoves have successfully slowed down the increasing trend, especially after the implementation of China's clean air action since 2013. However, compared to large emission decreases in other major air pollutants in China (e.g., SO2, NOx and primary PM) during 2013-2017, the relatively flat trend in NMVOC emissions and OFP revealed the absence of effective control measures, which might have contributed to the increase in ozone during the same period. Given their high contributions to emissions and OFP, tailored control measures for solvent use and industrial sources should be developed, and multi-pollutant control strategies should be designed to mitigate both PM2:5 and ozone pollution simultaneously.}, author = {Li, Meng and Zhang, Qiang and Zheng, Bo and Tong, Dan and Lei, Yu and Liu, Fei and Hong, Chaopeng and Kang, Sicong and Yan, Liu and Zhang, Yuxuan and Bo, Yu and Su, Hang and Cheng, Yafang and He, Kebin}, doi = {10.5194/acp-19-8897-2019}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {13}, pages = {8897--8913}, title = {{Persistent growth of anthropogenic non-methane volatile organic compound (NMVOC) emissions in China during 1990–2017: Drivers, speciation and ozone formation potential}}, volume = {19}, year = {2019} } @article{Li2019d, abstract = {Observations of surface ozone available from ∼1,000 sites across China for the past 5 years (2013–2017) show severe summertime pollution and regionally variable trends. We resolve the effect of meteorological variability on the ozone trends by using a multiple linear regression model. The residual of this regression shows increasing ozone trends of 1–3 ppbv a −1 in megacity clusters of eastern China that we attribute to changes in anthropogenic emissions. By contrast, ozone decreased in some areas of southern China. Anthropogenic NO x emissions in China are estimated to have decreased by 21{\%} during 2013–2017, whereas volatile organic compounds (VOCs) emissions changed little. Decreasing NO x would increase ozone under the VOC-limited conditions thought to prevail in urban China while decreasing ozone under rural NO x -limited conditions. However, simulations with the Goddard Earth Observing System Chemical Transport Model (GEOS-Chem) indicate that a more important factor for ozone trends in the North China Plain is the ∼40{\%} decrease of fine particulate matter (PM 2.5 ) over the 2013–2017 period, slowing down the aerosol sink of hydroperoxy (HO 2 ) radicals and thus stimulating ozone production.}, author = {Li, Ke and Jacob, Daniel J. and Liao, Hong and Shen, Lu and Zhang, Qiang and Bates, Kelvin H.}, doi = {10.1073/pnas.1812168116}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, keywords = {Aerosol chemistry,Air quality,China,Emission reductions,Surface ozone}, month = {jan}, number = {2}, pages = {422--427}, title = {{Anthropogenic drivers of 2013–2017 trends in summer surface ozone in China}}, url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1812168116}, volume = {116}, year = {2019} } @article{acp-20-11423-2020, author = {Li, K and Jacob, D J and Shen, L and Lu, X and {De Smedt}, I and Liao, H}, doi = {10.5194/acp-20-11423-2020}, journal = {Atmospheric Chemistry and Physics}, number = {19}, pages = {11423--11433}, title = {{Increases in surface ozone pollution in China from 2013 to 2019: anthropogenic and meteorological influences}}, url = {https://acp.copernicus.org/articles/20/11423/2020/}, volume = {20}, year = {2020} } @article{Li2016, abstract = {Two real-time instruments, NCSA (Nanoparticle Chemical Speciation Analyzer) and ACSA (Aerosol Chemical Speciation Analyzer), were both deployed in Beijing, China to explore the sized-dependent characterization of atmospheric particles. The mass concentrations of PM1, PM2.5, PM10, and sulfate and nitrate in the three size fractions were hourly measured in situ from 13 December 2013 to 7 January 2014. Generally, “sawtooth cycles” are common during winter in Beijing, with the PM concentrations increasing slowly over a few days, then falling to a low level abruptly in only a few hours. The secondary species, sulfate and nitrate, play important roles in haze formation and account for 10.5{\%} and 11.1{\%} of total PM1 mass on average. Based on the variation of PM1 mass concentrations, we classify the study periods into three categories, clean, slightly polluted, and polluted. The oxidation ratios of sulfur and nitrogen both increase from clean to polluted periods, indicating the significant contribution of secondary transformation to haze evolution. While the PM2.5/PM10 ratio shows high dependence on PM pollution level, the ratio of PM1/PM2.5 remains almost stable during the entire study, with an average of 0.90. With respect to the mass-size distribution of chemical components, both sulfate and nitrate show dominant contributions in PM1 size fraction, accounting for 80.7{\%} and 60.3{\%} of total sulfate and nitrate, respectively. Our results also reveal that the elevated sulfate in PM1, and the enhanced nitrate in PM1 and PM2.5–1 size fraction, prompt the formation of haze pollution.}, author = {Li, Haiyan and Duan, Fengkui and He, Kebin and Ma, Yongliang and Kimoto, Takashi and Huang, Tao}, doi = {10.3390/atmos7030036}, journal = {Atmosphere}, number = {3}, pages = {36}, title = {{Size-Dependent Characterization of Atmospheric Particles during Winter in Beijing}}, url = {https://doi.org/10.3390/atmos7030036}, volume = {7}, year = {2016} } @article{Li2020, abstract = {The outbreak of COVID-19 has spreaded rapidly across the world. To control the rapid dispersion of the virus, China has imposed national lockdown policies to practise social distancing. This has led to reduced human activities and hence primary air pollutant emissions, which caused improvement of air quality as a side-product. To investigate the air quality changes during the COVID-19 lockdown over the YRD Region, we apply the WRF-CAMx modelling system together with monitoring data to investigate the impact of human activity pattern changes on air quality. Results show that human activities were lowered significantly during the period: industrial operations, VKT, constructions in operation, etc. were significantly reduced, leading to lowered SO2, NOx, PM2.5 and VOCs emissions by approximately 16–26{\%}, 29–47{\%}, 27–46{\%} and 37–57{\%} during the Level I and Level II response periods respectively. These emission reduction has played a significant role in the improvement of air quality. Concentrations of PM2.5, NO2 and SO2 decreased by 31.8{\%}, 45.1{\%} and 20.4{\%} during the Level I period; and 33.2{\%}, 27.2{\%} and 7.6{\%} during the Level II period compared with 2019. However, ozone did not show any reduction and increased greatly. Our results also show that even during the lockdown, with primary emissions reduction of 15{\%}–61{\%}, the daily average PM2.5 concentrations range between 15 and 79 {\$}\mu{\$}g m−3, which shows that background and residual pollutions are still high. Source apportionment results indicate that the residual pollution of PM2.5 comes from industry (32.2–61.1{\%}), mobile (3.9–8.1{\%}), dust (2.6–7.7{\%}), residential sources (2.1–28.5{\%}) in YRD and 14.0–28.6{\%} contribution from long-range transport coming from northern China. This indicates that in spite of the extreme reductions in primary emissions, it cannot fully tackle the current air pollution. Re-organisation of the energy and industrial strategy together with trans-regional joint-control for a full long-term air pollution plan need to be further taken into account.}, author = {Li, Li and Li, Qing and Huang, Ling and Wang, Qian and Zhu, Ansheng and Xu, Jian and Liu, Ziyi and Li, Hongli and Shi, Lishu and Li, Rui and Azari, Majid and Wang, Yangjun and Zhang, Xiaojuan and Liu, Zhiqiang and Zhu, Yonghui and Zhang, Kun and Xue, Shuhui and Ooi, Maggie Chel Gee and Zhang, Dongping and Chan, Andy}, doi = {10.1016/j.scitotenv.2020.139282}, issn = {18791026}, journal = {Science of the Total Environment}, keywords = {Air quality,COVID-19,Yangtze River Delta}, month = {aug}, pages = {139282}, pmid = {32413621}, publisher = {Elsevier B.V.}, title = {{Air quality changes during the COVID-19 lockdown over the Yangtze River Delta Region: An insight into the impact of human activity pattern changes on air pollution variation}}, volume = {732}, year = {2020} } @article{LI2010405, abstract = {PM2.5 aerosols were collected in forests along north latitude in boreal-temperate, temperate, subtropical and tropical climatic zones in eastern China, i.e., Changbai Mountain Nature Reserve (CB), Dongping National Forest Park in Chongming Island (CM), Dinghu Mountain Nature Reserve (DH), Jianfengling Nature Reserve in Hainan Island (HN). The mass concentrations of PM2.5, organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC) as well as concentrations of ten inorganic ions (F−, Cl−, NO3−, SO42−, C2O42−, NH4+, Na+, K+, Ca2+, Mg2+) were determined. Aerosol chemical mass closures were achieved. The 24-hr average concentrations of PM2.5 were 38.8, 89.2, 30.4, 18 $\mu$g/m3 at CB, CM, DH and HN, respectively. Organic matter and EC accounted for 21{\%}–33{\%} and 1.3{\%}–2.3{\%} of PM2.5 mass, respectively. The sum of three dominant secondary ions (SO42−, NO3−, NH4+) accounted for 44{\%}, 50{\%}, 45{\%} and 16{\%} of local PM2.5 mass at CB, CM, DH and HN, respectively. WSOC comprised 35{\%}–65{\%} of OC. The sources of PM2.5 include especially important regional anthropogenic pollutions at Chinese forest areas.}, author = {Li, Li and Wang, Wu and Feng, Jialiang and Zhang, Dongping and Li, Huaijian and Gu, Zeping and Wang, Bangjin and Sheng, Guoying and Fu, Jiamo}, doi = {https://doi.org/10.1016/S1001-0742(09)60122-4}, issn = {1001-0742}, journal = {Journal of Environmental Sciences}, keywords = {OC/EC,PM aerosols,WSOC,forests,inorganic ions}, number = {3}, pages = {405--412}, title = {{Composition, source, mass closure of PM2.5 aerosols for four forests in eastern China}}, url = {http://www.sciencedirect.com/science/article/pii/S1001074209601224}, volume = {22}, year = {2010} } @article{Li2018f, abstract = {Climate policies targeting energy-related CO2 emissions, which act on a global scale over long time horizons, can result in localized, near-term reductions in both air pollution and adverse human health impacts. Focusing on China, the largest energy-using and CO2-emitting nation, we develop a cross-scale modelling approach to quantify these air quality co-benefits, and compare them to the economic costs of climate policy. We simulate the effects of an illustrative climate policy, a price on CO2 emissions. In a policy scenario consistent with China's recent pledge to reach a peak in CO2 emissions by 2030, we project that national health co-benefits from improved air quality would partially or fully offset policy costs depending on chosen health valuation. Net health co-benefits are found to rise with increasing policy stringency.}, author = {Li, Mingwei and Zhang, Da and Li, Chiao-Ting and Mulvaney, Kathleen M and Selin, Noelle E and Karplus, Valerie J}, doi = {10.1038/s41558-018-0139-4}, issn = {17586798}, journal = {Nature Climate Change}, number = {5}, pages = {398--403}, title = {{Air quality co-benefits of carbon pricing in China}}, url = {https://doi.org/10.1038/s41558-018-0139-4}, volume = {8}, year = {2018} } @article{Lin2015a, abstract = {Satellite retrievals of vertical column densities (VCDs) of tropospheric nitrogen dioxide (NO2) normally do not explicitly account for aerosol optical effects and surface reflectance anisotropy that vary with space and time. Here, we conduct an improved retrieval of NO2 VCDs over China, called the POMINO algorithm, based on measurements from the Ozone Monitoring Instrument (OMI), and we test the importance of a number of aerosol and surface reflectance treatments in this algorithm. POMINO uses a parallelized LIDORT-driven AMFv6 package to derive tropospheric air mass factors via pixel-specific radiative transfer calculations with no look-up tables, taking slant column densities from DOMINO v2. Prerequisite cloud optical properties are derived from a dedicated cloud retrieval process that is fully consistent with the main NO2 retrieval. Aerosol optical properties are taken from GEOS-Chem simulations constrained by MODIS AOD values. MODIS bi-directional reflectance distribution function (BRDF) data are used for surface reflectance over land. For the present analysis, POMINO level-2 data for 2012 are aggregated into monthly means on a 0.25° long. × 0.25° lat. grid. POMINO-retrieved annual mean NO2 VCDs vary from 15–25 × 1015 cm−2 over the polluted North China Plain (NCP) to below 1015 cm−2 over much of west China. The subsequently-constrained Chinese annual anthropogenic emissions are 9.05 TgN yr−1, an increase from 2006 (Lin, 2012) by about 19{\%}. Replacing the MODIS BRDF data with the OMLER v1 monthly climatological albedo data affects NO2 VCDs by up to 40{\%} for certain locations and seasons. The effect on constrained NOx emissions is small. Excluding aerosol information from the retrieval process (this is the traditional "implicit" treatment) enhances annual mean NO2 VCDs by 15–40{\%} over much of east China. Seasonally, NO2 VCDs are reduced by 10–20{\%} over parts of the NCP in spring and over north China in winter, despite the general enhancements in summer and fall. The effect on subsequently-constrained annual emissions is (−5)–(+30) {\%} with large seasonal and spatial dependence. The implicit aerosol treatment also tends to exclude days with high pollution, a potentially important sampling bias. Therefore an explicit treatment of aerosols is important for space-based NO2 retrievals and emission constraints.}, author = {Lin, J. T. and Liu, M. Y. and Xin, J. Y. and Boersma, K. F. and Spurr, R. and Martin, R. and Zhang, Q.}, doi = {10.5194/acp-15-11217-2015}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {oct}, number = {19}, pages = {11217--11241}, publisher = {Copernicus Publications}, title = {{Influence of aerosols and surface reflectance on satellite NO2 retrieval: Seasonal and spatial characteristics and implications for NOx emission constraints}}, url = {https://www.atmos-chem-phys.net/15/11217/2015/ https://www.atmos-chem-phys.net/15/11217/2015/acp-15-11217-2015.pdf}, volume = {15}, year = {2015} } @article{Liu2016, abstract = {Tropospheric nitrogen dioxide (NO2) column densities detected from space are widely used to infer trends in terrestrial nitrogen oxide (NOx) emissions. We study changes in NO2 column densities using the Ozone Monitoring Instrument (OMI) over China from 2005 to 2015 and compare them with the bottom-up inventory to examine NOx emission trends and their driving forces. From OMI measurements we detect the peak of NO2 column densities at a national level in the year 2011, with average NO2 column densities deceasing by 32{\%} from 2011 to 2015 and corresponding to a simultaneous decline of 21{\%} in bottom-up emission estimates. A significant variation in the peak year of NO2 column densities over regions is observed. Because of the reasonable agreement between the peak year of NO2 columns and the start of deployment of denitration devices, we conclude that power plants are the primary contributor to the NO2 decline, which is further supported by the emission reduction of 56{\%} from the power sector in the bottom-up emission inventory associated with the penetration of selective catalytic reduction (SCR) increasing from 18{\%} to 86{\%} during 2011-2015. Meanwhile, regulations for vehicles also make a significant contribution to NOx emission reductions, in particular for a few urbanized regions (e.g., Beijing and Shanghai), where they implemented strict regulations for vehicle emissions years before the national schedule for SCR installations and thus reached their NO2 peak 2-3 years ahead of the deployment of denitration devices for power plants.}, annote = {Times Cited: 36 Zhang, Qiang/D-9034-2012; Liu, Fei/ Liu, Fei/0000-0002-0357-0274 0 38}, author = {Liu, Fei and Zhang, Qiang and Ronald, J van der A and Zheng, Bo and Tong, Dan and Yan, Liu and Zheng, Yixuan and He, Kebin}, doi = {10.1088/1748-9326/11/11/114002}, isbn = {1748-9326}, journal = {Environmental Research Letters}, number = {11}, pages = {114002}, title = {{Recent reduction in NOx emissions over China: synthesis of satellite observations and emission inventories}}, volume = {11}, year = {2016} } @article{Liu2018, abstract = {AbstractAtmospheric aerosols such as sulfate and black carbon (BC) generate inhomogeneous radiative forcing and can affect precipitation in distinct ways compared to greenhouse gases (GHGs). Their regional effects on the atmospheric energy budget and circulation can be important for understanding and predicting global and regional precipitation changes, which act on top of the background GHG-induced hydrological changes. Under the framework of the Precipitation Driver Response Model Intercomparison Project (PDRMIP), multiple models were used for the first time to simulate the influence of regional (Asian and European) sulfate and BC forcing on global and regional precipitation. The results show that, as in the case of global aerosol forcing, the global fast precipitation response to regional aerosol forcing scales with global atmospheric absorption, and the slow precipitation response scales with global surface temperature response. Asian sulfate aerosols appear to be a stronger driver of global temperature and precipitation change compared to European aerosols, but when the responses are normalized by unit radiative forcing or by aerosol burden change, the picture reverses, with European aerosols being more efficient in driving global change. The global apparent hydrological sensitivities of these regional forcing experiments are again consistent with those for corresponding global aerosol forcings found in the literature. However, the regional responses and regional apparent hydrological sensitivities do not align with the corresponding global values. Through a holistic approach involving analysis of the energy budget combined with exploring changes in atmospheric dynamics, we provide a framework for explaining the global and regional precipitation responses to regional aerosol forcing.}, annote = {doi: 10.1175/JCLI-D-17-0439.1}, author = {Liu, L and Shawki, D and Voulgarakis, A and Kasoar, M and Samset, B H and Myhre, G and Forster, P M and Hodnebrog, {\O} and Sillmann, J and Aalbergsj{\o}, S G and Boucher, O and Faluvegi, G and Iversen, T and Kirkev{\aa}g, A and Lamarque, J.-F. and Olivi{\'{e}}, D and Richardson, T and Shindell, D and Takemura, T}, doi = {10.1175/JCLI-D-17-0439.1}, issn = {0894-8755}, journal = {Journal of Climate}, month = {mar}, number = {11}, pages = {4429--4447}, publisher = {American Meteorological Society}, title = {{A PDRMIP Multimodel Study on the Impacts of Regional Aerosol Forcings on Global and Regional Precipitation}}, url = {https://doi.org/10.1175/JCLI-D-17-0439.1}, volume = {31}, year = {2018} } @article{Liu2018c, abstract = {Abstract. The North China Plain has been identified as a significant hotspot of ammonia (NH3) due to extensive agricultural activities. Satellite observations suggest a significant increase of about 30{\%} in tropospheric gas-phase NH3 concentrations in this area during 2008{\&}ndash;2016. However, the estimated NH3 emissions decreased slightly because of changes in Chinese agricultural practices, i.e., the transition in fertilizer types from ammonium carbonate fertilizer to urea, and in the livestock rearing system from free-range to intensive farming. We note that the emissions of sulfur dioxide (SO2) have rapidly declined by 60{\%} over recent few years. By integrating in situ measurement datasets, multi-year NH3 emission inventories, and chemical transport model simulations, we demonstrate that the increases in NH3 can be almost entirely attributable to this rapid SO2 emission reduction. The annual average sulfate concentrations decreased by about 50{\%}, which significantly weakened the formation of ammonium sulfate and increased the average proportions of gas phase NH3 within the total NH3 column concentrations from 26{\%} (2008) to 37{\%} (2016). Both the decreases in sulfate and increases in NH3 concentrations show highest values in summer, possibly because the formation of sulfate aerosols is more sensitive to SO2 emission reductions in summer than in other seasons.}, author = {Liu, Mingxu and Huang, Xin and Song, Yu and Xu, Tingting and Wang, Shuxiao and Wu, Zhijun and Hu, Min and Zhang, Lin and Zhang, Qiang and Pan, Yuepeng and Liu, Xuejun and Zhu, Tong}, doi = {10.5194/acp-18-17933-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {sep}, number = {24}, pages = {17933--17943}, publisher = {Copernicus Publications}, title = {{Rapid SO2 emission reductions significantly increase tropospheric ammonia concentrations over the North China Plain}}, volume = {18}, year = {2018} } @article{Liu2016a, abstract = {East Asia has the most rapidly growing shipping emissions of both CO2 and traditional air pollutants, but the least in-depth analysis. Full evaluation of all pollutants is needed to assess the impacts of shipping emissions. Here, using an advanced method based on detailed dynamic ship activity data, we show that shipping emissions in East Asia accounted for 16{\%} of global shipping CO2 in 2013, compared to only 4-7{\%} in 2002-2005. Increased emissions lead to large adverse health impacts, with 14,500-37,500 premature deaths per year. Global mean radiative forcing from East Asian shipping is initially negative, but would become positive after approximately eight years for constant current emissions. As a large fraction of vessels are registered elsewhere, joint efforts are necessary to reduce emissions and mitigate the climate and health impacts of shipping in the region.}, author = {Liu, Huan and Fu, Mingliang and Jin, Xinxin and Shang, Yi and Shindell, Drew and Faluvegi, Greg and Shindell, Cary and He, Kebin}, doi = {10.1038/nclimate3083}, issn = {17586798}, journal = {Nature Climate Change}, number = {11}, pages = {1037--1041}, title = {{Health and climate impacts of ocean-going vessels in East Asia}}, url = {https://doi.org/10.1038/nclimate3083}, volume = {6}, year = {2016} } @article{Liu2020b, abstract = {The COVID-19 pandemic is impacting human activities, and in turn energy use and carbon dioxide (CO 2 ) emissions. Here we present daily estimates of country-level CO 2 emissions for different sectors based on near-real-time activity data. The key result is an abrupt 8.8{\%} decrease in global CO 2 emissions (−1551 Mt CO 2 ) in the first half of 2020 compared to the same period in 2019. The magnitude of this decrease is larger than during previous economic downturns or World War II. The timing of emissions decreases corresponds to lockdown measures in each country. By July 1st, the pandemic's effects on global emissions diminished as lockdown restrictions relaxed and some economic activities restarted, especially in China and several European countries, but substantial differences persist between countries, with continuing emission declines in the U.S. where coronavirus cases are still increasing substantially.}, author = {Liu, Zhu and Ciais, Philippe and Deng, Zhu and Lei, Ruixue and Davis, Steven J. and Feng, Sha and Zheng, Bo and Cui, Duo and Dou, Xinyu and Zhu, Biqing and Guo, Rui and Ke, Piyu and Sun, Taochun and Lu, Chenxi and He, Pan and Wang, Yuan and Yue, Xu and Wang, Yilong and Lei, Yadong and Zhou, Hao and Cai, Zhaonan and Wu, Yuhui and Guo, Runtao and Han, Tingxuan and Xue, Jinjun and Boucher, Olivier and Boucher, Eulalie and Chevallier, Fr{\'{e}}d{\'{e}}ric and Tanaka, Katsumasa and Wei, Yimin and Zhong, Haiwang and Kang, Chongqing and Zhang, Ning and Chen, Bin and Xi, Fengming and Liu, Miaomiao and Br{\'{e}}on, Fran{\c{c}}ois-Marie and Lu, Yonglong and Zhang, Qiang and Guan, Dabo and Gong, Peng and Kammen, Daniel M. and He, Kebin and Schellnhuber, Hans Joachim}, doi = {10.1038/s41467-020-18922-7}, issn = {2041-1723}, journal = {Nature Communications}, month = {dec}, number = {1}, pages = {5172}, title = {{Near-real-time monitoring of global CO2 emissions reveals the effects of the COVID-19 pandemic}}, url = {http://www.nature.com/articles/s41467-020-18922-7}, volume = {11}, year = {2020} } @article{acp-19-12051-2019, author = {Liu, L and Zhang, X and Wong, A Y H and Xu, W and Liu, X and Li, Y and Mi, H and Lu, X and Zhao, L and Wang, Z and Wu, X and Wei, J}, doi = {10.5194/acp-19-12051-2019}, journal = {Atmospheric Chemistry and Physics}, number = {18}, pages = {12051--12066}, title = {{Estimating global surface ammonia concentrations inferred from satellite retrievals}}, url = {https://acp.copernicus.org/articles/19/12051/2019/}, volume = {19}, year = {2019} } @article{Llorens2009b, author = {Llorens, L. and Llusi{\`{a}}, J. and Murchie, E. H. and Pe{\~{n}}uelas, J. and Beerling, D. J.}, doi = {10.1029/2008JG000802}, issn = {0148-0227}, journal = {Journal of Geophysical Research: Biogeosciences}, month = {jan}, number = {G1}, pages = {G01005}, title = {{Monoterpene emissions and photoinhibition of “living fossil” trees grown under CO2 enrichment in a simulated Cretaceous polar environment}}, url = {http://doi.wiley.com/10.1029/2008JG000802}, volume = {114}, year = {2009} } @article{bg-10-6815-2013, author = {Lombardozzi, D and Sparks, J P and Bonan, G}, doi = {10.5194/bg-10-6815-2013}, journal = {Biogeosciences}, number = {11}, pages = {6815--6831}, title = {{Integrating O3 influences on terrestrial processes: photosynthetic and stomatal response data available for regional and global modeling}}, url = {https://www.biogeosciences.net/10/6815/2013/}, volume = {10}, year = {2013} } @article{doi:10.1175/JCLI-D-14-00223.1, abstract = {AbstractOzone (O3) is a phytotoxic greenhouse gas that has increased more than threefold at Earth's surface from preindustrial values. In addition to directly increasing radiative forcing as a greenhouse gas, O3 indirectly impacts climate through altering the plant processes of photosynthesis and transpiration. While global estimates of gross primary productivity (GPP) have incorporated the effects of O3, few studies have explicitly determined the independent effects of O3 on transpiration. In this study, the authors include effects of O3 on photosynthesis and stomatal conductance from a recent literature review to determine the impact on GPP and transpiration and highlight uncertainty in modeling plant responses to O3. Using the Community Land Model, the authors estimate that present-day O3 exposure reduces GPP and transpiration globally by 8{\%}–12{\%} and 2{\%}–2.4{\%}, respectively. The largest reductions were in midlatitudes, with GPP decreasing up to 20{\%} in the eastern United States, Europe, and Southeast Asia and transpiration reductions of up to 15{\%} in the same regions. Larger reductions in GPP compared to transpiration decreased water-use efficiency 5{\%}–10{\%} in the eastern United States, Southeast Asia, Europe, and central Africa; increased surface runoff more than 15{\%} in eastern North America; and altered patterns of energy fluxes in the tropics, high latitudes, and eastern North America. Future climate predictions will be improved if plant responses to O3 are incorporated into models such that stomatal conductance is modified independently of photosynthesis and the effects on transpiration are explicitly considered in surface energy budgets. Improvements will help inform regional decisions for managing changes in hydrology and surface temperatures in response to O3 pollution.}, author = {Lombardozzi, D and Levis, Samuel and Bonan, G and Hess, P G and Sparks, J P}, doi = {10.1175/JCLI-D-14-00223.1}, journal = {Journal of Climate}, number = {1}, pages = {292--305}, title = {{The Influence of Chronic Ozone Exposure on Global Carbon and Water Cycles}}, url = {https://doi.org/10.1175/JCLI-D-14-00223.1}, volume = {28}, year = {2015} } @article{Lorente2017, abstract = {Air mass factor (AMF) calculation is the largest source of uncertainty in NO2 and HCHO satellite retrievals in situations with enhanced trace gas concentrations in the lower troposphere. Structural uncertainty arises when different retrieval methodologies are applied in the scientific community to the same satellite observations. Here, we address the issue of AMF structural uncertainty via a detailed comparison of AMF calculation methods that are structurally different between seven retrieval groups for measurements from the Ozone Monitoring Instrument (OMI). We estimate the escalation of structural uncertainty in every sub-step of the AMF calculation process. This goes beyond the algorithm uncertainty estimates provided in state-of-the-art retrievals, which address the theoretical propagation of uncertainties for one particular retrieval algorithm only. We find that top-of-atmosphere reflectances simulated by four radiative transfer models (RTMs) (DAK, McArtim, SCIATRAN and VLIDORT) agree within 1.5{\&}thinsp;{\%}. We find that different retrieval groups agree well in the calculations of altitude resolved AMFs from different RTMs (to within 3{\&}thinsp;{\%}), and in the tropospheric AMFs (to within 6{\&}thinsp;{\%}) as long as identical ancillary data (surface albedo, terrain height, cloud parameters and trace gas profile) and cloud and aerosol correction procedures are being used. Structural uncertainty increases sharply when retrieval groups use their preference for ancillary data, cloud and aerosol correction. On average, we estimate the AMF structural uncertainty to be 42{\&}thinsp;{\%} over polluted regions and 31{\&}thinsp;{\%} over unpolluted regions, mostly driven by substantial differences in the a priori trace gas profiles, surface albedo and cloud parameters. Sensitivity studies for one particular algorithm indicate that different cloud correction approaches result in substantial AMF differences in polluted situations (5 to 40{\&}thinsp;{\%} depending on cloud fraction and cloud pressure, and 11{\&}thinsp;{\%} on average) even for low cloud fractions ( 2 and HCHO retrievals.}, author = {Lorente, Alba and {Folkert Boersma}, K. and Yu, Huan and D{\"{o}}rner, Steffen and Hilboll, Andreas and Richter, Andreas and Liu, Mengyao and Lamsal, Lok N. and Barkley, Michael and {De Smedt}, Isabelle and {Van Roozendael}, Michel and Wang, Yang and Wagner, Thomas and Beirle, Steffen and Lin, Jin Tai and Krotkov, Nickolay and Stammes, Piet and Wang, Ping and Eskes, Henk J. and Krol, Maarten}, doi = {10.5194/amt-10-759-2017}, issn = {18678548}, journal = {Atmospheric Measurement Techniques}, month = {mar}, number = {3}, pages = {759--782}, publisher = {Copernicus Publications}, title = {{Structural uncertainty in air mass factor calculation for NO2 and HCHO satellite retrievals}}, url = {https://www.atmos-meas-tech.net/10/759/2017/ https://www.atmos-meas-tech.net/10/759/2017/amt-10-759-2017.pdf}, volume = {10}, year = {2017} } @article{doi:10.1111/pce.12369, abstract = {Abstract Volatile organic compounds emitted by plants represent the largest part of biogenic volatile organic compounds (BVOCs) released into our atmosphere. Plant volatiles are formed through many biochemical pathways, constitutively and after stress induction. In recent years, our understanding of the functions of these molecules has made constant and rapid progress. From being considered in the past as a mere waste of carbon, BVOCs have now emerged as an essential element of an invisible language that is perceived and exploited by the plants' enemies, the enemies of plant enemies, and neighbouring plants. In addition, BVOCs have important functions in protecting plants from abiotic stresses. Recent advances in our understanding of the role of BVOC in direct and indirect defences are driving further attention to these emissions. This special issue gathers some of the latest and most original research that further expands our knowledge of BVOC. BVOC emissions and functions in (1) unexplored terrestrial (including the soil) and marine environments, (2) in changing climate conditions, and (3) under anthropic pressures, or (4) in complex trophic communities are comprehensively reviewed. Stepping up from scientific awareness, the presented information shows that the manipulation and exploitation of BVOC is a realistic and promising strategy for agricultural applications and biotechnological exploitations.}, author = {Loreto, Francesco and Dicke, Marcel and Schnitzler, J{\"{o}}rg-Peter and Turlings, Ted C J}, doi = {10.1111/pce.12369}, issn = {01407791}, journal = {Plant, Cell {\&} Environment}, keywords = {abiotic and biotic stresses,biogenic volatile organic compounds (BVOC),biosphere–atmosphere interactions,plant communication with herbivores and carnivores}, month = {aug}, number = {8}, pages = {1905--1908}, title = {{Plant volatiles and the environment}}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/pce.12369 http://doi.wiley.com/10.1111/pce.12369}, volume = {37}, year = {2014} } @article{Loreto2001b, author = {Loreto, Francesco and Fischbach, Robert J. and Schnitzler, J{\"{o}}rg-Peter and Ciccioli, Paolo and Brancaleoni, ENZO and Calfapietra, Carlo and Seufert, Guenther}, doi = {10.1046/j.1354-1013.2001.00442.x}, issn = {13541013}, journal = {Global Change Biology}, month = {aug}, number = {6}, pages = {709--717}, title = {{Monoterpene emission and monoterpene synthase activities in the Mediterranean evergreen oak Quercus ilex L. grown at elevated CO2 concentrations}}, url = {http://doi.wiley.com/10.1046/j.1354-1013.2001.00442.x}, volume = {7}, year = {2001} } @article{Lowe2018, abstract = {A number of studies have examined the size of the allowable global cumulative carbon budget compatible with limiting twenty-first century global average temperature rise to below 2°C and below 1.5°C relative to pre-industrial levels. These estimates of cumulative emissions have a number of uncertainties including those associated with the climate sensitivity and the global carbon cycle. Although the IPCC fifth assessment report contained information on a range of Earth system feedbacks, such as carbon released by thawing of permafrost or methane production by wetlands as a result of climate change, the impact of many of these Earth system processes on the allowable carbon budgets remains to be quantified. Here, we make initial estimates to show that the combined impact from typically unrepresented Earth system processes may be important for the achievability of limiting warming to 1.5°C or 2°C above pre-industrial levels. The size of the effects range up to around a 350GtCO2 budget reduction for a 1.5°C warming limit and around a 500 GtCO2 reduction for achieving a warming limit of 2°C. Median estimates for the extra Earth system forcing lead to around 100GtCO2 and 150GtCO2, respectively for the two warming limits. Our estimates are equivalent to several years of anthropogenic carbon dioxide emissions at present rates. In addition to the likely reduction of the allowable global carbon budgets, the extra feedbacks also bring forward the date at which a given warming threshold is likely to be exceeded for a particular emission pathway. This article is part of the theme issue 'The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.}, author = {Lowe, Jason A. and Bernie, Daniel}, doi = {10.1098/rsta.2017.0263}, issn = {1364503X}, journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences}, keywords = {Carbon budget,Climate sensitivity,Earth system processes,Mitigation}, language = {eng}, month = {may}, number = {2119}, pages = {20170263}, publisher = {The Royal Society Publishing}, title = {{The impact of Earth system feedbacks on carbon budgets and climate response}}, volume = {376}, year = {2018} } @article{Lu2017, author = {Lu, Xiaoliang and Chen, Min and Liu, Yaling and Miralles, Diego G. and Wang, Faming}, doi = {10.1016/j.agrformet.2017.02.002}, issn = {01681923}, journal = {Agricultural and Forest Meteorology}, month = {may}, pages = {39--49}, title = {{Enhanced water use efficiency in global terrestrial ecosystems under increasing aerosol loadings}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0168192317300345}, volume = {237-238}, year = {2017} } @article{Lucas2007, abstract = {A methodology is presented here to assess the potential long-term contribution of non-CO2 greenhouse gases in mitigation scenarios. The analysis shows the future development of the mitigation potential of non-CO2 gases (as a function of changes in technology and implementation barriers) to represent a crucial parameter for the overall costs of mitigation scenarios. The recently developed marginal abatement cost curves for 2010 in the EMF-21 project are taken as the starting point. First-order estimates were made of the future maximum attainable reduction potentials and costs on the basis of available literature. The set of MAC curves developed was used in a multi-gas analysis for stabilising greenhouse gas concentrations at 550 ppm CO2-equivalent. Including future development for the non-CO2 mitigation options not only increases their mitigation potential but also lowers the overall costs compared to situations where no development is assumed (3-21{\%} lower in 2050 and 4-26{\%} lower in 2100 in our analysis). Along with the fluorinated gases, energy-related methane emissions make up the largest share in total non-CO2 abatement potential as they represent a large emission source and have a large potential for reduction (towards 90{\%} compared to baseline in 2100). Most methane and nitrous oxide emissions from landuse-related sources are less simple to abate, with an estimated abatement potential in 2100 of around 60{\%} and 40{\%}, respectively. {\textcopyright} 2006 Elsevier Ltd. All rights reserved.}, author = {Lucas, Paul L. and van Vuuren, Detlef P. and Olivier, Jos G.J. and den Elzen, Michel G.J.}, doi = {10.1016/j.envsci.2006.10.007}, issn = {14629011}, journal = {Environmental Science {\&} Policy}, keywords = {Abatement potential,Mitigation scenarios,Non-CO2,Technology development}, language = {en}, month = {jul}, number = {2}, pages = {85--103}, title = {{Long-term reduction potential of non-CO2 greenhouse gases}}, url = {http://linkinghub.elsevier.com/retrieve/pii/S1462901106001316}, volume = {10}, year = {2007} } @article{Lund2020, abstract = {Mitigation of non-CO2 emissions plays a key role in meeting the Paris Agreement ambitions and sustainable development goals. Implementation of respective policies addressing these targets mainly occur at sectoral and regional levels, and designing efficient mitigation strategies therefore relies on detailed knowledge about the mix of emissions from individual sources and their subsequent climate impact. Here we present a comprehensive dataset of near- and long-term global temperature responses to emissions of CO2 and individual short-lived climate forcers (SLCFs) from 7 sectors and 13 regions – for both present-day emissions and their continued evolution as projected under the Shared Socioeconomic Pathways (SSPs). We demonstrate the key role of CO2 in driving both near- and long-term warming and highlight the importance of mitigating methane emissions from agriculture, waste management, and energy production as the primary strategy to further limit near-term warming. Due to high current emissions of cooling SLCFs, policies targeting end-of-pipe energy sector emissions may result in net added warming unless accompanied by simultaneous methane and/or CO2 reductions. We find that SLCFs are projected to play a continued role in many regions, particularly those including low- to medium-income countries, under most of the SSPs considered here. East Asia, North America, and Europe will remain the largest contributors to total net warming until 2100, regardless of scenario, while South Asia and Africa south of the Sahara overtake Europe by the end of the century in SSP3-7.0 and SSP5-8.5. Our dataset is made available in an accessible format, aimed also at decision makers, to support further assessment of the implications of policy implementation at the sectoral and regional scales.}, author = {Lund, Marianne T. and Aamaas, Borgar and Stjern, Camilla W. and Klimont, Zbigniew and Berntsen, Terje K. and Samset, Bj{\o}rn H.}, doi = {10.5194/esd-11-977-2020}, file = {::}, issn = {2190-4987}, journal = {Earth System Dynamics}, month = {nov}, number = {4}, pages = {977--993}, title = {{A continued role of short-lived climate forcers under the Shared Socioeconomic Pathways}}, url = {https://esd.copernicus.org/articles/11/977/2020/}, volume = {11}, year = {2020} } @article{Lund2018_BClifetime, abstract = {Using a lacZ plasmid transgenic mouse model, spectra of spontaneous point mutations were determined in brain, heart, liver, spleen and small intestine in young and old mice. While similar at a young age, the mutation spectra among these organs were significantly different in old age. In brain and heart G:C--{\textgreater}A:T transitions at CpG sites were the predominant mutation, suggesting that oxidative damage is not a major mutagenic event in these tissues. Other base changes, especially those affecting A:T base pairs, positively correlated with increasing proliferative activity of the different tissues. A relatively high percentage of base changes at A:T base pairs and compound mutants were found in both spleen and spontaneous lymphoma, suggesting a possible role of the hypermutation process in splenocytes in carcinogenesis. The similar mutant spectra observed at a young age may reflect a common mutation mechanism for all tissues that could be driven by the rapid cell division that takes place during development. However, the spectra of the young tissues did not resemble that of the most proliferative aged tissue, implying that replicative history per se is not the underlying causal factor of age-related organ-specific differences in mutation spectra. Rather, differences in organ function, possibly in association with replicative history, may explain the divergence in mutation spectra during aging.}, author = {Lund, Marianne T. and Samset, Bj{\o}rn H. and Skeie, Ragnhild B. and Watson-Parris, Duncan and Katich, Joseph M. and Schwarz, Joshua P. and Weinzierl, Bernadett}, doi = {10.1038/s41612-018-0040-x}, isbn = {2397-3722}, issn = {2397-3722}, journal = {npj Climate and Atmospheric Science}, number = {1}, pages = {31}, title = {{Short Black Carbon lifetime inferred from a global set of aircraft observations}}, url = {https://doi.org/10.1038/s41612-018-0040-x}, volume = {1}, year = {2018} } @article{Lund2018a, abstract = {We document the ability of the new-generation Oslo chemistry-transport model, Oslo CTM3, to accurately simulate present-day aerosol distributions. The model is then used with the new Community Emission Data System (CEDS) historical emission inventory to provide updated time series of anthropogenic aerosol concentrations and consequent direct radiative forcing (RFari) from 1750 to 2014.Overall, Oslo CTM3 performs well compared with measurements of surface concentrations and remotely sensed aerosol optical depth. Concentrations are underestimated in Asia, but the higher emissions in CEDS than previous inventories result in improvements compared to observations. The treatment of black carbon (BC) scavenging in Oslo CTM3 gives better agreement with observed vertical BC profiles relative to the predecessor Oslo CTM2. However, Arctic wintertime BC concentrations remain underestimated, and a range of sensitivity tests indicate that better physical understanding of processes associated with atmospheric BC processing is required to simultaneously reproduce both the observed features. Uncertainties in model input data, resolution, and scavenging affect the distribution of all aerosols species, especially at high latitudes and altitudes. However, we find no evidence of consistently better model performance across all observables and regions in the sensitivity tests than in the baseline configuration.Using CEDS, we estimate a net RFari in 2014 relative to 1750 of-0.17-W-mg-2, significantly weaker than the IPCC AR5 2011-1750 estimate. Differences are attributable to several factors, including stronger absorption by organic aerosol, updated parameterization of BC absorption, and reduced sulfate cooling. The trend towards a weaker RFari over recent years is more pronounced than in the IPCC AR5, illustrating the importance of capturing recent regional emission changes.}, author = {Lund, Marianne Tronstad and Myhre, Gunnar and {S{\o}vde Haslerud}, Amund and {Bieltvedt Skeie}, Ragnhild and Griesfeller, Jan and {Matthew Platt}, Stephen and Kumar, Rajesh and {Lund Myhre}, Cathrine and Schulz, Michael}, doi = {10.5194/gmd-11-4909-2018}, issn = {19919603}, journal = {Geoscientific Model Development}, month = {dec}, number = {12}, pages = {4909--4931}, title = {{Concentrations and radiative forcing of anthropogenic aerosols from 1750 to 2014 simulated with the Oslo CTM3 and CEDS emission inventory}}, volume = {11}, year = {2018} } @article{Lund2017, abstract = {This study examines the impacts of emissions from aviation in six source regions on global and regional temperatures. We consider the NOx-induced impacts on ozone and methane, aerosols and contrail-cirrus formation and calculate the global and regional emission metrics global warming potential (GWP), global temperature change potential (GTP) and absolute regional temperature change potential (ARTP). The GWPs and GTPs vary by a factor of 2-4 between source regions. We find the highest aviation aerosol metric values for South Asian emissions, while contrail-cirrus metrics are higher for Europe and North America, where contrail formation is prevalent, and South America plus Africa, where the optical depth is large once contrails form. The ARTP illustrate important differences in the latitudinal patterns of radiative forcing (RF) and temperature response: the temperature response in a given latitude band can be considerably stronger than suggested by the RF in that band, also emphasizing the importance of large-scale circulation impacts. To place our metrics in context, we quantify temperature change in four broad latitude bands following 1 year of emissions from present-day aviation, including CO2. Aviation over North America and Europe causes the largest net warming impact in all latitude bands, reflecting the higher air traffic activity in these regions. Contrail cirrus gives the largest warming contribution in the short term, but remain important at about 15{\%} of the CO2 impact in several regions even after 100 years. Our results also illustrate both the short- and long-term impacts of CO2: while CO2 becomes dominant on longer timescales, it also gives a notable warming contribution already 20 years after the emission. Our emission metrics can be further used to estimate regional temperature change under alternative aviation emission scenarios. A first evaluation of the ARTP in the context of aviation suggests that further work to account for vertical sensitivities in the relationship between RF and temperature response would be valuable for further use of the concept.}, author = {Lund, Marianne T. and Aamaas, Borgar and Berntsen, Terje and Bock, Lisa and Burkhardt, Ulrike and Fuglestvedt, Jan S. and Shine, Keith P.}, doi = {10.5194/esd-8-547-2017}, issn = {21904987}, journal = {Earth System Dynamics}, month = {jul}, number = {3}, pages = {547--563}, title = {{Emission metrics for quantifying regional climate impacts of aviation}}, url = {https://www.earth-syst-dynam.net/8/547/2017/}, volume = {8}, year = {2017} } @article{TronstadLund2012a, abstract = {We utilize a range of emission scenarios for shipping to determine the induced global-mean radiative forcing and temperature change. Ship emission scenarios consistent with the new regulations on nitrogen oxides (NO x ) and sulfur dioxide (SO 2 ) from the International Maritime Organization and two of the Representative Concentration Pathways are used as input to a simple climate model (SCM). Based on a complex aerosol-climate model we develop and test new parametrizations of the indirect aerosol effect (IAE) in the SCM that account for nonlinearities in radiative forcing of ship-induced IAE. We find that shipping causes a net global cooling impact throughout the period 1900-2050 across all parametrizations and scenarios. However, calculated total net global-mean temperature change in 2050 ranges from -0.03[-0.07,-0.002]°C to -0.3[-0.6,-0.2]°C in the A1B scenario. This wide range across parametrizations emphasizes the importance of properly representing the IAE in SCMs and to reflect the uncertainties from complex global models. Furthermore, our calculations show that the future ship-induced temperature response is likely a continued cooling if SO 2 and NO x emissions continue to increase due to a strong increase in activity, despite current emission regulations. However, such cooling does not negate the need for continued efforts to reduce CO 2 emissions, since residual warming from CO 2 is long-lived. {\textcopyright} 2012 American Chemical Society.}, author = {Lund, Marianne Tronstad and Eyring, Veronika and Fuglestvedt, Jan and Hendricks, Johannes and Lauer, Axel and Lee, David and Righi, Mattia}, doi = {10.1021/es301166e}, issn = {0013-936X}, journal = {Environmental Science {\&} Technology}, month = {aug}, number = {16}, pages = {8868--8877}, title = {{Global-Mean Temperature Change from Shipping toward 2050: Improved Representation of the Indirect Aerosol Effect in Simple Climate Models}}, url = {https://pubs.acs.org/doi/10.1021/es301166e}, volume = {46}, year = {2012} } @article{Lund2014b, abstract = {Diesel vehicles are a significant source of black carbon (BC) and ozone precursors, which are important contributors to climate warming, degrade air quality and harm human health. Reducing diesel emissions could mitigate near-term climate change with significant co-benefits. This study quantifies the global and regional climate impacts of BC and co-emitted short-lived climate forcers (SLCFs) from present-day on-road diesel vehicles, as well as future impacts following a current legislation emission scenario. Atmospheric concentrations are calculated by the chemical transport model OsloCTM2. The following radiative forcing (RF) and equilibrium surface temperature responses are estimated. For year 2010 on-road diesel emissions we estimate a global-mean direct RF from BC of 44mW/m2 and an equilibrium surface temperature response of 59mK, including the impact of BC deposition on snow. Accounting for cooling and warming impacts of co-emitted SLCFs results in a net global-mean RF and warming of 28mW/m2 and 48mK, respectively. Using the concept of Regional Temperature change Potential (RTP), we find significant geographical differences in the responses to regional emissions. Accounting for the vertical sensitivities of the forcing/response relation amplifies these differences. In terms of individual source regions, emissions in Europe give the largest regional contribution to equilibrium warming caused by year 2010 on-road diesel BC, while Russia is most important for Arctic warming per unit emission. The largest contribution to warming caused by the year 2050 on-road diesel sector is from emissions in South Asia, followed by East Asia and the Middle East. Hence, in regions where current legislation is not sufficient to outweigh the expected growth in activity, accelerated policy implementation is important for further future mitigation. {\textcopyright} 2014 Elsevier Ltd.}, annote = {From Duplicate 1 (Global and regional climate impacts of black carbon and co-emitted species from the on-road diesel sector - Lund, Marianne T.; Berntsen, Terje K.; Heyes, Chris; Klimont, Zbigniew; Samset, Bj{\o}rn H.) From Duplicate 2 (Global and regional climate impacts of black carbon and co-emitted species from the on-road diesel sector - Lund, Marianne T.; Berntsen, Terje K.; Heyes, Chris; Klimont, Zbigniew; Samset, Bj{\o}rn H.) From Duplicate 1 (Global and regional climate impacts of black carbon and co-emitted species from the on-road diesel sector - Lund, Marianne T.; Berntsen, Terje K.; Heyes, Chris; Klimont, Zbigniew; Samset, Bj{\o}rn H.) Times Cited: 11 Klimont, Zbigniew/P-7641-2015; Samset, Bjorn H./B-9248-2012; Lund, Marianne/J-6465-2016; Heyes, Chris/ Klimont, Zbigniew/0000-0003-2630-198X; Samset, Bjorn H./0000-0001-8013-1833; Lund, Marianne/0000-0001-9911-4160; Heyes, Chris/0000-0001-5254-493X 0 11 1873-2844}, author = {Lund, Marianne T. and Berntsen, Terje K. and Heyes, Chris and Klimont, Zbigniew and Samset, Bj{\o}rn H.}, doi = {10.1016/j.atmosenv.2014.08.033}, isbn = {1352-2310}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Black carbon,Chemistry-transport modeling,On-road diesel,Regional temperature response,Short-lived climate forcers}, month = {dec}, pages = {50--58}, title = {{Global and regional climate impacts of black carbon and co-emitted species from the on-road diesel sector}}, url = {https://www.sciencedirect.com/science/article/pii/S135223101400627X?via{\%}3Dihub http://linkinghub.elsevier.com/retrieve/pii/S135223101400627X https://linkinghub.elsevier.com/retrieve/pii/S135223101400627X}, volume = {98}, year = {2014} } @article{Luo2015, abstract = {Ammonia (NH3) and carbon monoxide (CO) are primary pollutants emitted to the Earth's atmosphere from common as well as distinct sources associated with anthropogenic and natural activities. The seasonal and global distributions and correlations of NH3and CO from the Tropospheric Emission Spectrometer (TES) satellite observations and GEOS-Chem model simulations for 2007 are investigated to evaluate how well the global and seasonal pollutant sources are prescribed in the model. Although the GEOS-Chem simulations of NH3and CO atmospheric mixing ratio values are lower than the TES satellite observations, the global distribution patterns from the model reasonably agree with the observations, indicating that the model represents the general location of the source regions and the seasonal enhancements of NH3and CO globally over large regional scales. In regions and seasons where biomass burning is the dominant source of both NH3and CO emissions into the atmosphere, there are strong NH3:CO correlations, which is consistent with the relationship demonstrated by surface measurements over fires. In regions where the enhanced NH3and CO are known to be produced by different sources, the NH3:CO correlations from TES observations and model simulations are weak or non-existent. For biomass burning regions the NH3:CO ratios are 0.015 (TES) and 0.013 (GEOS-Chem). In regions of high-population density, known heavy traffic, and limited biomass burning sources, such as the rapidly developing areas of South Asia and northern China, which include mixtures of megacities, industrial, and agricultural areas, the two species show weaker but still positive correlations and NH3:CO ratios of 0.051 (TES) and 0.036 (GEOS-Chem). These enhancement ratios of NH3relative to CO are useful in constraining NH3emission inventories when CO emission inventories are better known for some events or regions (i.e. biomass burning).}, author = {Luo, Ming and Shephard, Mark W. and Cady-Pereira, Karen E. and Henze, Daven K. and Zhu, Liye and Bash, Jesse O. and Pinder, Robert W. and Capps, Shannon L. and Walker, John T. and Jones, Matthew R.}, doi = {10.1016/j.atmosenv.2015.02.007}, issn = {13522310}, journal = {Atmospheric Environment}, keywords = {GEOS-Chem model simulations,Satellite observations of carbon monoxide and ammo}, month = {apr}, pages = {262--277}, pmid = {2015727115}, title = {{Satellite observations of tropospheric ammonia and carbon monoxide: Global distributions, regional correlations and comparisons to model simulations}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1352231015001260}, volume = {106}, year = {2015} } @article{Mulmenstadt2018, author = {M{\"{u}}lmenst{\"{a}}dt, Johannes and Feingold, Graham}, doi = {10.1007/s40641-018-0089-y}, issn = {2198-6061}, journal = {Current Climate Change Reports}, month = {mar}, number = {1}, pages = {23--40}, title = {{The Radiative Forcing of Aerosol–Cloud Interactions in Liquid Clouds: Wrestling and Embracing Uncertainty}}, url = {http://link.springer.com/10.1007/s40641-018-0089-y}, volume = {4}, year = {2018} } @article{Macmartin2017, abstract = {By injecting different amounts of SO2 at multiple different latitudes, the spatial pattern of aerosol optical depth (AOD) can be partially controlled. This leads to the ability to influence the climate response to geoengineering with stratospheric aerosols, providing the potential for design. We use simulations from the fully coupled whole-atmosphere chemistry climate model CESM1(WACCM) to demonstrate that by appropriately combining injection at just four different locations, 30∘S, 15∘S, 15∘N, and 30∘N, then three spatial degrees of freedom of AOD can be achieved: an approximately spatially uniform AOD distribution, the relative difference in AOD between Northern and Southern Hemispheres, and the relative AOD in high versus low latitudes. For forcing levels that yield 1–2∘C cooling, the AOD and surface temperature response are sufficiently linear in this model so that the response to different combinations of injection at different latitudes can be estimated from single-latitude injection simulations; nonlinearities associated with both aerosol growth and changes to stratospheric circulation will be increasingly important at higher forcing levels. Optimized injection at multiple locations is predicted to improve compensation of CO2-forced climate change relative to a case using only equatorial aerosol injection (which overcools the tropics relative to high latitudes). The additional degrees of freedom can be used, for example, to balance the interhemispheric temperature gradient and the equator to pole temperature gradient in addition to the global mean temperature. Further research is needed to better quantify the impacts of these strategies on changes to long-term temperature, precipitation, and other climate parameters.}, author = {MacMartin, Douglas G. and Kravitz, Ben and Tilmes, Simone and Richter, Jadwiga H. and Mills, Michael J. and Lamarque, Jean‐Francois and Tribbia, Joseph J. and Vitt, Francis}, doi = {10.1002/2017JD026868}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {dec}, number = {23}, pages = {12574--12590}, title = {{The Climate Response to Stratospheric Aerosol Geoengineering Can Be Tailored Using Multiple Injection Locations}}, url = {https://onlinelibrary.wiley.com/doi/10.1002/2017JD026868}, volume = {122}, year = {2017} } @article{Mahmood2016a, abstract = {This study quantifies black carbon (BC) processes in three global climate models and one chemistry transport model, with focus on the seasonality of BC transport, emissions, wet and dry deposition in the Arctic. In the models, transport of BC to the Arctic from lower latitudes is the major BC source for this region. Arctic emissions are very small. All models simulated a similar annual cycle of BC transport from lower latitudes to the Arctic, with maximum transport occurring in July. Substantial differences were found in simulated BC burdens and vertical distributions, with CanAM (NorESM) producing the strongest (weakest) seasonal cycle. CanAM also has the shortest annual mean residence time for BC in the Arctic followed by SMHI-MATCH, CESM and NorESM. Overall, considerable differences in wet deposition efficiencies in the models exist and are a leading cause of differences in simulated BC burdens. Results from model sensitivity experiments indicate that convective scavenging outside the Arctic reduces the mean altitude of BC residing in the Arctic, making it more susceptible to scavenging by stratiform (layer) clouds in the Arctic. Consequently, scavenging of BC in convective clouds outside the Arctic acts to substantially increase the overall efficiency of BC wet deposition in the Arctic, which leads to low BC burdens and a more pronounced seasonal cycle compared to simulations without convective BC scavenging. In contrast, the simulated seasonality of BC concentrations in the upper troposphere is only weakly influenced by wet deposition in stratiform clouds whereas lower tropospheric concentrations are highly sensitive.}, annote = {Times Cited: 11 Flanner, Mark/C-6139-2011; Wang, Hailong/B-8061-2010 Flanner, Mark/0000-0003-4012-174X; Wang, Hailong/0000-0002-1994-4402 0 11 2169-8996}, author = {Mahmood, Rashed and von Salzen, Knut and Flanner, Mark and Sand, Maria and Langner, Joakim and Wang, Hailong and Huang, Lin}, doi = {10.1002/2016JD024849}, isbn = {2169-9291}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {jun}, number = {12}, pages = {7100--7116}, title = {{Seasonality of global and Arctic black carbon processes in the Arctic Monitoring and Assessment Programme models}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2016JD024849 http://doi.wiley.com/10.1002/2016JD024849}, volume = {121}, year = {2016} } @article{Mahowald2011, author = {Mahowald, N.M.}, doi = {10.1126/science.1207374}, issn = {0036-8075}, journal = {Science}, month = {nov}, number = {6057}, pages = {794--796}, title = {{Aerosol Indirect Effect on Biogeochemical Cycles and Climate}}, url = {http://www.sciencemag.org/cgi/doi/10.1126/science.1207374}, volume = {334}, year = {2011} } @article{Mahowald2003, abstract = {Atmospheric desert dust is potentially highly sensitive to changes in climate, carbon dioxide and human land use. In this study we use 6 different scenarios of the processes responsible for changes in source areas and explore changes in desert dust loading in pre-industrial and future climates, although all the scenario results are likely to be sensitive to the climate model simulations used for this study. Simulations suggest that future dust may be 20 to 60{\%} lower than current dust loadings. The anthropogenic portion of the current dust loading may be as large as 60{\%}, or humans may have caused a 24{\%} decrease in desert dust, depending on the relative importance of land use, carbon dioxide and human induced climate change. These results suggest there may be a high sensitivity of 'natural aerosols' to human intervention, which has enormous implications for climate and biogeochemistry in the future.}, author = {Mahowald, Natalie M. and Luo, Chao}, doi = {10.1029/2003GL017880}, issn = {00948276}, journal = {Geophysical Research Letters}, number = {17}, pages = {1903}, title = {{A less dusty future?}}, volume = {30}, year = {2003} } @article{Mahowald2017, abstract = {Purpose of Review: Atmospheric aerosol deposition is an important source of nutrients and pollution to many continental and marine ecosystems. Humans have heavily perturbed the cycles of several important aerosol species, potentially affecting terrestrial and marine carbon budgets and consequently climate. The most ecologically important aerosol elements impacted by humans are nitrogen, sulfur, iron, phosphorus, and base cations. Here, we review the latest research on the modification of the atmospheric cycles of these aerosols and their resulting effects on continental and marine ecosystems. Recent Findings: Recent studies have improved our understanding of how humans have perturbed atmospheric aerosol cycles and how they may continue to evolve in the future. Research in both aquatic and terrestrial environments has highlighted the role of atmospheric deposition as a nutrient subsidy, with effects on ecosystem productivity. These studies further emphasize the importance of local biogeochemical conditions and biota species composition to the regional responses to aerosol deposition. Summary: The size of the impact of anthropogenic aerosol deposition on the carbon cycle and the resulting climate forcing is at present not well understood. It is estimated that increases in nutrient subsidies from atmospheric deposition across all ecosystems are causing an increase in carbon dioxide uptake between 0.2 and 1.5 PgC/year. As aerosol emissions from industrial sources are reduced to improve air quality, these enhancements in carbon uptake may be reduced in the future leading to reduced carbon dioxide emission offsets. However, large uncertainties remain, not only because of limited information on how humans have modified and will modify aerosol emissions, but also because of a lack of quantitative understanding of how aerosol deposition impacts carbon cycling in many ecosystems.}, author = {Mahowald, Natalie M. and Scanza, Rachel and Brahney, Janice and Goodale, Christine L. and Hess, Peter G. and Moore, J. Keith and Neff, Jason}, doi = {10.1007/s40641-017-0056-z}, issn = {21986061}, journal = {Current Climate Change Reports}, keywords = {Aerosols,Biogeochemistry,Carbon cycle,Nutrients}, month = {mar}, number = {1}, pages = {16--31}, title = {{Aerosol Deposition Impacts on Land and Ocean Carbon Cycles}}, url = {http://link.springer.com/10.1007/s40641-017-0056-z}, volume = {3}, year = {2017} } @article{Mahowald2010, abstract = {Desert dust perturbs climate by directly and indirectly interacting with incoming solar and outgoing long wave radiation, thereby changing precipitation and temperature, in addition to modifying ocean and land biogeochemistry. While we know that desert dust is sensitive to perturbations in climate and human land use, previous studies have been unable to determine whether humans were increasing or decreasing desert dust in the global average. Here we present observational estimates of desert dust based on paleodata proxies showing a doubling of desert dust during the 20th century over much, but not all the globe. Large uncertainties remain in estimates of desert dust variability over 20th century due to limited data. Using these observational estimates of desert dust change in combination with ocean, atmosphere and land models, we calculate the net radiative effect of these observed changes (top of atmosphere) over the 20th century to be -0.14±0.11 W/m2 (1990-1999 vs. 1905-1914). The estimated radiative change due to dust is especially strong between the heavily loaded 1980-1989 and the less heavily loaded 1955-1964 time periods (-0.57±0.46 W/m2), which model simulations suggest may have reduced the rate of temperature increase between these time periods by 0.11 °C. Model simulations also indicate strong regional shifts in precipitation and temperature from desert dust changes, causing 6 ppm (12 PgC) reduction in model carbon uptake by the terrestrial biosphere over the 20th century. Desert dust carries iron, an important micronutrient for ocean biogeochemistry that can modulate ocean carbon storage; here we show that dust deposition trends increase ocean productivity by an estimated 6{\%} over the 20th century, drawing down an additional 4 ppm (8 PgC) of carbon dioxide into the oceans. Thus, perturbations to desert dust over the 20th century inferred from observations are potentially important for climate and biogeochemistry, and our understanding of these changes and their impacts should continue to be refined. {\textcopyright} 2010 Author(s).}, annote = {ACP}, author = {Mahowald, N. M. and Kloster, S. and Engelstaedter, S. and Moore, J. K. and Mukhopadhyay, S. and McConnell, J. R. and Albani, S. and Doney, S. C. and Bhattacharya, A. and Curran, M. A.J. and Flanner, M. G. and Hoffman, F. M. and Lawrence, D. M. and Lindsay, K. and Mayewski, P. A. and Neff, J. and Rothenberg, D. and Thomas, E. and Thornton, P. E. and Zender, C. S.}, doi = {10.5194/acp-10-10875-2010}, isbn = {1680-7324}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, number = {22}, pages = {10875--10893}, publisher = {Copernicus Publications}, title = {{Observed 20th century desert dust variability: Impact on climate and biogeochemistry}}, url = {http://www.atmos-chem-phys.net/10/10875/2010/ http://www.atmos-chem-phys.net/10/10875/2010/acp-10-10875-2010.pdf}, volume = {10}, year = {2010} } @article{Maione2016, abstract = {Anthropogenic activities are responsible for the emission of gaseous and particulate pollutants that modify atmospheric composition. Such changes are, in turn, responsible for the degradation of air quality at the regional/local scale as well as for changes of climate. Air pollution and climate change are two intimately connected environmental issues. However, these two environmental challenges are still viewed as separate issues, which are dealt with by different science communities and within different policy frameworks. Indeed, many mitigation options offer the possibility to both improve air quality and mitigate climate change but, at the same time, mitigation options that may provide benefits to one aspect, are worsening the situation in the other. Therefore, coordinated actions taking into account the air quality-climate linkages are required. These actions need to be based on strong scientific grounds, as recognised by the European Commission that in the past few years has promoted consultation processes among the science community, the policy makers and the relevant stakeholders. Here, the main fields in which such coordinated actions are needed are examined from a policy perspective.}, author = {Maione, Michela and Fowler, David and Monks, Paul S. and Reis, Stefan and Rudich, Yinon and Williams, Martin L. and Fuzzi, Sandro}, doi = {10.1016/j.envsci.2016.03.011}, issn = {18736416}, journal = {Environmental Science {\&} Policy}, keywords = {Air quality,Climate change,Policy,Short lived climate pollutants}, pages = {48--57}, title = {{Air quality and climate change: Designing new win-win policies for Europe}}, url = {http://dx.doi.org/10.1016/j.envsci.2016.03.011}, volume = {65}, year = {2016} } @article{Malavelle2017a, abstract = {Aerosols have a potentially large effect on climate, particularly through their interactions with clouds, but the magnitude of this effect is highly uncertain. Large volcanic eruptions produce sulfur dioxide, which in turn produces aerosols; these eruptions thus represent a natural experiment through which to quantify aerosol-cloud interactions. Here we show that the massive 2014-2015 fissure eruption in Holuhraun, Iceland, reduced the size of liquid cloud droplets - consistent with expectations - but had no discernible effect on other cloud properties. The reduction in droplet size led to cloud brightening and global-mean radiative forcing of around -0.2 watts per square metre for September to October 2014. Changes in cloud amount or cloud liquid water path, however, were undetectable, indicating that these indirect effects, and cloud systems in general, are well buffered against aerosol changes. This result will reduce uncertainties in future climate projections, because we are now able to reject results from climate models with an excessive liquid-water-path response.}, author = {Malavelle, Florent F. and Haywood, Jim M. and Jones, Andy and Gettelman, Andrew and Clarisse, Lieven and Bauduin, Sophie and Allan, Richard P. and Karset, Inger Helene H. and Kristj{\'{a}}nsson, J{\'{o}}n Egill and Oreopoulos, Lazaros and Cho, Nayeong and Lee, Dongmin and Bellouin, Nicolas and Boucher, Olivier and Grosvenor, Daniel P. and Carslaw, Ken S. and Dhomse, Sandip and Mann, Graham W. and Schmidt, Anja and Coe, Hugh and Hartley, Margaret E. and Dalvi, Mohit and Hill, Adrian A. and Johnson, Ben T. and Johnson, Colin E. and Knight, Jeff R. and O'Connor, Fiona M. and Partridge, Daniel G. and Stier, Philip and Myhre, Gunnar and Platnick, Steven and Stephens, Graeme L. and Takahashi, Hanii and Thordarson, Thorvaldur}, doi = {10.1038/nature22974}, issn = {0028-0836}, journal = {Nature}, month = {jun}, number = {7659}, pages = {485--491}, title = {{Strong constraints on aerosol–cloud interactions from volcanic eruptions}}, url = {http://www.nature.com/articles/nature22974}, volume = {546}, year = {2017} } @article{Malm2017, abstract = {Recent modeling and field studies have highlighted a relationship between sulfate concentrations and secondarily formed organic aerosols related to isoprene and other volatile biogenic gaseous emissions. The relationship between these biogenic emissions and sulfate is thought to be primarily associated with the effect of sulfate on aerosol acidity, increased aerosol water at high relative humidities, and aerosol volume. The Interagency Monitoring of Protected Visual Environments (IMPROVE) program provides aerosol concentration levels of sulfate (SO4) and organic carbon (OC) at 136 monitoring sites in rural and remote areas of the United States over time periods of between 15 and 28 years. This data set allows for an examination of relationships between these variables over time and space. The relative decreases in SO4 and OC were similar over most of the eastern United States, even though concentrations varied dramatically from one region to another. The analysis implied that for every unit decrease in SO4 there was about a 0.29 decrease in organic aerosol mass (OA = 1.8 × OC). This translated to a 2 $\mu$g/m3 decrease in biogenically derived secondary organic aerosol over 15 years in the southeastern United States. The analysis further implied that 35{\%} and 27{\%} in 2001 and 2015, respectively, of average total OA may be biogenically derived secondary organic aerosols and that there was a small but significant decrease in OA not linked to changes in SO4 concentrations. The analysis yields a constraint on ambient SO4–OC relationships that should help to refine and improve regional-scale chemical transport models.}, author = {Malm, William C. and Schichtel, Bret A. and Hand, Jenny L. and Collett, Jeffrey L.}, doi = {10.1002/2017JD026865}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {IMPROVE,SOA,isoprene,sulfate,trend}, month = {oct}, number = {19}, pages = {10462--10476}, title = {{Concurrent Temporal and Spatial Trends in Sulfate and Organic Mass Concentrations Measured in the IMPROVE Monitoring Program}}, url = {http://doi.wiley.com/10.1002/2017JD026865}, volume = {122}, year = {2017} } @article{Mangeon2015, abstract = {North American wildfire management teams routinely assess burned area on site during firefighting campaigns; meanwhile, satellite observations provide systematic and global burned-area data. Here we compare satellite and ground-based daily burned area for wildfire events for selected large fires across North America in 2007 on daily timescales. In a sample of 26 fires across North America, we found the Global Fire Emissions Database Version 4 (GFED4) estimated about 80{\%} of the burned area logged in ground-based Incident Status Summary (ICS-209) over 8-day analysis windows. Linear regression analysis found a slope between GFED and ICS-209 of 0.67 (with R = 0.96). The agreement between these data sets was found to degrade at short timescales (from R = 0.81 for 4-day to R = 0.55 for 2-day). Furthermore, during large burning days ({\textgreater} 3000 ha) GFED4 typically estimates half of the burned area logged in the ICS-209 estimates.}, annote = {doi: 10.1177/2053019615588790}, author = {Mangeon, St{\'{e}}phane and Field, Robert and Fromm, Michael and McHugh, Charles and Voulgarakis, Apostolos}, doi = {10.1177/2053019615588790}, issn = {2053-0196}, journal = {The Anthropocene Review}, month = {may}, number = {2}, pages = {76--92}, publisher = {SAGE Publications}, title = {{Satellite versus ground-based estimates of burned area: A comparison between MODIS based burned area and fire agency reports over North America in 2007}}, url = {https://doi.org/10.1177/2053019615588790}, volume = {3}, year = {2015} } @article{Mann2014, abstract = {Abstract. Many of the next generation of global climate models will include aerosol schemes which explicitly simulate the microphysical processes that determine the particle size distribution. These models enable aerosol optical properties and cloud condensation nuclei (CCN) concentrations to be determined by fundamental aerosol processes, which should lead to a more physically based simulation of aerosol direct and indirect radiative forcings. This study examines the global variation in particle size distribution simulated by 12 global aerosol microphysics models to quantify model diversity and to identify any common biases against observations. Evaluation against size distribution measurements from a new European network of aerosol supersites shows that the mean model agrees quite well with the observations at many sites on the annual mean, but there are some seasonal biases common to many sites. In particular, at many of these European sites, the accumulation mode number concentration is biased low during winter and Aitken mode concentrations tend to be overestimated in winter and underestimated in summer. At high northern latitudes, the models strongly underpredict Aitken and accumulation particle concentrations compared to the measurements, consistent with previous studies that have highlighted the poor performance of global aerosol models in the Arctic. In the marine boundary layer, the models capture the observed meridional variation in the size distribution, which is dominated by the Aitken mode at high latitudes, with an increasing concentration of accumulation particles with decreasing latitude. Considering vertical profiles, the models reproduce the observed peak in total particle concentrations in the upper troposphere due to new particle formation, although modelled peak concentrations tend to be biased high over Europe. Overall, the multi-model-mean data set simulates the global variation of the particle size distribution with a good degree of skill, suggesting that most of the individual global aerosol microphysics models are performing well, although the large model diversity indicates that some models are in poor agreement with the observations. Further work is required to better constrain size-resolved primary and secondary particle number sources, and an improved understanding of nucleation and growth (e.g. the role of nitrate and secondary organics) will improve the fidelity of simulated particle size distributions.}, author = {Mann, G. W. and Carslaw, K. S. and Reddington, C. L. and Pringle, K. J. and Schulz, M. and Asmi, A. and Spracklen, D. V. and Ridley, D. A. and Woodhouse, M. T. and Lee, L. A. and Zhang, K. and Ghan, S. J. and Easter, R. C. and Liu, X. and Stier, P. and Lee, Y. H. and Adams, P. J. and Tost, H. and Lelieveld, J. and Bauer, S. E. and Tsigaridis, K. and van Noije, T. P. C. and Strunk, A. and Vignati, E. and Bellouin, N. and Dalvi, M. and Johnson, C. E. and Bergman, T. and Kokkola, H. and von Salzen, K. and Yu, F. and Luo, G. and Petzold, A. and Heintzenberg, J. and Clarke, A. and Ogren, J. A. and Gras, J. and Baltensperger, U. and Kaminski, U. and Jennings, S. G. and O{\&}apos;Dowd, C. D. and Harrison, R. M. and Beddows, D. C. S. and Kulmala, M. and Viisanen, Y. and Ulevicius, V. and Mihalopoulos, N. and Zdimal, V. and Fiebig, M. and Hansson, H.-C. and Swietlicki, E. and Henzing, J. S.}, doi = {10.5194/acp-14-4679-2014}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {9}, pages = {4679--4713}, title = {{Intercomparison and evaluation of global aerosol microphysical properties among AeroCom models of a range of complexity}}, url = {https://www.atmos-chem-phys.net/14/4679/2014/}, volume = {14}, year = {2014} } @article{Marais2018, abstract = {Nitrogen oxides (NOx = NO+NO2) in the upper troposphere (UT) have a large impact on global tropospheric ozone and OH (the main atmospheric oxidant). New cloudsliced observations of UT NO2 at 450-280 hPa (∼ 6-9 km) from the Ozone Monitoring Instrument (OMI) produced by NASA and the Royal Netherlands Meteorological Institute (KNMI) provide global coverage to test our understanding of the factors controlling UT NOx. We find that these products offer useful information when averaged over coarse scales (20° ×32°, seasonal), and that the NASA product is more consistent with aircraft observations of UT NO2. Correlation with Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) satellite observations of lightning flash frequencies suggests that lightning is the dominant source of NOx to the upper troposphere except for extratropical latitudes in winter. The NO2 background in the absence of lightning is 10-20 pptv. We infer a global mean NOx yield of 280±80 moles per lightning flash, with no significant difference between the tropics and midlatitudes, and a global lightning NOx source of 5:9±1:7 TgNa-1. There is indication that the NOx yield per flash increases with lightning flash footprint and with flash energy.}, author = {Marais, Eloise A. and Jacob, Daniel J. and Choi, Sungyeon and Joiner, Joanna and Belmonte-Rivas, Maria and Cohen, Ronald C. and Beirle, Steffen and Murray, Lee T. and Schiferl, Luke D. and Shah, Viral and Jaegl{\'{e}}, Lyatt}, doi = {10.5194/acp-18-17017-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {nov}, number = {23}, pages = {17017--17027}, title = {{Nitrogen oxides in the global upper troposphere: Interpreting cloud-sliced NO2 observations from the OMI satellite instrument}}, url = {https://www.atmos-chem-phys.net/18/17017/2018/}, volume = {18}, year = {2018} } @article{MARIANI20072887, abstract = {The concentrations of PM2.5−10, PM2.5 and associated water-soluble inorganic species (WSIS) were determined in a coastal site of the metropolitan region of Rio de Janeiro, Southeastern Brazil, from October 1998 to September 1999 (n=50). Samples were dissolved in water and analyzed for major inorganic ions. The mean (± standard deviation; median) concentrations of PM2.5−10 and PM2.5 were, respectively, 26 (± 16; 21)$\mu$gm−3 and 17 (± 13; 14)$\mu$gm−3. Their mean concentrations were 1.7–1.8 times higher in dry season (May–October) than in rainy season (November–April). The WSIS comprised, respectively, 34{\%} and 28{\%} of the PM2.5−10 and PM2.5 masses. Chloride, Na+ and Mg2+ were the predominant ions in PM2.5−10, indicating a significant influence of sea-salt aerosols. In PM2.5, SO42− (∼97{\%} nss-SO42−) and NH4+ were the most abundant ions and their equivalent concentration ratio (SO42−/NH4+ ∼1.0) suggests that they were present as (NH4)2SO4 particles. The mean concentration of (NH4)2SO4 was 3.4$\mu$gm−3. The mean equivalent PM2.5 NO3− concentration was eight times smaller than those of SO42− and NH4+. The PM2.5 NO3− concentration in dry season was three times higher than in rainy season, probably due to reaction of NaCl (sea salt) with HNO3 as a result of higher levels of NOy during the dry season and/or reduced volatilization of NH4NO3 due to lower wintertime temperature. Chloride depletion was observed in both size ranges, although more pronouncely in PM2.5.}, author = {Mariani, Rauda L and de Mello, William Z}, doi = {10.1016/j.atmosenv.2006.12.009}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Aerosol chemistry,Ammonium sulfate,Chloride depletion,Niter{\'{o}}i,PM}, number = {13}, pages = {2887--2892}, title = {{PM2.5–10, PM2.5 and associated water-soluble inorganic species at a coastal urban site in the metropolitan region of Rio de Janeiro}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231006012635}, volume = {41}, year = {2007} } @misc{Markakis2014, abstract = {Ozone and PM2.5 concentrations over the city of Paris are modeled with the CHIMERE air-quality model at 4 km × 4 km horizontal resolution for two future emission scenarios. A high-resolution (1 km × 1 km) emission projection until 2020 for the greater Paris region is developed by local experts (AIRPARIF) and is further extended to year 2050 based on regional-scale emission projections developed by the Global Energy Assessment. Model evaluation is performed based on a 10-year control simulation. Ozone is in very good agreement with measurements while PM2.5 is underestimated by 20{\%} over the urban area mainly due to a large wet bias in wintertime precipitation. A significant increase of maximum ozone relative to present-day levels over Paris is modeled under the "business-as-usual" scenario (+7 ppb) while a more optimistic "mitigation" scenario leads to a moderate ozone decrease (ĝ̂'3.5 ppb) in year 2050. These results are substantially different to previous regional-scale projections where 2050 ozone is found to decrease under both future scenarios. A sensitivity analysis showed that this difference is due to the fact that ozone formation over Paris at the current urban-scale study is driven by volatile organic compound (VOC)-limited chemistry, whereas at the regional-scale ozone formation occurs under NOx-sensitive conditions. This explains why the sharp NOx reductions implemented in the future scenarios have a different effect on ozone projections at different scales. In rural areas, projections at both scales yield similar results showing that the longer timescale processes of emission transport and ozone formation are less sensitive to model resolution. PM2.5 concentrations decrease by 78{\%} and 89{\%} under business-as-usual and mitigation scenarios, respectively, compared to the present-day period. The reduction is much more prominent over the urban part of the domain due to the effective reductions of road transport and residential emissions resulting in the smoothing of the large urban increment modeled in the control simulation. {\textcopyright} Author(s) 2014. CC Attribution 3.0 License.}, author = {Markakis, K. and Valari, M. and Colette, A. and Sanchez, O. and Perrussel, O. and Honore, C. and Vautard, R. and Klimont, Z. and Rao, S.}, booktitle = {Atmospheric Chemistry and Physics}, doi = {10.5194/acp-14-7323-2014}, issn = {16807324}, number = {14}, pages = {7323--7340}, title = {{Air quality in the mid-21st century for the city of Paris under two climate scenarios; From the regional to local scale}}, volume = {14}, year = {2014} } @article{Markakis2016, abstract = {Abstract. Ozone, PM10 and PM2.5 concentrations over Paris, France and Stockholm, Sweden were modelled at 4 and 1 km horizontal resolutions respectively for the present and 2050 periods employing decade-long simulations. We account for large-scale global climate change (RCP-4.5) and fine-resolution bottom-up emission projections developed by local experts and quantify their impact on future pollutant concentrations. Moreover, we identify biases related to the implementation of regional-scale emission projections by comparing modelled pollutant concentrations between the fine- and coarse-scale simulations over the study areas. We show that over urban areas with major regional contribution (e.g. the city of Stockholm) the bias related to coarse-scale projections may be significant and lead to policy misclassification. Our results stress the need to better understand the mechanism of bias propagation across the modelling scales in order to design more successful local-scale strategies. We find that the impact of climate change is spatially homogeneous in both regions, implying strong regional influence. The climate benefit for ozone (daily mean and maximum) is up to −5 {\%} for Paris and −2 {\%} for Stockholm city. The climate benefit on PM2.5 and PM10 in Paris is between −5 and −10 {\%}, while for Stockholm we estimate mixed trends of up to 3 {\%} depending on season and size class. In Stockholm, emission mitigation leads to concentration reductions up to 15 {\%} for daily mean and maximum ozone and 20 {\%} for PM. Through a sensitivity analysis we show that this response is entirely due to changes in emissions at the regional scale. On the contrary, over the city of Paris (VOC-limited photochemical regime), local mitigation of NOx emissions increases future ozone concentrations due to ozone titration inhibition. This competing trend between the respective roles of emission and climate change, results in an increase in 2050 daily mean ozone by 2.5 {\%} in Paris. Climate and not emission change appears to be the most influential factor for maximum ozone concentration over the city of Paris, which may be particularly interesting from a health impact perspective.}, author = {Markakis, Konstantinos and Valari, Myrto and Engardt, Magnuz and Lacressonniere, Gwendoline and Vautard, Robert and Andersson, Camilla}, doi = {10.5194/acp-16-1877-2016}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {feb}, number = {4}, pages = {1877--1894}, title = {{Mid-21st century air quality at the urban scale under the influence of changed climate and emissions – case studies for Paris and Stockholm}}, url = {https://acp.copernicus.org/articles/16/1877/2016/}, volume = {16}, year = {2016} } @article{Markandya2018, annote = {doi: 10.1016/S2542-5196(18)30029-9}, author = {Markandya, Anil and Sampedro, Jon and Smith, Steven J and {Van Dingenen}, Rita and Pizarro-Irizar, Cristina and Arto, I{\~{n}}aki and Gonz{\'{a}}lez-Eguino, Mikel}, doi = {10.1016/S2542-5196(18)30029-9}, issn = {2542-5196}, journal = {The Lancet Planetary Health}, month = {mar}, number = {3}, pages = {e126--e133}, publisher = {Elsevier}, title = {{Health co-benefits from air pollution and mitigation costs of the Paris Agreement: a modelling study}}, url = {https://doi.org/10.1016/S2542-5196(18)30029-9}, volume = {2}, year = {2018} } @article{Marlier2020, abstract = {Abstract Fires burning across the Amazon in the summer of 2019 attracted global attention for the widespread destruction of natural ecosystems and regional smoke production. Using a combination of satellite fire observations and atmospheric modeling, Nawaz and Henze (2020, https://doi.org.10.1029/2020GH000268) provide new evidence for the widespread regional public health consequences attributed to these fires. They find that approximately 10{\%} of premature deaths in Brazil due to fine particulate matter (PM2.5) are attributable to smoke pollution and highlight how fire locations play a critical role in determining downwind health impacts.}, annote = {https://doi.org/10.1029/2020GH000331}, author = {Marlier, M E and Bonilla, E X and Mickley, L J}, doi = {https://doi.org/10.1029/2020GH000331}, file = {::}, issn = {2471-1403}, journal = {GeoHealth}, month = {dec}, number = {12}, pages = {e2020GH000331}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{How Do Brazilian Fires Affect Air Pollution and Public Health?}}, url = {https://doi.org/10.1029/2020GH000331}, volume = {4}, year = {2020} } @article{bg-13-3225-2016, abstract = {Abstract. The location, timing, spatial extent, and frequency of wildfires are changing rapidly in many parts of the world, producing substantial impacts on ecosystems, people, and potentially climate. Paleofire records based on charcoal accumulation in sediments enable modern changes in biomass burning to be considered in their long-term context. Paleofire records also provide insights into the causes and impacts of past wildfires and emissions when analyzed in conjunction with other paleoenvironmental data and with fire models. Here we present new 1000-year and 22 000-year trends and gridded biomass burning reconstructions based on the Global Charcoal Database version 3 (GCDv3), which includes 736 charcoal records (57 more than in version 2). The new gridded reconstructions reveal the spatial patterns underlying the temporal trends in the data, allowing insights into likely controls on biomass burning at regional to global scales. In the most recent few decades, biomass burning has sharply increased in both hemispheres but especially in the north, where charcoal fluxes are now higher than at any other time during the past 22 000 years. We also discuss methodological issues relevant to data–model comparisons and identify areas for future research. Spatially gridded versions of the global data set from GCDv3 are provided to facilitate comparison with and validation of global fire simulations.}, author = {Marlon, Jennifer R and Kelly, Ryan and Daniau, Anne-Laure and Vanni{\`{e}}re, Boris and Power, Mitchell J and Bartlein, Patrick and Higuera, Philip and Blarquez, Olivier and Brewer, Simon and Br{\"{u}}cher, Tim and Feurdean, Angelica and Romera, Graciela Gil and Iglesias, Virginia and Maezumi, S Yoshi and Magi, Brian and {Courtney Mustaphi}, Colin J and Zhihai, Tonishtan}, doi = {10.5194/bg-13-3225-2016}, issn = {1726-4189}, journal = {Biogeosciences}, month = {jun}, number = {11}, pages = {3225--3244}, title = {{Reconstructions of biomass burning from sediment-charcoal records to improve data–model comparisons}}, url = {https://www.biogeosciences.net/13/3225/2016/}, volume = {13}, year = {2016} } @article{Marsh2016, abstract = {The Community Earth System Model-Whole Atmosphere Community Climate Model (CESM1-WACCM) is used to assess the importance of including chemistry feedbacks in determining the equilibrium climate sensitivity (ECS). Two 4×CO2 model experiments were conducted: one with interactive chemistry and one with chemical constituents other than CO2 held fixed at their preindustrial values. The ECS determined from these two experiments agrees to within 0.01 K. Similarly, the net feedback parameter agrees to within 0.01 W m-2 K-1. This agreement occurs in spite of large changes in stratospheric ozone found in the simulation with interactive chemistry: a 30{\%} decrease in the tropical lower stratosphere and a 40{\%} increase in the upper stratosphere, broadly consistent with other published estimates. Off-line radiative transfer calculations show that ozone changes alone account for the difference in radiative forcing. We conclude that at least for determining global climate sensitivity metrics, the exclusion of chemistry feedbacks is not a critical source of error in CESM.}, author = {Marsh, Daniel R. and Lamarque, Jean Fran{\c{c}}ois and Conley, Andrew J. and Polvani, Lorenzo M.}, doi = {10.1002/2016GL068344}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {4×CO2,CESM,WACCM,climate senstitivity,feedbacks,ozone}, number = {8}, pages = {3928--3934}, title = {{Stratospheric ozone chemistry feedbacks are not critical for the determination of climate sensitivity in CESM1(WACCM)}}, volume = {43}, year = {2016} } @article{doi:10.1029/2008RG000280, abstract = {This review provides a comprehensive account of what is known presently about Amazonian aerosol particles and concludes by formulating outlook and priorities for further research. The review is organized to follow the life cycle of Amazonian aerosol particles. It begins with a discussion of the primary and secondary sources relevant to the Amazonian particle burden, followed by a presentation of the particle properties that characterize the mixed populations present over the Amazon Basin at different times and places. These properties include number and mass concentrations and distributions, chemical composition, hygroscopicity, and cloud nucleation ability. The review presents Amazonian aerosol particles in the context of natural compared to anthropogenic sources as well as variability with season and meteorology. This review is intended to facilitate an understanding of the current state of knowledge on Amazonian aerosol particles specifically and tropical continental aerosol particles in general and thereby to enhance future research in this area.}, author = {Martin, Scot T and Andreae, Meinrat O and Artaxo, Paulo and Baumgardner, Darrel and Chen, Qi and Goldstein, Allen H and Guenther, Alex and Heald, Colette L and Mayol-Bracero, Olga L and McMurry, Peter H and Pauliquevis, Theotonio and P{\"{o}}schl, Ulrich and Prather, Kimberly A and Roberts, Gregory C and Saleska, Scott R and {Silva Dias}, M A and Spracklen, Dominick V and Swietlicki, Erik and Trebs, Ivonne}, doi = {10.1029/2008RG000280}, journal = {Reviews of Geophysics}, keywords = {Amazon,CCN,SOA,aerosol}, number = {2}, pages = {RG2002}, title = {{Sources and properties of Amazonian aerosol particles}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2008RG000280}, volume = {48}, year = {2010} } @article{Masiol2015, abstract = {The Veneto region lies in the eastern part of the Po Valley (Italy). This is one of the hotspots in Europe for air quality, where efforts to meet the European standard for PM2.5 according to current and future legislation have been generally unsuccessful. Recent data indicating that ammonium, nitrate and sulphate account for about one third of total PM2.5 mass show that secondary inorganic aerosol (SIA) plays a key role in the exceedence of the standards. A sampling campaign for PM2.5 was carried out simultaneously in six major cities (2012-2013). The water soluble inorganic ions were quantified and data processed to: (1) investigate the seasonal trends and the spatial variations of the ionic component of aerosol; (2) identify chemical characteristics at the regional-scale and (3) assess the potential effects of long-range transport using back-trajectory cluster analysis and concentration-weighted trajectory (CWT) models. Results indicated that PM2.5 and SIA ions have an increasing gradient in concentrations from North (mountain) to South (lowland) and from East (coastal) to West (more continental), whereas K+ and Ca2+ levels are quite uniformly distributed. Similar seasonal trends in PM2.5 and ions are seen across the region. Simultaneous daily changes were observed and interpreted as a consequence of similar emission sources, secondary pollutant generation and accumulation/removal processes. Sulphate and nitrate were not directly related to the concentrations of their precursor gases and were generally largely, but not completely, neutralised by ammonium. The clustering of back-trajectories and CWT demonstrate that the long-range movement of the air masses has a major impact upon PM2.5 and ion concentrations: an area spreading from Eastern to Central Europe was identified as a main potential source for most ions. The valley sites are also heavily influenced by local emissions in slow moving northerly air masses. Finally, two episodes of high nitrate levels were investigated to explain why some sites are experiencing much higher concentrations than others. This study identifies some key features in the generation of SIA in the Po Valley, demonstrating that SIA generation is a regional pollution phenomenon and mitigation policies are required at regional, national and even European scales.}, author = {Masiol, Mauro and Benetello, Francesca and Harrison, Roy M. and Formenton, Gianni and {De Gaspari}, Francesco and Pavoni, Bruno}, doi = {10.1016/j.atmosenv.2015.06.044}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Ionic composition,Long-range transport,PM2.5,Po valley,Secondary inorganic aerosol}, month = {sep}, pages = {19--31}, publisher = {Elsevier {\{}BV{\}}}, title = {{Spatial, seasonal trends and transboundary transport of PM2.5 inorganic ions in the Veneto region (Northeastern Italy)}}, volume = {117}, year = {2015} } @article{McCollum2018a, abstract = {The United Nations' Sustainable Development Goals (SDGs) provide guide-posts to society as it attempts to respond to an array of pressing challenges. One of these challenges is energy; thus, the SDGs have become paramount for energy policy-making. Yet, while governments throughout the world have already declared the SDGs to be 'integrated and indivisible', there are still knowledge gaps surrounding how the interactions between the energy SDG targets and those of the non-energy-focused SDGs might play out in different contexts. In this review, we report on a large-scale assessment of the relevant energy literature, which we conducted to better our understanding of key energy-related interactions between SDGs, as well as their context-dependencies (relating to time, geography, governance, technology, and directionality). By (i) evaluating the nature and strength of the interactions identified, (ii) indicating the robustness of the evidence base, the agreement of that evidence, and our confidence in it, and (iii) highlighting critical areas where better understanding is needed or context dependencies should be considered, our review points to potential ways forward for both the policy making and scientific communities. First, we find that positive interactions between the SDGs outweigh the negative ones, both in number and magnitude. Second, of relevance for the scientific community, in order to fill knowledge gaps in critical areas, there is an urgent need for interdisciplinary research geared toward developing new data, scientific tools, and fresh perspectives. Third, of relevance for policy-making, wider efforts to promote policy coherence and integrated assessments are required to address potential policy spillovers across sectors, sustainability domains, and geographic and temporal boundaries. The task of conducting comprehensive science-to-policy assessments covering all SDGs, such as for the UN's Global Sustainable Development Report, remains manageable pending the availability of systematic reviews focusing on a limited number of SDG dimensions in each case.}, author = {McCollum, David L. and Echeverri, Luis Gomez and Busch, Sebastian and Pachauri, Shonali and Parkinson, Simon and Rogelj, Joeri and Krey, Volker and Minx, Jan C. and Nilsson, M{\aa}ns and Stevance, Anne Sophie and Riahi, Keywan}, doi = {10.1088/1748-9326/aaafe3}, issn = {17489326}, journal = {Environmental Research Letters}, keywords = {Energy,Integrated assessment,Sustainable development goals,Systems analysis}, number = {3}, pages = {33006}, publisher = {IOP Publishing}, title = {{Connecting the sustainable development goals by their energy inter-linkages}}, url = {http://dx.doi.org/10.1088/1748-9326/aaafe3}, volume = {13}, year = {2018} } @article{McCollum2013, author = {McCollum, David L. and Krey, Volker and Riahi, Keywan and Kolp, Peter and Grubler, Arnulf and Makowski, Marek and Nakicenovic, Nebojsa}, doi = {10.1007/s10584-013-0710-y}, issn = {0165-0009}, journal = {Climatic Change}, month = {jul}, number = {2}, pages = {479--494}, title = {{Climate policies can help resolve energy security and air pollution challenges}}, url = {http://link.springer.com/10.1007/s10584-013-0710-y}, volume = {119}, year = {2013} } @article{McDonald760, abstract = {Transport-derived emissions of volatile organic compounds (VOCs) have decreased owing to stricter controls on air pollution. This means that the relative importance of chemicals in pesticides, coatings, printing inks, adhesives, cleaning agents, and personal care products has increased. McDonald et al. show that these volatile chemical products now contribute fully one-half of emitted VOCs in 33 industrialized cities (see the Perspective by Lewis). Thus, the focus of efforts to mitigate ozone formation and toxic chemical burdens need to be adjusted.Science, this issue p. 760; see also p. 744A gap in emission inventories of urban volatile organic compound (VOC) sources, which contribute to regional ozone and aerosol burdens, has increased as transportation emissions in the United States and Europe have declined rapidly. A detailed mass balance demonstrates that the use of volatile chemical products (VCPs){\{}$\backslash$textemdash{\}}including pesticides, coatings, printing inks, adhesives, cleaning agents, and personal care products{\{}$\backslash$textemdash{\}}now constitutes half of fossil fuel VOC emissions in industrialized cities. The high fraction of VCP emissions is consistent with observed urban outdoor and indoor air measurements. We show that human exposure to carbonaceous aerosols of fossil origin is transitioning away from transportation-related sources and toward VCPs. Existing U.S. regulations on VCPs emphasize mitigating ozone and air toxics, but they currently exempt many chemicals that lead to secondary organic aerosols.}, author = {McDonald, Brian C and de Gouw, Joost A and Gilman, Jessica B and Jathar, Shantanu H and Akherati, Ali and Cappa, Christopher D and Jimenez, Jose L and Lee-Taylor, Julia and Hayes, Patrick L and McKeen, Stuart A and Cui, Yu Yan and Kim, Si-Wan and Gentner, Drew R and Isaacman-VanWertz, Gabriel and Goldstein, Allen H and Harley, Robert A and Frost, Gregory J and Roberts, James M and Ryerson, Thomas B and Trainer, Michael}, doi = {10.1126/science.aaq0524}, issn = {0036-8075}, journal = {Science}, number = {6377}, pages = {760--764}, publisher = {American Association for the Advancement of Science}, title = {{Volatile chemical products emerging as largest petrochemical source of urban organic emissions}}, url = {http://science.sciencemag.org/content/359/6377/760}, volume = {359}, year = {2018} } @article{McDuffie2020, author = {McDuffie, E E and Smith, S J and O'Rourke, P and Tibrewal, K and Venkataraman, C and Marais, E A and Zheng, B and Crippa, M and Brauer, M and Martin, R V}, doi = {10.5194/essd-12-3413-2020}, journal = {Earth System Science Data}, number = {4}, pages = {3413--3442}, title = {{A global anthropogenic emission inventory of atmospheric pollutants from sector- and fuel-specific sources (1970–2017): an application of the Community Emissions Data System (CEDS)}}, url = {https://essd.copernicus.org/articles/12/3413/2020/}, volume = {12}, year = {2020} } @article{McFiggans2019, abstract = {Secondary organic aerosol contributes to the atmospheric particle burden with implications for air quality and climate. Biogenic volatile organic compounds such as terpenoids emitted from plants are important secondary organic aerosol precursors with isoprene dominating the emissions of biogenic volatile organic compounds globally. However, the particle mass from isoprene oxidation is generally modest compared to that of other terpenoids. Here we show that isoprene, carbon monoxide and methane can each suppress the instantaneous mass and the overall mass yield derived from monoterpenes in mixtures of atmospheric vapours. We find that isoprene ‘scavenges' hydroxyl radicals, preventing their reaction with monoterpenes, and the resulting isoprene peroxy radicals scavenge highly oxygenated monoterpene products. These effects reduce the yield of low-volatility products that would otherwise form secondary organic aerosol. Global model calculations indicate that oxidant and product scavenging can operate effectively in the real atmosphere. Thus highly reactive compounds (such as isoprene) that produce a modest amount of aerosol are not necessarily net producers of secondary organic particle mass and their oxidation in mixtures of atmospheric vapours can suppress both particle number and mass of secondary organic aerosol. We suggest that formation mechanisms of secondary organic aerosol in the atmosphere need to be considered more realistically, accounting for mechanistic interactions between the products of oxidizing precursor molecules (as is recognized to be necessary when modelling ozone production).}, author = {McFiggans, Gordon and Mentel, Thomas F. and Wildt, J{\"{u}}rgen and Pullinen, Iida and Kang, Sungah and Kleist, Einhard and Schmitt, Sebastian and Springer, Monika and Tillmann, Ralf and Wu, Cheng and Zhao, Defeng and Hallquist, Mattias and Faxon, Cameron and {Le Breton}, Michael and Hallquist, {\AA}sa M. and Simpson, David and Bergstr{\"{o}}m, Robert and Jenkin, Michael E. and Ehn, Mikael and Thornton, Joel A. and Alfarra, M. Rami and Bannan, Thomas J. and Percival, Carl J. and Priestley, Michael and Topping, David and Kiendler-Scharr, Astrid}, doi = {10.1038/s41586-018-0871-y}, issn = {14764687}, journal = {Nature}, number = {7741}, pages = {587--593}, title = {{Secondary organic aerosol reduced by mixture of atmospheric vapours}}, volume = {565}, year = {2019} } @article{Mcnorton2016a, abstract = {The growth in atmospheric methane (CH4) concentrations over the past 2 decades has shown large variability on a timescale of several years. Prior to 1999 the globally averaged CH4 concentration was increasing at a rate of 6.0ĝ€ppbĝ€yrĝ'1, but during a stagnation period from 1999 to 2006 this growth rate slowed to 0.6ĝ€ppbĝ€yrĝ'1. From 2007 to 2009 the growth rate again increased to 4.9ĝ€ppbĝ€yrĝ'1. These changes in growth rate are usually ascribed to variations in CH4 emissions. We have used a 3-D global chemical transport model, driven by meteorological reanalyses and variations in global mean hydroxyl (OH) concentrations derived from CH3CCl3 observations from two independent networks, to investigate these CH4 growth variations. The model shows that between 1999 and 2006 changes in the CH4 atmospheric loss contributed significantly to the suppression in global CH4 concentrations relative to the pre-1999 trend. The largest factor in this is relatively small variations in global mean OH on a timescale of a few years, with minor contributions of atmospheric transport of CH4 to its sink region and of atmospheric temperature. Although changes in emissions may be important during the stagnation period, these results imply a smaller variation is required to explain the observed CH4 trends. The contribution of OH variations to the renewed CH4 growth after 2007 cannot be determined with data currently available.}, author = {McNorton, Joe and Chipperfield, Martyn P. and Gloor, Manuel and Wilson, Chris and Feng, Wuhu and Hayman, Garry D. and Rigby, Matt and Krumme, Paul B. and O'Doherty, Simon and Prinn, Ronald G. and Weiss, Ray F. and Young, Dickon and Dlugokencky, Ed and Montzka, Steve A.}, doi = {10.5194/acp-16-7943-2016}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {12}, pages = {7943--7956}, title = {{Role of OH variability in the stalling of the global atmospheric CH4 growth rate from 1999 to 2006}}, volume = {16}, year = {2016} } @article{McNorton2018, abstract = {The atmospheric methane (CH4) growth rate has varied considerably in recent decades. Unexplained renewed growth after 2006 followed 7 years of stagnation and coincided with an isotopic trend toward CH4 more depleted in 13C, suggesting changes in sources and/or sinks. Using surface observations of both CH4 and the relative change of isotopologue ratio ($\delta$13 CH4) to constrain a global 3-D chemical transport model (CTM), we have performed a synthesis inversion for source and sink attribution. Our method extends on previous studies by providing monthly and regional attribution of emissions from six different sectors and changes in atmospheric sinks for the extended 2003-2015 period. Regional evaluation of the model CH4 tracer with independent column observations from the Greenhouse Gases Observing Satellite (GOSAT) shows improved performance when using posterior fluxes (R =0:94-0.96, RMSE= 8:3- 16.5 ppb), relative to prior fluxes (R =0:60-0.92, RMSE= 48:6-64.6 ppb). Further independent validation with data from the Total Carbon Column Observing Network (TCCON) shows a similar improvement in the posterior fluxes (R =0:87, RMSE= 18:8 ppb) compared to the prior fluxes (R =0:69, RMSE= 55:9 ppb). Based on these improved posterior fluxes, the inversion results suggest the most likely cause of the renewed methane growth is a post-2007 1:8± 0:4{\%} decrease in mean OH, a 12:9±2:7{\%} increase in energy sector emissions, mainly from Africa-Middle East and southern Asia-Oceania, and a 2:6±1:8{\%}increase in wetland emissions, mainly from northern Eurasia. The posterior wetland flux increases are in general agreement with bottom-up estimates, but the energy sector growth is greater than estimated by bottom-up methods. The model results are consistent across a range of sensitivity analyses. When forced to assume a constant (annually repeating) OH distribution, the inversion requires a greater increase in energy sector (13:6±2:7 {\%}) and wetland (3:6±1:8 {\%}) emissions and an 11:5±3:8{\%} decrease in biomass burning emissions. Assuming no prior trend in sources and sinks slightly reduces the posterior growth rate in energy sector and wetland emissions and further increases the magnitude of the negative OH trend. We find that possible tropospheric Cl variations do not influence $\delta$13CH4 and CH4 trends, although we suggest further work on Cl variability is required to fully diagnose this contribution. While the study provides quantitative insight into possible emissions variations which may explain the observed trends, uncertainty in prior source and sink estimates and a paucity of $\delta$13CH4 observations limit the robustness of the posterior estimates.}, author = {McNorton, Joe and Wilson, Chris and Gloor, Manuel and Parker, Rob J. and Boesch, Hartmut and Feng, Wuhu and Hossaini, Ryan and Chipperfield, Martyn P.}, doi = {10.5194/acp-18-18149-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {dec}, number = {24}, pages = {18149--18168}, publisher = {Copernicus Publications}, title = {{Attribution of recent increases in atmospheric methane through 3-D inverse modelling}}, volume = {18}, year = {2018} } @article{Medici2017a, abstract = {Background • GOES-R is going to have a GLM which will provide Total Lightning through the day and night. • It is expected to significantly improve our ability to nowcast severe weather over land and ocean. • Optimal use of changes in Total Lightning flash rate for individual ... $\backslash$n}, author = {Medici, Gina and Cummins, Kenneth L. and Cecil, Daniel J. and Koshak, William J. and Rudlosky, Scott D.}, doi = {10.1175/MWR-D-16-0426.1}, isbn = {0027-0644}, issn = {0027-0644}, journal = {Monthly Weather Review}, number = {11}, pages = {4481--4499}, title = {{The Intracloud Lightning Fraction in the Contiguous United States}}, url = {http://journals.ametsoc.org/doi/10.1175/MWR-D-16-0426.1}, volume = {145}, year = {2017} } @article{Meehl2020, abstract = {For the current generation of earth system models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6), the range of equilibrium climate sensitivity (ECS, a hypothetical value of global warming at equilibrium for a doubling of CO2) is 1.8°C to 5.6°C, the largest of any generation of models dating to the 1990s. Meanwhile, the range of transient climate response (TCR, the surface temperature warming around the time of CO2 doubling in a 1{\%} per year CO2 increase simulation) for the CMIP6 models of 1.7°C (1.3°C to 3.0°C) is only slightly larger than for the CMIP3 and CMIP5 models. Here we review and synthesize the latest developments in ECS and TCR values in CMIP, compile possible reasons for the current values as supplied by the modeling groups, and highlight future directions. Cloud feedbacks and cloud-aerosol interactions are the most likely contributors to the high values and increased range of ECS in CMIP6.}, author = {Meehl, Gerald A and Senior, Catherine A and Eyring, Veronika and Flato, Gregory and Lamarque, Jean-Francois and Stouffer, Ronald J and Taylor, Karl E and Schlund, Manuel}, doi = {10.1126/sciadv.aba1981}, journal = {Science Advances}, month = {jun}, number = {26}, pages = {eaba1981}, title = {{Context for interpreting equilibrium climate sensitivity and transient climate response from the CMIP6 Earth system models}}, url = {http://advances.sciencemag.org/content/6/26/eaba1981.abstract}, volume = {6}, year = {2020} } @article{Megaritis20133423, abstract = {PMCAMx-2008, a three dimensional chemical transport model (CTM), was applied in Europe to quantify the changes in fine particle (PM 2.5) concentration in response to different emission reductions as well as to temperature in-crease. A summer and a winter simulation period were used, to investigate the seasonal dependence of the PM 2.5 response to 50 {\%} reductions of sulfur dioxide (SO 2), ammonia (NH 3), nitrogen oxides (NO x), anthropogenic volatile organic com-pounds (VOCs) and anthropogenic primary organic aerosol (POA) emissions and also to temperature increases of 2.5 and 5 K. Reduction of NH 3 emissions seems to be the most effective control strategy for reducing PM 2.5 , in both pe-riods, resulting in a decrease of PM 2.5 up to 5.1 µg m −3 and 1.8 µg m −3 (5.5 {\%} and 4 {\%} on average) during summer and winter respectively, mainly due to reduction of ammo-nium nitrate (NH 4 NO 3) (20 {\%} on average in both periods). The reduction of SO 2 emissions decreases PM 2.5 in both periods having a significant effect over the Balkans (up to 1.6 µg m −3) during the modeled summer period, mainly due to decrease of sulfate (34 {\%} on average over the Balkans). The anthropogenic POA control strategy reduces total OA by 15 {\%} during the modeled winter period and 8 {\%} in the sum-mer period. The reduction of total OA is higher in urban areas close to its emissions sources. A slight decrease of OA (8 {\%} in the modeled summer period and 4 {\%} in the modeled win-ter period) is also predicted after a 50 {\%} reduction of VOCs emissions due to the decrease of anthropogenic SOA. The re-duction of NO x emissions reduces PM 2.5 (up to 3.4 µg m −3) during the summer period, due to a decrease of NH 4 NO 3 , causing although an increase of ozone concentration in ma-jor urban areas and over Western Europe. Additionally, the NO x control strategy actually increases PM 2.5 levels during the winter period, due to more oxidants becoming available to react with SO 2 and VOCs. The increase of temperature results in a decrease of PM 2.5 in both periods over Central Europe, mainly due to a decrease of NH 4 NO 3 during sum-mer (18 {\%}) and fresh POA during wintertime (35 {\%}). Signif-icant increases of OA are predicted during the summer due mainly to the increase of biogenic VOC emissions. On the contrary, OA is predicted to decrease in the modeled win-ter period due to the dominance of fresh POA reduction and the small biogenic SOA contribution to OA. The resulting in-crease of oxidant levels from the temperature rise lead to an increase of sulfate levels in both periods, mainly over North Europe and the Atlantic Ocean. The substantial reduction of PM 2.5 components due to emissions reductions of their pre-cursors outlines the importance of emissions for improving air quality, while the sensitivity of PM 2.5 concentrations to temperature changes indicate that climate interactions need to be considered when predicting future levels of PM, with different net effects in different parts of Europe.}, annote = {cited By 48}, author = {Megaritis, A. G. and Fountoukis, C. and Charalampidis, P. E. and Pilinis, C. and Pandis, S. N.}, doi = {10.5194/acp-13-3423-2013}, isbn = {1680-7324}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, number = {6}, pages = {3423--3443}, title = {{Response of fine particulate matter concentrations to changes of emissions and temperature in Europe}}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84875728217{\&}doi=10.5194{\%}2Facp-13-3423-2013{\&}partnerID=40{\&}md5=5697f5ec85dbb1676b9b8ec2be4d6a61}, volume = {13}, year = {2013} } @article{Meinshausen2020, author = {Meinshausen, Malte and Nicholls, Zebedee R J and Lewis, Jared and Gidden, Matthew J and Vogel, Elisabeth and Freund, Mandy and Beyerle, Urs and Gessner, Claudia and Nauels, Alexander and Bauer, Nico and Canadell, Josep G and Daniel, John S and John, Andrew and Krummel, Paul B and Luderer, Gunnar and Meinshausen, Nicolai and Montzka, Stephen A and Rayner, Peter J and Reimann, Stefan and Smith, Steven J and van den Berg, Marten and Velders, Guus J M and Vollmer, Martin K and Wang, Ray H J}, doi = {10.5194/gmd-13-3571-2020}, issn = {1991-9603}, journal = {Geoscientific Model Development}, month = {aug}, number = {8}, pages = {3571--3605}, publisher = {Copernicus Publications}, title = {{The shared socio-economic pathway (SSP) greenhouse gas concentrations and their extensions to 2500}}, url = {https://gmd.copernicus.org/articles/13/3571/2020/}, volume = {13}, year = {2020} } @article{Meinshausen2011, abstract = {We present the greenhouse gas concentrations for the Representative Concentration Pathways (RCPs) and their extensions beyond 2100, the Extended Concentration Pathways (ECPs). These projections include all major anthropogenic greenhouse gases and are a result of a multi-year effort to produce new scenarios for climate change research. We combine a suite of atmospheric concentration observations and emissions estimates for greenhouse gases (GHGs) through the historical period (1750–2005) with harmonized emissions projected by four different Integrated Assessment Models for 2005–2100. As concentrations are somewhat dependent on the future climate itself (due to climate feedbacks in the carbon and other gas cycles), we emulate median response characteristics of models assessed in the IPCC Fourth Assessment Report using the reduced-complexity carbon cycle climate model MAGICC6. Projected ‘best-estimate' global-mean surface temperature increases (using inter alia a climate sensitivity of 3°C) range from 1.5°C by 2100 for the lowest of the four RCPs, called both RCP3-PD and RCP2.6, to 4.5°C for the highest one, RCP8.5, relative to pre-industrial levels. Beyond 2100, we present the ECPs that are simple extensions of the RCPs, based on the assumption of either smoothly stabilizing concentrations or constant emissions: For example, the lower RCP2.6 pathway represents a strong mitigation scenario and is extended by assuming constant emissions after 2100 (including net negative CO2 emissions), leading to CO2 concentrations returning to 360 ppm by 2300. We also present the GHG concentrations for one supplementary extension, which illustrates the stringent emissions implications of attempting to go back to ECP4.5 concentration levels by 2250 after emissions during the 21st century followed the higher RCP6 scenario. Corresponding radiative forcing values are presented for the RCP and ECPs.}, author = {Meinshausen, Malte and Smith, S J and Calvin, K and Daniel, J S and Kainuma, M L T and Lamarque, J.-F. and Matsumoto, K and Montzka, S A and Raper, S C B and Riahi, K and Thomson, A and Velders, G J M and van Vuuren, D P P}, doi = {10.1007/s10584-011-0156-z}, issn = {0165-0009, 1573-1480}, journal = {Climatic Change}, keywords = {Meteorology/Climatology}, language = {en}, month = {jan}, number = {1-2}, pages = {213--241}, title = {{The RCP greenhouse gas concentrations and their extensions from 1765 to 2300}}, url = {http://link.springer.com/article/10.1007/s10584-011-0156-z http://link.springer.com/content/pdf/10.1007{\%}2Fs10584-011-0156-z http://www.springerlink.com/content/96n71712n613752g/}, volume = {109}, year = {2011} } @article{Melamed2016, abstract = {Air quality and climate change are inexorably linked from their emission sources to their impacts on climate, human health, and ecosystems, including agriculture. However, in global environmental change and sustainability policies the link between air quality and climate change is often ignored. To facilitate including the link between air pollution and climate change in the policy process, three key considerations (1) mix of emissions, (2) lifetime, and (3) benefits and trade-offs should be taken into account. These three key considerations will help decision makers understand how proposed policies may impact the emissions of air pollutants and greenhouse gases and their resulting impacts on climate, human health, and ecosystems, thus reducing unintended consequences and likely resulting in additional economic and environmental benefits.}, author = {Melamed, Megan L. and Schmale, Julia and von Schneidemesser, Erika}, doi = {10.1016/j.cosust.2016.12.003}, issn = {18773435}, journal = {Current Opinion in Environmental Sustainability}, pages = {85--91}, title = {{Sustainable policy – key considerations for air quality and climate change}}, volume = {23}, year = {2016} } @article{Mercado2009, author = {Mercado, Lina M. and Bellouin, Nicolas and Sitch, Stephen and Boucher, Olivier and Huntingford, Chris and Wild, Martin and Cox, Peter M.}, doi = {10.1038/nature07949}, issn = {0028-0836}, journal = {Nature}, month = {apr}, number = {7241}, pages = {1014--1017}, title = {{Impact of changes in diffuse radiation on the global land carbon sink}}, url = {http://www.nature.com/doifinder/10.1038/nature07949}, volume = {458}, year = {2009} } @incollection{Meredith2019SROCC_ch3, author = {Meredith, M. and Sommerkorn, M. and Cassotta, S. and Derksen, C. and Ekaykin, A. and Hollowed, A. and Kofinas, G. and Mackintosh, A. and Melbourne-Thomas, J. and Muelbert, M.M.C. and {G. Ottersen}, H. Pritchard and Schuur, E.A.G.}, booktitle = {IPCC Special Report on the Ocean and Cryosphere in a Changing Climate}, chapter = {3}, doi = {https://www.ipcc.ch/srocc/chapter/chapter-3-2}, editor = {Pörtner, H.-O. and Roberts, D.C. and Masson-Delmotte, V. and Zhai, P. and Tignor, M. and Poloczanska, E. and Mintenbeck, K. and Alegría, A. and Nicolai, M. and Okem, A. and Petzold, J. and Rama, B. and Weyer, N.M.}, pages = {203--320}, publisher = {In Press}, title = {{Polar Regions}}, url = {https://www.ipcc.ch/srocc/chapter/chapter-3-2}, year = {2019} } @article{acp-20-7843-2020, author = {Mertens, M and Kerkweg, A and Grewe, V and J{\"{o}}ckel, P and Sausen, R}, doi = {10.5194/acp-20-7843-2020}, journal = {Atmospheric Chemistry and Physics}, number = {13}, pages = {7843--7873}, title = {{Attributing ozone and its precursors to land transport emissions in Europe and Germany}}, url = {https://acp.copernicus.org/articles/20/7843/2020/}, volume = {20}, year = {2020} } @article{Messina2016a, abstract = {Abstract. A new version of the biogenic volatile organic compounds (BVOCs) emission scheme has been developed in the global vegetation model ORCHIDEE (Organizing Carbon and Hydrology in Dynamic EcosystEm), which includes an extended list of biogenic emitted compounds, updated emission factors (EFs), a dependency on light for almost all compounds and a multi-layer radiation scheme. Over the 2000–2009 period, using this model, we estimate mean global emissions of 465 Tg C yr−1 for isoprene, 107.5 Tg C yr−1 for monoterpenes, 38 Tg C yr−1 for methanol, 25 Tg C yr−1 for acetone and 24 Tg C yr−1 for sesquiterpenes. The model results are compared to state-of-the-art emission budgets, showing that the ORCHIDEE emissions are within the range of published estimates. ORCHIDEE BVOC emissions are compared to the estimates of the Model of Emissions of Gases and Aerosols from Nature (MEGAN), which is largely used throughout the biogenic emissions and atmospheric chemistry community. Our results show that global emission budgets of the two models are, in general, in good agreement. ORCHIDEE emissions are 8 {\%} higher for isoprene, 8 {\%} lower for methanol, 17 {\%} higher for acetone, 18 {\%} higher for monoterpenes and 39 {\%} higher for sesquiterpenes, compared to the MEGAN estimates. At the regional scale, the largest differences between ORCHIDEE and MEGAN are highlighted for isoprene in northern temperate regions, where ORCHIDEE emissions are higher by 21 Tg C yr−1, and for monoterpenes, where they are higher by 4.4 and 10.2 Tg C yr−1 in northern and southern tropical regions compared to MEGAN. The geographical differences between the two models are mainly associated with different EF and plant functional type (PFT) distributions, while differences in the seasonal cycle are mostly driven by differences in the leaf area index (LAI). Sensitivity tests are carried out for both models to explore the response to key variables or parameters such as LAI and light-dependent fraction (LDF). The ORCHIDEE and MEGAN emissions are differently affected by LAI changes, with a response highly depending on the compound considered. Scaling the LAI by a factor of 0.5 and 1.5 changes the isoprene global emission by −21 and +8 {\%} for ORCHIDEE and −15 and +7 {\%} for MEGAN, and affects the global emissions of monoterpenes by −43 and +40 {\%} for ORCHIDEE and −11 and +3 {\%} for MEGAN. Performing a further sensitivity test, forcing ORCHIDEE with the MODIS LAI, confirms the high sensitivity of the ORCHIDEE emiss{\ldots}}, author = {Messina, Palmira and Lathi{\`{e}}re, Juliette and Sindelarova, Katerina and Vuichard, Nicolas and Granier, Claire and Ghattas, Josefine and Cozic, Anne and Hauglustaine, Didier A.}, doi = {10.5194/acp-16-14169-2016}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {nov}, number = {22}, pages = {14169--14202}, title = {{Global biogenic volatile organic compound emissions in the ORCHIDEE and MEGAN models and sensitivity to key parameters}}, volume = {16}, year = {2016} } @article{Meul2018b, abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Using a state-of-the-art chemistry–climate model we investigate the future change in stratosphere–troposphere exchange (STE) of ozone, the drivers of this change, as well as the future distribution of stratospheric ozone in the troposphere. Supplementary to previous work, our focus is on changes on the monthly scale. The global mean annual influx of stratospheric ozone into the troposphere is projected to increase by 53{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%} between the years 2000 and 2100 under the RCP8.5 greenhouse gas scenario. The change in ozone mass flux (OMF) into the troposphere is positive throughout the year with maximal increase in the summer months of the respective hemispheres. In the Northern Hemisphere (NH) this summer maximum STE increase is a result of increasing greenhouse gas (GHG) concentrations, whilst in the Southern Hemisphere(SH) it is due to equal contributions from decreasing levels of ozone depleting substances (ODS) and increasing GHG concentrations. In the SH the GHG effect is dominating in the winter months. A large ODS-related ozone increase in the SH stratosphere leads to a change in the seasonal breathing term which results in a future decrease of the OMF into the troposphere in the SH in September and October. The resulting distributions of stratospheric ozone in the troposphere differ for the GHG and ODS changes due to the following: (a) ozone input occurs at different regions for GHG- (midlatitudes) and ODS-changes (high latitudes); and (b) stratospheric ozone is more efficiently mixed towards lower tropospheric levels in the case of ODS changes, whereas tropospheric ozone loss rates grow when GHG concentrations rise. The comparison between the moderate RCP6.0 and the extreme RCP8.5 emission scenarios reveals that the annual global OMF trend is smaller in the moderate scenario, but the resulting change in the contribution of ozone with stratospheric origin (O3s) to ozone in the troposphere is of comparable magnitude in both scenarios. This is due to the larger tropospheric ozone precursor emissions and hence ozone production in the RCP8.5 scenario.{\textless}/p{\textgreater}{\textless}/p{\textgreater}}, author = {Meul, Stefanie and Langematz, Ulrike and Kr{\"{o}}ger, Philipp and Oberl{\"{a}}nder-Hayn, Sophie and J{\"{o}}ckel, Patrick}, doi = {10.5194/acp-18-7721-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {jun}, number = {10}, pages = {7721--7738}, title = {{Future changes in the stratosphere-to-troposphere ozone mass flux and the contribution from climate change and ozone recovery}}, url = {https://www.atmos-chem-phys.net/18/7721/2018/}, volume = {18}, year = {2018} } @article{Miller2019, abstract = {Anthropogenic methane emissions from China are likely greater than in any other country in the world. The largest fraction of China's anthropogenic emissions is attributable to coal mining, but these emissions may be changing; China enacted a suite of regulations for coal mine methane (CMM) drainage and utilization that came into full effect in 2010. Here, we use methane observations from the GOSAT satellite to evaluate recent trends in total anthropogenic and natural emissions from Asia with a particular focus on China. We find that emissions from China rose by 1.1 ± 0.4 Tg CH4 yr−1 from 2010 to 2015, culminating in total anthropogenic and natural emissions of 61.5 ± 2.7 Tg CH4 in 2015. The observed trend is consistent with pre-2010 trends and is largely attributable to coal mining. These results indicate that China's CMM regulations have had no discernible impact on the continued increase in Chinese methane emissions.}, author = {Miller, Scot M and Michalak, Anna M and Detmers, Robert G and Hasekamp, Otto P and Bruhwiler, Lori M P and Schwietzke, Stefan}, doi = {10.1038/s41467-018-07891-7}, issn = {2041-1723}, journal = {Nature Communications}, number = {1}, pages = {303}, title = {{China's coal mine methane regulations have not curbed growing emissions}}, url = {https://doi.org/10.1038/s41467-018-07891-7}, volume = {10}, year = {2019} } @article{Miller2014, author = {Miller, D J and Sun, K and Tao, L and Khan, M A and Zondlo, M A}, doi = {10.5194/amt-7-81-2014}, journal = {Atmospheric Measurement Techniques}, month = {jan}, number = {1}, pages = {81--93}, publisher = {Copernicus {\{}GmbH{\}}}, title = {{Open-path, quantum cascade-laser-based sensor for high-resolution atmospheric ammonia measurements}}, volume = {7}, year = {2014} } @article{Mills2016, abstract = {This paper provides a process-oriented perspective on the combined effects of ozone (O3), climate change and/or nitrogen (N) on vegetation. Whereas increasing CO2 in controlled environments or open-top chambers often ameliorates effects of O3 on leaf physiology, growth and C allocation, this is less likely in the field. Combined responses to elevated temperature and O3 have rarely been studied even though some critical growth stages such as seed initiation are sensitive to both. Under O3 exposure, many species have smaller roots, thereby enhancing drought sensitivity. Of the 68 species assessed for stomatal responses to ozone, 22.5{\%} were unaffected, 33.5{\%} had sluggish or increased opening and 44{\%} stomatal closure. The beneficial effect of N on root development was lost at higher O3 treatments whilst the effects of increasing O3 on root biomass became more pronounced as N increased. Both responses to gradual changes in pollutants and climate and those under extreme weather events require further study.}, author = {Mills, Gina and Harmens, Harry and Wagg, Serena and Sharps, Katrina and Hayes, Felicity and Fowler, David and Sutton, Mark and Davies, Bill}, doi = {10.1016/j.envpol.2015.09.038}, issn = {18736424}, journal = {Environmental Pollution}, keywords = {Climate change,Drought,Nitrogen,Ozone,Vegetation}, month = {jan}, pages = {898--908}, title = {{Ozone impacts on vegetation in a nitrogen enriched and changing climate}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0269749115300853}, volume = {208}, year = {2016} } @article{https://doi.org/10.1029/2020GL091699, abstract = {Abstract The Coronavirus Disease 2019 (COVID-19) pandemic led to a widespread reduction in aerosol emissions. Using satellite observations and climate model simulations, we study the underlying mechanisms of the large decreases in solar clear-sky reflection (3.8 W m−2 or 7{\%}) and aerosol optical depth (0.16 W m−2 or 32{\%}) observed over the East Asian Marginal Seas in March 2020. By separating the impacts from meteorology and emissions in the model simulations, we find that about one-third of the clear-sky anomalies can be attributed to pandemic-related emission reductions, and the rest to weather variability and long-term emission trends. The model is skillful at reproducing the observed interannual variations in solar all-sky reflection, but no COVID-19 signal is discerned. The current observational and modeling capabilities will be critical for monitoring, understanding, and predicting the radiative forcing and climate impacts of the ongoing crisis.}, annote = {e2020GL091699 2020GL091699}, author = {Ming, Yi and Lin, Pu and Naik, Vaishali and Paulot, Fabien and Horowitz, Larry W and Ginoux, Paul A and Ramaswamy, V and Loeb, Norman G and Shen, Zhaoyi and Singer, Clare E and Ward, Ryan X and Zhang, Zhibo and Bellouin, Nicolas}, doi = {https://doi.org/10.1029/2020GL091699}, journal = {Geophysical Research Letters}, number = {3}, pages = {e2020GL091699}, title = {{Assessing the Influence of COVID-19 on the Shortwave Radiative Fluxes Over the East Asian Marginal Seas}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL091699}, volume = {48}, year = {2021} } @article{Mitchell2009, abstract = {Greenhouse gases and cirrus clouds regulate outgoing longwave radiation (OLR) and cirrus cloud coverage is predicted to be sensitive to the ice fall speed which depends on ice crystal size. The higher the cirrus, the greater their impact is on OLR. Thus by changing ice crystal size in the coldest cirrus, OLR and climate might be modified. Fortunately the coldest cirrus have the highest ice supersaturation due to the dominance of homogeneous freezing nucleation. Seeding such cirrus with very efficient heterogeneous ice nuclei should produce larger ice crystals due to vapor competition effects, thus increasing OLR and surface cooling. Preliminary estimates of this global net cloud forcing are more negative than -2.8Wm-2 and could neutralize the radiative forcing due to a CO2 doubling (3.7Wm-2). A potential delivery mechanism for the seeding material is already in place: the airline industry. Since seeding aerosol residence times in the troposphere are relatively short, the climate might return to its normal state within months after stopping the geoengineering experiment. The main known drawback to this approach is that it would not stop ocean acidification. It does not have many of the drawbacks that stratospheric injection of sulfur species has. {\textcopyright} 2009 IOP Publishing Ltd.}, author = {Mitchell, David L. and Finnegan, William}, doi = {10.1088/1748-9326/4/4/045102}, issn = {1748-9326}, journal = {Environmental Research Letters}, keywords = {Cirrus clouds,Climate modeling,Geoengineering}, month = {oct}, number = {4}, pages = {045102}, title = {{Modification of cirrus clouds to reduce global warming}}, url = {https://iopscience.iop.org/article/10.1088/1748-9326/4/4/045102}, volume = {4}, year = {2009} } @article{Miyazaki2014, abstract = {The global source of lightning-produced NOx (LNOx) is estimated by assimilating observations of NO2, O3, HNO3, and CO measured by multiple satellite measurements into a chemical transport model. Included are observations from the Ozone Monitoring Instrument (OMI), Microwave Limb Sounder (MLS), Tropospheric Emission Spectrometer (TES), and Measurements of Pollution in the Troposphere (MOPITT) instruments. The assimilation of multiple chemical data sets with different vertical sensitivity profiles provides comprehensive constraints on the global LNOx source while improving the representations of the entire chemical system affecting atmospheric NOx, including surface emissions and inflows from the stratosphere. The annual global LNOx source amount and NO production efficiency are estimated at 6.3 Tg N yr−1 and 310 mol NO flash−1, respectively. Sensitivity studies with perturbed satellite data sets, model and data assimilation settings lead to an error estimate of about 1.4 Tg N yr−1 on this global LNOx source. These estimates are significantly different from those estimated from a parameter inversion that optimizes only the LNOx source from NO2 observations alone, which may lead to an overestimate of the source adjustment. The total LNOx source is predominantly corrected by the assimilation of OMI NO2 observations, while TES and MLS observations add important constraints on the vertical source profile. The results indicate that the widely used lightning parameterization based on the C-shape assumption underestimates the source in the upper troposphere and overestimates the peak source height by up to about 1 km over land and the tropical western Pacific. Adjustments are larger over ocean than over land, suggesting that the cloud height dependence is too weak over the ocean in the Price and Rind (1992) approach. The significantly improved agreement between the analyzed ozone fields and independent observations gives confidence in the performance of the LNOx source estimation.}, author = {Miyazaki, K. and Eskes, H. J. and Sudo, K. and Zhang, C.}, doi = {10.5194/acp-14-3277-2014}, isbn = {1680-7324}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {7}, pages = {3277--3305}, publisher = {Copernicus Publications}, title = {{Global lightning NOx production estimated by an assimilation of multiple satellite data sets}}, volume = {14}, year = {2014} } @article{acp-15-8315-2015, abstract = {We present the results from an eight-year tropospheric chemistry reanalysis for the period 2005–2012 obtained by assimilating multiple retrieval data sets from the OMI, MLS, TES, and MOPITT satellite instruments. The reanalysis calculation was conducted using a global chemical transport model and an ensemble Kalman filter technique that simultaneously optimises the chemical concentrations of various species and emissions of several precursors. The optimisation of both the concentration and the emission fields is an efficient method to correct the entire tropospheric profile and its year-to-year variations, and to adjust various tracers chemically linked to the species assimilated. Comparisons against independent aircraft, satellite, and ozonesonde observations demonstrate the quality of the analysed O3, NO2, and CO concentrations on regional and global scales and for both seasonal and year-to-year variations from the lower troposphere to the lower stratosphere. The data assimilation statistics imply persistent reduction of model error and improved representation of emission variability, but also show that discontinuities in the availability of the measurements lead to a degradation of the reanalysis. The decrease in the number of assimilated measurements increased the ozonesonde minus analysis difference after 2010 and caused spurious variations in the estimated emissions. The Northern/Southern Hemisphere OH ratio was modified considerably due to the multiple species assimilation and became closer to an observational estimate, which played an important role in propagating observational information among various chemical fields and affected the emission estimates. The consistent concentration and emission products provide unique information on year-to-year variations of the atmospheric environment.}, author = {Miyazaki, K. and Eskes, H. J. and Sudo, K.}, doi = {10.5194/acp-15-8315-2015}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {14}, pages = {8315--8348}, title = {{A tropospheric chemistry reanalysis for the years 2005–2012 based on an assimilation of OMI, MLS, TES, and MOPITT satellite data}}, url = {https://www.atmos-chem-phys.net/15/8315/2015/}, volume = {15}, year = {2015} } @article{acp-17-807-2017, author = {Miyazaki, K and Eskes, H and Sudo, K and Boersma, K F and Bowman, K and Kanaya, Y}, doi = {10.5194/acp-17-807-2017}, journal = {Atmospheric Chemistry and Physics}, number = {2}, pages = {807--837}, title = {{Decadal changes in global surface NOx emissions from multi-constituent satellite data assimilation}}, url = {https://acp.copernicus.org/articles/17/807/2017/}, volume = {17}, year = {2017} } @article{MKOMA2009631, abstract = {Ambient daily PM10 aerosol samples were collected at two sites in Tanzania in May and June 2005 (during the wet season), and their chemical characteristics were studied. The sites were a rural site in Morogoro and an urban kerbside site in Dar es Salaam. A Gent PM10 stacked filter unit sampler with sequential Nuclepore polycarbonate filters, providing fine and coarse size fractions, and a PM10 sampler with quartz fibre filters were deployed. Parallel collections of 24h were made with the two samplers and the number of these collections was 13 in Morogoro and 16 in Dar es Salaam. The average mass concentration of PM10 was 27±11$\mu$g/m3 in Morogoro and 51±21$\mu$g/m3 in Dar es Salaam. In Morogoro, the mean concentrations of organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC) were 6.8, 0.51, and 2.8$\mu$g/m3, respectively. In contrast, higher mean concentrations (11.9, 4.6, and 3.3$\mu$g/m3, respectively) were obtained for Dar es Salaam. At both sites, species and elements, such as black carbon, NH4+, non-sea-salt SO42−, K, and Ni (and at Dar es Salaam also V, As, Br, and Pb) were mainly present in the fine size fraction. The common crustal and sea-salt elements, including Na, Mg, Al, Si, Cl, Ca, Ti, Mn, Fe, and Sr, and also NO3− and P (and to a lesser extent Cu and Zn) were concentrated in the coarse particles. Aerosol chemical mass closure indicated that the PM10 mass in Morogoro consisted, on average, of 48{\%} organic matter (OM), 44{\%} crustal matter, 4{\%} sea salt, and 2{\%} EC, while in Dar es Salaam OM, crustal matter, sea salt, and EC represented 37{\%}, 32{\%}, 9{\%}, and 9{\%} of the PM10 mass. The contributions of the secondary inorganic aerosol (non-sea-salt sulphate, nitrate, and ammonium) were small, i.e., only 5{\%} in total at each site. Carbonaceous materials and crustal matter were thus the most important components of the PM10 mass. It is suggested that biomass burning is a major contributor to the OM; at Dar es Salaam there is also a very substantial contribution from traffic. A source apportionment calculation indicated that 68{\%} of the OC at this site originated from traffic exhaust versus 32{\%} from charcoal burning. The crustal matter at Morogoro is likely mainly attributable to soil dust resuspension, whereas in Dar es Salaam it is likely mostly resuspended road dust.}, author = {Mkoma, Stelyus L and Maenhaut, Willy and Chi, Xuguang and Wang, Wan and Raes, Nico}, doi = {https://doi.org/10.1016/j.atmosenv.2008.10.008}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Aerosol chemical mass closure,Carbonaceous species,Elements,PM aerosols,Tanzania,Water-soluble ions}, number = {3}, pages = {631--639}, title = {{Characterisation of PM10 atmospheric aerosols for the wet season 2005 at two sites in East Africa}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231008009412}, volume = {43}, year = {2009} } @phdthesis{470145, abstract = {Three aerosol sampling campaigns were conducted at two sites (i.e., Dar es Salaam and Morogoro) in Tanzania, during different seasons from May 2005 through May 2006. A Gent PM10 stacked filter unit sampler with sequential Nuclepore polycarbonate filters, providing coarse (2-10 µm diameter) and fine ({\textless}2 µm) size fractions, and PM2.5 and PM10 tandem filter samplers with pre-fired quartz fibre filters were deployed. Depending upon the season and the location, either 24-hour collections or separate daytime and nighttime samplings were performed. The samples were analysed for the particulate matter (PM) mass, total carbon (TC), organic carbon, elemental carbon, water-soluble organic carbon, black carbon, major inorganic cationic and anionic species, and 28 elements. Most aerosol components measured exhibited higher levels in the dry season campaign than in the wet season campaigns. Besides, the levels were higher at the kerbside of Dar es Salaam than at the rural site of Morogoro. The differences between the campaigns resulted from differences in meteorological conditions and anthropogenic sources. At Morogoro, the median levels of the PM10 mass for the 2005 wet season, 2005 dry season, and 2006 wet season campaigns were 23, 45, and 13 µg/m3 and at Dar es Salaam they were 46, 58, and 40 µg/m3, respectively. In Morogoro, TC accounted, on average, for 31{\%} of the PM10 mass in the 2005 wet season, for 27{\%} in the 2005 dry season, and for 33{\%} in the 2006 wet season. At Dar es Salaam TC represented 29{\%} of PM10 mass in the 2005 dry season campaign, versus 37{\%} and 35{\%} in the 2005 and 2006 wet season campaigns, respectively. Aerosol chemical mass closure calculations indicated that organic matter and crustal matter were the dominant aerosol types in the PM10 aerosol; at Dar es Salaam, they explained, on average, 37{\%} and 33{\%} of the PM mass, and at Morogoro 40{\%} and 36{\%}, respectively. Using non-crustal, non-sea-salt K as an indicator for biomass burning, the organic matter at Dar es Salaam was apportioned to its contributions from charcoal burning and traffic. It appeared that, on average, around 70{\%} originated from traffic versus 30{\%} from charcoal.}, address = {Ghent, Belgium}, author = {Mkoma, Stelyus}, doi = {1854/9881}, pages = {182}, school = {Ghent University, Faculty of Sciences}, title = {{Physico-Chemical Characterisation of Atmospheric Aerosols in Tanzania, with Emphasis on the Carbonaceous Aerosol Components and on Chemical Mass Closure}}, type = {PhD}, url = {http://dx.doi.org/1854/9881}, year = {2008} } @article{MohankumarSajeev2018, author = {{Mohankumar Sajeev}, Erangu Purath and Winiwarter, Wilfried and Amon, Barbara}, doi = {10.2134/jeq2017.05.0199}, issn = {0047-2425}, journal = {Journal of Environmental Quality}, language = {en}, month = {dec}, number = {1}, pages = {30--41}, title = {{Greenhouse Gas and Ammonia Emissions from Different Stages of Liquid Manure Management Chains: Abatement Options and Emission Interactions}}, url = {https://dl.sciencesocieties.org/publications/jeq/abstracts/47/1/30 https://dl.sciencesocieties.org/publications/jeq/pdfs/47/1/30}, volume = {47}, year = {2018} } @article{acp-10-8697-2010, abstract = {MILAGRO (Megacity Initiative: Local And Global Research Observations) is an international collaborative project to examine the behavior and the export of atmospheric emissions from a megacity. The Mexico City Metropolitan Area (MCMA) – one of the world's largest megacities and North America's most populous city – was selected as the case study to characterize the sources, concentrations, transport, and transformation processes of the gases and fine particles emitted to the MCMA atmosphere and to evaluate the regional and global impacts of these emissions. The findings of this study are relevant to the evolution and impacts of pollution from many other megacities. The measurement phase consisted of a month-long series of carefully coordinated observations of the chemistry and physics of the atmosphere in and near Mexico City during March 2006, using a wide range of instruments at ground sites, on aircraft and satellites, and enlisting over 450 scientists from 150 institutions in 30 countries. Three ground supersites were set up to examine the evolution of the primary emitted gases and fine particles. Additional platforms in or near Mexico City included mobile vans containing scientific laboratories and mobile and stationary upward-looking lidars. Seven instrumented research aircraft provided information about the atmosphere over a large region and at various altitudes. Satellite-based instruments peered down into the atmosphere, providing even larger geographical coverage. The overall campaign was complemented by meteorological forecasting and numerical simulations, satellite observations and surface networks. Together, these research observations have provided the most comprehensive characterization of the MCMA's urban and regional atmospheric composition and chemistry that will take years to analyze and evaluate fully. In this paper we review over 120 papers resulting from the MILAGRO/INTEX-B Campaign that have been published or submitted, as well as relevant papers from the earlier MCMA-2003 Campaign, with the aim of providing a road map for the scientific community interested in understanding the emissions from a megacity such as the MCMA and their impacts on air quality and climate. This paper describes the measurements performed during MILAGRO and the results obtained on MCMA's atmospheric meteorology and dynamics, emissions of gases and fine particles, sources and concentrations of volatile organic compounds, urban and regional photochemistry, ambient particulate matter, aerosol radiative properties, urban plume characterization, and health studies. A summary of key findings from the field study is presented.}, author = {Molina, L T and Madronich, S and Gaffney, J S and Apel, E and de Foy, B and Fast, J and Ferrare, R and Herndon, S and Jimenez, J L and Lamb, B and Osornio-Vargas, A R and Russell, P and Schauer, J J and Stevens, P S and Volkamer, R and Zavala, M}, doi = {10.5194/acp-10-8697-2010}, journal = {Atmospheric Chemistry and Physics}, number = {18}, pages = {8697--8760}, title = {{An overview of the MILAGRO 2006 Campaign: Mexico City emissions and their transport and transformation}}, url = {https://acp.copernicus.org/articles/10/8697/2010/}, volume = {10}, year = {2010} } @article{acp-7-2447-2007, abstract = {Exploratory field measurements in the Mexico City Metropolitan Area (MCMA) in February 2002 set the stage for a major air quality field measurement campaign in the spring of 2003 (MCMA-2003). Involving over 100 scientists from more than 30 institutions in Mexico, the United States and Europe, MCMA-2003 revealed important new insights into the meteorology, primary pollutant emissions, ambient secondary pollutant precursor concentrations, photochemical oxidant production and secondary aerosol particle formation in North America's most populated and polluted megacity. A description of meteorological and atmospheric chemistry and aerosol microphysics measurements performed during MCMA-2003 is presented. More than 40 published or submitted MCMA-2003 research papers are reviewed and key discoveries pertinent to understanding and improving air quality in Mexico City and similar megacities in the developing world are summarized.}, author = {Molina, L T and Kolb, C E and de Foy, B and Lamb, B K and Brune, W H and Jimenez, J L and Ramos-Villegas, R and Sarmiento, J and Paramo-Figueroa, V H and Cardenas, B and Gutierrez-Avedoy, V and Molina, M J}, doi = {10.5194/acp-7-2447-2007}, journal = {Atmospheric Chemistry and Physics}, number = {10}, pages = {2447--2473}, title = {{Air quality in North America's most populous city – overview of the MCMA-2003 campaign}}, url = {https://acp.copernicus.org/articles/7/2447/2007/}, volume = {7}, year = {2007} } @article{Monks2015, abstract = {Using observations from aircraft, surface stations and satellite, we comprehensively evaluate multi-model simulations of carbon monoxide (CO) and ozone (O{\textless}sub{\textgreater}3{\textless}/sub{\textgreater}) in the Arctic and over lower latitude emission regions, as part of the POLARCAT Model Inter-comparison Project (POLMIP). Evaluation of eleven atmospheric models with chemistry shows that they generally underestimate CO throughout the Arctic troposphere, with the largest biases found during winter and spring. Negative CO biases are also found throughout the Northern Hemisphere, with multi-model mean gross errors (9–12{\%}) suggesting models perform similarly over Asia, North America and Europe. A multi-model annual mean tropospheric OH (10.8 ± 0.6 {\&}times; 10{\textless}sup{\textgreater}5{\textless}/sup{\textgreater} molec cm{\textless}sup{\textgreater}{\&}minus;3{\textless}/sup{\textgreater}) is found to be slightly higher than previous estimates of OH constrained by methyl chloroform, suggesting negative CO biases in models may be improved through better constraints on OH. Models that have lower Arctic OH do not always show a substantial improvement in their negative CO biases, suggesting that Arctic OH is not the dominant factor controlling the Arctic CO burden in these models. In addition to these general biases, models do not capture the magnitude of CO enhancements observed in the Arctic free troposphere in summer, suggesting model errors in the simulation of plumes that are transported from anthropogenic and biomass burning sources at lower latitudes. O{\textless}sub{\textgreater}3{\textless}/sub{\textgreater} in the Arctic is also generally underestimated, particularly at the surface and in the upper troposphere. Summer O{\textless}sub{\textgreater}3{\textless}/sub{\textgreater} comparisons over lower latitudes show several models overestimate upper tropospheric concentrations. {\textless}br{\textgreater}{\textless}br{\textgreater} Simulated CO, O{\textless}sub{\textgreater}3{\textless}/sub{\textgreater} and OH all demonstrate a substantial degree of inter-model variability. Idealised CO-like tracers are used to quantitatively compare the impact of inter-model differences in transport and OH on CO in the Arctic troposphere. The tracers show that model differences in transport from Europe in winter and from Asia throughout the year are important sources of model variability at the Barrow. Unlike transport, inter-model variability in OH similarly affects all regional tracers at Barrow. Comparisons of fixed lifetime and OH-loss idealised CO-like tracers throughout the Arctic troposphere show that OH differences are a much larger source of inter-model variability than transport differences. The concentration of OH in the models is found to be correlated with inter-model differences in H{\textless}sub{\textgreater}2{\textless}/sub{\textgreater}O, suggesting it to be an important driver of differences in simulated concentrations of CO and OH at high latitudes in these simulations. Despite inter-model differences in transport and OH, the relative contributions from the different source regions (North America, Europe and Asia) and different source types (anthropogenic and biomass burning) are comparable across the models. Fire emissions from the boreal regions in 2008 contribute 33, 43 and 19{\%} to the total Arctic CO-like tracer in spring, summer and autumn, respectively, highlighting the importance of boreal fire emissions in controlling pollutant burdens in the Arctic.}, author = {Monks, S. A. and Arnold, S. R. and Emmons, L. K. and Law, K. S. and Turquety, S. and Duncan, B. N. and Flemming, J. and Huijnen, V. and Tilmes, S. and Langner, J. and Mao, J. and Long, Y. and Thomas, J. L. and Steenrod, S. D. and Raut, J. C. and Wilson, C. and Chipperfield, M. P. and Diskin, G. S. and Weinheimer, A. and Schlager, H. and Ancellet, G.}, doi = {10.5194/acp-15-3575-2015}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {6}, pages = {3575--3603}, title = {{Multi-model study of chemical and physical controls on transport of anthropogenic and biomass burning pollution to the Arctic}}, volume = {15}, year = {2015} } @article{MonteirodosSantos2016, abstract = {The S{\~{a}}o Paulo Metropolitan Area (SPMA) is a megacity with about 20 million people and about 8 million vehicles, most of which are fueled with a significant fraction of ethanol - making it a unique case worldwide. This study presents organic and elemental carbon measurements using thermal-optical analysis from quartz filters collected in four sampling sites within the SPMA. Overall Organic Carbon (OC) concentration was comparable at all sites, where Street Canyon had the highest concentration (3.37 $\mu$g m−3) and Park site the lowest (2.65 $\mu$g m−3). Elemental Carbon (EC), emitted as result of incomplete combustion, has been significantly higher at the Street Canyon site (6.11 $\mu$g m−3) in contrast to all other three sites, ranging from 2.25 $\mu$g m−3 (Downtown) to 1.50 $\mu$g m-3 (Park). For all sampling sites, the average OC:EC ratio are found on the lower bound ({\textless}2) of what is usually observed for other megacities, highlighting the significant contribution of EC in Sao Paulo. At the Street Canyon site, average OC:EC ratio was 0.56, to our knowledge the lowest value ever observed for any urban site. An approach for apportionment between primary and secondary organic carbon based on primary OC:EC ratio was evaluated. The secondary OC was estimated to be 30–40{\%} of total OC concentrations throughout the various sampling sites. The organic carbon dynamics has been further studied using each of the thermally-derived organic carbon fractions. Each of these has been studied regarding their correlation with EC and the correlation between different sites. The analyses have identified that the OC3 and OC4, i.e., the carbon fraction which evolves from the filter at temperatures above 450 °C, presents a regional behavior, with high correlation among all sites. Conversely, OC1, the first fraction to evolve, has depicted a more local characteristic. Furthermore, the fraction of OC which becomes char during the temperature increase under inert atmosphere (the Pyrolytic Carbon-PC) has been the only fraction not to present a significant correlation with EC. Since that EC is assumed to be a primary emission marker, it indicates that PC is not significant in traffic emissions. This study provided innovative insights of the organic aerosol content associated with air pollution dynamics in a megacity impacted by a unique vehicular fleet. It also shows the need of implementation of EURO VI technology and to improve mass transport systems such a metro and more bus corridors to allow better transport for 19 million people in the SPMA.}, author = {{Monteiro dos Santos}, Djacinto A. and Brito, Joel F. and Godoy, Jos{\'{e}} Marcus and Artaxo, Paulo}, doi = {10.1016/j.atmosenv.2016.08.081}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Carbonaceous aerosol,Megacity,Urban air pollution}, month = {nov}, pages = {226--233}, title = {{Ambient concentrations and insights on organic and elemental carbon dynamics in S{\~{a}}o Paulo, Brazil}}, url = {http://linkinghub.elsevier.com/retrieve/pii/S1352231016306872 https://linkinghub.elsevier.com/retrieve/pii/S1352231016306872}, volume = {144}, year = {2016} } @article{Montzka2015, abstract = {Global-scale atmospheric measurements are used to investigate the effectiveness of recent adjustments to production and consumption controls on hydrochlorofluorocarbons (HCFCs) under the Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol) and to assess recent projections of large increases in hydrofluorocarbon (HFC) production and emission. The results show that aggregate global HCFC emissions did not increase appreciably during 2007–2012 and suggest that the 2007 Adjustments to the Montreal Protocol played a role in limiting HCFC emissions well in advance of the 2013 cap on global production. HCFC emissions varied between 27 and 29 kt CFC-11-equivalent (eq)/y or 0.76 and 0.79 GtCO2-eq/y during this period. Despite slower than projected increases in aggregate HCFC emissions since 2007, total emissions of HFCs used as substitutes for HCFCs and chlorofluorocarbons (CFCs) have not increased more rapidly than rates projected [Velders, G. J. M.; Fahey, D. W.; Daniel, J. S.; McFarland, M.; Andersen, S. O. The Large Contribution of Projected HFC Emissions to Future Climate Forcing. Proc. Natl. Acad. Sci. U.S.A. 2009, 106, 10949−10954] for 2007–2012. HFC global emission magnitudes related to this substitution totaled 0.51 (−0.03, +0.04) GtCO2-eq/y in 2012, a magnitude about two times larger than emissions reported to the United Nations Framework Convention on Climate Change (UNFCCC) for these HFCs. Assuming accurate reporting to the UNFCCC, the results imply that developing countries (non-Annex I Parties) not reporting to the UNFCCC now account for nearly 50{\%} of global HFC emissions used as substitutes for ozone-depleting substances (ODSs). Global HFC emissions (as CO2-eq) from ODS substitution can be attributed approximately equally to mobile air conditioning, commercial refrigeration, and the sum of all other applications.}, annote = {doi: 10.1021/jp5097376}, author = {Montzka, S A and McFarland, M and Andersen, S O and Miller, B R and Fahey, D W and Hall, B D and Hu, L and Siso, C and Elkins, J W}, doi = {10.1021/jp5097376}, issn = {1089-5639}, journal = {The Journal of Physical Chemistry A}, month = {may}, number = {19}, pages = {4439--4449}, publisher = {American Chemical Society}, title = {{Recent Trends in Global Emissions of Hydrochlorofluorocarbons and Hydrofluorocarbons: Reflecting on the 2007 Adjustments to the Montreal Protocol}}, url = {https://doi.org/10.1021/jp5097376}, volume = {119}, year = {2015} } @article{Montzka2011a, abstract = {The oxidizing capacity of the global atmosphere is largely determined by hydroxyl (OH) radicals and is diagnosed by analyzing methyl chloroform (CH3CCl3) measurements. Previously, large year-to-year changes in global mean OH concentrations have been inferred from such measurements, suggesting that the atmospheric oxidizing capacity is sensitive to perturbations by widespread air pollution and natural influences. We show how the interannual variability in OH has been more precisely estimated from CH3CCl3 measurements since 1998, when atmospheric gradients of CH3CCl3 had diminished as a result of the Montreal Protocol. We infer a small interannual OH variability as a result, indicating that global OH is generally well buffered against perturbations. This small variability is consistent with measurements of methane and other trace gases oxidized primarily by OH, as well as global photochemical model calculations.}, author = {Montzka, S A and Krol, M and Dlugokencky, E and Hall, B and J{\"{o}}ckel, P and Lelieveld, J}, doi = {10.1126/science.1197640}, journal = {Science}, number = {6013}, pages = {67--69}, title = {{Small Interannual Variability of Global Atmospheric Hydroxyl}}, url = {http://www.sciencemag.org/content/331/6013/67.abstract}, volume = {331}, year = {2011} } @article{Morgan2019b, abstract = {Abstract. We present a range of airborne in situ observations of biomass burning carbonaceous aerosol over tropical South America, including a case study of a large tropical forest wildfire and a series of regional survey flights across the Brazilian Amazon and Cerrado. The study forms part of the South American Biomass Burning Analysis (SAMBBA) project, which was conducted during September and October 2012. We find limited evidence for net increases in aerosol mass through atmospheric ageing combined with substantial changes in the chemical properties of organic aerosol (OA). Oxidation of the OA increases significantly and rapidly on the scale of 2.5–3 h based on our case study analysis and is consistent with secondary organic aerosol production. The observations of limited net enhancement in OA coupled with such changes in chemical composition imply that evaporation of OA is also occurring to balance these changes. We observe significant coatings on black carbon particles at source, but with limited changes with ageing in both particle core size and coating thickness. We quantify variability in the ratio of OA to carbon monoxide across our study as a key parameter representing both initial fire conditions and an indicator of net aerosol production with atmospheric ageing. We observe ratios of 0.075–0.13 µgsm-3ppbv-1 in the west of our study region over the Amazon tropical forest in air masses less influenced by precipitation and a value of 0.095 µgsm-3ppbv-1 over the Cerrado environment in the east (where sm−3 refers to standard metre cubed). Such values are consistent with emission factors used by numerical models to represent biomass burning OA emissions. Black carbon particle core sizes typically range from mean mass diameters of 250 to 290 nm, while coating thicknesses range from 40 to 110 nm in air masses less influenced by precipitation. The primary driver of the variability we observe appears to be related to changes at the initial fire source. A key lesson from our study is that simply aggregating our observations as a function of atmospheric ageing would have been misleading due to the complex nature of the regional aerosol and its drivers, due to the many conflating and competing factors that are present. Our study explores and quantifies key uncertainties in the evolution of biomass burning aerosol at both near-field and regional scales. Our results suggest that the initial conditions of the fire are the primary driver of carbonaceous aerosol physical and chemical properties over tropical South America, aside from significant oxidation of OA during atmospheric ageing. Such findings imply that uncertainties in the magnitude of the aerosol burden and its impact on weather, climate, health and natural ecosystems most likely lie in quantifying emission sources, alongside atmospheric dispersion, transport and removal rather than chemical enhancements in mass.}, author = {Morgan, William T. and Allan, James D. and Bauguitte, St{\'{e}}phane and Darbyshire, Eoghan and Flynn, Michael J. and Lee, James and Liu, Dantong and Johnson, Ben and Haywood, Jim and Longo, Karla M. and Artaxo, Paulo E. and Coe, Hugh}, doi = {10.5194/acp-20-5309-2020}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, keywords = {Aerosol,Air mass,Amazon rainforest,Atmospheric dispersion modeling,Atmospheric sciences,Biomass,Black carbon,Chemistry,Climatology,Particle,Precipitation}, month = {may}, number = {9}, pages = {5309--5326}, title = {{Transformation and ageing of biomass burning carbonaceous aerosol over tropical South America from aircraft in situ measurements during SAMBBA}}, url = {https://acp.copernicus.org/articles/20/5309/2020/}, volume = {20}, year = {2020} } @article{Morgenstern2018a, abstract = {{\textless}p{\textgreater}Ozone fields simulated for the Chemistry-Climate Model Initiative (CCMI) will be used as forcing data in the 6th Coupled Model Intercomparison Project (CMIP6). Here we assess, using reference and sensitivity simulations produced for phase 1 of CCMI, the suitability of CCMI-1 model results for this process, investigating the degree of consistency amongst models regarding their responses to variations in individual forcings. We consider the influences of methane, nitrous oxide, a combination of chlorinated or brominated ozone-depleting substances (ODSs), and a combination of carbon dioxide and other greenhouse gases (GHGs). We find varying degrees of consistency in the models' responses in ozone to these individual forcings, including some considerable disagreement. In particular, the response of total-column ozone to these forcings is less consistent across the multi-model ensemble than profile comparisons. The likely cause of this is lower-stratospheric transport and dynamical responses exhibiting substantial inter-model differences. The findings imply that the ozone fields derived from CCMI-1 are subject to considerable uncertainties regarding the impacts of these anthropogenic forcings.{\textless}/p{\textgreater}}, author = {Morgenstern, Olaf and Stone, Kane A. and Schofield, Robyn and Akiyoshi, Hideharu and Yamashita, Yousuke and Kinnison, Douglas E. and Garcia, Rolando R. and Sudo, Kengo and Plummer, David A. and Scinocca, John and Oman, Luke D. and Manyin, Michael E. and Zeng, Guang and Rozanov, Eugene and Stenke, Andrea and Revell, Laura E. and Pitari, Giovanni and Mancini, Eva and {DI Genova}, Glauco and Visioni, Daniele and Dhomse, Sandip S. and Chipperfield, Martyn P.}, doi = {10.5194/acp-18-1091-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {jan}, number = {2}, pages = {1091--1114}, title = {{Ozone sensitivity to varying greenhouse gases and ozone-depleting substances in CCMI-1 simulations}}, url = {https://www.atmos-chem-phys.net/18/1091/2018/}, volume = {18}, year = {2018} } @article{Morgenstern2017, abstract = {We present an overview of state-of-the-art chemistry–climate and chemistry transport models that are used within phase 1 of the Chemistry–Climate Model Initiative (CCMI-1). The CCMI aims to conduct a detailed evaluation of participating models using process-oriented diagnostics derived from observations in order to gain confidence in the models' projections of the stratospheric ozone layer, tropospheric composition, air quality, where applicable global climate change, and the interactions between them. Interpretation of these diagnostics requires detailed knowledge of the radiative, chemical, dynamical, and physical processes incorporated in the models. Also an understanding of the degree to which CCMI-1 recommendations for simulations have been followed is necessary to understand model responses to anthropogenic and natural forcing and also to explain inter-model differences. This becomes even more important given the ongoing development and the ever-growing complexity of these models. This paper also provides an overview of the available CCMI-1 simulations with the aim of informing CCMI data users.}, author = {Morgenstern, Olaf and Hegglin, Michaela I and Rozanov, Eugene and O'Connor, Fiona M and Abraham, N Luke and Akiyoshi, Hideharu and Archibald, Alexander T and Bekki, Slimane and Butchart, Neal and Chipperfield, Martyn P and Deushi, Makoto and Dhomse, Sandip S and Garcia, Rolando R and Hardiman, Steven C and Horowitz, Larry W and J{\"{o}}ckel, Patrick and Josse, Beatrice and Kinnison, Douglas and Lin, Meiyun and Mancini, Eva and Manyin, Michael E and Marchand, Marion and Mar{\'{e}}cal, Virginie and Michou, Martine and Oman, Luke D and Pitari, Giovanni and Plummer, David A and Revell, Laura E and Saint-Martin, David and Schofield, Robyn and Stenke, Andrea and Stone, Kane and Sudo, Kengo and Tanaka, Taichu Y and Tilmes, Simone and Yamashita, Yousuke and Yoshida, Kohei and Zeng, Guang}, doi = {10.5194/gmd-10-639-2017}, isbn = {1991-9603}, issn = {1991-9603}, journal = {Geoscientific Model Development}, month = {feb}, number = {2}, pages = {639--671}, publisher = {Copernicus Publications}, title = {{Review of the global models used within phase 1 of the Chemistry–Climate Model Initiative (CCMI)}}, url = {https://gmd.copernicus.org/articles/10/639/2017/}, volume = {10}, year = {2017} } @article{10.1002/essoar.10502742.1, author = {Morgenstern, Olaf and O'Connor, Fiona M. and Johnson, Ben T. and Zeng, Guang and Mulcahy, Jane P. and Williams, Jonny and Teixeira, Jo{\~{a}}o and Michou, Martine and Nabat, Pierre and Horowitz, Larry W. and Naik, Vaishali and Sentman, Lori T. and Deushi, Makoto and Bauer, Susanne E. and Tsigaridis, Kostas and Shindell, Drew T. and Kinnison, Douglas E.}, doi = {10.1029/2020GL088295}, issn = {0094-8276}, journal = {Geophysical Research Letters}, month = {oct}, number = {20}, pages = {e2020GL088295}, title = {{Reappraisal of the Climate Impacts of Ozone‐Depleting Substances}}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2020GL088295}, volume = {47}, year = {2020} } @article{Mortier2020, abstract = {Abstract. This study presents a multiparameter analysis of aerosol trends over the last 2 decades at regional and global scales. Regional time series have been computed for a set of nine optical, chemical-composition and mass aerosol properties by using the observations from several ground-based networks. From these regional time series the aerosol trends have been derived for the different regions of the world. Most of the properties related to aerosol loading exhibit negative trends, both at the surface and in the total atmospheric column. Significant decreases in aerosol optical depth (AOD) are found in Europe, North America, South America, North Africa and Asia, ranging from −1.2 {\%} yr−1 to −3.1 {\%} yr−1. An error and representativity analysis of the spatially and temporally limited observational data has been performed using model data subsets in order to investigate how much the observed trends represent the actual trends happening in the regions over the full study period from 2000 to 2014. This analysis reveals that significant uncertainty is associated with some of the regional trends due to time and space sampling deficiencies. The set of observed regional trends has then been used for the evaluation of 10 models (6 AeroCom phase III models and 4 CMIP6 models) and the CAMS reanalysis dataset and of their skills in reproducing the aerosol trends. Model performance is found to vary depending on the parameters and the regions of the world. The models tend to capture trends in AOD, the column {\AA}ngstr{\"{o}}m exponent, sulfate and particulate matter well (except in North Africa), but they show larger discrepancies for coarse-mode AOD. The rather good agreement of the trends, across different aerosol parameters between models and observations, when co-locating them in time and space, implies that global model trends, including those in poorly monitored regions, are likely correct. The models can help to provide a global picture of the aerosol trends by filling the gaps in regions not covered by observations. The calculation of aerosol trends at a global scale reveals a different picture from that depicted by solely relying on ground-based observations. Using a model with complete diagnostics (NorESM2), we find a global increase in AOD of about 0.2 {\%} yr−1 between 2000 and 2014, primarily caused by an increase in the loads of organic aerosols, sulfate and black carbon.}, author = {Mortier, Augustin and Gli{\ss}, Jonas and Schulz, Michael and Aas, Wenche and Andrews, Elisabeth and Bian, Huisheng and Chin, Mian and Ginoux, Paul and Hand, Jenny and Holben, Brent and Zhang, Hua and Kipling, Zak and Kirkev{\aa}g, Alf and Laj, Paolo and Lurton, Thibault and Myhre, Gunnar and Neubauer, David and Olivi{\'{e}}, Dirk and von Salzen, Knut and Skeie, Ragnhild Bieltvedt and Takemura, Toshihiko and Tilmes, Simone}, doi = {10.5194/acp-20-13355-2020}, file = {::}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, keywords = {Aerosol,Angstrom exponent,Atmospheric sciences,Black carbon,Chemistry,Climate model,Climatology,Global model,Optical depth,Particulates,Sampling (statistics)}, month = {nov}, number = {21}, pages = {13355--13378}, title = {{Evaluation of climate model aerosol trends with ground-based observations over the last 2 decades – an AeroCom and CMIP6 analysis}}, url = {https://acp.copernicus.org/articles/20/13355/2020/}, volume = {20}, year = {2020} } @article{Moteki2019, abstract = {Quantitative simulation of an aerosol's lifecycle by regional-scale and global-scale atmospheric models is mandatory for unbiased analysis and prediction of aerosol radiative forcing and climate change. Globally, aerosol deposition is dominated by the rainout process, which is mostly triggered by activation of aerosols to liquid droplets in supersaturated domains of precipitating clouds. However, the actual environmental supersaturation value that aerosols experience in precipitating clouds is difficult for models to predict, and it has never been constrained by observations; as a result, there is large uncertainty in atmospheric aerosol simulations. Here, by a particle-tracer analysis of 37 rainfall events in East Asia, near the largest source region of anthropogenic aerosols in the northern hemisphere, we observed that the environmental supersaturation actually experienced by the removed aerosols in precipitating clouds averaged 0.08 ± 0.03{\%} and ranged from 0.03 to 0.2{\%}. Simulations by a mixing-state-resolved global aerosol model showed that the simulated long-range transport efficiency and global atmospheric burden of black carbon aerosols can be changed by a factor of two or three as a result of a change in the environmental supersaturation in precipitating clouds within just 0.08 ± 0.03{\%}. This result is attributable to the fact that the sensitivity of an aerosol's rainout efficiency to environmental supersaturation is higher for the less-aged black carbon concentrated near source regions. Our results suggest that observational constraints of environmental supersaturation in precipitating clouds, particularly near source regions, are of fundamental importance for accurate simulation of the atmospheric burden of black carbon and other aerosols.}, author = {Moteki, Nobuhiro and Mori, Tatsuhiro and Matsui, Hitoshi and Ohata, Sho}, doi = {10.1038/s41612-019-0063-y}, issn = {2397-3722}, journal = {npj Climate and Atmospheric Science}, number = {1}, pages = {6}, title = {{Observational constraint of in-cloud supersaturation for simulations of aerosol rainout in atmospheric models}}, volume = {2}, year = {2019} } @article{Motos2019, author = {Motos, Ghislain and Schmale, Julia and Corbin, Joel C. and Modini, Rob L. and Karlen, Nadine and Bert{\`{o}}, Michele and Baltensperger, Urs and Gysel-Beer, Martin}, doi = {10.5194/acp-19-3833-2019}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {6}, pages = {3833--3855}, title = {{Cloud droplet activation properties and scavenged fraction of black carbon in liquid-phase clouds at the high-alpine research station Jungfraujoch (3580 m a.s.l.)}}, url = {https://acp.copernicus.org/articles/19/3833/2019/}, volume = {19}, year = {2019} } @article{Muri2018, abstract = {Considering the ambitious climate targets of the Paris Agreement to limit global warming to 2°C, with aspirations of even 1.5°C, questions arise on how to achieve this. Climate geoengineering has been proposed as a potential tool to minimize global harm from anthropogenic climate change. Here, an Earth system model is used to evaluate the climate response when transferring from a high CO 2 forcing scenario, RCP8.5, to a middle-of-the-road forcing scenario, like RCP4.5, using aerosol geoengineering. Three different techniques are considered: stratospheric aerosol injections (SAI), marine sky brightening (MSB), and cirrus cloud thinning (CCT). The climate states appearing in the climate geoengineering cases are found to be closer to RCP4.5 than RCP8.5 and many anthropogenic global warming symptoms are alleviated. All three techniques result in comparable global mean temperature evolutions. However, there are some notable differences in other climate variables due to the nature of the forcings applied. CCT acts mainly on the longwave part of the radiation budget, as opposed to MSB and SAI acting in the shortwave. This yields a difference in the response, particularly in the hydrological cycle. The responses in sea ice, sea level, ocean heat, and circulation, as well as the carbon cycle, are furthermore compared. Sudden termination of the aerosol injection geoengineering shows that the climate very rapidly (within two decades) reverts to the path of RCP8.5, questioning the sustainable nature of such climate geoengineering, and simultaneous mitigation during any such form of climate geoengineering would be needed to limit termination risks.}, author = {Muri, Helene and Tjiputra, Jerry and Otter{\aa}, Odd Helge and Adakudlu, Muralidhar and Lauvset, Siv K. and Grini, Alf and Schulz, Michael and Niemeier, Ulrike and Kristj{\'{a}}nsson, J{\'{o}}n Egill}, doi = {10.1175/JCLI-D-17-0620.1}, issn = {0894-8755}, journal = {Journal of Climate}, keywords = {Atmosphere,Carbon cycle,Clouds,General circulation models,North Atlantic Oscillation,Ocean}, month = {aug}, number = {16}, pages = {6319--6340}, title = {{Climate Response to Aerosol Geoengineering: A Multimethod Comparison}}, url = {https://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0620.1}, volume = {31}, year = {2018} } @article{Murray2016a, abstract = {Lightning generates relatively large but uncertain quantities of nitrogen oxides (NOx ), critical precursors for ozone and hydroxyl radical (OH), the primary tropospheric oxidants. Lightning NOx strongly influences background ozone and OH due to high ozone production efficiencies in the free troposphere, effecting small but non-negligible contributions to surface pollutant concentrations. Lightning globally contributes 3–4 ppbv of simulated annual-mean policy-relevant background (PRB) surface ozone, comprised of local, regional, and hemispheric components, and up to 18 ppbv during individual events. Feedbacks via methane may counter some of these effects on decadal time scales. Lightning contributes ∼1 {\%} to annual-mean surface particulate matter, as a direct precursor and by promoting faster oxidation of other precursors. Lightning also ignites wildfires and contributes to nitrogen deposition. Urban pollution influences lightning itself, with implications for regional lightning-NOx production and feedbacks on downwind surface pollution. How lightning emissions will change in a warming world remains uncertain.}, author = {Murray, Lee T.}, doi = {10.1007/s40726-016-0031-7}, issn = {2198-6592}, journal = {Current Pollution Reports}, keywords = {Air quality,Lightning,Pol,Reactive nitrogen oxides,air,lightning,policy-relevant background,quality,reactive nitrogen oxides}, number = {2}, pages = {115--133}, publisher = {Current Pollution Reports}, title = {{Lightning NOx and Impacts on Air Quality}}, url = {http://link.springer.com/10.1007/s40726-016-0031-7}, volume = {2}, year = {2016} } @article{doi:10.1002/jgrd.50857, abstract = {Nitrogen oxide radicals (NOx) produced by lightning are natural precursors for the production of the dominant tropospheric oxidants, OH and ozone. Observations of the interannual variability (IAV) of tropical ozone and of global mean OH (from the methyl chloroform proxy) offer a window for understanding the sensitivity of ozone and OH to environmental factors. We present the results of simulations for 1998–2006 using the GEOS-Chem chemical transport model (CTM) with IAV in tropical lightning constrained by satellite observations from the Lightning Imaging Sensor. We find that this imposed IAV in lightning NOx improves the ability of the model to reproduce observed IAV in tropical ozone and OH. Lightning is far more important than biomass burning in driving the IAV of tropical ozone, even though the IAV of NOx emissions from fires is greater than that from lightning. Our results indicate that the IAV in tropospheric OH is highly sensitive to lightning relative to other emissions and suggest that lightning contributes an important fraction of the observed IAV in OH inferred from the methyl chloroform proxy. Lightning affects OH through the HO2+ NO reaction, an effect compounded by positive feedback from the resulting increase in ozone production and in CO loss. We can account in the model for the observed increase in OH in 1998–2004 and for its IAV, but the model fails to explain the OH decrease in 2004–2006. We find that stratospheric ozone plays little role in driving IAV in OH during 1998–2006, in contrast to previous studies that examined earlier periods.}, author = {Murray, Lee T and Logan, Jennifer A and Jacob, Daniel J}, doi = {10.1002/jgrd.50857}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {OH,interannual variability,lightning,ozone}, month = {oct}, number = {19}, pages = {11468--11480}, title = {{Interannual variability in tropical tropospheric ozone and OH: The role of lightning}}, url = {http://doi.wiley.com/10.1002/jgrd.50857}, volume = {118}, year = {2013} } @article{Murray2014a, abstract = {The oxidative capacity of past atmospheres is highly uncertain. We present here a new climate-biosphere-chemistry modeling framework to determine oxidant levels in the present and past troposphere. We use the GEOS-Chem chemical transport model driven by meteorological fields from the NASA Goddard Institute of Space Studies (GISS) ModelE, with land cover and fire emissions from dynamic global vegetation models. We present time-slice simulations for the present day, late preindustrial era (AD 1770), and the Last Glacial Maximum (LGM, 19-23 ka), and we test the sensitivity of model results to uncertainty in lightning and fire emissions. We find that most preindustrial and paleo climate simulations yield reduced oxidant levels relative to the present day. Contrary to prior studies, tropospheric mean OH in our ensemble shows little change at the LGM relative to the preindustrial era (0.5 ± 12 {\%}), despite large reductions in methane concentrations. We find a simple linear relationship between tropospheric mean ozone photolysis rates, water vapor, and total emissions of NOx and reactive carbon that explains 72 {\%} of the variability in global mean OH in 11 different simulations across the last glacial-interglacial time interval and the industrial era. Key parameters controlling the tropospheric oxidative capacity over glacial-interglacial periods include overhead stratospheric ozone, tropospheric water vapor, and lightning NOx emissions. Variability in global mean OH since the LGM is insensitive to fire emissions. Our simulations are broadly consistent with ice-core records of "17O in sulfate and nitrate at the LGM, and CO, HCHO, and H2O2 in the preindustrial era. Our results imply that the glacial-interglacial changes in atmospheric methane observed in ice cores are predominantly driven by changes in its sources as opposed to its sink with OH. {\textcopyright}Author(s) 2014. CC Attribution 3.0 License.}, annote = {From Duplicate 1 (Factors controlling variability in the oxidative capacity of the troposphere since the Last Glacial Maximum - Murray, L. T.; Mickley, L. J.; Kaplan, J. O.; Sofen, E. D.; Pfeiffer, M.; Alexander, B.) Af3jo Times Cited:1 Cited References Count:237}, author = {Murray, L. T. and Mickley, L. J. and Kaplan, J. O. and Sofen, E. D. and Pfeiffer, M. and Alexander, B.}, doi = {10.5194/acp-14-3589-2014}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, keywords = {aerosol transport model,biomass-burning emissions,chemical tracer model,chemistry-climate interactions,general-circulation model,global lightning distributions,intercomparison project accmip,long-range transport,pmip2 coupled simulations,sea-surface temperature}, language = {English}, number = {7}, pages = {3589--3622}, shorttitle = {Factors controlling variability in the oxidative c}, title = {{Factors controlling variability in the oxidative capacity of the troposphere since the Last Glacial Maximum}}, volume = {14}, year = {2014} } @article{Muthers2014, abstract = {Abstract. The newly developed atmosphere–ocean–chemistry–climate model SOCOL-MPIOM is presented by demonstrating the influence of chemistry–climate interactions on the climate state and the variability. Therefore, we compare pre-industrial control simulations with (CHEM) and without (NOCHEM) interactive chemistry. In general, the influence of the chemistry on the mean state and the variability is small and mainly restricted to the stratosphere and mesosphere. The atmospheric dynamics mainly differ in polar regions, with slightly stronger polar vortices in the austral and boreal winter, respectively. The strengthening of the vortex is related to larger stratospheric temperature gradients, which are attributed to a parameterisation of the absorption of ozone and oxygen in different wavelength intervals, which is considered in the version with interactive chemistry only. A second reason for the temperature differences between CHEM and NOCHEM is related to diurnal variations in the ozone concentrations in the higher atmosphere, which are missing in NOCHEM. Furthermore, stratospheric water vapour concentrations substantially differ between the two experiments, but their effect on temperature is small. In both setups, the simulated intensity and variability of the northern polar vortex is inside the range of present-day observations. Additionally, the performance of SOCOL-MPIOM under changing external forcings is assessed for the period 1600–2000 using an ensemble of simulations. In the industrial period from 1850 onward SOCOL-MPIOM overestimates the global mean surface air temperature increase in comparison to observational data sets. Sensitivity simulations show that this overestimation can be attributed to a combination of factors: the solar forcing reconstruction, the simulated ozone changes, and incomplete aerosol effects and land use changes.}, author = {Muthers, S and Anet, J G and Stenke, A and Raible, C C and Rozanov, E and Br{\"{o}}nnimann, S and Peter, T and Arfeuille, F X and Shapiro, A I and Beer, J and Steinhilber, F and Brugnara, Y and Schmutz, W}, doi = {10.5194/gmd-7-2157-2014}, issn = {1991-9603}, journal = {Geoscientific Model Development}, month = {sep}, number = {5}, pages = {2157--2179}, publisher = {Copernicus Publications}, title = {{The coupled atmosphere–chemistry–ocean model SOCOL-MPIOM}}, url = {https://gmd.copernicus.org/articles/7/2157/2014/}, volume = {7}, year = {2014} } @article{Myhre2017b, abstract = {Over the past few decades, the geographical distribution of emissions of substances that alter the atmospheric energy balance has changed due to economic growth and air pollution regulations. Here, we show the resulting changes to aerosol and ozone abundances and their radiative forcing using recently updated emission data for the period 1990-2015, as simulated by seven global atmospheric composition models. The models broadly reproduce large-scale changes in surface aerosol and ozone based on observations (e.g.-1 to-3{\%}yr-1 in aerosols over the USA and Europe). The global mean radiative forcing due to ozone and aerosol changes over the 1990-2015 period increased by +0.17±0.08Wm-2, with approximately one-third due to ozone. This increase is more strongly positive than that reported in IPCC AR5. The main reasons for the increased positive radiative forcing of aerosols over this period are the substantial reduction of global mean SO2 emissions, which is stronger in the new emission inventory compared to that used in the IPCC analysis, and higher black carbon emissions.}, author = {Myhre, Gunnar and Aas, Wenche and Cherian, Ribu and Collins, William and Faluvegi, Greg and Flanner, Mark and Forster, Piers and Hodnebrog, {\O}ivind and Klimont, Zbigniew and Lund, Marianne T. and M{\"{u}}lmenst{\"{a}}dt, Johannes and {Lund Myhre}, Cathrine and Olivi{\'{e}}, Dirk and Prather, Michael and Quaas, Johannes and Samset, Bj{\o}rn H. and Schnell, Jordan L. and Schulz, Michael and Shindell, Drew and Skeie, Ragnhild B. and Takemura, Toshihiko and Tsyro, Svetlana}, doi = {10.5194/acp-17-2709-2017}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, keywords = {pzanis}, month = {feb}, number = {4}, pages = {2709--2720}, title = {{Multi-model simulations of aerosol and ozone radiative forcing due to anthropogenic emission changes during the period 1990–2015}}, url = {https://www.atmos-chem-phys.net/17/2709/2017/}, volume = {17}, year = {2017} } @article{Myhre2004, author = {Myhre, Gunnar and Berglen, Tore F and Myhre, Cathrine E L and Isaksen, Ivar S A}, doi = {10.3402/tellusb.v56i3.16431}, issn = {null}, journal = {Tellus B: Chemical and Physical Meteorology}, month = {jan}, number = {3}, pages = {294--299}, publisher = {Taylor {\&} Francis}, title = {{The radiative effect of the anthropogenic influence on the stratospheric sulfate aerosol layer}}, volume = {56}, year = {2004} } @incollection{Myhre2013a, author = {Myhre, Gunnar and Shindell, Drew and Br{\'{e}}on, Francois-Marie and Collins, William and Fuglestvedt, Jan and Huang, Jianping and Koch, Dorothy and Lamarque, Jean-Francois and Lee, David and Mendoza, Blanca and Nakajima, Teruyuki and Robock, Alan and Stephens, Graeme and Takemura, Toshihiko and Zhang, Hua}, booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change}, chapter = {8}, doi = {10.1017/CBO9781107415324.018}, editor = {Stocker, T F and Qin, D and Plattner, G.-K. and Tignor, M and Allen, S K and Boschung, J and Nauels, A and Xia, Y and Bex, V and Midgley, P M}, isbn = {9781107661820}, pages = {659--740}, publisher = {Cambridge University Press}, title = {{Anthropogenic and Natural Radiative Forcing}}, url = {https://www.ipcc.ch/report/ar5/wg1}, year = {2013} } @article{Myriokefalitakis2016, abstract = {The importance of the long-range transport (LRT) on O3and CO budgets over the Eastern Mediterranean has been investigated using the state-of-the-art 3-dimensional global chemistry-transport model TM4-ECPL. A 3-D budget analysis has been performed separating the Eastern from the Western basins and the boundary layer (BL) from the free troposphere (FT). The FT of the Eastern Mediterranean is shown to be a strong receptor of polluted air masses from the Western Mediterranean, and the most important source of polluted air masses for the Eastern Mediterranean BL, with about 40{\%} of O3and of CO in the BL to be transported from the FT aloft. Regional anthropogenic sources are found to have relatively small impact on regional air quality in the area, contributing by about 8{\%} and 18{\%} to surface levels of O3and CO, respectively. Projections using anthropogenic emissions for the year 2050 but neglecting climate change calculate a surface O3decrease of about 11{\%} together with a surface CO increase of roughly 10{\%} in the Eastern Mediterranean.}, author = {Myriokefalitakis, S. and Daskalakis, N. and Fanourgakis, G. S. and Voulgarakis, A. and Krol, M. C. and {Aan de Brugh}, J. M.J. and Kanakidou, M.}, doi = {10.1016/j.scitotenv.2016.04.061}, issn = {18791026}, journal = {Science of the Total Environment}, keywords = {Carbon monoxide (CO),Eastern Mediterranean (EM),Free Troposphere (FT),Long-range transport (LRT),Ozone (O3)}, pages = {40--52}, title = {{Ozone and carbon monoxide budgets over the Eastern Mediterranean}}, volume = {563-564}, year = {2016} } @article{Naik2013, abstract = {We have analysed time-slice simulations from 17 global models, participating in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), to explore changes in present-day (2000) hydroxyl radical (OH) concentration and methane (CH4) lifetime relative to preindustrial times (1850) and to 1980. A comparison of modeled and observation-derived methane and methyl chloroform lifetimes suggests that the present-day global multi-model mean OH concentration is overestimated by 5 to 10{\%} but is within the range of uncertainties. The models consistently simulate higher OH concentrations in the Northern Hemisphere (NH) compared with the Southern Hemisphere (SH) for the present-day (2000; inter-hemispheric ratios of 1.13 to 1.42), in contrast to observation-based approaches which generally indicate higher OH in the SH although uncertainties are large. Evaluation of simulated carbon monoxide (CO) concentrations, the primary sink for OH, against ground-based and satellite observations suggests low biases in the NH that may contribute to the high north-south OH asymmetry in the models. The models vary widely in their regional distribution of present-day OH concentrations (up to 34{\%}). Despite large regional changes, the multi-model global mean (mass-weighted) OH concentration changes little over the past 150 yr, due to concurrent increases in factors that enhance OH (humidity, tropospheric ozone, nitrogen oxide (NOx) emissions, and UV radiation due to decreases in stratospheric ozone), compensated by increases in OH sinks (methane abundance, carbon monoxide and non-methane volatile organic carbon (NMVOC) emissions). The large inter-model diversity in the sign and magnitude of preindustrial to present-day OH changes (ranging from a decrease of 12.7{\%} to an increase of 14.6{\%}) indicate that uncertainty remains in our understanding of the long-term trends in OH and methane lifetime. We show that this diversity is largely explained by the different ratio of the change in global mean tropospheric CO and NOx burdens ($\Delta$CO/$\Delta$NOx, approximately represents changes in OH sinks versus changes in OH sources) in the models, pointing to a need for better constraints on natural precursor emissions and on the chemical mechanisms in the current generation of chemistry-climate models. For the 1980 to 2000 period, we find that climate warming and a slight increase in mean OH (3.5 ± 2.2{\%}) leads to a 4.3 ± 1.9{\%} decrease in the methane lifetime. Analysing sensitivity simulations performed by 10 models, we find that preindustrial to present-day climate change decreased the methane lifetime by about four months, representing a negative feedback on the climate system. Further, we analysed attribution experiments performed by a subset of models relative to 2000 conditions with only one precursor at a time set to 1860 levels. We find that global mean OH increased by 46.4 ± 12.2{\%} in response to preindustrial to present-day anthropogenic NOx emission increases, and decreased by 17.3 ± 2.3{\%}, 7.6 ± 1.5{\%}, and 3.1 ± 3.0{\%} due to methane burden, and anthropogenic CO, and NMVOC emissions increases, respectively. {\textcopyright} Author(s) 2013.}, annote = {From Duplicate 1 (Preindustrial to present-day changes in tropospheric hydroxyl radical and methane lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) - Naik, V.; Voulgarakis, A.; Fiore, A. M.; Horowitz, L. W.; Lamarque, J. F.; Lin, M.; Prather, M. J.; Young, P. J.; Bergmann, D.; Cameron-Smith, P. J.; Cionni, I.; Collins, W. J.; Dals{\o}ren, S. B.; Doherty, R.; Eyring, V.; Faluvegi, G.; Folberth, G. A.; Josse, B.; Lee, Y. H.; MacKenzie, I. A.; Nagashima, T.; Van Noije, T. P.C.; Plummer, D. A.; Righi, M.; Rumbold, S. T.; Skeie, R.; Shindell, D. T.; Stevenson, D. S.; Strode, S.; Sudo, K.; Szopa, S.; Zeng, G.) ACP From Duplicate 4 (Preindustrial to present-day changes in tropospheric hydroxyl radical and methane lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) - DuplicateNaik2013, NoCite; Naik, V; Voulgarakis, A; Fiore, A M; Horowitz, L W; Lamarque, J F; Lin, M; Prather, M J; Young, P J; Bergmann, D; Cameron-Smith, P J; Cionni, I; Collins, W J; Dalsoren, S B; Doherty, R; Eyring, V; Faluvegi, G; Folberth, G A; Josse, B; Lee, Y H; MacKenzie, I A; Nagashima, T; van Noije, T P C; Plummer, D A; Righi, M; Rumbold, S T; Skeie, R; Shindell, D T; Stevenson, D S; Strode, S; Sudo, K; Szopa, S; Zeng, G) Times Cited: 112 Bergmann, Daniel/F-9801-2011; Lee, Yunha/Q-7222-2016; Eyring, Veronika/O-9999-2016; Cameron-Smith, Philip/E-2468-2011; Lamarque, Jean-Francois/L-2313-2014; CIONNI, Irene/E-8204-2017; Szopa, Sophie/F-8984-2010; Horowitz, Larry/D-8048-2014; Righi, Mattia/I-5120-2013; Stevenson, David/C-8089-2012; Manager, CSD Publications/B-2789-2015; Collins, William/A-5895-2010; Shindell, Drew/D-4636-2012; Skeie, Ragnhild/K-1173-2015; Naik, Vaishali/A-4938-2013; Young, Paul/E-8739-2010; Strode, Sarah/H-2248-2012; Lin, Meiyun/D-6107-2013; Faluvegi, Gregory/; Righi, Mattia/; Folberth, Gerd/; Zeng, Guang/; Dalsoren, Stig/ Bergmann, Daniel/0000-0003-4357-6301; Lee, Yunha/0000-0001-7478-2672; Eyring, Veronika/0000-0002-6887-4885; Cameron-Smith, Philip/0000-0002-8802-8627; Lamarque, Jean-Francois/0000-0002-4225-5074; CIONNI, Irene/0000-0002-0591-9193; Szopa, Sophie/0000-0002-8641-1737; Horowitz, Larry/0000-0002-5886-3314; Stevenson, David/0000-0002-4745-5673; Collins, William/0000-0002-7419-0850; Skeie, Ragnhild/0000-0003-1246-4446; Naik, Vaishali/0000-0002-2254-1700; Young, Paul/0000-0002-5608-8887; Strode, Sarah/0000-0002-8103-1663; Lin, Meiyun/0000-0003-3852-3491; Faluvegi, Gregory/0000-0001-9011-3663; Righi, Mattia/0000-0003-3827-5950; Folberth, Gerd/0000-0002-1075-440X; Zeng, Guang/0000-0002-9356-5021; Dalsoren, Stig/0000-0002-6752-4728 0 113 1680-7324}, author = {Naik, V. and Voulgarakis, A. and Fiore, A. M. and Horowitz, L. W. and Lamarque, J. F. and Lin, M. and Prather, M. J. and Young, P. J. and Bergmann, D. and Cameron-Smith, P. J. and Cionni, I. and Collins, W. J. and Dals{\o}ren, S. B. and Doherty, R. and Eyring, V. and Faluvegi, G. and Folberth, G. A. and Josse, B. and Lee, Y. H. and MacKenzie, I. A. and Nagashima, T. and {Van Noije}, T. P.C. and Plummer, D. A. and Righi, M. and Rumbold, S. T. and Skeie, R. and Shindell, D. T. and Stevenson, D. S. and Strode, S. and Sudo, K. and Szopa, S. and Zeng, G.}, doi = {10.5194/acp-13-5277-2013}, isbn = {1680-7316}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, keywords = {v}, number = {10}, pages = {5277--5298}, publisher = {Copernicus Publications}, title = {{Preindustrial to present-day changes in tropospheric hydroxyl radical and methane lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)}}, url = {http://www.atmos-chem-phys.net/13/5277/2013/ http://www.atmos-chem-phys.net/13/5277/2013/acp-13-5277-2013.pdf}, volume = {13}, year = {2013} } @article{Nault2017a, abstract = {Lightning is one of the most important sources of upper tropospheric NOx; however, there is a large spread in estimates of the global emission rates (2-8 Tg N yr(-1)). We combine upper tropospheric in situ observations from the Deep Convective Clouds and Chemistry (DC3) experiment and global satellite-retrieved NO2 tropospheric column densities to constrain mean lightning NOx (LNOx) emissions per flash. Insights from DC3 indicate that the NOx lifetime is similar to 3 h in the region of outflow of thunderstorms, mainly due to production of methyl peroxy nitrate and alkyl and multifunctional nitrates. The lifetime then increases farther downwind from the region of outflow. Reinterpreting previous analyses using the 3 h lifetime reduces the spread among various methods that have been used to calculate mean LNOx emissions per flash and indicates a global LNOx emission rate of similar to 9 Tg N yr(-1), a flux larger than the high end of recent estimates. Plain Language Summary Lightning is an important source of upper troposphere nitrogen oxides; however, there is high uncertainty in the amount of nitrogen oxides produced from lightning. Using recent updates in upper tropospheric nitrogen oxides chemistry, this study decreases this uncertainty from a factor of 4 to less than a factor of 2 and shows that the amount of nitrogen oxides produced from lightning should be higher.}, author = {Nault, B. A. and Laughner, J. L. and Wooldridge, P. J. and Crounse, J. D. and Dibb, J. and Diskin, G. and Peischl, J. and Podolske, J. R. and Pollack, I. B. and Ryerson, T. B. and Scheuer, E. and Wennberg, P. O. and Cohen, R. C.}, doi = {10.1002/2017GL074436}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {DC3,GEOS-Chem,NOxproduction per flash,OMI,lightning,upper tropospheric chemistry}, number = {18}, pages = {9479--9488}, title = {{Lightning NOx Emissions: Reconciling Measured and Modeled Estimates With Updated NOx Chemistry}}, volume = {44}, year = {2017} } @article{Naus2018, abstract = {{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} The hydroxyl radical (OH) is the main atmospheric oxidant and the primary sink of the greenhouse gas CH{\textless}sub{\textgreater}4{\textless}/sub{\textgreater}. In two recent studies, constraints on the hydroxyl radical (OH) were derived using a tropospheric two-box model of methyl chloroform (MCF) and CH{\textless}sub{\textgreater}4{\textless}/sub{\textgreater}. When OH variations as derived in this set-up were propagated to the CH{\textless}sub{\textgreater}4{\textless}/sub{\textgreater} budget, the constraints on OH from MCF still allowed for a wide range of CH{\textless}sub{\textgreater}4{\textless}/sub{\textgreater} emission scenarios. This is important, because global CH{\textless}sub{\textgreater}4{\textless}/sub{\textgreater} emissions are generally considered best constrained by the global lifetime of CH{\textless}sub{\textgreater}4{\textless}/sub{\textgreater}, which is determined mainly by OH. Here, we investigate how the use of a tropospheric two-box model in these studies can have affected derived constraints on OH, due to the simplifying assumptions inherent to a two-box model. First, instead of prescribing fixed model parameters for interhemispheric transport, chemical loss rates and loss to the stratosphere, we derive species- and time-dependent quantities from a full 3D transport model simulation. We find significant deviations between the magnitude and time-dependence of the parameters we derive, and the assumptions commonly reported and adopted in literature. Moreover, using output from the 3D model simulations, we investigated differences between the burden seen by the surface measurement network of the National Oceanic and Atmospheric Administration and the true tropospheric burden. Next, we accounted for these biases in a two-box model inversion of MCF and CH{\textless}sub{\textgreater}4{\textless}/sub{\textgreater}, to investigate the impact of the biases on OH constraints.{\textless}/p{\textgreater} {\textless}p{\textgreater}We find that the sensitivity of interannual OH anomalies to the biases is modest (1{\&}ndash;2{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}), relative to the significant uncertainties on derived OH (5{\&}ndash;8{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}). However, in an inversion where we implemented all four bias corrections simultaneously, we did find a shift to a positive OH trend over the 1994{\&}ndash;2015 period. Moreover, the magnitude of derived global mean OH and by extent that of global CH{\textless}sub{\textgreater}4{\textless}/sub{\textgreater} emissions are affected much more strongly by the bias corrections than their anomalies ({\&}sim;{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}10{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}). In this way, we identified and quantified direct limitations in the two-box model approach that can possibly be corrected for when a full 3D simulation is used to inform the two-box model. This derivation is, however, an extensive and species-dependent exercise. Therefore, a good alternative would be to move the inversion problem of OH to a 3D model completely. It is crucial to account for the limitations of two-box models in future attempts to constrain the atmospheric oxidative capacity, especially because though MCF and CH{\textless}sub{\textgreater}4{\textless}/sub{\textgreater} behave similarly in large parts of our analysis, it is not obvious that this should be the case for alternative tracers that potentially constrain OH, other than MCF.{\textless}/p{\textgreater}}, annote = {ACPD}, author = {Naus, Stijn and Montzka, Stephen A. and Pandey, Sudhanshu and Basu, Sourish and Dlugokencky, Ed J. and Krol, Maarten}, doi = {10.5194/acp-19-407-2019}, isbn = {1680-7375}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {1}, pages = {407--424}, publisher = {Copernicus Publications}, title = {{Constraints and biases in a tropospheric two-box model of OH}}, url = {https://www.atmos-chem-phys-discuss.net/acp-2018-798/}, volume = {19}, year = {2019} } @article{Navarro2016, abstract = {The Arctic region is warming considerably faster than the rest of the globe, with important consequences for the ecosystems and human exploration of the region. However, the reasons behind this Arctic amplification are not entirely clear. As a result of measures to enhance air quality, anthropogenic emissions of particulate matter and its precursors have drastically decreased in parts of the Northern Hemisphere over the past three decades. Here we present simulations with an Earth system model with comprehensive aerosol physics and chemistry that show that the sulfate aerosol reductions in Europe since 1980 can potentially explain a significant fraction of Arctic warming over that period. Specifically, the Arctic region receives an additional 0.3 W m-2 of energy, and warms by 0.5 °C on annual average in simulations with declining European sulfur emissions in line with historical observations, compared with a model simulation with fixed European emissions at 1980 levels. Arctic warming is amplified mainly in fall and winter, but the warming is initiated in summer by an increase in incoming solar radiation as well as an enhanced poleward oceanic and atmospheric heat transport. The simulated summertime energy surplus reduces sea-ice cover, which leads to a transfer of heat from the Arctic Ocean to the atmosphere. We conclude that air quality regulations in the Northern Hemisphere, the ocean and atmospheric circulation, and Arctic climate are inherently linked.}, author = {Navarro, J. C.Acosta and Varma, V. and Riipinen, I. and Seland and Kirkev{\aa}g, A. and Struthers, H. and Iversen, T. and Hansson, H. C. and Ekman, A. M.L.}, doi = {10.1038/ngeo2673}, issn = {17520908}, journal = {Nature Geoscience}, month = {apr}, number = {4}, pages = {277--281}, title = {{Amplification of Arctic warming by past air pollution reductions in Europe}}, url = {http://www.nature.com/articles/ngeo2673}, volume = {9}, year = {2016} } @article{doi:10.1002/2016JD025809, abstract = {Abstract The effect of changing cloud cover on climate, based on cloud-aerosol interactions, is one of the major unknowns for climate forcing and climate sensitivity. It has two components: (1) the impact of aerosols on clouds and climate due to in situ interactions (i.e., rapid response) and (2) the effect of aerosols on the cloud feedback that arises as climate changes—climate feedback response. We examine both effects utilizing the NASA Goddard Institute for Space Studies ModelE2 to assess the indirect effect, with both mass-based and microphysical aerosol schemes, in transient twentieth century simulations. We separate the rapid response and climate feedback effects by making simulations with a coupled version of the model as well as one with no sea surface temperature or sea ice response (“atmosphere-only” simulations). We show that the indirect effect of aerosols on temperature is altered by the climate feedbacks following the ocean response, and this change differs depending upon which aerosol model is employed. Overall, the effective radiative forcing (ERF) for the “direct effect” of aerosol-radiation interaction (ERFari) ranges between −0.2 and −0.6 W m−2 for atmosphere-only experiments, while the total effective radiative forcing, including the indirect effect (ERFari+aci) varies between about −0.4 and −1.1 W m−2 for atmosphere-only simulations; both ranges are in agreement with those given in Intergovernmental Panel on Climate Change (2013). Including the full feedback of the climate system lowers these ranges to −0.2 to −0.5 W m−2 for ERFari and −0.3 to −0.74 W m−2 for ERFari+aci. With both aerosol schemes, the climate change feedbacks have reduced the global average indirect radiative effect of atmospheric aerosols relative to what the emission changes would have produced, at least partially due to its effect on tropical upper tropospheric clouds.}, author = {Nazarenko, L and Rind, D and Tsigaridis, K and {Del Genio}, A D and Kelley, M and Tausnev, N}, doi = {10.1002/2016JD025809}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {climate change,cloud-aerosol interactions}, number = {6}, pages = {3457--3480}, title = {{Interactive nature of climate change and aerosol forcing}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2016JD025809}, volume = {122}, year = {2017} } @article{Nenes2020, author = {Nenes, Athanasios and Pandis, Spyros N and Weber, Rodney J and Russell, Armistead}, doi = {10.5194/acp-20-3249-2020}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {5}, pages = {3249--3258}, publisher = {Copernicus Publications}, title = {{Aerosol pH and liquid water content determine when particulate matter is sensitive to ammonia and nitrate availability}}, url = {https://acp.copernicus.org/articles/20/3249/2020/}, volume = {20}, year = {2020} } @article{Nguyen2010, abstract = {Abstract As a sequel to our communication on a proposed new isoprene oxidation mechanism aiming to rationalize the unexpectedly high OH and HO2 levels observed in isoprene-rich areas (J. Peeters, T. L. Nguyen, L. Vereecken, Phys. Chem. Chem. Phys. 2009, 11, 5935), we report herein the detailed quantum chemical and statistical kinetics characterization of the crucial 1,6-H shifts in the two Z-$\delta$-hydroxy-peroxy radicals from isoprene. Geometries, energies and vibration frequencies of all conformers of the reactant radicals and transition states are computed at the B3LYP/6-31+G(d,p) level of theory and the energies of the lowest-lying conformers are then refined at various higher levels of theory, including CBS-QB3, IRCMax(CBS-QB3//B3LYP) and CBS-APNO. The rate coefficients over a wide temperature range are calculated using multi-conformer transition state theory with WKB tunneling factors evaluated for the barrier shape found by CBS-QB3//B3LYP IRC analyses. The WKB tunneling factors for these allyl-stabilisation-assisted reactions are about 25 at ambient temperatures. The rate coefficients can be represented by Arrhenius expressions over the 250?350 K range: k(T)=1.4?109 exp(?6380/T)?s?1 for the Z-1-OH-4-OO?-isoprene radical, and k(T)=0.72?109?exp(?5520/T)?s?1 for Z-1-OH-4-OO?-isoprene. With the k(1,6-H) of order 1 s?1 at ambient temperatures, these isomerisations can compete with and even outrun the traditional peroxy reactions at low and moderate NO levels. The importance of these reactions as key processes in the newly proposed, OH-regenerating isoprene oxidation scheme is discussed.}, annote = {doi: 10.1002/cphc.201000480}, author = {Nguyen, Thanh Lam and Vereecken, Luc and Peeters, Jozef}, doi = {10.1002/cphc.201000480}, issn = {1439-4235}, journal = {ChemPhysChem}, keywords = {ab initio calculations,hydroxyl regeneration,isomerisation,oxidation,radicals}, month = {sep}, number = {18}, pages = {3996--4001}, publisher = {Wiley-Blackwell}, title = {{HOx Regeneration in the Oxidation of Isoprene III: Theoretical Study of the key Isomerisation of the Z-$\delta$-hydroxy-peroxy Isoprene Radicals}}, url = {https://doi.org/10.1002/cphc.201000480}, volume = {11}, year = {2010} } @article{Nguyen2019, abstract = {Changing climate will impact future air quality. In this study, an online coupled meteorology and chemistry WRF-CMAQ model was applied to simulate such impacts on future O3 and PM2.5 air quality over Continental Southeast Asia. Simulations were conducted for present (2006–2015) and future (2046–2055) years under two climate scenarios, RCP4.5 and RCP8.5. Future climate projections were obtained by implementing a downscaling dynamical method based on pseudo global warming technique. In order to estimate the impacts of climate change alone, anthropogenic and biomass burning emissions were held constant at present level while biogenic emissions varying with climate were used. The model results indicated a future regional meteorology characterized by a warmer and more humid atmosphere, increased precipitation, and more stagnant condition. Affected by climate change, NOx and NMVOCs biogenic emissions increase which contribute to the increasing effects on O3 and PM2.5 precursors concentrations. Subsequently, the changes in meteorology and biogenic emission affect air quality. These influence on ground level O3 and PM2.5 are different between the two climate scenarios. Under RCP4.5 scenario, future atmosphere appears to be reduced in O3 and PM2.5 concentrations, suggesting a potential “climate benefit” for air quality. At four target countries, namely Cambodia, Laos, Thailand, and Vietnam, O3 concentration decreases by −0.76 ppb (−2.40{\%}), PM2.5 concentration decreases by −0.95 $\mu$g/m3 (−4.32{\%}) on average for the entire year. However, climate change worsen O3 and PM2.5 air pollution under RCP8.5 scenario. O3 concentration increases by +0.26 ppb (+0.84{\%}), PM2.5 concentration increases by +0.92 $\mu$g/m3 (+4.20{\%}) on average for the entire year. Significant increases were generally located in northern Vietnam (for O3) and southern Vietnam (for PM2.5) during the dry season. The analysis suggests that the decrease in O3 concentration is due to the dominancy of the negative effect of water vapor increase and the increase in O3 concentration is affected largely by the temperature increase, stagnant condition, and biogenic emission increase. The responses of PM2.5 to climate change depend on the physical and chemical characteristics of each PM2.5 species. The major climate change effect on PM2.5 is the physical effect, rather than the chemical effect.}, author = {Nguyen, Giang Tran Huong and Shimadera, Hikari and Uranishi, Katsushige and Matsuo, Tomohito and Kondo, Akira}, doi = {10.1016/j.atmosenv.2019.116901}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Climate change impacts,Continental Southeast Asia,Fine particulate matter,Online coupled WRF-CMAQ model,Ozone}, pages = {116901}, title = {{Numerical assessment of PM2.5 and O3 air quality in Continental Southeast Asia: Impacts of potential future climate change}}, volume = {215}, year = {2019} } @article{Nicely2017, abstract = {The hydroxyl radical (OH) is the primary daytime oxidant in the troposphere and provides the main loss mechanism for many pollutants and greenhouse gases, including methane (CH4). Global mean tropospheric OH differs by as much as 80{\%} among various global models, for reasons that are not well understood. We use neural networks (NNs), trained using archived output from eight chemical transport models (CTMs) that participated in the Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols and Transport Model Intercomparison Project (POLMIP), to quantify the factors responsible for differences in tropospheric OH and resulting CH4 lifetime (tau(CH4)) between these models. Annual average tau(CH4), for loss by OH only, ranges from 8.0 to 11.6 years for the eight POLMIP CTMs. The factors driving these differences were quantified by inputting 3-D chemical fields from one CTM into the trained NN of another CTM. Across all CTMs, the largest mean differences in tCH4 (Delta tau(CH4)) result from variations in chemical mechanisms (Delta tau(CH4) = 0.46 years), the photolysis frequency (J) of O-3 -{\textgreater} O(D-1) (0.31 years), local O-3 (0.30 years), and CO (0.23 years). The Delta tau(CH4) due to CTM differences in NOx (NO + NO2) is relatively low (0.17 years), although large regional variation in OH between the CTMs is attributed to NOx. Differences in isoprene and J(NO2) have negligible overall effect on globally averaged tropospheric OH, although the extent of OH variations due to each factor depends on the model being examined. This study demonstrates that NNs can serve as a useful tool for quantifying why tropospheric OH varies between global models, provided that essential chemical fields are archived.}, annote = {Times Cited: 3 Canty, Timothy/F-2631-2010; Anderson, Daniel/I-4398-2014; Salawitch, Ross/B-4605-2009; Chipperfield, Martyn/H-6359-2013; Mao, Jingqiu/F-2511-2010; Nicely, Julie/; Huijnen, Vincent/; Kinnison, Douglas/ Canty, Timothy/0000-0003-0618-056X; Anderson, Daniel/0000-0002-9826-9811; Salawitch, Ross/0000-0001-8597-5832; Chipperfield, Martyn/0000-0002-6803-4149; Mao, Jingqiu/0000-0002-4774-9751; Nicely, Julie/0000-0003-4828-0032; Huijnen, Vincent/0000-0002-2814-8475; Kinnison, Douglas/0000-0002-3418-0834 0 3 2169-8996}, author = {Nicely, Julie M and Salawitch, Ross J and Canty, Timothy and Anderson, Daniel C and Arnold, Steve R and Chipperfield, Martyn P and Emmons, Louisa K and Flemming, Johannes and Huijnen, Vincent and Kinnison, Douglas E and Lamarque, Jean‐Fran{\c{c}}ois and Mao, Jingqiu and Monks, Sarah A and Steenrod, Stephen D and Tilmes, Simone and Turquety, Solene}, doi = {10.1002/2016JD026239}, isbn = {2169-897X}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {feb}, number = {3}, pages = {1983--2007}, title = {{Quantifying the causes of differences in tropospheric OH within global models}}, url = {https://onlinelibrary.wiley.com/doi/10.1002/2016JD026239}, volume = {122}, year = {2017} } @article{doi:10.1029/2018JD028388, abstract = {Abstract The oxidizing capacity of the troposphere is controlled primarily by the abundance of hydroxyl radical (OH). The global mean concentration of tropospheric OH, [OH]TROP (the burden of OH in the global troposphere appropriate for calculating the lifetime of methane) inferred from measurements of methyl chloroform has remained relatively constant during the past several decades despite rising levels of methane that should have led to a decline. Here we examine other factors that may have affected [OH]TROP such as the changing values of stratospheric ozone, rising tropospheric H2O, varying burden of NOx (=NO+NO2), rising temperatures, and widening of the climatological tropics due to expansion of the Hadley cell. Our analysis suggests the positive trends in [OH]TROP due to H2O, NOx, and overhead O3, and tropical expansion are large enough ($\Delta$ [OH]TROP = +0.95 ± 0.18{\%}/decade) to counter almost all of the expected decrease in [OH]TROP due to rising methane ($\Delta$ [OH]TROP = −1.01 ± 0.05{\%}/decade) over the period 1980 to 2015, while variations in temperature contribute almost no trend ($\Delta$ [OH]TROP = −0.02 ± 0.02{\%}/decade) in [OH]TROP. The approximated impact of Hadley cell expansion on [OH]TROP is also a small but not insignificant factor partially responsible for the steadiness of tropospheric oxidizing capacity over the past several decades, which free-running models likely do not capture.}, author = {Nicely, Julie M and Canty, Timothy P and Manyin, Michael and Oman, Luke D and Salawitch, Ross J and Steenrod, Stephen D and Strahan, Susan E and Strode, Sarah A}, doi = {10.1029/2018JD028388}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {climate change,hydroxyl radical,methane lifetime,oxidizing capacity,tropospheric chemistry}, number = {18}, pages = {10774--10795}, title = {{Changes in Global Tropospheric OH Expected as a Result of Climate Change Over the Last Several Decades}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JD028388}, volume = {123}, year = {2018} } @article{doi:10.1002/2015GL066854, abstract = {Abstract Ethane levels were measured in air extracted from Greenland and Antarctic ice cores ranging in age from 994 to 1918 Common Era (C.E.) There is good temporal overlap between the two data sets from 1600 to 1750 C.E. with ethane levels stable at 397 ± 28 parts per trillion (ppt) (±2 standard error (s.e.)) over Greenland and 103 ± 9 ppt over Antarctica. The observed north/south interpolar ratio of ethane (3.9 ± 0.1, 1$\sigma$) implies considerably more ethane emissions in the Northern Hemisphere than in the Southern Hemisphere, suggesting geologic ethane sources contribute significantly to the preindustrial ethane budget. Box model simulations based on these data constrain the global geologic emissions of ethane to 2.2–3.5 Tg yr−1 and biomass burning emissions to 1.2–2.5 Tg yr−1 during the preindustrial era. The results suggest biomass burning emissions likely increased since the preindustrial period. Biomass burning and geologic outgassing are also sources of atmospheric methane. The results place constraints on preindustrial methane emissions from these sources.}, author = {Nicewonger, Melinda R and Verhulst, Kristal R and Aydin, Murat and Saltzman, Eric S}, doi = {10.1002/2015GL066854}, journal = {Geophysical Research Letters}, keywords = {biomass burning,ethane,geologic,ice cores,paleoatmosphere,trace gases}, number = {1}, pages = {214--221}, title = {{Preindustrial atmospheric ethane levels inferred from polar ice cores: A constraint on the geologic sources of atmospheric ethane and methane}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2015GL066854}, volume = {43}, year = {2016} } @article{Nicewonger2018, abstract = {Biomass burning drives changes in greenhouse gases, climate-forcing aerosols, and global atmospheric chemistry. There is controversy about the magnitude and timing of changes in biomass burning emissions on millennial time scales from preindustrial to present and about the relative importance of climate change and human activities as the underlying cause. Biomass burning is one of two notable sources of ethane in the preindustrial atmosphere. Here, we present ice core ethane measurements from Antarctica and Greenland that contain information about changes in biomass burning emissions since 1000 CE (Common Era). The biomass burning emissions of ethane during the Medieval Period (1000–1500 CE) were higher than present day and declined sharply to a minimum during the cooler Little Ice Age (1600–1800 CE). Assuming that preindustrial atmospheric reactivity and transport were the same as in the modern atmosphere, we estimate that biomass burning emissions decreased by 30 to 45{\%} from the Medieval Period to the Little Ice Age. The timing and magnitude of this decline in biomass burning emissions is consistent with that inferred from ice core methane stable carbon isotope ratios but inconsistent with histories based on sedimentary charcoal and ice core carbon monoxide measurements. This study demonstrates that biomass burning emissions have exceeded modern levels in the past and may be highly sensitive to changes in climate.}, author = {Nicewonger, Melinda R. and Aydin, Murat and Prather, Michael J. and Saltzman, Eric S.}, doi = {10.1073/pnas.1807172115}, issn = {10916490}, journal = {Proceedings of the National Academy of Sciences}, keywords = {Biomass burning,Ethane,Geologic hydrocarbons,Ice cores,Little Ice Age}, number = {49}, pages = {12413--12418}, title = {{Large changes in biomass burning over the last millennium inferred from paleoatmospheric ethane in polar ice cores}}, volume = {115}, year = {2018} } @article{Niemeier2015, abstract = {Abstract. The injection of sulfur dioxide (SO2) into the stratosphere to form an artificial stratospheric aerosol layer is discussed as an option for solar radiation management. The related reduction of radiative forcing depends upon the injected amount of sulfur dioxide, but aerosol model studies indicate a decrease in forcing efficiency with increasing injection rate. None of these studies, however, consider injection rates greater than 20 Tg(S) yr−1. But this would be necessary to counteract the strong anthropogenic forcing expected if "business as usual" emission conditions continue throughout this century. To understand the effects of the injection of larger amounts of SO2, we have calculated the effects of SO2 injections up to 100 Tg(S) yr−1. We estimate the reliability of our results through consideration of various injection strategies and from comparison with results obtained from other models. Our calculations show that the efficiency of such a geoengineering method, expressed as the ratio between sulfate aerosol forcing and injection rate, decays exponentially. This result implies that the sulfate solar radiation management strategy required to keep temperatures constant at that anticipated for 2020, while maintaining business as usual conditions, would require atmospheric injections of approximately 45 Tg(S) yr−1 (±15 {\%} or 7 Tg(S) yr−1) at a height corresponding to 60 hPa. This emission is equivalent to 5 to 7 times the Mt. Pinatubo eruption each year.}, author = {Niemeier, U. and Timmreck, C.}, doi = {10.5194/acp-15-9129-2015}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {aug}, number = {16}, pages = {9129--9141}, title = {{What is the limit of climate engineering by stratospheric injection of SO2?}}, url = {https://acp.copernicus.org/articles/15/9129/2015/}, volume = {15}, year = {2015} } @article{Niemeier2017, abstract = {Abstract. The injection of sulfur dioxide (SO2) into the stratosphere to form an artificial stratospheric aerosol layer is discussed as an option for solar radiation management. Sulfate aerosol scatters solar radiation and absorbs infrared radiation, which warms the stratospheric sulfur layer. Simulations with the general circulation model ECHAM5-HAM, including aerosol microphysics, show consequences of this warming, including changes of the quasi-biennial oscillation (QBO) in the tropics. The QBO slows down after an injection of 4 Tg(S) yr−1 and completely shuts down after an injection of 8 Tg(S) yr−1. Transport of species in the tropics and sub-tropics depends on the phase of the QBO. Consequently, the heated aerosol layer not only impacts the oscillation of the QBO but also the meridional transport of the sulfate aerosols. The stronger the injection, the stronger the heating and the simulated impact on the QBO and equatorial wind systems. With increasing injection rate the velocity of the equatorial jet streams increases, and the less sulfate is transported out of the tropics. This reduces the global distribution of sulfate and decreases the radiative forcing efficiency of the aerosol layer by 10 to 14 {\%} compared to simulations with low vertical resolution and without generated QBO. Increasing the height of the injection increases the radiative forcing only for injection rates below 10 Tg(S) yr−1 (8–18 {\%}), a much smaller value than the 50 {\%} calculated previously. Stronger injection rates at higher levels even result in smaller forcing than the injections at lower levels.}, author = {Niemeier, Ulrike and Schmidt, Hauke}, doi = {10.5194/acp-17-14871-2017}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {dec}, number = {24}, pages = {14871--14886}, title = {{Changing transport processes in the stratosphere by radiative heating of sulfate aerosols}}, url = {https://acp.copernicus.org/articles/17/14871/2017/}, volume = {17}, year = {2017} } @article{NIINEMETS2014a, author = {Niinemets, {\"{U}}lo and Fares, S. and Hardley, P. and Jardine, K.J.}, doi = {10.1111/pce.12322}, issn = {01407791}, journal = {Plant, Cell {\&} Environment}, month = {aug}, number = {8}, pages = {1790--1809}, title = {{Bidirectional exchange of biogenic volatiles with vegetation: emission sources, reactions, breakdown and deposition}}, url = {http://doi.wiley.com/10.1111/pce.12322}, volume = {37}, year = {2014} } @article{Nolte2018, abstract = {The potential impacts of climate change on regional ozone (O3) and fine particulate (PM2.5) air quality in the United States (US) are investigated by linking global climate simulations with regional-scale meteorological and chemical transport models. Regional climate at 2000 and at 2030 under three Representative Concentration Pathways (RCPs) is simulated by using the Weather Research and Forecasting (WRF) model to downscale 11-year time slices from the Community Earth System Model (CESM). The downscaled meteorology is then used with the Community Multiscale Air Quality (CMAQ) model to simulate air quality during each of these 11-year periods. The analysis isolates the future air quality differences arising from climate-driven changes in meteorological parameters and specific natural emissions sources that are strongly influenced by meteorology. Other factors that will affect future air quality, such as anthropogenic air pollutant emissions and chemical boundary conditions, are unchanged across the simulations. The regional climate fields represent historical daily maximum and daily minimum temperatures well, with mean biases of less than 2K for most regions of the US and most seasons of the year and good representation of variability. Precipitation in the central and eastern US is well simulated for the historical period, with seasonal and annual biases generally less than 25 {\%}, with positive biases exceeding 25 {\%} in the western US throughout the year and in part of the eastern US during summer. Maximum daily 8 h ozone (MDA8 O3) is projected to increase during summer and autumn in the central and eastern US. The increase in summer mean MDA8 O3 is largest under RCP8.5, exceeding 4 ppb in some locations, with smaller seasonal mean increases of up to 2 ppb simulated during autumn and changes during spring generally less than 1 ppb. Increases are magnified at the upper end of the O3 distribution, particularly where projected increases in temperature are greater. Annual average PM2.5 concentration changes range from-1.0 to 1.0 $\mu$g m-3. Organic PM2.5 concentrations increase during summer and autumn due to increased biogenic emissions. Aerosol nitrate decreases during winter, accompanied by lesser decreases in ammonium and sulfate, due to warmer temperatures causing increased partitioning to the gas phase. Among meteorological factors examined to account for modeled changes in pollution, temperature and isoprene emissions are found to have the largest changes and the greatest impact on O3 concentrations.}, author = {Nolte, Christopher G. and Spero, Tanya L. and Bowden, Jared H. and Mallard, Megan S. and Dolwick, Patrick D.}, doi = {10.5194/acp-18-15471-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {oct}, number = {20}, pages = {15471--15489}, title = {{The potential effects of climate change on air quality across the conterminous US at 2030 under three Representative Concentration Pathways}}, url = {https://www.atmos-chem-phys.net/18/15471/2018/}, volume = {18}, year = {2018} } @article{Nowack2015, abstract = {State-of-the-art climate models now include more climate processes simulated at higher spatial resolution than ever. Nevertheless, some processes, such as atmospheric chemical feedbacks, are still computationally expensive and are often ignored in climate simulations. Here we present evidence that the representation of stratospheric ozone in climate models can have a first-order impact on estimates of effective climate sensitivity. Using a comprehensive atmosphere-ocean chemistry-climate model, we find an increase in global mean surface warming of around 1 °C (∼ 20{\%}) after 75 years when ozone is prescribed at pre-industrial levels compared with when it is allowed to evolve self-consistently in response to an abrupt 4×CO2 forcing. The difference is primarily attributed to changes in long-wave radiative feedbacks associated with circulation-driven decreases in tropical lower stratospheric ozone and related stratospheric water vapour and cirrus cloud changes. This has important implications for global model intercomparison studies in which participating models often use simplified treatments of atmospheric composition changes that are consistent with neither the specified greenhouse gas forcing scenario nor the associated atmospheric circulation feedbacks.}, author = {Nowack, Peer J. and {Luke Abraham}, N. and Maycock, Amanda C. and Braesicke, Peter and Gregory, Jonathan M. and Joshi, Manoj M. and Osprey, Annette and Pyle, John A.}, doi = {10.1038/nclimate2451}, isbn = {1758-678X}, issn = {17586798}, journal = {Nature Climate Change}, number = {1}, pages = {41--45}, publisher = {Nature Publishing Group}, title = {{A large ozone-circulation feedback and its implications for global warming assessments}}, volume = {5}, year = {2015} } @techreport{NationalAcademyofSciences2015, abstract = {The growing problem of changing environmental conditions caused by climate destabilization is well recognized as one of the defining issues of our time. The root problem is greenhouse gas emissions, and the fundamental solution is curbing those emissions. Climate geoengineering has often been considered to be a "last-ditch" response to climate change, to be used only if climate change damage should produce extreme hardship. Although the likelihood of eventually needing to resort to these efforts grows with every year of inaction on emissions control, there is a lack of information on these ways of potentially intervening in the climate system. As one of a two-book report, this volume of Climate Intervention discusses albedo modification - changing the fraction of incoming solar radiation that reaches the surface. This approach would deliberately modify the energy budget of Earth to produce a cooling designed to compensate for some of the effects of warming associated with greenhouse gas increases. The prospect of large-scale albedo modification raises political and governance issues at national and global levels, as well as ethical concerns. Climate Intervention: Reflecting Sunlight to Cool Earth discusses some of the social, political, and legal issues surrounding these proposed techniques. It is far easier to modify Earth's albedo than to determine whether it should be done or what the consequences might be of such an action. One serious concern is that such an action could be unilaterally undertaken by a small nation or smaller entity for its own benefit without international sanction and regardless of international consequences. Transparency in discussing this subject is critical. In the spirit of that transparency, Climate Intervention: Reflecting Sunlight to Cool Earth was based on peer-reviewed literature and the judgments of the authoring committee; no new research was done as part of this study and all data and information used are from entirely open sources. By helping to bring light to this topic area, this book will help leaders to be far more knowledgeable about the consequences of albedo modification approaches before they face a decision whether or not to use them.}, address = {Washington, DC, USA}, author = {NRC}, doi = {10.17226/18988}, isbn = {0309314828}, pages = {260}, publisher = {National Research Council (NRC). The National Academies Press}, title = {{Climate Intervention: Reflecting Sunlight to Cool Earth}}, year = {2015} } @article{OConnor2021, abstract = {Quantifying forcings from anthropogenic perturbations to the Earth system (ES) is important for understanding changes in climate since the pre-industrial (PI) period. Here, we quantify and analyse a wide range of present-day (PD) anthropogenic effective radiative forcings (ERFs) with the UK's Earth System Model (ESM), UKESM1, following the protocols defined by the Radiative Forcing Model Intercomparison Project (RFMIP) and the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP). In particular, quantifying ERFs that include rapid adjustments within a full ESM enables the role of various chemistry–aerosol–cloud interactions to be investigated. Global mean ERFs for the PD (year 2014) relative to the PI (year 1850) period for carbon dioxide (CO2), nitrous oxide (N2O), ozone-depleting substances (ODSs), and methane (CH4) are 1.89 ± 0.04, 0.25 ± 0.04, −0.18 ± 0.04, and 0.97 ± 0.04 W m−2, respectively. The total greenhouse gas (GHG) ERF is 2.92 ± 0.04 W m−2. UKESM1 has an aerosol ERF of −1.09 ± 0.04 W m−2. A relatively strong negative forcing from aerosol–cloud interactions (ACI) and a small negative instantaneous forcing from aerosol–radiation interactions (ARI) from sulfate and organic carbon (OC) are partially offset by a substantial forcing from black carbon (BC) absorption. Internal mixing and chemical interactions imply that neither the forcing from ARI nor ACI is linear, making the aerosol ERF less than the sum of the individual speciated aerosol ERFs. Ozone (O3) precursor gases consisting of volatile organic compounds (VOCs), carbon monoxide (CO), and nitrogen oxides (NOx), but excluding CH4, exert a positive radiative forcing due to increases in O3. However, they also lead to oxidant changes, which in turn cause an indirect aerosol ERF. The net effect is that the ERF from PD–PI changes in NOx emissions is negligible at 0.03 ± 0.04 W m−2, while the ERF from changes in VOC and CO emissions is 0.33 ± 0.04 W m−2. Together, aerosol and O3 precursors (called near-term climate forcers (NTCFs) in the context of AerChemMIP) exert an ERF of −1.03 ± 0.04 W m−2, mainly due to changes in the cloud radiative effect (CRE). There is also a negative ERF from land use change (−0.17 ± 0.04 W m−2). When adjusted from year 1850 to 1700, it is more negative than the range of previous estimates, and is most likely due to too strong an albedo response. In combination, the net anthropogenic ERF (1.76 ± 0.04 W m−2) is consistent with other estimates. By including interactions between GHGs, stratospheric and tropospheric O3, aerosols, and clouds, this work demonstrates the importance of ES interactions when quantifying ERFs. It also suggests that rapid adjustments need to include chemical as well as physical adjustments to fully account for complex ES interactions.}, author = {O'Connor, Fiona M and Abraham, Nathan Luke and Dalvi, Mohit and Folberth, Gerd A. and Griffiths, Paul T. and Hardacre, Catherine and Keeble, James and Jamil, Omar and Johnson, Ben and Kahana, Ron and Byeongheyon, Kim and Manners, James and Morgenstern, Olaf and Mulcahy, Jane and Robertson, Eddy and Seo, Jeongbin and Shim, Sungbo and Teixeira, Joao and Turnock, Steven and Williams, Jonny and Wiltshire, Andy and Zeng, Guang}, doi = {10.5194/acp-21-1211-2021}, journal = {Atmospheric Chemistry and Physics}, pages = {1211--1243}, title = {{Assessment of pre-industrial to present-day anthropogenic effective radiative forcing in UKESM1}}, url = {https://doi.org/10.5194/acp-21-1211-2021}, volume = {21}, year = {2021} } @article{ONeill2016, abstract = {Abstract. Projections of future climate change play a fundamental role in improving understanding of the climate system as well as characterizing societal risks and response options. The Scenario Model Intercomparison Project (ScenarioMIP) is the primary activity within Phase 6 of the Coupled Model Intercomparison Project (CMIP6) that will provide multi-model climate projections based on alternative scenarios of future emissions and land use changes produced with integrated assessment models. In this paper, we describe ScenarioMIP's objectives, experimental design, and its relation to other activities within CMIP6. The ScenarioMIP design is one component of a larger scenario process that aims to facilitate a wide range of integrated studies across the climate science, integrated assessment modeling, and impacts, adaptation, and vulnerability communities, and will form an important part of the evidence base in the forthcoming Intergovernmental Panel on Climate Change (IPCC) assessments. At the same time, it will provide the basis for investigating a number of targeted science and policy questions that are especially relevant to scenario-based analysis, including the role of specific forcings such as land use and aerosols, the effect of a peak and decline in forcing, the consequences of scenarios that limit warming to below 2 °C, the relative contributions to uncertainty from scenarios, climate models, and internal variability, and long-term climate system outcomes beyond the 21st century. To serve this wide range of scientific communities and address these questions, a design has been identified consisting of eight alternative 21st century scenarios plus one large initial condition ensemble and a set of long-term extensions, divided into two tiers defined by relative priority. Some of these scenarios will also provide a basis for variants planned to be run in other CMIP6-Endorsed MIPs to investigate questions related to specific forcings. Harmonized, spatially explicit emissions and land use scenarios generated with integrated assessment models will be provided to participating climate modeling groups by late 2016, with the climate model simulations run within the 2017–2018 time frame, and output from the climate model projections made available and analyses performed over the 2018–2020 period.}, author = {O'Neill, Brian C and Tebaldi, Claudia and van Vuuren, Detlef P and Eyring, Veronika and Friedlingstein, Pierre and Hurtt, George and Knutti, Reto and Kriegler, Elmar and Lamarque, Jean-Francois and Lowe, Jason and Meehl, Gerald A and Moss, Richard and Riahi, Keywan and Sanderson, Benjamin M}, doi = {10.5194/gmd-9-3461-2016}, issn = {1991-9603}, journal = {Geoscientific Model Development}, month = {sep}, number = {9}, pages = {3461--3482}, publisher = {Copernicus Publications}, title = {{The Scenario Model Intercomparison Project (ScenarioMIP) for CMIP6}}, url = {https://www.geosci-model-dev.net/9/3461/2016/ https://gmd.copernicus.org/articles/9/3461/2016/}, volume = {9}, year = {2016} } @article{doi:10.1002/2014JD022843, abstract = {Model simulations indicate an acceleration of the Brewer-Dobson circulation (BDC) in the past with a direct impact on the exchange of air masses between the troposphere and the stratosphere. However, most observational data sets do not confirm the model results. B{\"{o}}nisch et al. (2011) and Ray et al. (2010) indicate a strengthening of the BDC in its shallow branch and a weakening in its deep branch. In contrast, balloon-borne measurements and Michelson Interferometer for Passive Atmospheric Sounding satellite observations show no significant acceleration of the BDC at Northern Hemisphere (NH) midlatitudes. In our study, the change of the BDC in the recent past is analyzed from simulations with the chemistry-climate model ECHAM/MESSy Atmospheric Chemistry. As the sign of change considerably depends on the underlying forcings, namely, changes in concentrations of greenhouse gases (GHGs) and ozone-depleting substances (ODSs), as well as their interactions, we separate their contributions by using sensitivity simulations. The changes in tropical upward mass flux indicate a strengthening of the BDC between 1960 and 2000 in NH winter season in the lower and a weakening in the upper stratosphere with a change in sign at 10 hPa. While the lower stratospheric increase of about 2{\%}/decade is caused by equal contributions from rising GHGs and ODSs, rising ODS concentrations counteract the GHG effect in the middle and upper stratosphere with a total decrease of about 0.5{\%}/decade. Changes in mean age of air show a decrease of about 0.13 yr/decade in the lower and middle stratosphere and a slight increase in the Arctic upper stratosphere and lower mesosphere, which is induced by interactions between the forcings.}, author = {Oberl{\"{a}}nder-Hayn, Sophie and Meul, Stefanie and Langematz, Ulrike and Abalichin, Janna and Haenel, Florian}, doi = {10.1002/2014JD022843}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {Brewer-Dobson circulation,age of stratospheric air,greenhouse gas concentrations,past changes}, month = {jul}, number = {14}, pages = {6742--6757}, title = {{A chemistry–climate model study of past changes in the Brewer–Dobson circulation}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2014JD022843 http://doi.wiley.com/10.1002/2014JD022843}, volume = {120}, year = {2015} } @article{Ohata2016, abstract = {The lifetime and spatial distributions of accumulation-mode aerosols in a size range of approximately 0.05-1 $\mu$m, and thus their global and regional climate impacts, are primarily constrained by their removal via cloud and precipitation (wet removal). However, the microphysical process that predominantly controls the removal efficiency remains unidentified because of observational difficulties. Here, we demonstrate that the activation of aerosols to cloud droplets (nucleation scavenging) predominantly controls the wet removal efficiency of accumulation-mode aerosols, using water-insoluble black carbon as an observable particle tracer during the removal process. From simultaneous ground-based observations of black carbon in air (prior to removal) and in rainwater (after removal) in Tokyo, Japan, we found that the wet removal efficiency depends strongly on particle size, and the size dependence can be explained quantitatively by the observed size-dependent cloud-nucleating ability. Furthermore, our observational method provides an estimate of the effective supersaturation of water vapour in precipitating cloud clusters, a key parameter controlling nucleation scavenging. These novel data firmly indicate the importance of quantitative numerical simulations of the nucleation scavenging process to improve the model's ability to predict the atmospheric aerosol burden and the resultant climate forcings, and enable a new validation of such simulations.}, author = {Ohata, Sho and Moteki, Nobuhiro and Mori, Tatsuhiro and Koike, Makoto and Kondo, Yutaka}, doi = {10.1038/srep34113}, issn = {20452322}, journal = {Scientific Reports}, keywords = {Atmospheric chemistry}, month = {oct}, number = {1}, pages = {1--9}, publisher = {Nature Publishing Group}, title = {{A key process controlling the wet removal of aerosols: New observational evidence}}, url = {www.nature.com/scientificreports}, volume = {6}, year = {2016} } @article{Oliveira2007, author = {Oliveira, Paulo H. F. and Artaxo, Paulo and Pires, Carlos and {De Lucca}, Silvia and Proc{\'{o}}Pio, Aline and Holben, Brent and Schafer, Joel and Cardoso, Luiz F. and Wofsy, Steven C. and Rocha, Humberto R.}, doi = {10.1111/j.1600-0889.2007.00270.x}, issn = {1600-0889}, journal = {Tellus B: Chemical and Physical Meteorology}, month = {jan}, number = {3}, pages = {338--349}, title = {{The effects of biomass burning aerosols and clouds on the CO2 flux in Amazonia}}, url = {https://www.tandfonline.com/doi/full/10.1111/j.1600-0889.2007.00270.x}, volume = {59}, year = {2007} } @article{bg-15-4245-2018, author = {Oliver, R J and Mercado, L M and Sitch, S and Simpson, D and Medlyn, B E and Lin, Y.-S. and Folberth, G A}, doi = {10.5194/bg-15-4245-2018}, journal = {Biogeosciences}, number = {13}, pages = {4245--4269}, title = {{Large but decreasing effect of ozone on the European carbon sink}}, url = {https://www.biogeosciences.net/15/4245/2018/}, volume = {15}, year = {2018} } @article{esd-4-267-2013, author = {Olivi{\'{e}}, D J L and Peters, G P}, doi = {10.5194/esd-4-267-2013}, journal = {Earth System Dynamics}, number = {2}, pages = {267--286}, title = {{Variation in emission metrics due to variation in CO2 and temperature impulse response functions}}, url = {https://www.earth-syst-dynam.net/4/267/2013/}, volume = {4}, year = {2013} } @article{Oram2017, abstract = {Abstract. Large and effective reductions in emissions of long-lived ozone-depleting substance (ODS) are being achieved through the Montreal Protocol, the effectiveness of which can be seen in the declining atmospheric abundances of many ODSs. An important remaining uncertainty concerns the role of very short-lived substances (VSLSs) which, owing to their relatively short atmospheric lifetimes (less than 6 months), are not regulated under the Montreal Protocol. Recent studies have found an unexplained increase in the global tropospheric abundance of one VSLS, dichloromethane (CH2Cl2), which has increased by around 60{\%} over the past decade. Here we report dramatic enhancements of several chlorine-containing VSLSs (Cl-VSLSs), including CH2Cl2 and CH2ClCH2Cl (1,2-dichloroethane), observed in surface and upper-tropospheric air in East and South East Asia. Surface observations were, on occasion, an order of magnitude higher than previously reported in the marine boundary layer, whilst upper-tropospheric data were up to 3 times higher than expected. In addition, we provide further evidence of an atmospheric transport mechanism whereby substantial amounts of industrial pollution from East Asia, including these chlorinated VSLSs, can rapidly, and regularly, be transported to tropical regions of the western Pacific and subsequently uplifted to the tropical upper troposphere. This latter region is a major provider of air entering the stratosphere, and so this mechanism, in conjunction with increasing emissions of Cl-VSLSs from East Asia, could potentially slow the expected recovery of stratospheric ozone.}, author = {Oram, David E. and Ashfold, Matthew J. and Laube, Johannes C. and Gooch, Lauren J. and Humphrey, Stephen and Sturges, William T. and Leedham-Elvidge, Emma and Forster, Grant L. and Harris, Neil R. P. and Mead, Mohammed Iqbal and Samah, Azizan Abu and Phang, Siew Moi and Ou-Yang, Chang-Feng and Lin, Neng-Huei and Wang, Jia-Lin and Baker, Angela K. and Brenninkmeijer, Carl A. M. and Sherry, David}, doi = {10.5194/acp-17-11929-2017}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {oct}, number = {19}, pages = {11929--11941}, title = {{A growing threat to the ozone layer from short-lived anthropogenic chlorocarbons}}, url = {https://www.atmos-chem-phys.net/17/11929/2017/}, volume = {17}, year = {2017} } @article{Jockel2018, abstract = {Abstract. Understanding and modeling the large-scale transport of trace gases and aerosols is important for interpreting past (and projecting future) changes in atmospheric composition. Here we show that there are large differences in the global-scale atmospheric transport properties among the models participating in the IGAC SPARC Chemistry–Climate Model Initiative (CCMI). Specifically, we find up to 40{\%} differences in the transport timescales connecting the Northern Hemisphere (NH) midlatitude surface to the Arctic and to Southern Hemisphere high latitudes, where the mean age ranges between 1.7 and 2.6 years. We show that these differences are related to large differences in vertical transport among the simulations, in particular to differences in parameterized convection over the oceans. While stronger convection over NH midlatitudes is associated with slower transport to the Arctic, stronger convection in the tropics and subtropics is associated with faster interhemispheric transport. We also show that the differences among simulations constrained with fields derived from the same reanalysis products are as large as (and in some cases larger than) the differences among free-running simulations, most likely due to larger differences in parameterized convection. Our results indicate that care must be taken when using simulations constrained with analyzed winds to interpret the influence of meteorology on tropospheric composition.}, author = {Orbe, Clara and Yang, Huang and J{\"{o}}ckel, Patrick and Stone, Kane A. and Kinnison, Douglas E. and Oman, Luke D. and Lamarque, Jean-Francois and Orbe, Clara and Rozanov, Eugene and Sukhodolov, Timofei and Akiyoshi, Hideharu and Yamashita, Yousuke and Yoshida, Kohei and Josse, Beatrice and Strahan, Susan E. and Revell, Laura and Marecal, Virginie and Scinocca, John F. and Banerjee, Antara and Waugh, Darryn W. and Yang, Huang and Plummer, David A. and Schofield, Robyn and Tanaka, Taichu Y. and Visioni, Daniele and Zeng, Guang and Tilmes, Simone and Pitari, Giovanni and Morgenstern, Olaf and Stenke, Andreas and Deushi, Makoto}, doi = {10.5194/acp-18-7217-2018}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {10}, pages = {7217--7235}, title = {{Large-scale tropospheric transport in the Chemistry–Climate Model Initiative (CCMI) simulations}}, url = {https://www.atmos-chem-phys.net/18/7217/2018/}, volume = {18}, year = {2018} } @article{Oswald2015, abstract = {The goal of this study is to better understand the linkages between the climate system and surface-level ozone concentrations in the Northeastern U.S. We focus on the regularity of observed high ozone concentrations between May 15 and August 30 during the 1993-2012 period. The first portion of this study establishes relationships between ozone and meteorological predictors. The second examines the linkages between ozone and large-scale teleconnections within the climate system. Statistical models for each station are constructed using a combination of Correlation Analysis, Principal Components Analysis and Multiple Linear Regression. In general, the strongest meteorological predictors of ozone are the frequency of high temperatures and precipitation and the amount of solar radiation flux. Statistical models of meteorological variables explain about 60-75{\%} of the variability in the annual ozone time series, and have typical error-to-variability ratios of 0.50-0.65. Teleconnection patterns such as the Arctic Oscillation, Quasi-Biennial Oscillation and Pacific Decadal Oscillation are best linked to ozone in the region. Statistical models of these patterns explain 40-60{\%} of the variability in the ozone annual time series, and have a typical error-to-variability ratio of 0.60-0.75.}, author = {Oswald, Evan M. and Dupigny-Giroux, Lesley Ann and Leibensperger, Eric M. and Poirot, Rich and Merrell, Jeff}, doi = {10.1016/j.atmosenv.2015.04.019}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Meteorology,Northeastern U.S,Teleconnections,Tropospheric ozone}, month = {jul}, pages = {278--288}, publisher = {Pergamon}, title = {{Climate controls on air quality in the Northeastern U.S.: An examination of summertime ozone statistics during 1993–2012}}, url = {https://www.sciencedirect.com/science/article/pii/S1352231015300200?via{\%}3Dihub}, volume = {112}, year = {2015} } @article{Ovadnevaite2014, abstract = {A new sea spray source function (SSSF), termed Oceanflux Sea Spray Aerosol or OSSA, was derived based on in-situ sea spray aerosol measurements along with meteorological/physical parameters. Submicron sea spray aerosol fluxes derived from particle number concentration measurements at the Mace Head coastal station, on the west coast of Ireland, were used together with open-ocean eddy correlation flux measurements from the Eastern Atlantic Sea Spray, Gas Flux, and Whitecap (SEASAW) project cruise. In the overlapping size range, the data for Mace Head and SEASAW were found to be in a good agreement, which allowed deriving the new SSSF from the combined dataset spanning the dry diameter range from 15 nm to 6 $\mu$m. The OSSA source function has been parameterized in terms of five lognormal modes and the Reynolds number instead of the more commonly used wind speed, thereby encapsulating important influences of wave height, wind history, friction velocity, and viscosity. This formulation accounts for the different flux relationships associated with rising and waning wind speeds since these are included in the Reynolds number. Furthermore, the Reynolds number incorporates the kinematic viscosity of water, thus the SSSF inherently includes dependences on sea surface temperature and salinity. The temperature dependence of the resulting SSSF is similar to that of other in-situ derived source functions and results in lower production fluxes for cold waters and enhanced fluxes from warm waters as compared with SSSF formulations that do not include temperature effects.{\textcopyright}Author(s) 2014.}, author = {Ovadnevaite, J. and Manders, A. and {De Leeuw}, G. and Ceburnis, D. and Monahan, C. and Partanen, A. I. and Korhonen, H. and O'Dowd, C. D.}, doi = {10.5194/acp-14-1837-2014}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, number = {4}, pages = {1837--1852}, title = {{A sea spray aerosol flux parameterization encapsulating wave state}}, volume = {14}, year = {2014} } @article{Petron2014, abstract = {Emissions of methane (CH4) from oil and natural gas (O{\&}G) operations in the most densely drilled area of the Denver-Julesburg Basin in Weld County located in northeastern Colorado are estimated for 2 days in May 2012 using aircraft-based CH4 observations and planetary boundary layer height and ground-based wind profile measurements. Total top-down CH4 emission estimates are 25.8 ± 8.4 and 26.2 ± 10.7 t CH4/h for the 29 and 31 May flights, respectively. Using inventory data, we estimate the total emissions of CH4 from non-O{\&}G gas-related sources at 7.1 ± 1.7 and 6.3 ± 1.0 t CH4/h for these 2 days. The difference in emissions is attributed to O{\&}G sources in the study region, and their total emission is on average 19.3 ± 6.9 t/h, close to 3 times higher than an hourly emission estimate based on Environmental Protection Agency's Greenhouse Gas Reporting Program data for 2012. We derive top-down emissions estimates for propane, n-butane, i-pentane, n-pentane, and benzene from our total top-down CH4 emission estimate and the relative hydrocarbon abundances in aircraft-based discrete air samples. Emissions for these five nonmethane hydrocarbons alone total 25.4 ± 8.2 t/h. Assuming that these emissions are solely originating from O{\&}G-related activities in the study region, our results show that the state inventory for total volatile organic compounds emitted by O{\&}G activities is at least a factor of 2 too low for May 2012. Our top-down emission estimate of benzene emissions from O{\&}G operations is 173 ± 64 kg/h, or 7 times larger than in the state inventory.}, author = {P{\'{e}}tron, Gabrielle and Karion, Anna and Sweeney, Colm and Miller, Benjamin R. and Montzka, Stephen A. and Frost, Gregory J. and Trainer, Michael and Tans, Pieter and Andrews, Arlyn and Kofler, Jonathan and Helmig, Detlev and Guenther, Douglas and Dlugokencky, Ed and Lang, Patricia and Newberger, Tim and Wolter, Sonja and Hall, Bradley and Novelli, Paul and Brewer, Alan and Conley, Stephen and Hardesty, Mike and Banta, Robert and White, Allen and Noone, David and Wolfe, Dan and Schnell, Russ}, doi = {10.1002/2013JD021272}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {jun}, number = {11}, pages = {6836--6852}, title = {{A new look at methane and nonmethane hydrocarbon emissions from oil and natural gas operations in the Colorado Denver‐Julesburg Basin}}, url = {https://onlinelibrary.wiley.com/doi/10.1002/2013JD021272}, volume = {119}, year = {2014} } @misc{Petron2019, address = {Boulder, CO, USA}, author = {P{\'{e}}tron, G. and Crotwell, A.M. and Dlugokencky, E. and Mund, J. W.}, publisher = {National Oceanic {\&} Atmospheric Administration (NOAA) Earth System Research Laboratory (ESRL)}, title = {{Atmospheric carbon monoxide dry air mole fractions from the NOAA ESRL carbon cycle cooperative global air sampling network, 1988–2017, Version: 2019‐08}}, url = {ftp://aftp.cmdl.noaa.gov/data/trace{\_}gases/co/flask/surface/}, year = {2019} } @article{Paasonen2013, abstract = {Atmospheric aerosol particles influence the climate system directly by scattering and absorbing solar radiation, and indirectly by acting as cloud condensation nuclei. Apart from black carbon aerosol, aerosols cause a negative radiative forcing at the top of the atmosphere and substantially mitigate the warming caused by greenhouse gases. In the future, tightening of controls on anthropogenic aerosol and precursor vapour emissions to achieve higher air quality may weaken this beneficial effect. Natural aerosols, too, might affect future warming. Here we analyse long-term observations of concentrations and compositions of aerosol particles and their biogenic precursor vapours in continental mid- and high-latitude environments. We use measurements of particle number size distribution together with boundary layer heights derived from reanalysis data to show that the boundary layer burden of cloud condensation nuclei increases exponentially with temperature. Our results confirm a negative feedback mechanism between the continental biosphere, aerosols and climate: aerosol cooling effects are strengthened by rising biogenic organic vapour emissions in response to warming, which in turn enhance condensation on particles and their growth to the size of cloud condensation nuclei. This natural growth mechanism produces roughly 50{\%} of particles at the size of cloud condensation nuclei across Europe. We conclude that biosphere-atmosphere interactions are crucial for aerosol climate effects and can significantly influence the effects of anthropogenic aerosol emission controls, both on climate and air quality. {\textcopyright} 2013 Macmillan Publishers Limited. All rights reserved.}, author = {Paasonen, Pauli and Asmi, Ari and Pet{\"{a}}j{\"{a}}, Tuukka and Kajos, Maija K. and {\"{A}}ij{\"{a}}l{\"{a}}, Mikko and Junninen, Heikki and Holst, Thomas and Abbatt, Jonathan P.D. and Arneth, Almut and Birmili, Wolfram and {Van Der Gon}, Hugo Denier and Hamed, Amar and Hoffer, Andr{\'{a}}s and Laakso, Lauri and Laaksonen, Ari and {Richard Leaitch}, W. and Plass-D{\"{u}}lmer, Christian and Pryor, Sara C. and R{\"{a}}is{\"{a}}nen, Petri and Swietlicki, Erik and Wiedensohler, Alfred and Worsnop, Douglas R. and Kerminen, Veli Matti and Kulmala, Markku}, doi = {10.1038/ngeo1800}, issn = {17520894}, journal = {Nature Geoscience}, number = {6}, pages = {438--442}, publisher = {NATURE PUBLISHING GROUP}, title = {{Warming-induced increase in aerosol number concentration likely to moderate climate change}}, volume = {6}, year = {2013} } @article{Pacifico2012, abstract = {We have implemented a process-based isoprene emission model in the HadGEM2 Earth-system model with coupled atmospheric chemistry in order to examine the feedback between isoprene emission and climate. Isoprene emissions and their impact on atmospheric chemistry and climate are estimated for preindustrial (1860-1869), present-day (2000-2009), and future (2100-2109) climate conditions. The estimate of 460 TgC/yr for present-day global total isoprene emission is consistent with previous estimates. Preindustrial isoprene emissions are estimated to be 26{\%} higher than present-day. Future isoprene emissions using the RCP8.5 scenario are similar to present-day because increased emissions resulting from climate warming are countered by CO2 inhibition of isoprene emissions. The impact of biogenic isoprene emissions on the global O-3 burden and CH4 lifetime is small but locally significant, and the impact of changes in isoprene emissions on atmospheric chemistry depends strongly on the state of climate and chemistry.}, author = {Pacifico, F and Folberth, G A and Jones, C D and Harrison, S P and Collins, W J}, doi = {10.1029/2012JD018276}, issn = {01480227}, journal = {Journal of Geophysical Research: Atmospheres}, month = {nov}, number = {D22}, pages = {D22302}, title = {{Sensitivity of biogenic isoprene emissions to past, present, and future environmental conditions and implications for atmospheric chemistry}}, url = {http://doi.wiley.com/10.1029/2012JD018276}, volume = {117}, year = {2012} } @article{Palmer2006, abstract = {Quantifying isoprene emissions using satellite observations of the formaldehyde (HCHO) columns is subject to errors involving the column retrieval and the assumed relationship between HCHO columns and isoprene emissions,taken here from the GEOSCHEM chemical transport model. Here we use a 6-year (1996-2001) HCHO column data set from the Global Ozone Monitoring Experiment (GOME) satellite instrument to (1) quantify these errors, (2) evaluate GOME-derived isoprene emissions with in situ flux measurements and a process-based emission inventory (Model of Emissions of Gases and Aerosols from Nature, MEGAN), and (3) investigate the factors driving the seasonal and interannual variability of North American isoprene emissions. The error in the GOME HCHO column retrieval is estimated to be 40{\%}. We use the Master Chemical Mechanism (MCM) to quantify the time-dependent HCHO production from isoprene, $\alpha$-and $\beta$-pinenes, and methylbutenol and show that only emissions of isoprene are detectable by GOME. The time-dependent HCHO yield from isoprene oxidation calculated by MCM is 20-30{\%} larger than in GEOS-CHEM. GOME-derived isoprene fluxes track the observed seasonal variation of in situ measurements at a Michigan forest site with a -30{\%} bias. The seasonal variation of North American isoprene emissions during 2001 inferred from GOME is similar to MEGAN, with GOME emissions typically 25{\%} higher (lower) at the beginning (end) of the growing season. GOME and MEGAN both show a maximum over the southeastern United States, but they differ in the precise location. The observed interannual variability of this maximum is 20-30{\%}, depending on month. The MEGAN isoprene emission dependence on surface air temperature explains 75{\%} of the month-to-month variability in GOME-derived isoprene emissions over the southeastern United States during May-September 1996-2001. Copyright 2006 by the American Geophysical Union.}, author = {Palmer, Paul I. and Abbot, Dorian S. and Fu, Tzung-May and Jacob, Daniel J. and Chance, Kelly and Kurosu, Thomas P. and Guenther, Alex and Wiedinmyer, Christine and Stanton, Jenny C. and Pilling, Michael J. and Pressley, Shelley N. and Lamb, Brian and Sumner, Anne Louise}, doi = {10.1029/2005JD006689}, isbn = {0148-0227}, issn = {0148-0227}, journal = {Journal of Geophysical Research: Atmospheres}, number = {D12}, pages = {D12315}, title = {{Quantifying the seasonal and interannual variability of North American isoprene emissions using satellite observations of the formaldehyde column}}, url = {http://doi.wiley.com/10.1029/2005JD006689}, volume = {111}, year = {2006} } @article{Pan2018, abstract = {The limited availability of ammonia (NH3) measurements is currently a barrier to understanding the vital role of NH3 in secondary aerosol formation during haze pollution events and prevents a full assessment of the atmospheric deposition of reactive nitrogen. The observational gaps motivated us to design this study to investigate the spatial distributions and seasonal variations in atmospheric NH3 on a national scale in China. On the basis of a 1-year observational campaign at 53 sites with uniform protocols, we confirm that abundant concentrations of NH3 [1 to 23.9 $\mu$g m-3] were identified in typical agricultural regions, especially over the North China Plain (NCP). The spatial pattern of the NH3 surface concentration was generally similar to those of the satellite column concentrations as well as a bottom-up agriculture NH3 emission inventory. However, the observed NH3 concentrations at urban and desert sites were comparable with those from agricultural sites and 2-3 times those of mountainous/forest/grassland/waterbody sites. We also found that NH3 deposition fluxes at urban sites account for only half of the emissions in the NCP, suggesting the transport of urban NH3 emissions to downwind areas. This finding provides policy makers with insights into the potential mitigation of nonagricultural NH3 sources in developed regions.}, author = {Pan, Yuepeng and Tian, Shili and Zhao, Yuanhong and Zhang, Lin and Zhu, Xiaying and Gao, Jian and Huang, Wei and Zhou, Yanbo and Song, Yu and Zhang, Qiang and Wang, Yuesi}, doi = {10.1021/acs.est.7b05235}, issn = {15205851}, journal = {Environmental Science {\&} Technology}, month = {mar}, number = {7}, pages = {3926--3934}, publisher = {American Chemical Society ({\{}ACS{\}})}, title = {{Identifying Ammonia Hotspots in China Using a National Observation Network}}, volume = {52}, year = {2018} } @article{Pant2015, abstract = {Ambient PM2.5 samples were collected at a high-traffic location (summer and winter 2013) and characterized for a large suite of elemental and organic markers. Concentrations were found to exceed the Indian PM2.5 air quality standard on several occasions, especially in the winter. Winter concentrations of several individual tracer species were several fold higher compared to summer, particularly for some PAHs and trace metals. Enrichment factors relative to crustal material showed significant enrichment for elements such as Ti, Sb, Pb and As, although Ba, often used as a marker for non-exhaust emissions from traffic was not found to be enriched appreciably. Crustal material was found to be an important contributor in the summer (14.3{\%}), while wood burning (23.3{\%}), nitrates (12.4{\%}) and chlorides (12.3{\%}) were found to be major contributors in winter. The contribution of road traffic exhaust emissions was estimated to be 18.7{\%} in summer and 16.2{\%} in winter. Other combustion sources (wood and other biomass/waste/coal) were found to be a significant source in winter, and contribute to the higher concentrations. Secondary sulphates, nitrates and chloride (the latter two in winter) and organic matter also contribute substantially to PM2.5 mass.}, author = {Pant, Pallavi and Shukla, Anuradha and Kohl, Steven D. and Chow, Judith C. and Watson, John G. and Harrison, Roy M.}, doi = {10.1016/j.atmosenv.2015.02.074}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {India,Mass closure,Molecular markers,Particulate matter,Traffic}, month = {may}, pages = {178--189}, publisher = {Elsevier {\{}BV{\}}}, title = {{Characterization of ambient PM2.5 at a pollution hotspot in New Delhi, India and inference of sources}}, volume = {109}, year = {2015} } @article{Papanastasiou2018a, abstract = {Hydrochlorofluorocarbons (HCFCs) are ozone depleting substances and potent greenhouse gases that are controlled under the Montreal Protocol. However, the majority of the 274 HCFCs included in Annex C of the protocol do not have reported global warming potentials (GWPs) which are used to guide the phaseout of HCFCs and the future phase down of hydrofluorocarbons (HFCs). In this study, GWPs for all C1-C3 HCFCs included in Annex C are reported based on estimated atmospheric lifetimes and theoretical methods used to calculate infrared absorption spectra. Atmospheric lifetimes were estimated from a structure activity relationship (SAR) for OH radical reactivity and estimated O(1D) reactivity and UV photolysis loss processes. The C1-C3 HCFCs display a wide range of lifetimes (0.3 to 62 years) and GWPs (5 to 5330, 100-year time horizon) dependent on their molecular structure and the H-atom content of the individual HCFC. The results from this study provide estimated policy-relevant GWP metrics for the HCFCs included in the Montreal Protocol in the absence of experimentally derived metrics.}, author = {Papanastasiou, Dimitrios K. and Beltrone, Allison and Marshall, Paul and Burkholder, James B.}, doi = {10.5194/acp-18-6317-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {9}, pages = {6317--6330}, publisher = {Copernicus Publications}, title = {{Global warming potential estimates for the C1-C3 hydrochlorofluorocarbons (HCFCs) included in the Kigali Amendment to the Montreal Protocol}}, url = {https://www.atmos-chem-phys.net/18/6317/2018/ https://www.atmos-chem-phys.net/18/6317/2018/acp-18-6317-2018.pdf}, volume = {18}, year = {2018} } @article{ISI:000298120400001, abstract = {Air quality progress in the North American megacities of Los Angeles, New York, and Mexico City is reviewed, compared, and contrasted. Enormous progress made in North America over the last 5 decades provides a template for other megacities of the world, especially in developing countries, attempting to achieve rapid economic growth without compromising air quality. While the progress to date has been impressive, many challenges remain including the need to improve air quality while simultaneously mitigating climate change. The impact of pollutant emissions from megacities is felt long distances away from the local sources but no policy mechanisms currently exist to mitigate air quality impacts resulting from such pollution transport. {\textcopyright} 2011.}, author = {Parrish, David D. and Singh, Hanwant B. and Molina, Luisa and Madronich, Sasha}, doi = {10.1016/j.atmosenv.2011.09.039}, isbn = {1352-2310; 1873-2844}, issn = {13522310}, journal = {Atmospheric Environment}, keywords = {Air quality,Megacities,Ozone,Particulate matter,Pollution}, number = {39}, pages = {7015--7025}, title = {{Air quality progress in North American megacities: A review}}, volume = {45}, year = {2011} } @article{Partanen2012, abstract = {Climate-aerosol model ECHAM5.5-HAM2 was used to investigate how geoengineering with artificial sea salt emissions would affect marine clouds and the Earth's radiative balance. Prognostic cloud droplet number concentration and interaction of aerosol particles with clouds and radiation were calculated explicitly, thus making this the first time that aerosol direct effects of sea spray geoengineering are considered. When a wind speed dependent baseline geoengineering flux was applied over all oceans (total annual emissions 443.9 Tg), we predicted a radiative flux perturbation (RFP) of -5.1 W m-2, which is enough to counteract warming from doubled CO2 concentration. When the baseline flux was limited to three persistent stratocumulus regions (3.3{\%} of Earth's surface, total annual emissions 20.6 Tg), the RFP was -0.8 Wm-2 resulting mainly from a 74-80{\%} increase in cloud droplet number concentration and a 2.5-4.4 percentage point increase in cloud cover. Multiplying the baseline mass flux by 5 or reducing the injected particle size from 250 to 100 nm had comparable effects on the geoengineering efficiency with RFPs -2.2 and -2.1 Wm-2, respectively. Within regions characterized with persistent stratocumulus decks, practically all of the radiative effect originated from aerosol indirect effects. However, when all oceanic regions were seeded, the direct effect with the baseline flux was globally about 29{\%} of the total radiative effect. Together with previous studies, our results indicate that there are still large uncertainties associated with the sea spray geoengineering efficiency due to variations in e.g., background aerosol concentration, updraft velocity, cloud altitude and onset of precipitation. Copyright 2012 by the American Geophysical Union.}, author = {Partanen, Antti-Ilari and Kokkola, Harri and Romakkaniemi, Sami and Kerminen, Veli-Matti and Lehtinen, Kari E. J. and Bergman, Tommi and Arola, Antti and Korhonen, Hannele}, doi = {10.1029/2011JD016428}, issn = {01480227}, journal = {Journal of Geophysical Research: Atmospheres}, month = {jan}, number = {D2}, pages = {D02203}, title = {{Direct and indirect effects of sea spray geoengineering and the role of injected particle size}}, url = {http://doi.wiley.com/10.1029/2011JD016428}, volume = {117}, year = {2012} } @article{Partanen2013, abstract = {Abstract. Aerosol particles from shipping emissions both cool the climate and cause adverse health effects. The cooling effect is, however, declining because of shipping emission controls aiming to improve air quality. We used an aerosol-climate model ECHAM-HAMMOZ to test whether by altering ship fuel sulfur content, the present-day aerosol-induced cooling effect from shipping could be preserved, while at the same time reducing premature mortality rates related to shipping emissions. We compared the climate and health effects of a present-day shipping emission scenario (ship fuel sulfur content of 2.7{\%}) with (1) a simulation with strict emission controls in the coastal waters (ship fuel sulfur content of 0.1{\%}) and twofold the present-day fuel sulfur content (i.e. 5.4{\%}) elsewhere; and (2) a scenario with global strict shipping emission controls (ship fuel sulfur content of 0.1{\%} in coastal waters and 0.5{\%} elsewhere) roughly corresponding to international agreements to be enforced by the year 2020. Scenario 1 had a slightly stronger aerosol-induced effective radiative forcing (ERF) from shipping than the present-day scenario (−0.43 W m−2 vs. −0.39 W m−2) while reducing premature mortality from shipping by 69{\%} (globally 34 900 deaths avoided per year). Scenario 2 decreased the ERF to −0.06 W m−2 and annual deaths by 96{\%} (globally 48 200 deaths avoided per year) compared to present-day. Our results show that the cooling effect of present-day emissions could be retained with simultaneous notable improvements in air quality, even though the shipping emissions from the open ocean clearly have a significant effect on continental air quality. However, increasing ship fuel sulfur content in the open ocean would violate existing international treaties, could cause detrimental side-effects, and could be classified as geoengineering.}, author = {Partanen, A.-I.. and Laakso, A. and Schmidt, A. and Kokkola, H. and Kuokkanen, T. and Pietik{\"{a}}inen, J.-P. and Kerminen, V.-M. and Lehtinen, K. E. J. and Laakso, L. and Korhonen, H.}, doi = {10.5194/acp-13-12059-2013}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {dec}, number = {23}, pages = {12059--12071}, title = {{Climate and air quality trade-offs in altering ship fuel sulfur content}}, url = {https://acp.copernicus.org/articles/13/12059/2013/}, volume = {13}, year = {2013} } @article{PATHAK2011318, abstract = {Although laboratory studies suggest that aerosol acidity ([H+]) significantly enhances the production of secondary organic aerosol (SOA) through heterogeneous chemistry, field studies have provided limited evidence of such enhancement. In this study, correlation of strong aerosol acidity with WSOC was investigated using the 24-hr PM2.5 samples collected at sites near four major cities of China – Beijing (BJ), Shanghai (SH), Lanzhou (LZ), and Guangzhou (GZ) – during the summers of 2004–2006. PM2.5 samples were characterized by high atmospheric loadings of PM2.5, OC, EC, sulfate, nitrate, aerosol acidity, and aerosol-water, especially in Beijing and Shanghai. On average, OC and EC were distributed in the ratio of approximately 2:1 among carbonaceous aerosols (TC = OC + EC) in all four cities. However, the WSOC fraction in OC differed across the four cities (BJ ∼ 55{\%} of OC; SH ∼ 35{\%}; LZ ∼ 40{\%}; GZ ∼ 32{\%}). We found an increased WSOC content in organic carbon (OC) fraction in the samples with elevated aerosol acidity (H+) and the WSOC was thought to be influenced by aerosol acidity. The WSOC/OC ratio showed a strong positive correlation with the normalized strong acid concentration ([H+]/[OC]) in the four cities. The higher WSOC fraction in OC at higher strong acidity is postulated to be linked to the conversion of OC to WSOC via heterogeneous acid-catalyzed chemistry.}, author = {Pathak, Ravi Kant and Wang, Tao and Ho, K F and Lee, S C}, doi = {https://doi.org/10.1016/j.atmosenv.2010.10.021}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Acid catalyzed reaction,Acidity,EC,OC,SOA,WSOC}, number = {2}, pages = {318--325}, title = {{Characteristics of summertime PM2.5 organic and elemental carbon in four major Chinese cities: Implications of high acidity for water-soluble organic carbon (WSOC)}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231010008836}, volume = {45}, year = {2011} } @article{Patra2021, abstract = {Abstract Trends and variability in tropospheric hydroxyl (OH) radicals influence budgets of many greenhouse gases, air pollutant species, and ozone depleting substances. Estimations of tropospheric OH trends and variability based on budget analysis of methyl chloroform (CH3CCl3) and process-based chemistry transport models often produce conflicting results. Here we use a previously tested transport model to simulate atmospheric CH3CCl3 for the period 1985?2018. Based on mismatches between model output and observations, we derive consistent anomalies in the inverse lifetime of CH3CCl3 (KG) using measurements from two independent observational networks (National Oceanic and Atmospheric Administration and Advanced Global Atmospheric Gases Experiment). Our method allows a separation between ?physical? (transport, temperature) and ?chemical? (i.e., abundance) influences on OH + CH3CCl3 reaction rate in the atmosphere. Small increases in KG due to ?physical? influences are mostly driven by increases in the temperature-dependent reaction between OH and CH3CCl3 and resulted in a smoothly varying increase of 0.80{\%} decade?1. Chemical effects on KG, linked to global changes in OH sources and sinks, show larger year-to-year variations (?2{\%}?3{\%}), and have a negative correlation with the El Ni{\~{n}}o Southern Oscillation. A significant positive trend in KG can be derived after 2001, but it persists only through 2015 and only if we assume that CH3CCl3 emissions decayed more slowly over time than our best estimate suggests. If global CH3CCl3 emissions dropped below 3 Gg year?1 after 2015, recent CH3CCl3 measurements indicate that the 2015?2018 loss rate of CH3CCl3 due to reaction with OH is comparable to its value 2 decades ago.}, annote = {https://doi.org/10.1029/2020JD033862}, author = {Patra, P K and Krol, M C and Prinn, R G and Takigawa, M and M{\"{u}}hle, J and Montzka, S A and Lal, S and Yamashita, Y and Naus, S and Chandra, N and Weiss, R F and Krummel, P B and Fraser, P J and O'Doherty, S and Elkins, J W}, doi = {https://doi.org/10.1029/2020JD033862}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {hydroxyl radical (OH) interannual variability,inverse lifetime of CH3CCl3,methyl chloroform (CH3CCl3)}, month = {feb}, number = {4}, pages = {e2020JD033862}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Methyl Chloroform Continues to Constrain the Hydroxyl (OH) Variability in the Troposphere}}, url = {https://doi.org/10.1029/2020JD033862}, volume = {126}, year = {2021} } @article{Patris2002, abstract = {Sulfur isotopes of sulfate have been measured in a discontinuous set of polar ice core samples from Summit, central Greenland, covering the preindustrial (from the fourteenth to the eighteenth century) and industrial (from 1872 to 1969 A.D.) periods. Results have been used to estimate the different source contributions to the deposited sulfate and their evolution along the last centuries. They indicate that the preindustrial background sulfate budget is slightly dominated on a year-round average by marine biogenic emissions, amounting to close to half of the non-sea-salt sulfate (49{\%}). The second contribution is provided by continental sources of secondary sulfate, including background volcanism and, to a lesser extent, continental biota (44{\%} of the non-sea-salt sulfate). Sulfur emitted by relatively weak eruptions is found to be largely depleted in34S compared to bulk volcanic S, suggesting an efficient washout of the heavier isotope during the tropospheric transport. The impact of human-driven emissions on the sulfate deposited in central Greenland ice is visible in isotope data as early as 1870 A.D. The isotopic signature of anthropogenic sulfur deposited during the twentieth century is found to be constant ($\delta$14S ≈ + 3.0 ± 1.5‰), regardless of the changes of dominant source regions and emission processes. This signature is slightly but measurably lighter than the one reported for Arctic haze pollution events. Copyright 2002 by the American Geophysical Union.}, author = {Patris, Nicolas and Delmas, Robert and Legrand, Michel and {De Angelis}, Martine and Ferron, Francisco A. and Sti{\'{e}}venard, Michel and Jouzel, Jean}, doi = {10.1029/2001JD000672}, issn = {01480227}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {Greenland,Pollution transport,Sulfur isotopes}, month = {jun}, number = {D11}, pages = {ACH 6--1--ACH 6--11}, title = {{First sulfur isotope measurements in central Greenland ice cores along the preindustrial and industrial periods}}, url = {http://doi.wiley.com/10.1029/2001JD000672}, volume = {107}, year = {2002} } @article{Paulot2018, abstract = {We present estimates of changes in the direct aerosol effects (DRE) and its anthropogenic component (DRF) from 2001 to 2015 using the GFDL chemistry-climate model AM3 driven by CMIP6 historical emissions. AM3 is evaluated against observed changes in the clear-sky shortwave direct aerosol effect (DREswclr) derived from the Clouds and the Earth's Radiant Energy System (CERES) over polluted regions. From 2001 to 2015, observations suggest that DREclrsw increases (i.e., less radiation is scattered to space by aerosols) over western Europe (0.7-1Wm'2decade'1) and the eastern US (0.9-1.4Wm'2decade'1), decreases over India ('1 to'1.6Wm'2decade'1), and does not change significantly over eastern China. AM3 captures these observed regional changes in DREclrsw well in the US and western Europe, where they are dominated by the decline of sulfate aerosols, but not in Asia, where the model overestimates the decrease of DREclrsw. Over India, the model bias can be partly attributed to a decrease of the dust optical depth, which is not captured by our model and offsets some of the increase of anthropogenic aerosols. Over China, we find that the decline of SO2 emissions after 2007 is not represented in the CMIP6 emission inventory. Accounting for this decline, using the Modular Emission Inventory for China, and for the heterogeneous oxidation of SO2 significantly reduces the model bias. For both India and China, our simulations indicate that nitrate and black carbon contribute more to changes in DREclrsw than in the US and Europe. Indeed, our model suggests that black carbon (+0.12Wm'2) dominates the relatively weak change in DRF from 2001 to 2015 (+0.03Wm'2). Over this period, the changes in the forcing from nitrate and sulfate are both small and of the same magnitude ('0.03Wm'2 each). This is in sharp contrast to the forcing from 1850 to 2001 in which forcings by sulfate and black carbon largely cancel each other out, with minor contributions from nitrate. The differences between these time periods can be well understood from changes in emissions alone for black carbon but not for nitrate and sulfate; this reflects non-linear changes in the photochemical production of nitrate and sulfate associated with changes in both the magnitude and spatial distribution of anthropogenic emissions.}, author = {Paulot, Fabien and Paynter, David and Ginoux, Paul and Naik, Vaishali and Horowitz, Larry W.}, doi = {10.5194/acp-18-13265-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {feb}, number = {17}, pages = {13265--13281}, publisher = {Copernicus {\{}GmbH{\}}}, title = {{Changes in the aerosol direct radiative forcing from 2001 to 2015: Observational constraints and regional mechanisms}}, volume = {18}, year = {2018} } @article{acp-18-17963-2018, abstract = {{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Reactive nitrogen (N) emissions have increased over the last 150 years as a result of greater fossil fuel combustion and food production. The resulting increase in N deposition can alter the function of ecosystems, but characterizing its ecological impacts remains challenging, in part because of uncertainties in model-based estimates of N dry deposition. Here, we leverage the tiled structure of the land component (LM3) of the Geophysical Fluid Dynamics Laboratory (GFDL) Earth System Model to represent the impact of physical, hydrological, and ecological heterogeneities on the surface removal of chemical tracers. We show that this framework can be used to estimate N deposition at more ecologically-relevant scales (e.g., natural vegetation, water bodies) than from the coarse-resolution global chemistry{\&}ndash;climate model (GFDL-AM3). Focusing on North America, we show that the faster removal of N over forested ecosystems relative to cropland and pasture implies that coarse resolution estimates of N deposition from global models systematically underestimate N deposition to natural vegetation by 10 to 30{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%} in the Central and Eastern US. Neglecting the subgrid scale heterogeneity of dry deposition velocities also results in an underestimate (overestimate) of the amount of reduced (oxidized) nitrogen deposited to water bodies. Overall, changes in land cover associated with human activities are found to slow down the removal of N from the atmosphere, causing a reduction in the dry oxidized, dry reduced, and total N deposition over the contiguous US of 8{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}, 26{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}, and 6{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}, respectively. We also find that the reduction in the overall rate of removal of N associated with land-use change tends to increase N deposition on the remaining natural vegetation and facilitate N export to Canada. We show that subgrid scale differences in the surface removal of oxidized and reduced nitrogen imply that near-term (2010{\&}ndash;2050) changes in oxidized ({\&}minus;47{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}) and reduced (+40{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}) US N emissions will cause opposite changes in N deposition to water bodies (increase) and natural vegetation (decrease) in the Eastern US, with potential implications for acidification and ecosystems.{\textless}/p{\textgreater}}, author = {Paulot, Fabien and Malyshev, Sergey and Nguyen, Tran and Crounse, D. John and Shevliakova, Elena and Horowitz, W. Larry}, doi = {10.5194/acp-18-17963-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {24}, pages = {17963--17978}, title = {{Representing sub-grid scale variations in nitrogen deposition associated with land use in a global Earth system model: Implications for present and future nitrogen deposition fluxes over North America}}, url = {https://www.atmos-chem-phys.net/18/17963/2018/}, volume = {18}, year = {2018} } @article{Paulot2016, abstract = {We update and evaluate the treatment of nitrate aerosols in the Geophysical Fluid Dynamics Laboratory (GFDL) atmospheric model (AM3). Accounting for the radiative effects of nitrate aerosols generally improves the simulated aerosol optical depth, although nitrate concentrations at the surface are biased high. This bias can be reduced by increasing the deposition of nitrate to account for the near-surface volatilization of ammonium nitrate or by neglecting the heterogeneous production of nitric acid to account for the inhibition of N2O5 reactive uptake at high nitrate concentrations. Globally, uncertainties in these processes can impact the simulated nitrate optical depth by up to 25 {\%}, much more than the impact of uncertainties in the seasonality of ammonia emissions (6 {\%}) or in the uptake of nitric acid on dust (13 {\%}). Our best estimate for fine nitrate optical depth at 550 nm in 2010 is 0.006 (0.0050.008). In wintertime, nitrate aerosols are simulated to account for over 30 {\%} of the aerosol optical depth over western Europe and North America. Simulated nitrate optical depth increases by less than 30 {\%} (0.00610.010) in response to projected changes in anthropogenic emissions from 2010 to 2050 (e.g., 40 {\%} for SO2 and +38 {\%} for ammonia). This increase is primarily driven by greater concentrations of nitrate in the free troposphere, while surface nitrate concentrations decrease in the midlatitudes following lower concentrations of nitric acid. With the projected increase of ammonia emissions, we show that better constraints on the vertical distribution of ammonia (e.g., convective transport and biomass burning injection) and on the sources and sinks of nitric acid (e.g., heterogeneous reaction on dust) are needed to improve estimates of future nitrate optical depth.}, author = {Paulot, F. and Ginoux, P. and Cooke, W. F. and Donner, L. J. and Fan, S. and Lin, M. Y. and Mao, J. and Naik, V. and Horowitz, L. W.}, doi = {10.5194/acp-16-1459-2016}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {3}, pages = {1459--1477}, title = {{Sensitivity of nitrate aerosols to ammonia emissions and to nitrate chemistry: Implications for present and future nitrate optical depth}}, volume = {16}, year = {2016} } @article{Paulot2009a, abstract = {Emissions of nonmethane hydrocarbon compounds to the atmosphere from the biosphere exceed those from anthropogenic activity. Isoprene, a five-carbon diene, contributes more than 40{\%} of these emissions. Once emitted to the atmosphere, isoprene is rapidly oxidized by the hydroxyl radical OH. We report here that under pristine conditions isoprene is oxidized primarily to hydroxyhydroperoxides. Further oxidation of these hydroxyhydroperoxides by OH leads efficiently to the formation of dihydroxyepoxides and OH reformation. Global simulations show an enormous flux - nearly 100 teragrams of carbon per year - of these epoxides to the atmosphere. The discovery of these highly soluble epoxides provides a missing link tying the gas-phase degradation of isoprene to the observed formation of organic aerosols.}, author = {Paulot, Fabien and Crounse, John D. and Kjaergaard, Henrik G. and K{\"{u}}rten, Andreas and Clair, Jason M.St and Seinfeld, John H. and Wennberg, Paul O.}, doi = {10.1126/science.1172910}, issn = {00368075}, journal = {Science}, number = {5941}, pages = {730--733}, title = {{Unexpected epoxide formation in the gas-phase photooxidation of isoprene}}, volume = {325}, year = {2009} } @article{Paulot2020, abstract = {Abstract Recent laboratory and field studies point to an increase of sea salt aerosol (SSA) emissions with temperature, suggesting that SSA may lower climate sensitivity. We assess the impact of a strong (4.2{\%}?K ) and weak (0.7{\%}?K ) temperature response of SSA emissions on the climate sensitivity of the coupled climate model CM4. We find that the stronger temperature dependence improves the simulation of marine aerosol optical depth sensitivity to temperature and lowers CM4 Transient Climate Response (-0.12 K) and Equilibrium Climate Sensitivity (-0.5 K). At doubling, the higher SSA emission sensitivity causes a negative radiative feedback (-0.125 ), which can only be partly explained by changes in the radiative effect of SSA (-0.08 ). Stronger radiative feedbacks are dominated by more negative low-level cloud feedbacks in the Northern Hemisphere, which are partly offset by more positive feedbacks in the Southern Hemisphere associated with a weaker Atlantic Meridional Overturning Circulation.}, author = {Paulot, Fabien and Paynter, David and Winton, Michael and Ginoux, Paul and Zhao, Ming and Horowitz, Larry W}, doi = {10.1029/2019GL085601}, issn = {0094-8276}, journal = {Geophysical Research Letters}, month = {feb}, number = {3}, pages = {e2019GL085601}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Revisiting the Impact of Sea Salt on Climate Sensitivity}}, volume = {47}, year = {2020} } @article{Paulot2014, abstract = {We use the adjoint of a global 3-D chemical transport model (GEOS-Chem) to optimize ammonia (NH3) emissions in the U.S., European Union, and China by inversion of 2005?2008 network data for wet deposition fluxes. Optimized emissions are derived on a 2°???2.5° grid for individual months and years. Error characterization in the optimization includes model errors in precipitation. Annual optimized emissions are 2.8 Tg?NH3?N?a?1 for the contiguous U.S., 3.1 Tg?NH3?N a?1 for the European Union, and 8.4 Tg NH3?N?a?1 for China. Comparisons to previous inventories for the U.S. and European Union show consistency (?±15{\%}) in annual totals but some large spatial and seasonal differences. We develop a new global bottom-up inventory of NH3 emissions (Magnitude And Seasonality of Agricultural Emissions model for NH3 (MASAGE{\_}NH3)) to interpret the results of the adjoint optimization. MASAGE{\_}NH3 provides information on the magnitude and seasonality of NH3 emissions from individual crop and livestock sources on a 0.5°???0.5° grid. We find that U.S. emissions peak in the spring in the Midwest due to corn fertilization and in the summer elsewhere due to manure. The seasonality of European emissions is more homogeneous with a well-defined maximum in spring associated with manure and mineral fertilizer application. There is some evidence for the effect of European regulations of NH3 emissions, notably a large fall decrease in northern Europe. Emissions in China peak in summer because of the summertime application of fertilizer for double cropping.}, annote = {https://doi.org/10.1002/2013JD021130}, author = {Paulot, F and Jacob, D J and Pinder, R W and Bash, J O and Travis, K and Henze, D K}, doi = {https://doi.org/10.1002/2013JD021130}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {agriculture,ammonia,emission inventory,inverse method}, month = {apr}, number = {7}, pages = {4343--4364}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Ammonia emissions in the United States, European Union, and China derived by high-resolution inversion of ammonium wet deposition data: Interpretation with a new agricultural emissions inventory (MASAGE{\_}NH3)}}, url = {https://doi.org/10.1002/2013JD021130}, volume = {119}, year = {2014} } @article{Penuelas2010a, author = {Pe{\~{n}}uelas, Josep and Staudt, Michael}, doi = {10.1016/j.tplants.2009.12.005}, issn = {13601385}, journal = {Trends in Plant Science}, month = {mar}, number = {3}, pages = {133--144}, title = {{BVOCs and global change}}, volume = {15}, year = {2010} } @article{Peeters2009, abstract = {We propose, and quantify from first principles, two novel HOx-regenerating unimolecular reactions in isoprene oxidation, which are estimated to yield in pristine tropical forest conditions about 0.7 HO2 and 0.03 OH radicals per isoprene oxidized; it is further argued that the photolabile coproduct of HO2 can be a major source of OH, with a yield of the order of 1. The newly proposed chemistry could provide a rationalization for the unexpectedly high OH concentrations often observed in forested environments, such as over the Amazon forest in the recent Gabriel campaign.}, author = {Peeters, J and Nguyen, T L and Vereecken, L}, doi = {10.1039/B908511D}, issn = {1463-9076}, journal = {Physical Chemistry Chemical Physics}, number = {28}, pages = {5935--5939}, publisher = {The Royal Society of Chemistry}, title = {{HOx radical regeneration in the oxidation of isoprene}}, url = {http://dx.doi.org/10.1039/B908511D}, volume = {11}, year = {2009} } @article{Peeters2014, abstract = {The Leuven isoprene mechanism, proposed earlier to aid in rationalizing the unexpectedly high hydroxyl radical (OH) concentrations in isoprene-rich, low-nitric-oxide (NO) regions (Peeters; et al. Phys. Chem. Chem. Phys. 2009, 11, 5935), is presented in an upgraded and extended version, LIM1. The kinetics of the crucial reactions in the proposed isoprene-peroxy radical interconversion and isomerization pathways are re-evaluated theoretically, on the basis of energy barriers computed at the much higher CCSD(T)/aug-cc-pVTZ//QCISD/6-311G(d,p) level of theory, and using multiconformer partition functions obtained at the M06-2X/6-311++G(3df,2p) level that, different from the B3LYP level used in our earlier work, accounts for the crucial London dispersion effects in the H-bonded systems involved. The steady-state fraction of the specific Z-$\delta$-OH-peroxy radical isomers/conformers that can isomerize by a 1,6-H shift is shown to be largely governed by hydrogen-bond strengths, whereas their isomerization itself is found to occur quasi-exclusively by hydrogen atom tunneling. The isomer-specific Z-$\delta$-OH-peroxy 1,6-H-shift rate coefficients are predicted to be of the order of 1 s-1at 298 K, but the experimentally accessible bulk rate coefficients, which have to be clearly distinguished from the former, are 2 orders of magnitude lower due to the very low Z-$\delta$-OH-peroxy steady-state fractions that are only around or below 0.01 at low to moderate NO and depend on the peroxy lifetime. Two pathways subsequent to the peroxy radical 1,6-H shift are identified, the earlier predicted route yielding the photolabile hydroperoxy-methylbutenals (HPALDs), and a second, about equally important path, to dihydroperoxy-carbonyl peroxy radicals (di-HPCARP). Taking this into account, our predicted bulk peroxy isomerization rate coefficients are about a factor 1.8 higher than the available experimental results for HPALD production (Crounse; et al. Phys. Chem. Chem. Phys. 2011, 13, 13607), which is within the respective uncertainty margins. We also show that the experimental temperature dependence of the HPALD production rates as well as the observed kinetic isotope effect for per-deuterated isoprene support quantitatively our theoretical peroxy interconversion rates. Global modeling implementing LIM1 indicates that on average about 28{\%} of the isoprene peroxys react via the 1,6-H-shift isomerization route, representing 100-150 Tg carbon per year. The fast photolysis of HPALDs we proposed earlier as primary OH regeneration mechanism (Peeters and Muller. Phys. Chem. Chem. Phys. 2010, 12, 14227) found already experimental confirmation (Wolfe; et al. Phys. Chem. Chem. Phys. 2012, 14, 7276); based on further theoretical work in progress, reaction schemes are presented of the oxy coproduct radicals from HPALD photolysis and of the di-HPCARP radicals from the second pathway following peroxy isomerization that are both expected to initiate considerable additional OH recycling.}, author = {Peeters, Jozef and M{\"{u}}ller, Jean Fran{\c{c}}ois and Stavrakou, Trissevgeni and Nguyen, Vinh Son}, doi = {10.1021/jp5033146}, issn = {15205215}, journal = {Journal of Physical Chemistry A}, month = {sep}, number = {38}, pages = {8625--8643}, publisher = {American Chemical Society}, title = {{Hydroxyl radical recycling in isoprene oxidation driven by hydrogen bonding and hydrogen tunneling: The upgraded LIM1 mechanism}}, volume = {118}, year = {2014} } @article{ISI:000404504000110, abstract = {China is the world's top carbon emitter and suffers from severe air pollution. We examine near-term air quality and CO2co-benefits of various current sector-based policies in China. Using a 2015 base case, we evaluate the potential benefits of four sectoral mitigation strategies. All scenarios include a 20{\%} increase in conventional air pollution controls as well as the following sector-specific fuel switching or technology upgrade strategies. Power sector (POW): 80{\%} replacement of small coal power plants with larger more efficient ones; Industry sector (IND): 10{\%} improvement in energy efficiency; Transport sector (TRA): replacement of high emitters with average vehicle fleet emissions; and Residential sector (RES): replacement of 20{\%} of coal-based stoves with stoves using liquefied petroleum gas (LPG). Conducting an integrated assessment using the regional air pollution model WRF-Chem, we find that the IND scenario reduces national air-pollution-related deaths the most of the four scenarios examined (27,000, 24,000, 13,000 and 23,000 deaths reduced annually in IND, POW, TRA and RES, respectively). In addition, the IND scenario reduces CO2emissions more than 8 times as much as any other scenario (440, 53, 0 and 52 Mt CO2reduced in IND, POW, TRA and RES, respectively). We also examine the benefits of an industrial efficiency improvement of just 5{\%}. We find the resulting air quality and health benefits are still among the largest of the sectoral scenarios, while the carbon mitigation benefits remain more than 3 times larger than any other scenario. Our analysis hence highlights the importance of even modest industrial energy efficiency improvements and air pollution control technology upgrades for air quality, health and climate benefits in China.}, author = {Peng, Wei and Yang, Junnan and Wagner, Fabian and Mauzerall, Denise L.}, doi = {10.1016/j.scitotenv.2017.03.287}, issn = {18791026}, journal = {Science of the Total Environment}, keywords = {Air pollution,Climate change,Co-benefits,Industrial energy efficiency,Sectoral mitigation,WRF-Chem}, month = {nov}, pages = {1076--1084}, pmid = {28482455}, title = {{Substantial air quality and climate co-benefits achievable now with sectoral mitigation strategies in China}}, volume = {598}, year = {2017} } @article{acp-16-14545-2016, author = {Peng, S and Piao, S and Bousquet, P and Ciais, P and Li, B and Lin, X and Tao, S and Wang, Z and Zhang, Y and Zhou, F}, doi = {10.5194/acp-16-14545-2016}, journal = {Atmospheric Chemistry and Physics}, number = {22}, pages = {14545--14562}, title = {{Inventory of anthropogenic methane emissions in mainland China from 1980 to 2010}}, url = {https://www.atmos-chem-phys.net/16/14545/2016/}, volume = {16}, year = {2016} } @article{Penner2015, abstract = {Cirrus cloud seeding has been proposed as a possible technique that might thin cirrus clouds leading to reduced heating. The technique was shown to be viable in one model evaluation. Here we use an updated version of the Community Atmosphere Model version 5 (CAM5) and reevaluate whether seeding is a viable mechanism for cooling. We explore different model setups (with and without secondary organic aerosols acting as heterogeneous ice nuclei). None of the updated versions of the CAM5 lead to a significant amount of negative climate forcing and hence do not lead to cooling. We only calculate a net negative cloud forcing (-0.74 ± 0.25 W m-2) if we restrict the modeled subgrid-scale updraft velocity during nucleation to {\textless}0.2 m s-1 and if the deposition of water vapor onto preexisting ice crystals during nucleation is not included. Hence, we do not find that cirrus cloud seeding is a viable climate intervention technique. Key Points Cirrus cloud seeding only works to cool climate for restricted model setup The most recent version of CAM5 predicts warming Mechanisms that attempt to restrict seeding to polar regions may not cool}, author = {Penner, Joyce E. and Zhou, Cheng and Liu, Xiaohong}, doi = {10.1002/2015GL065992}, issn = {00948276}, journal = {Geophysical Research Letters}, keywords = {cirrus clouds,cloud seeding,geoengineering}, month = {oct}, number = {20}, pages = {8775--8782}, title = {{Can cirrus cloud seeding be used for geoengineering?}}, url = {http://doi.wiley.com/10.1002/2015GL065992}, volume = {42}, year = {2015} } @article{Penrod2014533, abstract = {Changes in climate and emissions will affect future air quality. In this work, simulations of regional air quality during current (2001-2005) and future (2026-2030) winter and summer are conducted with the newly released CMAQ version 5.0 to examine the impacts of simulated future climate and anthropogenic emission projections on air quality over the U.S. Current meteorological and chemical predictions are evaluated against observations to assess the model's capability in reproducing the seasonal differences. WRF and CMAQ capture the overall observational spatial patterns and seasonal differences. Biases in model predictions are attributed to uncertainties in emissions, boundary conditions, and limitations in model physical and chemical treatments as well as the use of a coarse grid resolution. Increased temperatures (up to 3.18°C) and decreased ventilation (up to 157m in planetary boundary layer height) are found in both future winter and summer, with more prominent changes in winter. Increases in future temperatures result in increased isoprene and terpene emissions in winter and summer, driving the increase in maximum 8-h average O3(up to 5.0ppb) over the eastern U.S. in winter while decreases in NOxemissions drive the decrease in O3over most of the U.S. in summer. Future PM2.5concentrations in winter and summer and many of its components decrease due to decreases in primary anthropogenic emissions and the concentrations of secondary anthropogenic pollutants as well as increased precipitation in winter. Future winter and summer dry and wet deposition fluxes are spatially variable and increase with decreasing surface resistance and precipitation, respectively. They decrease with a decrease in ambient particulate concentrations. Anthropogenic emissions play a more important role in summer than in winter for future O3and PM2.5levels, with a dominance of the effects of significant emission reductions over those of climate change on future PM2.5levels. {\textcopyright} 2014 Elsevier Ltd.}, annote = {cited By 33}, author = {Penrod, Ashley and Zhang, Yang and Wang, Kai and Wu, Shiang Yuh and Leung, L. Ruby}, doi = {10.1016/j.atmosenv.2014.01.001}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Air quality,CMAQ,Emissions,Future climate change,Model evaluation,WRF}, pages = {533--547}, title = {{Impacts of future climate and emission changes on U.S. air quality}}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84895991872{\&}doi=10.1016{\%}2Fj.atmosenv.2014.01.001{\&}partnerID=40{\&}md5=a9cb41cabf0b8d7c85e6d721576c262d}, volume = {89}, year = {2014} } @article{Persad2018a, author = {Persad, Geeta G. and Caldeira, Ken}, doi = {10.1038/s41467-018-05838-6}, issn = {2041-1723}, journal = {Nature Communications}, month = {dec}, number = {1}, pages = {3289}, title = {{Divergent global-scale temperature effects from identical aerosols emitted in different regions}}, url = {http://www.nature.com/articles/s41467-018-05838-6}, volume = {9}, year = {2018} } @article{Petetin2018, abstract = {In the framework of the In Service Aircraft for Global Observing System (IAGOS) program, airborne in-situ O3 and CO measurements are performed routinely using in-service aircraft, providing vertical profiles from the surface to about 10–12 km. Due to the specificity of IAGOS measurements (measurements around busy international airports), uncertainties exist on their representativeness in the lower troposphere as they may be impacted by emissions related to airport activities and/or other aircraft. In this study, we thus investigate how the IAGOS measurements in the lower troposphere compare with nearby surface stations (from the local Air Quality monitoring network (AQN)) and more distant regional surface stations (from the Global Atmospheric Watch (GAW) network). The study focuses on Frankfurt but some results at other European airports (Vienna, Paris) are also discussed.}, author = {Petetin, H. and Jeoffrion, M. and Sauvage, B. and Athier, G. and Blot, R. and Boulanger, D. and Clark, H. and Cousin, J.-M. and Gheusi, F. and Nedelec, P. and Steinbacher, M. and Thouret, V.}, doi = {10.1525/elementa.280}, editor = {Helmig, Detlev and Flocke, Frank}, issn = {2325-1026}, journal = {Elementa: Science of the Anthropocene}, month = {jan}, pages = {23}, title = {{Representativeness of the IAGOS airborne measurements in the lower troposphere}}, url = {https://online.ucpress.edu/elementa/article/doi/10.1525/elementa.280/112783/Representativeness-of-the-IAGOS-airborne}, volume = {6}, year = {2018} } @article{acp-15-2985-2015, abstract = {Aerosol mass spectrometer (AMS) measurements have been successfully used towards a better understanding of non-refractory submicron (PM1) aerosol chemical proper- ties based on short-term campaigns. The recently developed Aerosol Chemical Speciation Monitor (ACSM) has been de- signed to deliver quite similar artifact-free chemical infor- mation but for low cost, and to perform robust monitor- ing over long-term periods. When deployed in parallel with real-time black carbon (BC) measurements, the combined data set allows for a quasi-comprehensive description of the whole PM1 fraction in near real time. Here we present 2- year long ACSM and BC data sets, between mid-2011 and mid-2013, obtained at the French atmospheric SIRTA su- persite that is representative of background PM levels of the region of Paris. This large data set shows intense and time-limited (a few hours) pollution events observed dur- ing wintertime in the region of Paris, pointing to local car- bonaceous emissions (mainly combustion sources). A non- parametric wind regression analysis was performed on this 2-year data set for the major PM1 constituents (organic mat- ter, nitrate, sulfate and source apportioned BC) and ammo- nia in order to better refine their geographical origins and assess local/regional/advected contributions whose informa- tion is mandatory for efficient mitigation strategies. While ammonium sulfate typically shows a clear advected pattern, ammonium nitrate partially displays a similar feature, but, less expectedly, it also exhibits a significant contribution of regional and local emissions. The contribution of regional background organic aerosols (OA) is significant in spring and summer, while a more pronounced local origin is evi- denced during wintertime, whose pattern is also observed for BC originating from domestic wood burning. Using time- resolved ACSM and BC information, seasonally differenti- ated weekly diurnal profiles of these constituents were inves- tigated and helped to identify the main parameters control- ling their temporal variations (sources, meteorological pa- rameters). Finally, a careful investigation of all the major pol- lution episodes observed over the region of Paris between 2011 and 2013 was performed and classified in terms of chemical composition and the BC-to-sulfate ratio used here as a proxy of the local/regional/advected contribution of PM. In conclusion, these first 2-year quality-controlled measure- ments of ACSM clearly demonstrate their great potential to monitor on a long-term basis aerosol sources and their ge- ographical origin and provide strategic information in near real time during pollution episodes. They also support the ca- pacity of the ACSM to be proposed as a robust and credible alternative to filter-based sampling techniques for long-term monitoring strategies.}, author = {Petit, J.-E. and Favez, O and Sciare, J and Crenn, V and Sarda-Est{\`{e}}ve, R and Bonnaire, N and Mo{\v{c}}nik, G and Dupont, J.-C. and Haeffelin, M and Leoz-Garziandia, E}, doi = {10.5194/acp-15-2985-2015}, journal = {Atmospheric Chemistry and Physics}, number = {6}, pages = {2985--3005}, title = {{Two years of near real-time chemical composition of submicron aerosols in the region of Paris using an Aerosol Chemical Speciation Monitor (ACSM) and a multi-wavelength Aethalometer}}, url = {https://acp.copernicus.org/articles/15/2985/2015/}, volume = {15}, year = {2015} } @article{Petrenko2013, abstract = {{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} We present the first reconstruction of the Northern Hemisphere (NH) high latitude atmospheric carbon monoxide (CO) mole fraction from Greenland firn air. Firn air samples were collected at three deep ice core sites in Greenland (NGRIP in 2001, Summit in 2006 and NEEM in 2008). CO records from the three sites agree well with each other as well as with recent atmospheric measurements, indicating that CO is well preserved in the firn at these sites. CO atmospheric history was reconstructed back to the year 1950 from the measurements using a combination of two forward models of gas transport in firn and an inverse model. The reconstructed history suggests that Arctic CO in 1950 was 140–150 nmol mol{\textless}sup{\textgreater}−1{\textless}/sup{\textgreater}, which is higher than today's values. CO mole fractions rose by 10–15 nmol mol{\textless}sup{\textgreater}−1{\textless}/sup{\textgreater} from 1950 to the 1970s and peaked in the 1970s or early 1980s, followed by a ≈ 30 nmol mol{\textless}sup{\textgreater}−1{\textless}/sup{\textgreater} decline to today's levels. We compare the CO history with the atmospheric histories of methane, light hydrocarbons, molecular hydrogen, CO stable isotopes and hydroxyl radicals (OH), as well as with published CO emission inventories and results of a historical run from a chemistry-transport model. We find that the reconstructed Greenland CO history cannot be reconciled with available emission inventories unless unrealistically large changes in OH are assumed. We argue that the available CO emission inventories strongly underestimate historical NH emissions, and fail to capture the emission decline starting in the late 1970s, which was most likely due to reduced emissions from road transportation in North America and Europe.{\textless}/p{\textgreater}}, author = {Petrenko, V. V. and Martinerie, P. and Novelli, P. and Etheridge, D. M. and Levin, I. and Wang, Z. and Blunier, T. and Chappellaz, J. and Kaiser, J. and Lang, P. and Steele, L. P. and Hammer, S. and Mak, J. and Langenfelds, R. L. and Schwander, J. and Severinghaus, J. P. and Witrant, E. and Petron, G. and Battle, M. O. and Forster, G. and Sturges, W. T. and Lamarque, J. F. and Steffen, K. and White, J. W.C.}, doi = {10.5194/acp-13-7567-2013}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, number = {15}, pages = {7567--7585}, title = {{A 60 yr record of atmospheric carbon monoxide reconstructed from Greenland firn air}}, volume = {13}, year = {2013} } @article{Petzold2013a, abstract = {Although black carbon (BC) is one of the key atmospheric particulate components driving climate change and air quality, there is no agreement on the terminology that considers all aspects of specific properties, definitions, measurement methods, and related uncertainties. As a result, there is much ambiguity in the scientific literature of measurements and numerical models that refer to BC with different names and based on different properties of the particles, with no clear definition of the terms. The authors present here a recommended terminology to clarify the terms used for BC in atmospheric research, with the goal of establishing unambiguous links between terms, targeted material properties and associated measurement techniques. {\textcopyright} 2013 Author(s).}, author = {Petzold, A. and Ogren, J. A. and Fiebig, M. and Laj, P. and Li, S. M. and Baltensperger, U. and Holzer-Popp, T. and Kinne, S. and Pappalardo, G. and Sugimoto, N. and Wehrli, C. and Wiedensohler, A. and Zhang, X. Y.}, doi = {10.5194/acp-13-8365-2013}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, month = {aug}, number = {16}, pages = {8365--8379}, title = {{Recommendations for reporting black carbon measurements}}, url = {https://acp.copernicus.org/articles/13/8365/2013/}, volume = {13}, year = {2013} } @article{Pierce2010, abstract = {Recent analysis suggests that the effectiveness of stratospheric aerosol climate engineering through emission of non-condensable vapors such as SO {\textless}inf{\textgreater}2{\textless}/inf{\textgreater} is limited because the slow conversion to H{\textless}inf{\textgreater}2{\textless}/inf{\textgreater}SO {\textless}inf{\textgreater}4{\textless}/inf{\textgreater} tends to produce aerosol particles that are too large; SO {\textless}inf{\textgreater}2{\textless}/inf{\textgreater} injection may be so inefficient that it is difficult to counteract the radiative forcing due to a CO{\textless}inf{\textgreater}2{\textless}/inf{\textgreater} doubling. Here we describe an alternate method in which aerosol is formed rapidly in the plume following injection of H{\textless}inf{\textgreater}2{\textless}/inf{\textgreater}SO{\textless}inf{\textgreater}4{\textless}/inf{\textgreater}, a condensable vapor, from an aircraft. This method gives better control of particle size and can produce larger radiative forcing with lower sulfur loadings than SO{\textless}inf{\textgreater}2{\textless}/inf{\textgreater} injection. Relative to SO{\textless}inf{\textgreater}2{\textless}/inf{\textgreater} injection, it may reduce some of the adverse effects of geoengineering such as radiative heating of the lower stratosphere. This method does not, however, alter the fact that such a geoengineered radiative forcing can, at best, only partially compensate for the climate changes produced by CO{\textless}inf{\textgreater}2{\textless}/inf{\textgreater}. {\textcopyright} 2010 by the American Geophysical Union.}, author = {Pierce, Jeffrey R. and Weisenstein, Debra K. and Heckendorn, Patricia and Peter, Thomas and Keith, David W.}, doi = {10.1029/2010GL043975}, issn = {00948276}, journal = {Geophysical Research Letters}, month = {sep}, number = {18}, pages = {L18805}, title = {{Efficient formation of stratospheric aerosol for climate engineering by emission of condensible vapor from aircraft}}, url = {http://doi.wiley.com/10.1029/2010GL043975}, volume = {37}, year = {2010} } @article{Pierrehumbert2014b, abstract = {Although carbon dioxide emissions are by far the most important mediator of anthropogenic climate disruption, a number of shorter-lived substances with atmospheric lifetimes of under a few decades also contribute significantly to the radiative forcing that drives climate change. In recent years, the argument that early and aggressive mitigation of the emission of these substances or their precursors forms an essential part of any climate protection strategy has gained a considerable following. There is often an implication that such control can in some way make up for the current inaction on carbon dioxide emissions. The prime targets for mitigation, known collectively as short-lived climate pollution (SLCP), are methane, hydrofluo-rocarbons, black carbon, and ozone. A re-examination of the issues shows that the benefits of early SLCP mitigation have been greatly exaggerated, largely because of inadequacies in the methodologies used to compare the climate effects of short-lived substances with those of CO...}, annote = {From Duplicate 1 (Short-Lived Climate Pollution - Pierrehumbert, R.T. T) From Duplicate 1 (Short-Lived Climate Pollution - Pierrehumbert, R T) Times Cited: 37 Pierrehumbert, Raymond/0000-0002-5887-1197 0084-6597 From Duplicate 2 (Short-Lived Climate Pollution - Pierrehumbert, R T) Times Cited: 37 Pierrehumbert, Raymond/0000-0002-5887-1197 0084-6597}, author = {Pierrehumbert, R.T.}, doi = {10.1146/annurev-earth-060313-054843}, editor = {Jeanloz, R}, isbn = {978-0-8243-2042-3}, issn = {0084-6597}, journal = {Annual Review of Earth and Planetary Sciences}, keywords = {carbon dioxide,climate policy,gas mitigation,global warming,global warming potential,greenhouse,hfc,methane,short-lived climate pollution}, month = {may}, number = {1}, pages = {341--379}, title = {{Short-Lived Climate Pollution}}, url = {http://www.annualreviews.org/doi/10.1146/annurev-earth-060313-054843}, volume = {42}, year = {2014} } @article{Pinder2006, abstract = {Current regulation aimed at reducing inorganic atmospheric fine particulate matter (PM2.5) is focused on reductions in sulfur dioxide (SO2) and oxides of nitrogen (NOx ≡ NO + NO2); however, controls on these pollutants are likely to increase in cost and decrease in effectiveness in the future. A supplementary strategy is reduction in ammonia (NH3) emissions, yet an evaluation of controls on ammonia has been limited by uncertainties in emission levels and in the cost of control technologies. We use state of the science emission inventories, an emission-based regional air quality model, and an explicit treatment of uncertainty to estimate the cost-effectiveness and uncertainty of ammonia emission reductions on inorganic particulate matter in the Eastern United States. Since a paucity of data on agricultural operations precludes a direct calculation of the costs of ammonia control, we calculate the ?ammonia savings potential?, defined as the minimum cost of applying SO2 and NOx emission controls in order to achieve the same reduction in ambient inorganic PM2.5 concentration as obtained from a 1 ton decrease in ammonia emissions. Using 250 scenarios of NH3, SO2, and NOx emission reductions, we calculate the least-cost SO2 and NOx control scenarios that achieve the same reduction in ambient inorganic PM2.5 concentration as a decrease in ammonia emissions. We find that the lower-bound ammonia savings potential in the winter is {\$}8,000 per ton NH3; therefore, many currently available ammonia control technologies are cost-effective compared to current controls on SO2 and NOx sources. Larger reductions in winter inorganic particulate matter are available at lower cost through controls on ammonia emissions. Current regulation aimed at reducing inorganic atmospheric fine particulate matter (PM2.5) is focused on reductions in sulfur dioxide (SO2) and oxides of nitrogen (NOx ≡ NO + NO2); however, controls on these pollutants are likely to increase in cost and decrease in effectiveness in the future. A supplementary strategy is reduction in ammonia (NH3) emissions, yet an evaluation of controls on ammonia has been limited by uncertainties in emission levels and in the cost of control technologies. We use state of the science emission inventories, an emission-based regional air quality model, and an explicit treatment of uncertainty to estimate the cost-effectiveness and uncertainty of ammonia emission reductions on inorganic particulate matter in the Eastern United States. Since a paucity of data on agricultural operations precludes a direct calculation of the costs of ammonia control, we calculate the ?ammonia savings potential?, defined as the minimum cost of applying SO2 and NOx emission controls in order to achieve the same reduction in ambient inorganic PM2.5 concentration as obtained from a 1 ton decrease in ammonia emissions. Using 250 scenarios of NH3, SO2, and NOx emission reductions, we calculate the least-cost SO2 and NOx control scenarios that achieve the same reduction in ambient inorganic PM2.5 concentration as a decrease in ammonia emissions. We find that the lower-bound ammonia savings potential in the winter is {\$}8,000 per ton NH3; therefore, many currently available ammonia control technologies are cost-effective compared to current controls on SO2 and NOx sources. Larger reductions in winter inorganic particulate matter are available at lower cost through controls on ammonia emissions.}, author = {Pinder, Robert W and Adams, Peter J and Pandis, Spyros N}, doi = {10.1021/es060379a}, issn = {0013-936X}, journal = {Environmental Science {\&} Technology}, month = {jan}, number = {2}, pages = {380--386}, title = {{Ammonia Emission Controls as a Cost-Effective Strategy for Reducing Atmospheric Particulate Matter in the Eastern United States}}, url = {http://pubs.acs.org/doi/full/10.1021/es060379a https://pubs.acs.org/doi/10.1021/es060379a}, volume = {41}, year = {2007} } @article{Pommier2018, abstract = {Abstract. Eleven of the world's 20 most polluted cities are located in India and poor air quality is already a major public health issue. However, anthropogenic emissions are predicted to increase substantially in the short-term (2030) and medium-term (2050) futures in India, especially if no further policy efforts are made. In this study, the EMEP/MSC-W chemical transport model has been used to predict changes in surface ozone (O3) and fine particulate matter (PM2.5) for India in a world of changing emissions and climate. The reference scenario (for present-day) is evaluated against surface-based measurements, mainly at urban stations. The evaluation has also been extended to other data sets which are publicly available on the web but without quality assurance. The evaluation shows high temporal correlation for O3 (r = 0.9) and high spatial correlation for PM2.5 (r = 0.5 and r = 0.8 depending on the data set) between the model results and observations. While the overall bias in PM2.5 is small (lower than 6 {\%}), the model overestimates O3 by 35 {\%}. The underestimation in NOx titration is probably the main reason for the O3 overestimation in the model. However, the level of agreement can be considered satisfactory in this case of a regional model being evaluated against mainly urban measurements, and given the inevitable uncertainties in much of the input data.For the 2050s, the model predicts that climate change will have distinct effects in India in terms of O3 pollution, with a region in the north characterized by a statistically significant increase by up to 4 {\%} (2 ppb) and one in the south by a decrease up to −3 {\%} (−1.4 ppb). This variation in O3 is assumed to be partly related to changes in O3 deposition velocity caused by changes in soil moisture and, over a few areas, partly also by changes in biogenic non-methane volatile organic compounds.Our calculations suggest that PM2.5 will increase by up to 6.5 {\%} over the Indo-Gangetic Plain by the 2050s. The increase over India is driven by increases in dust, particulate organic matter (OM) and secondary inorganic aerosols (SIAs), which are mainly affected by the change in precipitation, biogenic emissions and wind speed.The large increase in anthropogenic emissions has a larger impact than climate change, causing O3 and PM2.5 levels to increase by 13 and 67 {\%} on average in the 2050s over the main part of India, respectively. By the 2030s, secondary inorganic aerosol is predicted to become the second largest contributor to PM2.5 in India, and the largest in the 2050s, exceeding OM and dust.}, author = {Pommier, Matthieu and Fagerli, Hilde and Gauss, Michael and Simpson, David and Sharma, Sumit and Sinha, Vinay and Ghude, Sachin D. and Landgren, Oskar and Nyiri, Agnes and Wind, Peter}, doi = {10.5194/acp-18-103-2018}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jan}, number = {1}, pages = {103--127}, title = {{Impact of regional climate change and future emission scenarios on surface O3 and PM2.5 over India}}, url = {https://acp.copernicus.org/articles/18/103/2018/}, volume = {18}, year = {2018} } @article{Ponater2005, abstract = {In equilibrium climate change simulations with a global climate model we estimate the climate sensitivity parameter to contrail cirrus to be 0.43 K/(Wm?2), only about 60{\%} of the corresponding value for a CO2 forcing. The spatial pattern of the surface temperature response is much smoother than the forcing pattern of contrails with little correlation between both. As the thermal inertia of the climate system causes a marked delay of the transient response, only about 30{\%} of the equilibrium surface warming to be expected from some aircraft induced radiative forcing is actually realised for aviation increase rates typical for the 1990s. Our findings do not confirm recent results of a dominating influence of contrail cirrus on temperature change over the United States between 1975 and 1994.}, annote = {https://doi.org/10.1029/2005GL022580}, author = {Ponater, M and Marquart, S and Sausen, R and Schumann, U}, doi = {https://doi.org/10.1029/2005GL022580}, issn = {0094-8276}, journal = {Geophysical Research Letters}, month = {may}, number = {10}, pages = {L10706}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{On contrail climate sensitivity}}, url = {https://doi.org/10.1029/2005GL022580}, volume = {32}, year = {2005} } @article{Porter201510349, abstract = {Air pollution variability is strongly dependent on meteorology. However, quantifying the impacts of changes in regional climatology on pollution extremes can be difficult due to the many non-linear and competing meteorological influences on the production, transport, and removal of pollutant species. Furthermore, observed pollutant levels at many sites show sensitivities at the extremes that differ from those of the overall mean, indicating relationships that would be poorly characterized by simple linear regressions. To address this challenge, we apply quantile regression to observed daily ozone (O-3) and fine particulate matter (PM2.5) levels and reanalysis meteorological fields in the USA over the past decade to specifically identify the meteorological sensitivities of higher pollutant levels. From an initial set of over 1700 possible meteorological indicators (including 28 meteorological variables with 63 different temporal options), we generate reduced sets of O-3 and PM2.5 indicators for both summer and winter months, analyzing pollutant sensitivities to each for response quantiles ranging from 2 to 98 {\%}. Primary covariates connected to high-quantile O-3 levels include temperature and relative humidity in the summer, while winter O-3 levels are most commonly associated with incoming radiation flux. Covariates associated with summer PM2.5 include temperature, wind speed, and tropospheric stability at many locations, while stability, humidity, and planetary boundary layer height are the key covariates most frequently associated with winter PM2.5. We find key differences in covariate sensitivities across regions and quantiles. For example, we find nationally averaged sensitivities of 95th percentile summer O-3 to changes in maximum daily temperature of approximately 0.9 ppb A degrees C-1, while the sensitivity of 50th percentile summer O-3 (the annual median) is only 0.6 ppb A degrees C-1. This gap points to differing sensitivities within various percentiles of the pollutant distribution, highlighting the need for statistical tools capable of identifying meteorological impacts across the entire response spectrum.}, annote = {cited By 13}, author = {Porter, W. C. and Heald, C. L. and Cooley, D. and Russell, B.}, doi = {10.5194/acp-15-10349-2015}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {18}, pages = {10349--10366}, title = {{Investigating the observed sensitivities of air-quality extremes to meteorological drivers via quantile regression}}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84942163801{\&}doi=10.5194{\%}2Facp-15-10349-2015{\&}partnerID=40{\&}md5=1b24744b800cacd300a560e1101aaa0f}, volume = {15}, year = {2015} } @article{Possell2005b, author = {Possell, Malcolm and {Nicholas Hewitt}, C. and Beerling, David J.}, doi = {10.1111/j.1365-2486.2004.00889.x}, issn = {1354-1013}, journal = {Global Change Biology}, month = {jan}, number = {1}, pages = {60--69}, title = {{The effects of glacial atmospheric CO2 concentrations and climate on isoprene emissions by vascular plants}}, url = {http://doi.wiley.com/10.1111/j.1365-2486.2004.00889.x}, volume = {11}, year = {2005} } @article{Potosnak2014b, author = {Potosnak, Mark J. and LeStourgeon, Lauren and Pallardy, Stephen G. and Hosman, Kevin P. and Gu, Lianhong and Karl, Thomas and Geron, Chris and Guenther, Alex B.}, doi = {10.1016/j.atmosenv.2013.11.055}, issn = {13522310}, journal = {Atmospheric Environment}, month = {feb}, pages = {314--322}, title = {{Observed and modeled ecosystem isoprene fluxes from an oak-dominated temperate forest and the influence of drought stress}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1352231013009059}, volume = {84}, year = {2014} } @incollection{Prather2001, address = {Cambridge, United Kingdom and New York, NY, USA}, author = {Prather, M J and Ehhalt, D and F.J.Dentener and Derwent, R and Dlugokencky, E and Holland, E and Isaksen, I and Katima, J and Kirchhoff, V and Matson, P and Midgley, P and Wang, M and Houghton, J T}, booktitle = {Climate Change 2001: The Physical Science Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change}, doi = {https://www.ipcc.ch/report/ar3/wg1}, editor = {{Y. Ding} and {D.J. Griggs} and {M. Noguer} and {P.J. van der Linden} and {X. Dai} and {K. Maskell} and Johnson, C A}, isbn = {0521807670}, pages = {239--287}, publisher = {Cambridge University Press}, title = {{Atmospheric Chemistry and Greenhouse Gases}}, url = {https://www.ipcc.ch/report/ar3/wg1}, year = {2001} } @article{Prather2012b, abstract = {Knowledge of the atmospheric chemistry of reactive greenhouse gases is needed to accurately quantify the relationship between human activities and climate, and to incorporate uncertainty in our projections of greenhouse gas abundances. We present a method for estimating the fraction of greenhouse gases attributable to human activities, both currently and for future scenarios. Key variables used to calculate the atmospheric chemistry and budgets of major non‐CO2greenhouse gases are codified along with their uncertainties, and then used to project budgets and abundances under the new climate‐change scenarios. This new approach uses our knowledge of changing abundances and lifetimes to estimate current total anthropogenic emissions, independently and possibly more accurately than inventory‐based scenarios. We derive a present‐day atmospheric lifetime for methane (CH4) of 9.1 ± 0.9 y and anthropogenic emissions of 352 ± 45 Tg/y (64{\%} of total emissions). For N2O, corresponding values are 131 ± 10 y and 6.5 ± 1.3 TgN/y (41{\%} of total); and for HFC‐134a, the lifetime is 14.2 ± 1.5 y.}, author = {Prather, Michael J and Holmes, Christopher D and Hsu, Juno}, doi = {10.1029/2012GL051440}, issn = {00948276}, journal = {Geophysical Research Letters}, month = {may}, number = {9}, pages = {L09803}, title = {{Reactive greenhouse gas scenarios: Systematic exploration of uncertainties and the role of atmospheric chemistry}}, url = {https://doi.org/10.1029/2012GL051440 http://doi.wiley.com/10.1029/2012GL051440}, volume = {39}, year = {2012} } @article{Prather1994, abstract = {The time scales and mode of the atmosphere's response to chemical perturbations are defined by the eigenvalues and eigenvectors of the system. The eigenstates of a simplified one‐box CH4‐CO‐OH system are analyzed. The longest time constant (smallest eigenvalue) always exceeds the lifetime defined by the steady‐state loss frequency for CH4, the longest lived gas. Thus, the extent of a CH4 perturbation—the methane response time—is always longer than predicted by the steady‐state lifetime and is independent of size of the perturbation in the linear limit. This lengthening of the atmospheric recovery time can be diagnosed by how close we are to a chemically unstable troposphere, i.e., how much OH production exceeds that minimum needed to oxidize just the global emissions of CH4, CO, and other hydrocarbons and species. Copyright 1994 by the American Geophysical Union.}, author = {Prather, Michael J.}, doi = {10.1029/94GL00840}, issn = {19448007}, journal = {Geophysical Research Letters}, number = {9}, pages = {801--804}, title = {{Lifetimes and eigenstates in atmospheric chemistry}}, volume = {21}, year = {1994} } @article{Prather2017, abstract = {Methane lies at the nexus of climate and air quality, being both a major anthropogenic greenhouse gas—causing about one-half of the warming of carbon dioxide—and a precursor of tropospheric ozone pollution. Over the industrial era, atmospheric methane abundances rose from about 720 parts per billion (ppb) (10−9 mole fraction) to over 1,850 ppb today. Humans have driven this change largely through agriculture, waste, and fossil fuel emissions. The community's regular review of the science of atmospheric methane via the Intergovernmental Panel on Climate Change (IPCC) Assessment Reports [First Assessment Report (FAR), 1990 (1); Second Assessment Report (SAR), 1995 (2); Third Assessment Report (TAR), 2001 (3); Fourth Assessment Report (AR4), 2007 (4); and Fifth Assessment Report (AR5), 2013 (5)] has maintained both a scientific interest and political urgency as nations seek to mitigate near-term climate change and keep the overall warming to less than 2 °C (6⇓⇓–9). The recent history (Fig. 1), based on ref. 10, shows a complex overall growth with different rates and even a pause from 2000 to 2006. The many conflicting reports of this recent variability (11⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓–23) suggest that it remains unexplained, or perhaps overexplained. Past work has separately used measurements of methane, its isotopes, and related gases to interpret the methane history. Two new publications (24, 25) combine these complementary data into a consistent Bayesian modeling framework and use advanced statistical methods to match all observations simultaneously subject to the prior constraints. Notably, they advance our understanding of what could have caused the variability. The similarities and differences of optimal solutions that emerge from both studies teach us about the information contained in present observations, as well as their limits.Fig. 1. (A) Timeline of the international assessments {\ldots} ↵1To whom correspondence should be addressed. Email: mprather{\{}at{\}}uci.edu.}, author = {Prather, Michael J and Holmes, Christopher D}, doi = {10.1073/pnas.1704884114}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, month = {may}, number = {21}, pages = {5324--5326}, title = {{Overexplaining or underexplaining methane's role in climate change}}, url = {http://www.pnas.org/content/114/21/5324.abstract http://www.pnas.org/lookup/doi/10.1073/pnas.1704884114}, volume = {114}, year = {2017} } @article{https://doi.org/10.1029/96GL02371, abstract = {Atmospheric CH4 perturbations, caused directly by CH4 emissions or indirectly by those of CO are enhanced by chemical feedbacks. They can be diagnosed in terms of the natural modes of atmospheric chemistry that are general solutions of the continuity equations. Each mode is a pattern in the global distribution of all chemical species, and each has a single time-constant that accurately describes its exponential decay about a given atmospheric state. This mathematical theory extends earlier work and is general for 2-D and 3-D chemistry-transport models. A formal proof relates the steady-state distribution and its lifetime to the integral of the true time-dependent response (properly included in the recent IPCC assessment). Changes in CO are also known to perturb CH4; however, the impact of CO emissions on climate has not been formally assessed in part because the short lifetime of CO (months) relative to that of CH4 (decade) was believed to limit the integrated impact. Using the IPCC model studies, this theory predicts that adding 5 CO molecules to today's atmosphere is equivalent to adding 1 CH4 molecule with the same decadal duration as direct CH4 addition. Extrapolating these results, CH4 sources would have to triple before runaway growth, wherein CH4 emissions exceed the oxidizing capacity of the troposphere.}, author = {Prather, Michael J}, doi = {https://doi.org/10.1029/96GL02371}, journal = {Geophysical Research Letters}, number = {19}, pages = {2597--2600}, title = {{Time scales in atmospheric chemistry: Theory, GWPs for CH4 and CO, and runaway growth}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/96GL02371}, volume = {23}, year = {1996} } @article{Price1992, abstract = {A simple parameterization has been developed to simulate global lightning distributions. Convective cloud top height is used as the variable in the parameterization, with different formulations for continental and marine thunderstorms. The parameterization has been validated using two lightning data sets: one global and one regional. In both cases the simulated lightning distributions and frequencies are in very good agreement with the observed lightning data. This parameterization could be used for global studies of lightning climatology; the Earth's electric circuit; in general circulation models for modeling global lightning activity, atmospheric NOx concentrations, and perhaps forest fire distributions for both the present and future climate; and, possibly, even as a short-term forecasting aid.}, author = {Price, Colin and Rind, David}, doi = {10.1029/92JD00719}, isbn = {0148-0227}, issn = {01480227}, journal = {Journal of Geophysical Research: Atmospheres}, month = {jun}, number = {D9}, pages = {9919--9933}, title = {{A simple lightning parameterization for calculating global lightning distributions}}, url = {http://doi.wiley.com/10.1029/92JD00719}, volume = {97}, year = {1992} } @article{Pringle2012, abstract = {Abstract. Artificially increasing the albedo of marine boundary layer clouds by the mechanical emission of sea spray aerosol has been proposed as a geoengineering technique to slow the warming caused by anthropogenic greenhouse gases. A previous global model study (Korhonen et al., 2010) found that only modest increases ( 250–300 nm, the background aerosol loading is large (≥ 150 cm−3) and the in-cloud updraught velocity is low ( 50{\%} cloud cover, irrespective of the amount of aerosol injected. But at stronger updraft speeds (0.2 m s−1), higher values of CDN are achievable due to the elevated in-cloud supersaturations. Achieving a value of 375 cm−3 in regions dominated by stratocumulus clouds with relatively weak updrafts cannot be attained regardless of the number of injected particles, thereby limiting the efficacy of sea spray geoengineering.}, author = {Pringle, K. J. and Carslaw, K. S. and Fan, T. and Mann, G.W. and Hill, A. and Stier, P. and Zhang, K. and Tost, H.}, doi = {10.5194/acp-12-11647-2012}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {dec}, number = {23}, pages = {11647--11663}, title = {{A multi-model assessment of the impact of sea spray geoengineering on cloud droplet number}}, url = {https://acp.copernicus.org/articles/12/11647/2012/}, volume = {12}, year = {2012} } @article{Prinn2018, abstract = {We present the organization, instrumentation, datasets, data interpretation, modeling, and accomplishments of the multinational global atmospheric measurement program AGAGE (Advanced Global Atmospheric Gases Experiment). AGAGE is distinguished by its capability to measure globally, at high frequency, and at multiple sites all the important species in the Montreal Protocol and all the important non-carbon-dioxide (non-CO2) gases assessed by the Intergovernmental Panel on Climate Change (CO2 is also measured at several sites). The scientific objectives of AGAGE are important in furthering our understanding of global chemical and climatic phenomena. They are the following: (1) to accurately measure the temporal and spatial distributions of anthropogenic gases that contribute the majority of reactive halogen to the stratosphere and/or are strong infrared absorbers (chlorocarbons, chlorofluorocarbons CFCs, bromocarbons, hydrochlorofluorocarbons HCFCs, hydrofluorocarbons HFCs and polyfluorinated compounds (perfluorocarbons PFCs), nitrogen trifluoride NF3, sulfuryl fluoride SO2F2, and sulfur hexafluoride SF6) and use these measurements to determine the global rates of their emission and/or destruction (i.e., lifetimes); (2) to accurately measure the global distributions and temporal behaviors and determine the sources and sinks of non-CO2 biogenic anthropogenic gases important to climate change and/or ozone depletion (methane CH4, nitrous oxide N20, carbon monoxide CO, molecular hydrogen H2, methyl chloride CH3C1, and methyl bromide CH3Br); (3) to identify new long-lived greenhouse and ozone -depleting gases (e.g., SO2F2, NF3, heavy PFCs (C4Fm, C5F12, C6F 14, C7F16, and C8F18) and hydrofluoroolefins (HF0s; e.g., CH2 = CFCF3) have been identified in AGAGE), initiate the real-time monitoring of these new gases, and reconstruct their past histories from AGAGE, air archive, and firn air measurements; (4) to determine the average concentrations and trends of tropospheric hydroxyl radicals (OH) from the rates of destruction of atmospheric trichloroethane (CH3CC13), HFCs, and HCFCs and estimates of their emissions; (5) to determine from atmospheric observations and estimates of their destruction rates the magnitudes and distributions by region of surface sources and sinks of all measured gases; (6) to provide accurate data on the global accumulation of many of these trace gases that are used to test the synoptic-, regional-, and global -scale circulations predicted by three-dimensional models; and (7) to provide global and regional measurements of methane, carbon monoxide, and molecular hydrogen and estimates of hydroxyl levels to test primary atmospheric oxidation pathways at midlatitudes and the tropics. Network Information and Data Repository: http://agage.mit.edu/data or http://cdiac.ess-dive.lbl.gov/ndps/alegage.html (https://doi.org/10.3334/CDIAC/atg.db1001).}, annote = {Times Cited: 0 Rigby, Matthew/A-5555-2012; Reimann, Stefan/A-2327-2009; Krummel, Paul/A-4293-2013; Steele, Paul/B-3185-2009; arduini, jgor/ Rigby, Matthew/0000-0002-2020-9253; Reimann, Stefan/0000-0002-9885-7138; Krummel, Paul/0000-0002-4884-3678; Steele, Paul/0000-0002-8234-3730; arduini, jgor/0000-0002-5199-3853 0 1866-3516}, author = {Prinn, Ronald G and Weiss, Ray F and Arduini, Jgor and Arnold, Tim and DeWitt, H Langley and Fraser, Paul J and Ganesan, Anita L and Gasore, Jimmy and Harth, Christina M and Hermansen, Ove and Kim, Jooil and Krummel, Paul B and Li, Shanlan and Loh, Zoe M and Lunder, Chris R and Maione, Michela and Manning, Alistair J and Miller, Ben R and Mitrevski, Blagoj and Muehle, Jens and O'Doherty, Simon and Park, Sunyoung and Reimann, Stefan and Rigby, Matt and Saito, Takuya and Salameh, Peter K and Schmidt, Roland and Simmonds, Peter G and Steele, L Paul and Vollmer, Martin K and Wang, Ray H and Yao, Bo and Yokouchi, Yoko and Young, Dickon and Zhou, Lingxi}, doi = {10.5194/essd-10-985-2018}, isbn = {1866-3508}, journal = {Earth System Science Data}, number = {2}, pages = {985--1018}, title = {{History of chemically and radiatively important atmospheric gases from the Advanced Global Atmospheric Gases Experiment (AGAGE)}}, volume = {10}, year = {2018} } @article{Purohit2017, abstract = {This study uses the GAINS model framework to estimate current and future emissions of the fluorinated greenhouse gases HFCs/HCFCs, PFCs and SF6 (F-gases), their abatement potentials and costs for twenty source sectors and 162 countries/regions, which are aggregated to produce global estimates. Global F-gas emissions are estimated at 0.95{\&}thinsp;Pg{\&}thinsp;CO2eq in 2005 with an expected increase to 3.7{\&}thinsp;Pg{\&}thinsp;CO2eq in 2050 if application of control technology remains at the current level. There are extensive opportunities to reduce emissions using existing technology and alternative substances with low global warming potential. Estimates show that it would be technically feasible to reduce cumulative F-gas emissions by 86 percent between 2018 and 2050. A reduction in cumulative emissions by 72 percent is estimated possible at a marginal abatement cost below 10{\&}thinsp;€{\&}thinsp;/{\&}thinsp;t{\&}thinsp;CO2eq. We also find that future F-gas abatement is expected to be relatively more costly for developing than for developed countries due to differences in the sector distribution of emissions and abatement potentials.}, author = {Purohit, Pallav and H{\"{o}}glund-Isaksson, Lena}, doi = {10.5194/acp-17-2795-2017}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {4}, pages = {2795--2816}, title = {{Global emissions of fluorinated greenhouse gases 2005-2050 with abatement potentials and costs}}, url = {http://www.atmos-chem-phys.net/17/2795/2017/ http://www.atmos-chem-phys.net/17/2795/2017/acp-17-2795-2017.pdf}, volume = {17}, year = {2017} } @article{acp-20-11305-2020, author = {Purohit, P and H{\"{o}}glund-Isaksson, L and Dulac, J and Shah, N and Wei, M and Rafaj, P and Sch{\"{o}}pp, W}, doi = {10.5194/acp-20-11305-2020}, journal = {Atmospheric Chemistry and Physics}, number = {19}, pages = {11305--11327}, title = {{Electricity savings and greenhouse gas emission reductions from global phase-down of hydrofluorocarbons}}, url = {https://acp.copernicus.org/articles/20/11305/2020/}, volume = {20}, year = {2020} } @article{Pusede2016, abstract = {Nitrogen oxides (NOx) have fallen steadily across the US over the last 15 years. At the same time, NOx concentrations decrease on weekends relative to weekdays, largely without co-occurring changes in other gas-phase emissions, due to patterns of diesel truck activities. These trends taken together provide two independent constraints on the role of NOx in the nonlinear chemistry of atmospheric oxidation. In this context, we interpret interannual trends in wintertime ammonium nitrate (NH4NO3) in the San Joaquin Valley of California, a location with the worst aerosol pollution in the US and where a large portion of aerosol mass is NH4NO3. Here, we show that NOx reductions have simultaneously decreased nighttime and increased daytime NH4NO3 production over the last decade. We find a substantial decrease in NH4NO3 since 2000 and conclude that this decrease is due to reduced nitrate radical-initiated production at night in residual layers that are decoupled from fresh emissions at the surface. Further reductions in NOx are imminent in California, and nationwide, and we make a quantitative prediction of the response of NH4NO3. We show that the combination of rapid chemical production and efficient NH4NO3 loss via deposition of gas-phase nitric acid implies that high aerosol days in cities in the San Joaquin Valley air basin are responsive to local changes in NOx within those individual cities. Our calculations indicate that large decreases in NOx in the future will not only lower wintertime NH4NO3 concentrations but also cause a transition in the dominant NH4NO3 source from nighttime to daytime chemistry.}, author = {Pusede, S. E. and Duffey, K. C. and Shusterman, A. A. and Saleh, A. and Laughner, J. L. and Wooldridge, P. J. and Zhang, Q. and Parworth, C. L. and Kim, H. and Capps, S. L. and Valin, L. C. and Cappa, C. D. and Fried, A. and Walega, J. and Nowak, J. B. and Weinheimer, A. J. and Hoff, R. M. and Berkoff, T. A. and Beyersdorf, A. J. and Olson, J. and Crawford, J. H. and Cohen, R. C.}, doi = {10.5194/acp-16-2575-2016}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {4}, pages = {2575--2596}, publisher = {Copernicus {\{}GmbH{\}}}, title = {{On the effectiveness of nitrogen oxide reductions as a control over ammonium nitrate aerosol}}, volume = {16}, year = {2016} } @article{Putaud2010, abstract = {This paper synthesizes data on aerosol (particulate matter, PM) physical and chemical characteristics, which were obtained over the past decade in aerosol research and monitoring activities at more than 60 natural background, rural, near-city, urban, and kerbside sites across Europe. The data include simultaneously measured PM10 and/or PM2.5 mass on the one hand, and aerosol particle number concentrations or PM chemistry on the other hand. The aerosol data presented in our previous works (Van Dingenen et al., 2004, Putaud et al., 2004) were updated and merged to those collected in the framework of the EU supported European Cooperation in the field of Scientific and Technical action COST633 (Particulate matter: Properties related to health effects). A number of conclusions from our previous studies were confirmed. There is no single ratio between PM2.5 and PM10 mass concentrations valid for all sites, although fairly constant ratios ranging from 0.5 to 0.9 are observed at most individual sites. There is no general correlation between PM mass and particle number concentrations, although particle number concentrations increase with PM2.5 levels at most sites. The main constituents of both PM10 and PM2.5 are generally organic matter, sulfate and nitrate. Mineral dust can also be a major constituent of PM10 at kerbside sites and in Southern Europe. There is a clear decreasing gradient in SO42− and NO3− contribution to PM10 when moving from rural to urban to kerbside sites. In contrast, the total carbon/PM10 ratio increases from rural to kerbside sites. Some new conclusions were also drawn from this work: the ratio between ultrafine particle and total particle number concentration decreases with PM2.5 concentration at all sites but one, and significant gradients in PM chemistry are observed when moving from Northwestern, to Southern to Central Europe. Compiling an even larger number of data sets would have further increased the significance of our conclusions, but collecting all the aerosol data sets obtained also through research projects remains a tedious task.}, author = {Putaud, J.-P. and {Van Dingenen}, R and Alastuey, A and Bauer, H and Birmili, W and Cyrys, J and Flentje, H and Fuzzi, S and Gehrig, R and Hansson, H C and Harrison, R M and Herrmann, H and Hitzenberger, R and H{\"{u}}glin, C and Jones, A M and Kasper-Giebl, A and Kiss, G and Kousa, A and Kuhlbusch, T A J and L{\"{o}}schau, G and Maenhaut, W and Molnar, A and Moreno, T and Pekkanen, J and Perrino, C and Pitz, M and Puxbaum, H and Querol, X and Rodriguez, S and Salma, I and Schwarz, J and Smolik, J and Schneider, J and Spindler, G and ten Brink, H and Tursic, J and Viana, M and Wiedensohler, A and Raes, F}, doi = {https://doi.org/10.1016/j.atmosenv.2009.12.011}, issn = {1352-2310}, journal = {Atmospheric Environment}, number = {10}, pages = {1308--1320}, title = {{A European aerosol phenomenology – 3: Physical and chemical characteristics of particulate matter from 60 rural, urban, and kerbside sites across Europe}}, volume = {44}, year = {2010} } @article{Qiao2018, abstract = {Source contributions to fine airborne particulate matter with aerodynamic diameters {\textless}2.5$\mu$m (PM2.5) during 2013 were determined for 25 Chinese provincial capitals and municipalities using a source-oriented version of the Community Multiscale Air Quality (CMAQ) model. Based on the hierarchical clustering analysis of the observed PM2.5 concentrations, the 25 cities were categorized into nine groups. Generally, annual PM2.5 concentrations were highest in the cities in the north (81–154$\mu$gm−3) and lowest in the cities close to seas in the south and east (27–57$\mu$gm−3). Seasonal PM2.5 observations in the cities were generally higher in winter than in the other seasons. Industrial or residential sources were predicted to be the largest contributor to PM2.5 for all the city groups, with annually fractional contributions of 25.0{\%}–38.6{\%} and 9.6{\%}–27{\%}, respectively. The annual contributions from power plants, agriculture NH3, windblown dust, and secondary organic aerosol (SOA) for the city groups were 8.7{\%}–12.7{\%}, 9.5{\%}–12{\%}, 6.1{\%}–12.5{\%}, and 5.4{\%}–15.5{\%}, respectively. Meanwhile, the annual contributions from transportation, sea salt, and open burning were relatively low ({\textless}8{\%}, {\textless}2{\%}, and {\textless}6{\%}, respectively). Secondary PM2.5 accounted for 47{\%}–63{\%} of total annual PM2.5 concentrations in the cities and contributed to as much as 70{\%} of daily PM2.5 concentrations on PM2.5 pollution days (daily concentrations{\textgreater}75$\mu$gm−3). Industrial or residential sources were generally the largest contributor on PM2.5 pollution days for all the city groups in each season, except that open burning, SOA, and windblown dust could be more important on some days, particularly in spring. The results of this study would be helpful to develop measures to reduce annual PM2.5 concentrations and the number of PM2.5 pollution days for different regions of China.}, author = {Qiao, Xue and Ying, Qi and Li, Xinghua and Zhang, Hongliang and Hu, Jianlin and Tang, Ya and Chen, Xue}, doi = {https://doi.org/10.1016/j.scitotenv.2017.08.272}, issn = {0048-9697}, journal = {Science of The Total Environment}, keywords = {Airborne particulate matter,Hierarchical cluster analysis,Secondary organic aerosol,Source apportionment,Source-oriented CMAQ}, pages = {462--471}, title = {{Source apportionment of PM2.5 for 25 Chinese provincial capitals and municipalities using a source-oriented Community Multiscale Air Quality model}}, url = {https://www.sciencedirect.com/science/article/pii/S0048969717322945}, volume = {612}, year = {2018} } @article{Querol2013, abstract = {We interpret here the variability of levels of carbonaceous aerosols based on a 12 yr database from 78 monitoring stations across Spain specially compiled for this article. Data did not evidence any spatial trends of carbonaceous aerosols across the country. Conversely, results show marked differences in average concentrations from the cleanest, most remote sites (around 1 $\mu$g m-3 of non-mineral carbon (nmC), mostly made of organic carbon (OC) with very little elemental carbon (EC), around 0.1 $\mu$g m-3; OC/EC Combining double low line 12-15), to the highly polluted major cities (8-10 $\mu$g m-3 of nmC; 3-4 $\mu$g m-3 of EC; 4-5 $\mu$g m-3 of OC; OC/EC Combining double low line 1-2). Thus, urban (and very specific industrial) pollution was found to markedly increase levels of carbonaceous aerosols in Spain, with much lower impact of biomass burning and of biogenic emissions. Correlations between yearly averaged OC/EC and EC concentrations adjust very well to a potential equation (OC Combining double low line 3.37 EC0.326, R2 Combining double low line 0.8). A similar equation is obtained when including average concentrations obtained at other European sites (OC Combining double low line 3.60EC0.491, R2 Combining double low line 0.7). A clear seasonal variability in OC and EC concentrations was detected. Both OC and EC concentrations were higher during winter at the traffic and urban sites, but OC increased during the warmer months at the rural sites. Hourly equivalent black carbon (EBC) concentrations at urban sites accurately depict road traffic contributions, varying with distance from road, traffic volume and density, mixing-layer height and wind speed. Weekday urban rush-hour EBC peaks are mimicked by concentrations of primary gaseous emissions from road traffic, whereas a single midday peak is characteristic of remote and rural sites. Decreasing annual trends for carbonaceous aerosols were observed between 1999 and 2011 at a large number of stations, probably reflecting the impact of the EURO4 and EURO5 standards in reducing the diesel PM emissions. This has resulted in some cases in an increasing trend for NO2/(OC+ EC) ratios as these standards have been much less effective for the abatement of NOx exhaust emissions in passenger diesel cars. This study concludes that EC, EBC, and especially nmC and OC+ EC are very good candidates for new air quality standards since they cover both emission impact and health-related issues. {\textcopyright} 2013 Author(s).}, author = {Querol, X. and Alastuey, A. and Viana, M. and Moreno, T. and Reche, C. and Minguill{\'{o}}n, M. C. and Ripoll, A. and Pandolfi, M. and Amato, F. and Karanasiou, A. and P{\'{e}}rez, N. and Pey, J. and Cusack, M. and V{\'{a}}zquez, R. and Plana, F. and Dall'Osto, M. and {De La Rosa}, J. and {S{\'{a}}nchez De La Campa}, A. and Fern{\'{a}}ndez-Camacho, R. and Rodr{\'{i}}guez, S. and Pio, C. and Alados-Arboledas, L. and Titos, G. and Art{\'{i}}{\~{n}}ano, B. and Salvador, P. and {Garc{\'{i}}a Dos Santos}, S. and {Fern{\'{a}}ndez Patier}, R.}, doi = {10.5194/acp-13-6185-2013}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, number = {13}, pages = {6185--6206}, title = {{Variability of carbonaceous aerosols in remote, rural, urban and industrial environments in Spain: Implications for air quality policy}}, volume = {13}, year = {2013} } @article{Quiquet2015, abstract = {All recent climatic projections for the next century suggest that we are heading towards a warmer climate than today (Intergovernmental Panel on Climate Change; Fifth Assessment Report), driven by increasing atmospheric burdens of anthropogenic greenhouse gases. In particular, the volume mixing ratio of methane, the second-most important anthropogenic greenhouse gas, has increased by a factor of similar to 2.5 from the beginning of the European Industrial Revolution. Due to their complex responses to climatic factors, understanding of the dynamics of future global methane emissions and sinks is crucial for the next generation of climate projections. Of relevance to this problem, the Earth likely experienced warmer average temperatures than today during the Last Interglacial (LIG) period (130-115 kaBP). Interestingly, ice cores do not indicate a different methane mixing ratio from the Pre-Industrial Holocene (PIH), in other words the current interglacial period prior to anthropogenic influence. This is surprising as warmer temperatures might be expected to increase methane emissions. The present study aims to improve our understanding of the changes in the global methane budget through quantifying the relative importance of sources and sinks of methane during the last full glacial interglacial cycle. A fairly limited number of studies have investigated this cycle at the millenium time scale with most of them examining the doubling in CH4 from the Last Glacial Maximum (LGM) to the PIH. Though it is still a matter of debate, a general consensus suggests a predominant role to the change in methane emissions from wetlands and only a limited change in the oxidising capacity of the atmosphere. In the present study we provide an estimate of the relative importance of sources and sinks during the LIG period, using a complex climate chemistry model to quantify the sinks, and a methane emissions model included in a global land surface model, for the sources. We are not aware of any previous studies that have explicitly tackled sources and sinks of methane in the previous interglacial. Our results suggest that both emissions and sinks of methane were higher during the LIG period, relative to the PIH, resulting in similar atmospheric concentrations of methane. Our simulated change in methane lifetime is primarily driven by climate (i.e. air temperature and humidity). However, a significant part of the reduced methane lifetime is also attributable to the impact of changes in NO emissions from lightning. An increase in biogenic emissions of non-methane volatile organic compounds during the LIG seems unlikely to have compensated for the impact of temperature and humidity. Surface methane emissions from wetlands were higher in northern latitudes due to an increase of summer temperature, whilst the change in the tropics is less certain. Simulated methane emissions are strongly sensitive to the atmospheric forcing, with most of this sensitivity related to changes in wetland extent. (C) 2015 Elsevier Ltd. All rights reserved.}, annote = {Times Cited: 5 Quiquet, Aurelien/P-6180-2014; Chappellaz, Jerome/A-4872-2011; Stone, Emma/H-9549-2012; Archibald, Alexander/ Quiquet, Aurelien/0000-0001-6207-3043; Stone, Emma/0000-0002-8633-8074; Archibald, Alexander/0000-0001-9302-4180 0 5}, author = {Quiquet, A and Archibald, A T and Friend, A D and Chappellaz, J and Levine, J G and Stone, E J and Telford, P J and Pyle, J A}, doi = {10.1016/j.quascirev.2015.01.004}, isbn = {0277-3791}, journal = {Quaternary Science Reviews}, pages = {1--16}, title = {{The relative importance of methane sources and sinks over the Last Interglacial period and into the last glaciation}}, volume = {112}, year = {2015} } @article{acp-10-5925-2010, abstract = {Mineral dust is one of the major components of the world's aerosol mix, having a number of impacts within the Earth system. However, the climate forcing impact of mineral dust is currently poorly constrained, with even its sign uncertain. As Australian deserts are more reddish than those in the Northern Hemisphere, it is important to better understand the physical, chemical and optical properties of this important aerosol. We have investigated the properties of Australian desert dust at a site in SW Queensland, which is strongly influenced by both dust and biomass burning aerosol. Three years of ground-based monitoring of spectral optical thickness has provided a statistical picture of gross aerosol properties. The aerosol optical depth data showed a clear though moderate seasonal cycle with an annual mean of 0.06 ± 0.03. The Angstrom coefficient showed a stronger cycle, indicating the influence of the winter-spring burning season in Australia's north. AERONET size distributions showed a generally bimodal character, with the coarse mode assumed to be mineral dust, and the fine mode a mixture of fine dust, biomass burning and marine biogenic material. In November 2006 we undertook a field campaign which collected 4 sets of size-resolved aerosol samples for laboratory analysis – ion beam analysis and ion chromatography. Ion beam analysis was used to determine the elemental composition of all filter samples, although elemental ratios were considered the most reliable output. Scatter plots showed that Fe, Al and Ti were well correlated with Si, and Co reasonably well correlated with Si, with the Fe/Al ratio somewhat higher than values reported from Northern Hemisphere sites (as expected). Scatter plots for Ca, Mn and K against Si showed clear evidence of a second population, which in some cases could be identified with a particular sample day or size fraction. These data may be used to attempt to build a signature of soil in this region of the Australian interior. Ion chromatography was used to quantify water soluble ions for 2 of our sample sets, complementing the picture provided by ion beam analysis. The strong similarities between the MSA and SO42− size distributions argue strongly for a marine origin of much of the SO42−. The similarity of the Na+, Cl− and Mg2+ size distributions also argue for a marine contribution. Further, we believe that both NO3− and NH4+ are the result of surface reactions with appropriate gases.}, author = {Radhi, M and Box, M A and Box, G P and Mitchell, R M and Cohen, D D and Stelcer, E and Keywood, M D}, doi = {10.5194/acp-10-5925-2010}, journal = {Atmospheric Chemistry and Physics}, number = {13}, pages = {5925--5942}, title = {{Optical, physical and chemical characteristics of Australian continental aerosols: results from a field experiment}}, url = {https://www.atmos-chem-phys.net/10/5925/2010/}, volume = {10}, year = {2010} } @article{Rafaj2018, abstract = {Air pollution is linked with many of the United Nations Sustainable Development Goals. Strategies aiming at the improved air quality interact directly with climate mitigation targets, access to clean energy services, waste management, and other aspects of socio-economic development. Continuation of current policies in the key emitting sectors implies that a number of sustainability goals will likely not be met within the next two decades: emissions of air pollutants would cause 40{\%} more premature deaths from outdoor air pollution than today, carbon emissions would rise globally by 0.4{\%} per year, while nearly two billion people would not have access to clean cooking. This paper examines integrated policies to put the world on track towards three interlinked goals of achieving universal energy access, limiting climate change and reducing air pollution. Scenario analysis suggests that these goals can be attained simultaneously with substantial benefits. By 2040, emissions of main pollutants are projected to drop by 60–80{\%} relative to today, and associated health impacts are quantified at two million avoided deaths from ambient and household air pollution combined. In comparison to costs needed for the decarbonization of global economy, additional investments in air pollution control and access to clean fuels are very modest against major societal gains. However, holistic and systemic policy assessment is required to avoid potential trade-offs.}, author = {Rafaj, Peter and Kiesewetter, Gregor and G{\"{u}}l, Timur and Sch{\"{o}}pp, Wolfgang and Cofala, Janusz and Klimont, Zbigniew and Purohit, Pallav and Heyes, Chris and Amann, Markus and Borken-Kleefeld, Jens and Cozzi, Laura}, doi = {10.1016/j.gloenvcha.2018.08.008}, issn = {09593780}, journal = {Global Environmental Change}, keywords = {Air quality policy,Emission control,Energy access,Health impacts,Sustainable development}, month = {sep}, pages = {1--11}, title = {{Outlook for clean air in the context of sustainable development goals}}, url = {http://www.sciencedirect.com/science/article/pii/S0959378018304035 https://ac.els-cdn.com/S0959378018304035/1-s2.0-S0959378018304035-main.pdf?{\_}tid=6a85953a-b8fc-4d62-997b-cf1c7d0e1b7b{\&}acdnat=1537279301{\_}5d94fd176a75cf8026803fbc96429a95 https://www.scienced}, volume = {53}, year = {2018} } @article{Rafaj2014, abstract = {This paper analyses factors that contributed to the evolution of SO2, NOx and CO2 emissions in Europe from 1960 to 2010. Historical energy balances, along with population and economic growth data, are used to quantify the impacts of major determinants of changing emission levels, including energy intensity, conversion efficiency, fuel mix, and pollution control. Time series of emission levels are compared for countries in Western and Eastern Europe, throwing light on differences in the importance of particular emission-driving forces. Three quarters of the decline in SO2 emissions in Western Europe resulted from a combination of reduced energy intensity and improved fuel mix, while dedicated end-of-pipe abatement measures played a dominant role in the reduction of NOx emissions. The increase in atmospheric emissions in Eastern Europe through the mid-1990s was associated with the growth of energy-intensive industries, which off-setted the positive impact of better fuel quality and changes in fuel mix. A continuous decrease in energy intensity and higher conversion efficiencies have been the main factors responsible for the moderate rate of growth of European CO2 emissions.}, author = {Rafaj, Peter and Amann, Markus and Siri, Jos{\'{e}} and Wuester, Henning}, doi = {10.1007/s10584-013-0826-0}, issn = {1573-1480}, journal = {Climatic Change}, number = {3}, pages = {477--504}, title = {{Changes in European greenhouse gas and air pollutant emissions 1960–2010: decomposition of determining factors}}, url = {https://doi.org/10.1007/s10584-013-0826-0}, volume = {124}, year = {2014} } @article{Rafaj2018b, abstract = {High levels of air pollution pose an urgent social and public health challenge in many Asian regions. This study evaluates the role of key factors that determined the changes in emission levels in China, India and Japan over the past 25 years. While emissions of air pollutants have been declining in Japan since the 1990s, China and India have experienced a rapid growth in pollution levels in recent years. Around 2005, control measures for sulfur emissions started to deliver expected reductions in China, followed by cuts in nitrogen oxides ten years later. Despite recent policy interventions, growing emission trends in India persist. A decomposition analysis of emission-driving factors indicates that emission levels would have been at least two-times higher without the improvements in energy intensity and efficiency, combined with end-of-pipe measures. Due to the continuous reliance on fossil fuels, the abatement effect of a cleaner fuel mix was in most cases significantly smaller than other factors. A reassessment of emission projections developed in the past suggests a decisive impact of energy and environmental policies. It is expected that targeted legislative instruments will play a dominant role in achieving future air-quality goals in Asia.}, author = {Rafaj, Peter and Amann, Markus}, doi = {10.3390/en11051299}, issn = {19961073}, journal = {Energies}, keywords = {Air pollution,Decomposition,Emission scenarios,End-of-pipe measures,Energy intensity}, month = {may}, number = {5}, pages = {1299}, title = {{Decomposing air pollutant emissions in Asia: Determinants and projections}}, volume = {11}, year = {2018} } @article{Randerson2012, abstract = {In several biomes, including croplands, wooded savannas, and tropical forests, many small fires occur each year that are well below the detection limit of the current generation of global burned area products derived from moderate resolution surface reflectance imagery. Although these fires often generate thermal anomalies that can be detected by satellites, their contributions to burned area and carbon fluxes have not been systematically quantified across different regions and continents. Here we developed a preliminary method for combining 1-km thermal anomalies (active fires) and 500m burned area observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) to estimate the influence of these fires. In our approach, we calculated the number of active fires inside and outside of 500m burn scars derived from reflectance data. We estimated small fire burned area by computing the difference normalized burn ratio (dNBR) for these two sets of active fires and then combining these observations with other information. In a final step, we used the Global Fire Emissions Database version 3 (GFED3) biogeochemical model to estimate the impact of these fires on biomass burning emissions. We found that the spatial distribution of active fires and 500m burned areas were in close agreement in ecosystems that experience large fires, including savannas across southern Africa and Australia and boreal forests in North America and Eurasia. In other areas, however, we observed many active fires outside of burned area perimeters. Fire radiative power was lower for this class of active fires. Small fires substantially increased burned area in several continental-scale regions, including Equatorial Asia (157{\%}), Central America (143{\%}), and Southeast Asia (90{\%}) during 2001-2010. Globally, accounting for small fires increased total burned area by approximately by 35{\%}, from 345 Mha/yr to 464 Mha/yr. A formal quantification of uncertainties was not possible, but sensitivity analyses of key model parameters caused estimates of global burned area increases from small fires to vary between 24{\%} and 54{\%}. Biomass burning carbon emissions increased by 35{\%} at a global scale when small fires were included in GFED3, from 1.9 Pg C/yr to 2.5 Pg C/yr. The contribution of tropical forest fires to year-to-year variability in carbon fluxes increased because small fires amplified emissions from Central America, South America and Southeast Asiaregions where drought stress and burned area varied considerably from year to year in response to El Nino-Southern Oscillation and other climate modes. {\textcopyright} 2012. American Geophysical Union. All Rights Reserved.}, author = {Randerson, J. T. and Chen, Y. and van der Werf, G. R. and Rogers, B. M. and Morton, D. C.}, doi = {10.1029/2012JG002128}, issn = {01480227}, journal = {Journal of Geophysical Research: Biogeosciences}, keywords = {agricultural management,atmospheric CO2,global carbon cycle,land use change,wildland and prescribed fire}, month = {dec}, number = {G4}, pages = {G04012}, title = {{Global burned area and biomass burning emissions from small fires}}, url = {http://doi.wiley.com/10.1029/2012JG002128}, volume = {117}, year = {2012} } @article{Randles2017, abstract = {The Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), updates NASA's previous satellite-era (1980 onward) reanalysis system to include additional observations and improvements to the Goddard Earth Observing System, version 5 (GEOS-5), Earth system model. As a major step toward a full Integrated Earth Systems Analysis (IESA), in addition to meteorological observations, MERRA-2 now includes assimilation of aerosol optical depth (AOD) from various ground- and space-based remote sensing platforms. Here, in the first of a pair of studies, the MERRA-2 aerosol assimilation is documented, including a description of the prognostic model (GEOS-5 coupled to the GOCART aerosol module), aerosol emissions, and the quality control of ingested observations. Initial validation and evaluation of the analyzed AOD fields are provided using independent observations from ground, aircraft, and shipborne instruments. The positive impact of the AOD assimilation on simulated aerosols is demonstrated by comparing MERRA-2 aerosol fields to an identical control simulation that does not include AOD assimilation. After showing the AOD evaluation, this paper takes a first look at aerosol-climate interactions by examining the shortwave, clear-sky aerosol direct radiative effect. The companion paper (Part II) evaluates and validates available MERRA-2 aerosol properties not directly impacted by the AOD assimilation (e.g., aerosol vertical distribution and absorption). Importantly, while highlighting the skill of the MERRA-2 aerosol assimilation products, both studies point out caveats that must be considered when using this new reanalysis product for future studies of aerosols and their interactions with weather and climate.}, author = {Randles, C. A. and da Silva, A. M. and Buchard, V. and Colarco, P. R. and Darmenov, A. and Govindaraju, R. and Smirnov, A. and Holben, B. and Ferrare, R. and Hair, J. and Shinozuka, Y. and Flynn, C. J.}, doi = {10.1175/JCLI-D-16-0609.1}, issn = {08948755}, journal = {Journal of Climate}, keywords = {Aerosols,Data assimilation,Model evaluation/performance,Radiative fluxes,Reanalysis data,Satellite observations}, month = {apr}, number = {17}, pages = {6823--6850}, publisher = {American Meteorological Society}, title = {{The MERRA-2 aerosol reanalysis, 1980 onward. Part I: System description and data assimilation evaluation}}, volume = {30}, year = {2017} } @article{Rao2017a, abstract = {Emissions of air pollutants such as sulfur and nitrogen oxides and particulates have significant health impacts as well as effects on natural and anthropogenic ecosystems. These same emissions also can change atmospheric chemistry and the planetary energy balance, thereby impacting global and regional climate. Long-term scenarios for air pollutant emissions are needed as inputs to global climate and chemistry models, and for analysis linking air pollutant impacts across sectors. In this paper we present methodology and results for air pollutant emissions in Shared Socioeconomic Pathways (SSP) scenarios. We first present a set of three air pollution narratives that describe high, central, and low pollution control ambitions over the 21st century. These narratives are then translated into quantitative guidance for use in integrated assessment models. The resulting pollutant emission trajectories under the SSP scenarios cover a wider range than the scenarios used in previous international climate model comparisons. In the SSP3 and SSP4 scenarios, where economic, institutional and technological limitations slow air quality improvements, global pollutant emissions over the 21stcentury can be comparable to current levels. Pollutant emissions in the SSP1 scenarios fall to low levels due to the assumption of technological advances and successful global action to control emissions.}, author = {Rao, Shilpa and Klimont, Zbigniew and Smith, Steven J. and {Van Dingenen}, Rita and Dentener, Frank and Bouwman, Lex and Riahi, Keywan and Amann, Markus and Bodirsky, Benjamin Leon and van Vuuren, Detlef P. and {Aleluia Reis}, Lara and Calvin, Katherine and Drouet, Laurent and Fricko, Oliver and Fujimori, Shinichiro and Gernaat, David and Havlik, Petr and Harmsen, Mathijs and Hasegawa, Tomoko and Heyes, Chris and Hilaire, J{\'{e}}r{\^{o}}me and Luderer, Gunnar and Masui, Toshihiko and Stehfest, Elke and Strefler, Jessica and van der Sluis, Sietske and Tavoni, Massimo}, doi = {10.1016/j.gloenvcha.2016.05.012}, isbn = {0959-3780}, issn = {09593780}, journal = {Global Environmental Change}, keywords = {Air pollution,Integrated assessment models,Scenarios}, pages = {346--358}, title = {{Future air pollution in the Shared Socio-economic Pathways}}, volume = {42}, year = {2017} } @article{Rao2016a, abstract = {We present a model comparison study that combines multiple integrated assessment models with a reduced-form global air quality model to assess the potential co-benefits of global climate mitigation policies in relation to the World Health Organization (WHO) goals on air quality and health.We include in our assessment, a range of alternative assumptions on the implementation of current and planned pollution control policies. The resulting air pollution emission ranges significantly extend those in the Representative Concentration Pathways. Climate mitigation policies complement current efforts on air pollution control through technology and fuel transformations in the energy system. A combination of stringent policies on air pollution control and climate change mitigation results in 40{\%} of the global population exposed toPMlevels below theWHOair quality guideline; with the largest improvements estimated for India, China, and Middle East. Our results stress the importance of integrated multisector policy approaches to achieve the Sustainable Development Goals.}, author = {Rao, Shilpa and Klimont, Zbigniew and Leitao, Joana and Riahi, Keywan and van Dingenen, Rita and Reis, Lara Aleluia and Calvin, Katherine and Dentener, Frank and Drouet, Laurent and Fujimori, Shinichiro and Harmsen, Mathijs and Luderer, Gunnar and Heyes, Chris and Strefler, Jessica and Tavoni, Massimo and van Vuuren, Detlef P}, doi = {10.1088/1748-9326/11/12/124013}, issn = {1748-9326}, journal = {Environmental Research Letters}, month = {dec}, number = {12}, pages = {124013}, title = {{A multi-model assessment of the co-benefits of climate mitigation for global air quality}}, url = {https://iopscience.iop.org/article/10.1088/1748-9326/11/12/124013}, volume = {11}, year = {2016} } @article{RAO20131122, author = {Rao, Shilpa and Pachauri, Shonali and Dentener, Frank and Kinney, Patrick and Klimont, Zbigniew and Riahi, Keywan and Schoepp, Wolfgang}, doi = {https://doi.org/10.1016/j.gloenvcha.2013.05.003}, issn = {0959-3780}, journal = {Global Environmental Change}, keywords = {Concentrations,Household energy access,Outdoor air pollution,Policies}, number = {5}, pages = {1122--1130}, title = {{Better air for better health: Forging synergies in policies for energy access, climate change and air pollution}}, url = {http://www.sciencedirect.com/science/article/pii/S0959378013000770}, volume = {23}, year = {2013} } @article{Rap2015, abstract = {Atmospheric aerosol scatters solar radiation increasing the fraction of diffuse radiation and the efficiency of photosynthesis. We quantify the impacts of biomass burning aerosol (BBA) on diffuse radiation and plant photosynthesis across Amazonia during 1998-2007. Evaluation against observed aerosol optical depth allows us to provide lower and upper BBA emissions estimates. BBA increases Amazon basin annual mean diffuse radiation by 3.4-6.8{\%} and net primary production (NPP) by 1.4-2.8{\%}, with quoted ranges driven by uncertainty in BBA emissions. The enhancement of Amazon basin NPP by 78-156 Tg C a-1 is equivalent to 33-65{\%} of the annual regional carbon emissions from biomass burning. This NPP increase occurs during the dry season and acts to counteract some of the observed effect of drought on tropical production. We estimate that 30-60 Tg C a-1 of this NPP enhancement is within woody tissue, accounting for 8-16{\%} of the observed carbon sink across mature Amazonian forests.}, author = {Rap, A. and Spracklen, D. V. and Mercado, L. and Reddington, C. L. and Haywood, J. M. and Ellis, R. J. and Phillips, O. L. and Artaxo, P. and Bonal, D. and {Restrepo Coupe}, N. and Butt, N.}, doi = {10.1002/2015GL063719}, isbn = {0094-8276}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {aerosol,biomass burning,deforestation fires,diffuse radiation,plant photosynthesis}, month = {jun}, number = {11}, pages = {4654--4662}, title = {{Fires increase Amazon forest productivity through increases in diffuse radiation}}, url = {http://doi.wiley.com/10.1002/2015GL063719 https://onlinelibrary.wiley.com/doi/abs/10.1002/2015GL063719}, volume = {42}, year = {2015} } @article{Rap2010, abstract = {The HadGEM2 global climate model is employed to investigate some of the linear contrail effects on climate. Our study parameterizes linear contrails as a thin layer of aerosol. We find that at 100 times the air traffic of year 2000, linear contrails would change the equilibrium global-mean temperature by +0.13 K, corresponding to a climate sensitivity of 0.3 K/(Wm?2) and a climate efficacy of 31{\%} (significantly smaller than the only previously published estimate of 59{\%}). Our model suggests that contrails cause a slight warming of the surface and, as noted by most global warming modelling studies, land areas are affected more than the oceans. Also, unlike the contrail coverage and radiative forcing, the contrail temperature change response is not geographically correlated with air traffic patterns. In terms of the contrail impact on precipitation, the main feature is the northern shift of the Inter-Tropical Convergence Zone. Finally, our model strongly indicates that the contrail impact on both the diurnal temperature range and regional climate is significantly smaller than some earlier studies suggested.}, annote = {https://doi.org/10.1029/2010GL045161}, author = {Rap, Alexandru and Forster, Piers M and Haywood, James M and Jones, Andy and Boucher, Olivier}, doi = {https://doi.org/10.1029/2010GL045161}, issn = {0094-8276}, journal = {Geophysical Research Letters}, keywords = {climate,contrails,global climate models,impact}, month = {oct}, number = {20}, pages = {L20703}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Estimating the climate impact of linear contrails using the UK Met Office climate model}}, url = {https://doi.org/10.1029/2010GL045161}, volume = {37}, year = {2010} } @article{Rasch2008, abstract = {Aerosols produced in the lower stratosphere can brighten the planet and counteract some of the effects of global warming. We explore scenarios in which the amount of precursors and the size of the aerosol are varied to assess their interactions with the climate system. Stratosphere-troposphere exchange processes change in response to greenhouse gas forcing and respond to geoengineering by aerosols. Nonlinear feedbacks influence the amount of aerosol required to counteract the warming. More aerosol precursor must be injected than would be needed if stratosphere troposphere exchange processes did not change in response to greenhouse gases or aerosols. Aerosol particle size has an important role in modulating the energy budget. A prediction of aerosol size requires a much more complex representation and assumptions about the delivery mechanism beyond the scope of this study, so we explore the response when particle size is prescribed. More aerosol is required to counteract greenhouse warming if aerosol particles are as large as those seen during volcanic eruptions (compared to the smaller aerosols found in quiescent conditions) because the larger particles are less effective at scattering incoming energy, and trap some outgoing energy. About 1.5 Tg S/yr are found to balance a doubling Of CO2 if the particles are small, while perhaps double that may be needed if the particles reach the size seen following eruptions. Copyright 2008 by the American Geophysical Union.}, author = {Rasch, Philip J. and Crutzen, Paul J. and Coleman, Danielle B.}, doi = {10.1029/2007GL032179}, issn = {00948276}, journal = {Geophysical Research Letters}, number = {2}, pages = {L02809}, title = {{Exploring the geoengineering of climate using stratospheric sulfate aerosols: The role of particle size}}, volume = {35}, year = {2008} } @article{Rasch2009, abstract = {General circulation model computations using a fully coupled ocean-atmosphere model indicate that increasing cloud reflectivity by seeding maritime boundary layer clouds with particles made from seawater may compensate for some of the effects on climate of increasing greenhouse gas concentrations. The chosen seeding strategy (one of many possible scenarios) can restore global averages of temperature, precipitation and sea ice to present day values, but not simultaneously. The response varies nonlinearly with the extent of seeding, and geoengineering generates local changes to important climatic features. The global tradeoffs of restoring ice cover, and cooling the planet, must be assessed alongside the local changes to climate features. {\textcopyright} 2009 IOP Publishing Ltd.}, author = {Rasch, Philip J. and Latham, John and Chen, Chih-Chieh (Jack)}, doi = {10.1088/1748-9326/4/4/045112}, issn = {1748-9326}, journal = {Environmental Research Letters}, keywords = {Aerosol indirect effect,Climate change,Cloud seeding,Geo-engineering,Global warming}, month = {oct}, number = {4}, pages = {045112}, title = {{Geoengineering by cloud seeding: influence on sea ice and climate system}}, url = {https://iopscience.iop.org/article/10.1088/1748-9326/4/4/045112}, volume = {4}, year = {2009} } @article{Reddington2017, abstract = {AbstractThe largest uncertainty in the historical radiative forcing of climate is caused by changes in aerosol particles due to anthropogenic activity. Sophisticated aerosol microphysics processes have been included in many climate models in an effort to reduce the uncertainty. However, the models are very challenging to evaluate and constrain because they require extensive in situ measurements of the particle size distribution, number concentration, and chemical composition that are not available from global satellite observations. The Global Aerosol Synthesis and Science Project (GASSP) aims to improve the robustness of global aerosol models by combining new methodologies for quantifying model uncertainty, to create an extensive global dataset of aerosol in situ microphysical and chemical measurements, and to develop new ways to assess the uncertainty associated with comparing sparse point measurements with low-resolution models. GASSP has assembled over 45,000 hours of measurements from ships and aircraft as well as data from over 350 ground stations. The measurements have been harmonized into a standardized format that is easily used by modelers and nonspecialist users. Available measurements are extensive, but they are biased to polluted regions of the Northern Hemisphere, leaving large pristine regions and many continental areas poorly sampled. The aerosol radiative forcing uncertainty can be reduced using a rigorous model?data synthesis approach. Nevertheless, our research highlights significant remaining challenges because of the difficulty of constraining many interwoven model uncertainties simultaneously. Although the physical realism of global aerosol models still needs to be improved, the uncertainty in aerosol radiative forcing will be reduced most effectively by systematically and rigorously constraining the models using extensive syntheses of measurements.}, annote = {doi: 10.1175/BAMS-D-15-00317.1}, author = {Reddington, C. L. and Carslaw, K. S. and Stier, P. and Schutgens, N. and Coe, H. and Liu, D. and Allan, J. and Browse, J. and Pringle, K. J. and Lee, L. A. and Yoshioka, M. and Johnson, J. S. and Regayre, L. A. and Spracklen, D. V. and Mann, G. W. and Clarke, A. and Hermann, M. and Henning, S. and Wex, H. and Kristensen, T. B. and Leaitch, W. R. and P{\"{o}}schl, U. and Rose, D. and Andreae, M. O. and Schmale, J. and Kondo, Y. and Oshima, N. and Schwarz, J. P. and Nenes, A. and Anderson, B. and Roberts, G. C. and Snider, J. R. and Leck, C. and Quinn, P. K. and Chi, X. and Ding, A. and Jimenez, J. L. and Zhang, Q.}, doi = {10.1175/BAMS-D-15-00317.1}, issn = {00030007}, journal = {Bulletin of the American Meteorological Society}, month = {feb}, number = {9}, pages = {1857--1877}, publisher = {American Meteorological Society}, title = {{The global aerosol synthesis and science project (GASSP): Measurements and modeling to reduce uncertainty}}, url = {https://doi.org/10.1175/BAMS-D-15-00317.1}, volume = {98}, year = {2017} } @article{Reddington2019, author = {Reddington, Carly L. and Conibear, Luke and Knote, Christoph and Silver, Ben J. and Li, Yong J. and Chan, Chak K. and Arnold, Steve R. and Spracklen, Dominick V.}, doi = {10.5194/acp-19-11887-2019}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {sep}, number = {18}, pages = {11887--11910}, title = {{Exploring the impacts of anthropogenic emission sectors on PM2.5 and human health in South and East Asia}}, url = {https://acp.copernicus.org/articles/19/11887/2019/}, volume = {19}, year = {2019} } @article{Reis2012, abstract = {Updated air pollution science and policies address human health, ecosystem effects, and climate change in Europe.}, author = {Reis, S. and Grennfelt, P. and Klimont, Z. and Amann, M. and ApSimon, H. and Hettelingh, J. P. and Holland, M. and LeGall, A. C. and Maas, R. and Posch, M. and Spranger, T. and Sutton, M. A. and Williams, M.}, doi = {10.1126/science.1226514}, issn = {10959203}, journal = {Science}, number = {6111}, pages = {1153--1154}, title = {{From acid rain to climate change}}, volume = {338}, year = {2012} } @article{Ren2020, author = {Ren, Lili and Yang, Yang and Wang, Hailong and Zhang, Rudong and Wang, Pinya and Liao, Hong}, doi = {10.5194/acp-20-9067-2020}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jul}, number = {14}, pages = {9067--9085}, publisher = {Copernicus Publications}, title = {{Source attribution of Arctic black carbon and sulfate aerosols and associated Arctic surface warming during 1980–2018}}, url = {https://acp.copernicus.org/articles/20/9067/2020/ https://acp.copernicus.org/articles/20/9067/2020/acp-20-9067-2020.pdf}, volume = {20}, year = {2020} } @article{Riahi2017a, abstract = {{\textcopyright} 2017 The Authors This paper presents the overview of the Shared Socioeconomic Pathways (SSPs) and their energy, land use, and emissions implications. The SSPs are part of a new scenario framework, established by the climate change research community in order to facilitate the integrated analysis of future climate impacts, vulnerabilities, adaptation, and mitigation. The pathways were developed over the last years as a joint community effort and describe plausible major global developments that together would lead in the future to different challenges for mitigation and adaptation to climate change. The SSPs are based on five narratives describing alternative socio-economic developments, including sustainable development, regional rivalry, inequality, fossil-fueled development, and middle-of-the-road development. The long-term demographic and economic projections of the SSPs depict a wide uncertainty range consistent with the scenario literature. A multi-model approach was used for the elaboration of the energy, land-use and the emissions trajectories of SSP-based scenarios. The baseline scenarios lead to global energy consumption of 400–1200 EJ in 2100, and feature vastly different land-use dynamics, ranging from a possible reduction in cropland area up to a massive expansion by more than 700 million hectares by 2100. The associated annual CO2emissions of the baseline scenarios range from about 25 GtCO2to more than 120 GtCO2per year by 2100. With respect to mitigation, we find that associated costs strongly depend on three factors: (1) the policy assumptions, (2) the socio-economic narrative, and (3) the stringency of the target. The carbon price for reaching the target of 2.6 W/m2that is consistent with a temperature change limit of 2 °C, differs in our analysis thus by about a factor of three across the SSP marker scenarios. Moreover, many models could not reach this target from the SSPs with high mitigation challenges. While the SSPs were designed to represent different mitigation and adaptation challenges, the resulting narratives and quantifications span a wide range of different futures broadly representative of the current literature. This allows their subsequent use and development in new assessments and research projects. Critical next steps for the community scenario process will, among others, involve regional and sectoral extensions, further elaboration of the adaptation and impacts dimension, as well as employing the SSP scenarios with the new generation of earth system models as part of the 6th climate model intercomparison project (CMIP6).}, author = {Riahi, K. and van Vuuren, D.P. and Kriegler, E. and Edmonds, J. and O'Neill, B.C. and Fujimori, S. and Bauer, N. and Calvin, K. and Dellink, R. and Fricko, O. and Lutz, W. and Popp, A. and Cuaresma, J.C. and KC, S. and Leimbach, M. and Jiang, L. and Kram, T. and Rao, S. and Emmerling, J. and Ebi, K. and Hasegawa, T. and Havlik, P. and Humpen{\"{o}}der, F. and {Da Silva}, L.A. and Smith, S. and Stehfest, E. and Bosetti, V. and Eom, J. and Gernaat, D. and Masui, T. and Rogelj, J. and Strefler, J. and Drouet, L. and Krey, V. and Luderer, G. and Harmsen, M. and Takahashi, K. and Baumstark, L. and Doelman, J.C. and Kainuma, M. and Klimont, Z. and Marangoni, G. and Lotze-Campen, H. and Obersteiner, M. and Tabeau, A. and Tavoni, M.}, doi = {10.1016/j.gloenvcha.2016.05.009}, issn = {09593780}, journal = {Global Environmental Change}, keywords = {Adaptation,Climate change,Community scenarios,Mitigation,RCP,SSP,Shared Socioeconomic Pathways}, pages = {153--168}, title = {{The Shared Socioeconomic Pathways and their energy, land use, and greenhouse gas emissions implications: An overview}}, volume = {42}, year = {2017} } @article{Ricciardelli2017, abstract = {The Supersito Project (www.supersito-er.it) has been active in the Emilia-Romagna region, southern part of the Po Valley (Italy), since 2011. Focal aim of the project is to enhance the knowledge on atmospheric aerosol and its impact on human health. In the framework of Supersito, major chemical components of daily PM2.5 were investigated over a period of more than three years at four sampling sites, representative of dissimilar territorial conditions: one rural background (SPC) and three urban background sites in the coastal (RN), central (MS) and inner area (PR) of the region. In all the sites, organic and elemental carbon and water soluble inorganic ions accounted for more than 70{\%} of PM2.5 mass, during all seasons. Nitrate and organic carbon (OC) were the main components of winter PM2.5, while summer aerosol was mainly contributed by OC and sulphate. OC was dominated by primary sources, with a potentially important contribution from biomass burning, in winter, while secondary processes dominated OC production in summer. A substantial homogeneity was observed on a regional scale in terms of spatial distribution of pollutants, with EC only presenting significant differences between urban and rural areas during winters. Nonetheless, differences were observed between the coastal and the inner part of the region, with the former being systematically characterized by higher concentrations of carbonaceous compounds and lower concentrations of ammonium nitrate. The coastal area was likely influenced by the aged OC from the Po Valley outflow in addition to local sources, while the scarcity of local sources of ammonia limited the formation of ammonium nitrate. In the studied area, local and regional meteorology - mostly governed by geographical collocation and orography – was responsible for PM2.5 mass and composition no less than local and regional emission sources.}, author = {Ricciardelli, Isabella and Bacco, Dimitri and Rinaldi, Matteo and Bonaf{\`{e}}, Giovanni and Scotto, Fabiana and Trentini, Arianna and Bertacci, Giulia and Ugolini, Pamela and Zigola, Claudia and Rovere, Flavio and Maccone, Claudio and Pironi, Claudia and Poluzzi, Vanes}, doi = {10.1016/j.atmosenv.2016.12.052}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Elemental carbon,Nitrate,Organic carbon,PM2.5,Po Valley}, month = {mar}, pages = {418--430}, publisher = {Elsevier {\{}BV{\}}}, title = {{A three-year investigation of daily PM2.5 main chemical components in four sites: the routine measurement program of the Supersito Project (Po Valley, Italy)}}, volume = {152}, year = {2017} } @article{bg-13-3397-2016, abstract = {Abstract. Nitrogen applied to the surface of the land for agricultural purposes represents a significant source of reactive nitrogen (Nr) that can be emitted as a gaseous Nr species, be denitrified to atmospheric nitrogen (N2), run off during rain events or form plant-useable nitrogen in the soil. To investigate the magnitude, temporal variability and spatial heterogeneity of nitrogen pathways on a global scale from sources of animal manure and synthetic fertilizer, we developed a mechanistic parameterization of these pathways within a global terrestrial land model, the Community Land Model (CLM). In this first model version the parameterization emphasizes an explicit climate-dependent approach while using highly simplified representations of agricultural practices, including manure management and fertilizer application. The climate-dependent approach explicitly simulates the relationship between meteorological variables and biogeochemical processes to calculate the volatilization of ammonia (NH3), nitrification and runoff of Nr following manure or synthetic fertilizer application. For the year 2000, approximately 125 Tg N yr−1 is applied as manure and 62 Tg N yr−1 is applied as synthetic fertilizer. We estimate the resulting global NH3 emissions are 21 Tg N yr−1 from manure (17 {\%} of manure production) and 12 Tg N yr−1 from fertilizer (19 {\%} of fertilizer application); reactive nitrogen runoff during rain events is calculated as 11 Tg N yr−1 from manure and 5 Tg N yr−1 from fertilizer. The remaining nitrogen from manure (93 Tg N yr−1) and synthetic fertilizer (45 Tg N yr−1) is captured by the canopy or transferred to the soil nitrogen pools. The parameterization was implemented in the CLM from 1850 to 2000 using a transient simulation which predicted that, even though absolute values of all nitrogen pathways are increasing with increased manure and synthetic fertilizer application, partitioning of nitrogen to NH3 emissions from manure is increasing on a percentage basis, from 14 {\%} of nitrogen applied in 1850 (3 Tg NH3 yr−1) to 17 {\%} of nitrogen applied in 2000 (21 Tg NH3 yr−1). Under current manure and synthetic fertilizer application rates we find a global sensitivity of an additional 1 Tg NH3 (approximately 3 {\%} of manure and fertilizer) emitted per year per °C of warming. While the model confirms earlier estimates of nitrogen fluxes made in a range of studies, its key purpose is to provide a theoretical framework that can be employed within a biogeochemical model, that can explicitly respond to climate and that can evolve and improve with further observation.}, author = {Riddick, Stuart and Ward, Daniel and Hess, Peter and Mahowald, Natalie and Massad, Raia and Holland, Elisabeth}, doi = {10.5194/bg-13-3397-2016}, issn = {1726-4189}, journal = {Biogeosciences}, month = {jun}, number = {11}, pages = {3397--3426}, title = {{Estimate of changes in agricultural terrestrial nitrogen pathways and ammonia emissions from 1850 to present in the Community Earth System Model}}, url = {https://bg.copernicus.org/articles/13/3397/2016/}, volume = {13}, year = {2016} } @article{Rieder2018, abstract = {While compliance with air quality standards is evaluated at individual monitoring stations, projections of future ambient air quality for global climate and emission scenarios often rely on coarse resolution models. We describe a statistical transfer approach that bridges the spatial gap between air quality projections, averaged over four broad U.S. regions, from a global chemistry-climate model and the local level (at specific U.S. CASTNet sites). Our site-level projections are intended as a line of evidence in planning for possible futures rather than the sole basis for policy decisions. We use a set of transient sensitivity simulations (2006–2100) from the Geophysical Fluid Dynamics Laboratory (GFDL) chemistry-climate model CM3, designed to isolate the effects of changes in anthropogenic ozone (O 3 ) precursor emissions, climate warming, and global background CH 4 on surface O 3 . We find that surface maximum daily 8-h average (MDA8) O 3 increases despite constant precursor emissions in a warmer climate during summer, particularly in the low tail of the MDA8 O 3 distribution for the Northeastern U.S., while MDA8 O 3 decreases slightly throughout the distribution over the West and Southeast during summer and fall. Under scenarios in which non-methane O 3 precursors decline as climate warms (RCP4.5 and RCP8.5), summertime MDA8 O 3 decreases with NO x emissions, most strongly in the upper tail of the MDA8 O 3 distribution. In a scenario where global methane abundances roughly double over the 21st century (RCP8.5), winter and spring MDA8 O 3 increases, particularly in the lower tail and over the Western U.S. In this RCP8.5 scenario, the number of days when MDA8 O 3 exceeds 70 ppb declines in summer with NO x emissions, but increases in spring (and winter); by the end of the century, the majority of sites in the WE and NE show probabilistic return values of the annual 4th highest MDA8 O 3 concentration above 70 ppb (the current O 3 NAAQS level). Continued increases in global CH 4 abundances can be thought of as a “methane penalty” offsetting benefits otherwise attainable by controlling non-CH 4 O 3 precursors.}, author = {Rieder, Harald E. and Fiore, Arlene M. and Clifton, Olivia E. and Correa, Gustavo and Horowitz, Larry W. and Naik, Vaishali}, doi = {10.1016/j.atmosenv.2018.07.042}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Climate change,Methane,Ozone precursor emissions,Representative concentration pathways,Seasonality,Surface ozone}, month = {nov}, pages = {302--315}, publisher = {Pergamon}, title = {{Combining model projections with site-level observations to estimate changes in distributions and seasonality of ozone in surface air over the U.S.A.}}, url = {https://www.sciencedirect.com/science/article/pii/S1352231018304941?via{\%}3Dihub}, volume = {193}, year = {2018} } @article{Rigby2017, abstract = {The growth in global methane (CH 4 ) concentration, which had been ongoing since the industrial revolution, stalled around the year 2000 before resuming globally in 2007. We evaluate the role of the hydroxyl radical (OH), the major CH 4 sink, in the recent CH 4 growth. We also examine the influence of systematic uncertainties in OH concentrations on CH 4 emissions inferred from atmospheric observations. We use observations of 1,1,1-trichloroethane (CH 3 CCl 3 ), which is lost primarily through reaction with OH, to estimate OH levels as well as CH 3 CC 3 emissions, which have uncertainty that previously limited the accuracy of OH estimates. We find a 64–70{\%} probability that a decline in OH has contributed to the post-2007 methane rise. Our median solution suggests that CH 4 emissions increased relatively steadily during the late 1990s and early 2000s, after which growth was more modest. This solution obviates the need for a sudden statistically significant change in total CH 4 emissions around the year 2007 to explain the atmospheric observations and can explain some of the decline in the atmospheric 13 CH 4 / 12 CH 4 ratio and the recent growth in C 2 H 6 . Our approach indicates that significant OH-related uncertainties in the CH 4 budget remain, and we find that it is not possible to implicate, with a high degree of confidence, rapid global CH 4 emissions changes as the primary driver of recent trends when our inferred OH trends and these uncertainties are considered.}, annote = {10.1073/pnas.1616426114}, author = {Rigby, Matthew and Montzka, Stephen A and Prinn, Ronald G and White, James W C and Young, Dickon and O'Doherty, Simon and Lunt, Mark F and Ganesan, Anita L and Manning, Alistair J and Simmonds, Peter G and Salameh, Peter K and Harth, Christina M and M{\"{u}}hle, Jens and Weiss, Ray F and Fraser, Paul J and Steele, L Paul and Krummel, Paul B and McCulloch, Archie and Park, Sunyoung}, doi = {10.1073/pnas.1616426114}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, month = {may}, number = {21}, pages = {5373--5377}, title = {{Role of atmospheric oxidation in recent methane growth}}, url = {http://www.pnas.org/content/early/2017/04/11/1616426114.abstract http://www.pnas.org/lookup/doi/10.1073/pnas.1616426114}, volume = {114}, year = {2017} } @article{Robinson2015, annote = {doi: 10.1080/10962247.2015.1005850}, author = {Robinson, Michael A and Olson, Michael R and Liu, Z Gerald and Schauer, James J}, doi = {10.1080/10962247.2015.1005850}, issn = {1096-2247}, journal = {Journal of the Air {\&} Waste Management Association}, month = {jun}, number = {6}, pages = {759--766}, publisher = {Taylor {\&} Francis}, title = {{The effects of emission control strategies on light-absorbing carbon emissions from a modern heavy-duty diesel engine}}, url = {https://doi.org/10.1080/10962247.2015.1005850}, volume = {65}, year = {2015} } @article{Robock2008a, abstract = {Anthropogenic stratospheric aerosol production, so as to reduce solar insolation and cool Earth, has been suggested as an emergency response to geoengineer the planet in response to global warming. While volcanic eruptions have been suggested as innocuous examples of stratospheric aerosols cooling the planet, the volcano analog actually argues against geoengineering because of ozone depletion and regional hydrologic and temperature responses. To further investigate the climate response, here we simulate the climate response to both tropical and Arctic stratospheric injection of sulfate aerosol precursors using a comprehensive atmosphere-ocean general circulation model, the National Aeronautics and Space Administration Goddard Institute for Space Studies ModelE. We inject SO2 and the model converts it to sulfate aerosols, transports the aerosols and removes them through dry and wet deposition, and calculates the climate response to the radiative forcing from the aerosols. We conduct simulations of future climate with the Intergovernmental Panel on Climate Change A1B business-as-usual scenario both with and without geoengineering and compare the results. We find that if there were a way to continuously inject SO2 into the lower stratosphere, it would produce global cooling. Tropical SO2 injection would produce sustained cooling over most of the world, with more cooling over continents. Arctic SO2 injection would not just cool the Arctic. Both tropical and Arctic SO2 injection would disrupt the Asian and African summer monsoons, reducing precipitation to the food supply for billions of people. These regional climate anomalies are but one of many reasons that argue against the implementation of this kind of geoengineering. Copyright 2008 by the American Geophysical Union.}, author = {Robock, Alan and Oman, Luke and Stenchikov, Georgiy L.}, doi = {10.1029/2008JD010050}, issn = {0148-0227}, journal = {Journal of Geophysical Research: Atmospheres}, month = {aug}, number = {D16}, pages = {D16101}, title = {{Regional climate responses to geoengineering with tropical and Arctic SO2 injections}}, url = {http://doi.wiley.com/10.1029/2008JD010050}, volume = {113}, year = {2008} } @incollection{Rogelj2018bSR15, author = {Rogelj, J. and Shindell, D. and Jiang, K. and Fifita, S. and Forster, P. and Ginzburg, V. and Handa, C. and Kheshgi, H. and Kobayashi, S. and Kriegler, E. and Mundaca, L. and Seferian, R. and Vilarino, M.V.}, booktitle = {Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change}, doi = {https://www.ipcc.ch/sr15/chapter/chapter-2/}, editor = {Masson-Delmotte, V. and Zhai, P. and Pörtner, H. O. and Roberts, D. and Skea, J. and Shukla, P.R. and Pirani, A. and Moufouma-Okia, W. and Péan, C. and Pidcock, R. and Connors, S. and Matthews, J. B. R. and Chen, Y. and Zhou, X. and Gomis, M. I. and Lonnoy, E. and Maycock, T. and Tignor, M. and Waterfield, T.}, pages = {93--174}, publisher = {In Press}, title = {{Mitigation Pathways Compatible With 1.5°C in the Context of Sustainable Development}}, url = {https://www.ipcc.ch/sr15/chapter/chapter-2/}, year = {2018} } @article{Rogelj2014b, abstract = {Anthropogenic global warming is driven by emissions of a wide variety of radiative forcers ranging from very short-lived climate forcers (SLCFs), like black carbon, to very long-lived, like CO2. These species are often released from common sources and are therefore intricately linked. However, for reasons of simplification, this CO2-SLCF linkage was often disregarded in long-term projections of earlier studies. Here we explicitly account for CO2-SLCF linkages and show that the short- and long-term climate effects of many SLCF measures consistently become smaller in scenarios that keep warming to below 2 °C relative to preindustrial levels. Although long-term mitigation of methane and hydrofluorocarbons are integral parts of 2 °C scenarios, early action on these species mainly influences near-term temperatures and brings small benefits for limiting maximum warming relative to comparable reductions taking place later. Furthermore, we find that maximum 21st-century warming in 2 °C-consistent scenarios is largely unaffected by additional black-carbon-related measures because key emission sources are already phased-out through CO2 mitigation. Our study demonstrates the importance of coherently considering CO2-SLCF coevolutions. Failing to do so leads to strongly and consistently overestimating the effect of SLCF measures in climate stabilization scenarios. Our results reinforce that SLCF measures are to be considered complementary rather than a substitute for early and stringent CO2 mitigation. Near-term SLCF measures do not allow for more time for CO2 mitigation. We disentangle and resolve the distinct benefits across different species and therewith facilitate an integrated strategy for mitigating both short and long-term climate change.}, author = {Rogelj, Joeri and Schaeffer, Michiel and Meinshausen, Malte and Shindell, Drew T. and Hare, William and Klimont, Zbigniew and Velders, Guus J. M. and Amann, Markus and Schellnhuber, Hans Joachim}, doi = {10.1073/pnas.1415631111}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, keywords = {Carbon Dioxide,Climate change mitigation,black carbon,short-lived climate forcers}, language = {en}, month = {nov}, number = {46}, pages = {16325--16330}, pmid = {25368182}, title = {{Disentangling the effects of CO2 and short-lived climate forcer mitigation}}, url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1415631111}, volume = {111}, year = {2014} } @article{Rogelj2014c, abstract = {The fifth phase of the Coupled Model Intercomparison Project1 uses four representative concentration pathways2 (RCPs) that span the literature range of total anthropogenic radiative forcing2,3 but not necessarily of each single forcing agent. We here explore a wide range of air-pollutant emissions over the twenty-first century consistent with the global CO2 paths of the RCPs, by varying assumptions on air-pollution controls and accounting for the possible phase-out of CO2 –emitting sources. We show that global air-pollutant emissions in the RCPs (including ozone and aerosol precursors) compare well to andare at times higher than cases that assume an extrapolation of current and planned air-pollution legislation in the absence of new policies to improve energy access for the poor. Stringent pollution controls and clean energy policies can thus further reduce the global atmospheric air-pollution loading below the RCP levels. When assuming pollution control frozen at 2005 levels, the RCP8.5-consistent loading of all species either stabilizes or increases during the twenty-first century, in contrast to RCP4.5 and RCP2.6, which see a consistent decrease in the long term. Our results inform the possible range of global aerosol loading. However, the net aerosol forcing depends strongly on the geographical location of emissions4. Therefore, a regional perspective is required to further explore the range of compatible forcing projections.}, author = {Rogelj, Joeri and Rao, Shilpa and McCollum, David L. and Pachauri, Shonali and Klimont, Zbigniew and Krey, Volker and Riahi, Keywan}, doi = {10.1038/nclimate2178}, isbn = {1758-678X}, issn = {17586798}, journal = {Nature Climate Change}, language = {en}, month = {aug}, number = {6}, pages = {446--450}, title = {{Air-pollution emission ranges consistent with the representative concentration pathways}}, url = {http://www.nature.com/nclimate/journal/v4/n6/full/nclimate2178.html http://www.nature.com/nclimate/journal/v4/n6/pdf/nclimate2178.pdf}, volume = {4}, year = {2014} } @article{Rogelj2018a, abstract = {The 2015 Paris Agreement calls for countries to pursue efforts to limit global-mean temperature rise to 1.5 °C. The transition pathways that can meet such a target have not, however, been extensively explored. Here we describe scenarios that limit end-of-century radiative forcing to 1.9 W m−2, and consequently restrict median warming in the year 2100 to below 1.5 °C. We use six integrated assessment models and a simple climate model, under different socio-economic, technological and resource assumptions from five Shared Socio-economic Pathways (SSPs). Some, but not all, SSPs are amenable to pathways to 1.5 °C. Successful 1.9 W m−2 scenarios are characterized by a rapid shift away from traditional fossil-fuel use towards large-scale low-carbon energy supplies, reduced energy use, and carbon-dioxide removal. However, 1.9 W m−2 scenarios could not be achieved in several models under SSPs with strong inequalities, high baseline fossil-fuel use, or scattered short-term climate policy. Further research can help policy-makers to understand the real-world implications of these scenarios.}, author = {Rogelj, Joeri and Popp, Alexander and Calvin, Katherine V and Luderer, Gunnar and Emmerling, Johannes and Gernaat, David and Fujimori, Shinichiro and Strefler, Jessica and Hasegawa, Tomoko and Marangoni, Giacomo and Krey, Volker and Kriegler, Elmar and Riahi, Keywan and van Vuuren, Detlef P and Doelman, Jonathan and Drouet, Laurent and Edmonds, Jae and Fricko, Oliver and Harmsen, Mathijs and Havl{\'{i}}k, Petr and Humpen{\"{o}}der, Florian and Stehfest, Elke and Tavoni, Massimo}, doi = {10.1038/s41558-018-0091-3}, issn = {1758-6798}, journal = {Nature Climate Change}, number = {4}, pages = {325--332}, title = {{Scenarios towards limiting global mean temperature increase below 1.5 °C}}, url = {https://doi.org/10.1038/s41558-018-0091-3}, volume = {8}, year = {2018} } @article{Rogelj2017, abstract = {The UN Paris Agreement puts in place a legally binding mechanism to increase mitigation action over time. Countries put forward pledges called nationally determined contributions (NDC) whose impact is assessed in global stocktaking exercises. Subsequently, actions can then be strengthened in light of the Paris climate objective: Limiting global mean temperature increase to well below 2 °C and pursuing efforts to limit it further to 1.5 °C. However, pledged actions are currently described ambiguously and this complicates the global stocktaking exercise. Here, we systematically explore possible interpretations of NDC assumptions, and show that this results in estimated emissions for 2030 ranging from 47 to 63 GtCO2e yr-1. We show that this uncertainty has critical implications for the feasibility and cost to limit warming well below 2 °C and further to 1.5 °C. Countries are currently working towards clarifying the modalities of future NDCs. We identify salient avenues to reduce the overall uncertainty by about 10 percentage points through simple, technical clarifications regarding energy accounting rules. Remaining uncertainties depend to a large extent on politically valid choices about how NDCs are expressed, and therefore raise the importance of a thorough and robust process that keeps track of where emissions are heading over time.}, author = {Rogelj, Joeri and Fricko, Oliver and Meinshausen, Malte and Krey, Volker and Zilliacus, Johanna J J and Riahi, Keywan}, doi = {10.1038/ncomms15748}, issn = {20411723}, journal = {Nature Communications}, keywords = {Climate,Socioeconomic scenarios,change mitigation,change policy}, month = {jun}, number = {1}, pages = {1--12}, pmid = {28585924}, publisher = {Nature Publishing Group}, title = {{Understanding the origin of Paris Agreement emission uncertainties}}, url = {www.nature.com/naturecommunications}, volume = {8}, year = {2017} } @article{Romer2018, abstract = {Surface ozone concentrations are observed to increase with rising temperatures, but the mechanisms responsible for this effect in rural and remote continental regions remain uncertain. Better understanding of the effects of temperature on ozone is crucial to understanding global air quality and how it may be affected by climate change. We combine measurements from a focused ground campaign in summer 2013 with a long-Term record from a forested site in the rural southeastern United States, to examine how daily average temperature affects ozone production. We find that changes to local chemistry are key drivers of increased ozone concentrations on hotter days, with integrated daily ozone production increasing by 2.3ĝ€ppbĝ€†°Cĝ'1. Nearly half of this increase is attributable to temperature-driven increases in emissions of nitrogen oxides (NOx), most likely by soil microbes. The increase of soil NOx emissions with temperature suggests that ozone will continue to increase with temperature in the future, even as direct anthropogenic NOx emissions decrease dramatically. The links between temperature, soil NOx, and ozone form a positive climate feedback.}, author = {Romer, Paul S. and Duffey, Kaitlin C. and Wooldridge, Paul J. and Edgerton, Eric and Baumann, Karsten and Feiner, Philip A. and Miller, David O. and Brune, William H. and Koss, Abigail R. and {De Gouw}, Joost A. and Misztal, Pawel K. and Goldstein, Allen H. and Cohen, Ronald C.}, doi = {10.5194/acp-18-2601-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {feb}, number = {4}, pages = {2601--2614}, title = {{Effects of temperature-dependent NOx emissions on continental ozone production}}, url = {https://www.atmos-chem-phys.net/18/2601/2018/}, volume = {18}, year = {2018} } @article{acp-20-14597-2020, author = {Rooney, B and Wang, Y and Jiang, J H and Zhao, B and Zeng, Z.-C. and Seinfeld, J H}, doi = {10.5194/acp-20-14597-2020}, file = {::}, journal = {Atmospheric Chemistry and Physics}, number = {23}, pages = {14597--14616}, title = {{Air quality impact of the Northern California Camp Fire of November 2018}}, url = {https://acp.copernicus.org/articles/20/14597/2020/}, volume = {20}, year = {2020} } @article{Rosenstiel2003, author = {Rosenstiel, Todd N. and Potosnak, Mark J. and Griffin, Kevin L. and Fall, Ray and Monson, Russell K.}, doi = {10.1038/nature01312}, issn = {0028-0836}, journal = {Nature}, month = {jan}, number = {6920}, pages = {256--259}, title = {{Increased CO2 uncouples growth from isoprene emission in an agriforest ecosystem}}, volume = {421}, year = {2003} } @article{doi:10.1002/2017JD027709, abstract = {Abstract Nonmethane hydrocarbons have been used as tracers in research on emissions and atmospheric oxidation chemistry. This research investigates source region mixing ratio trends of the nonmethane hydrocarbons i-butane, n-butane, i-pentane, and n-pentane, and the (i/n) isomeric ratios of these compounds between 2001 and 2015. Data collected at Photochemical Assessment Monitoring Stations, mandated by the U.S. Environmental Protection Agency in ozone nonattainment areas, and data collected at Global Greenhouse Gas Reference Network sites within the National Oceanic and Atmospheric Administration network, and analyzed at the Institute of Arctic and Alpine Research at the University of Colorado-Boulder, were examined. Among all considered species, linear regression analyses on concentration time series had negative slopes at 81{\%} of sites, indicating predominantly declining butane and pentane atmospheric concentrations. Mostly negative slopes (78{\%} of sites) were found for the (i/n) butane and pentane isomeric ratios, including all six and seven statistically significant (i/n) butane and pentane trends, respectively. Over the {\~{}}15 year investigation period and averaged over all sites, total relative changes were {\~{}}30 and 45{\%} for the (i/n) ratios of butanes and pentanes, respectively, with a relative increase in the prominence of the n-isomers. Most likely causes include changing isomeric ratios in gasoline sector emissions, and increasing influence of oil and natural gas industry emissions. Changes in concentrations and isomeric ratios depend on proximity of contributing emission sources to measurement sites.}, author = {Rossabi, Sam and Helmig, Detlev}, doi = {10.1002/2017JD027709}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {atmospheric,butanes,isomeric ratio,pentanes,trends}, number = {7}, pages = {3772--3790}, title = {{Changes in Atmospheric Butanes and Pentanes and Their Isomeric Ratios in the Continental United States}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017JD027709}, volume = {123}, year = {2018} } @article{Rowlinson2019, abstract = {The interannual variability of the greenhouse gases methane (span classCombining double low line"inline-formula"CH4/span) and tropospheric ozone (span classCombining double low line"inline-formula"O3/span) is largely driven by natural variations in global emissions and meteorology. The El Ni{\~{n}}o-Southern Oscillation (ENSO) is known to influence fire occurrence, wetland emission and atmospheric circulation, affecting sources and sinks of span classCombining double low line"inline-formula"CH4/span and tropospheric span classCombining double low line"inline-formula"O3/span, but there are still important uncertainties associated with the exact mechanism and magnitude of this effect. Here we use a modelling approach to investigate how fires and meteorology control the interannual variability of global carbon monoxide (CO), span classCombining double low line"inline-formula"CH4/span and span classCombining double low line"inline-formula"O3/span concentrations, particularly during large El Ni{\~{n}}o events. Using a three-dimensional chemical transport model (TOMCAT) coupled to a sophisticated aerosol microphysics scheme (GLOMAP) we simulate changes to CO, hydroxyl radical (OH) and span classCombining double low line"inline-formula"O3/span for the period 1997-2014. We then use an offline radiative transfer model to quantify the climate impact of changes to atmospheric composition as a result of specific drivers./p During the El Ni{\~{n}}o event of 1997-1998, there were increased emissions from biomass burning globally, causing global CO concentrations to increase by more than 40{\&}thinsp;{\%}. This resulted in decreased global mass-weighted tropospheric OH concentrations of up to 9{\&}thinsp;{\%} and a consequent 4{\&}thinsp;{\%} increase in the span classCombining double low line"inline-formula"CH4/span atmospheric lifetime. The change in span classCombining double low line"inline-formula"CH4/span lifetime led to a 7.5{\&}thinsp;ppb{\&}thinsp;yrspan classCombining double low line"inline-formula"-1/span increase in the global mean span classCombining double low line"inline-formula"CH4/span growth rate in 1998. Therefore, biomass burning emission of CO could account for 72{\&}thinsp;{\%} of the total effect of fire emissions on span classCombining double low line"inline-formula"CH4/span growth rate in 1998./p Our simulations indicate that variations in fire emissions and meteorology associated with El Ni{\~{n}}o have opposing impacts on tropospheric span classCombining double low line"inline-formula"O3/span burden. El Ni{\~{n}}o-related changes in atmospheric transport and humidity decrease global tropospheric span classCombining double low line"inline-formula"O3/span concentrations leading to a span classCombining double low line"inline-formula"-0.03/span{\&}thinsp;W{\&}thinsp;mspan classCombining double low line"inline-formula"-2/span change in the span classCombining double low line"inline-formula"O3/span radiative effect (RE). However, enhanced fire emission of precursors such as nitrogen oxides (span classCombining double low line"inline-formula"NOix/i/span) and CO increase span classCombining double low line"inline-formula"O3/span and lead to an span classCombining double low line"inline-formula"O3/span RE of 0.03{\&}thinsp;W{\&}thinsp;mspan classCombining double low line"inline-formula"-2/span. While globally the two mechanisms nearly cancel out, causing only a small change in global mean span classCombining double low line"inline-formula"O3/span RE, the regional changes are large - up to span classCombining double low line"inline-formula"-0.33/span{\&}thinsp;W{\&}thinsp;mspan classCombining double low line"inline-formula"-2/span with potentially important consequences for atmospheric heating and dynamics.}, author = {Rowlinson, Matthew J. and Rap, Alexandru and Arnold, Stephen R. and Pope, Richard J. and Chipperfield, Martyn P. and Mcnorton, Joe and Forster, Piers and Gordon, Hamish and Pringle, Kirsty J. and Feng, Wuhu and Kerridge, Brian J. and Latter, Barry L. and Siddans, Richard}, doi = {10.5194/acp-19-8669-2019}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {jul}, number = {13}, pages = {8669--8686}, publisher = {Copernicus Publications}, title = {{Impact of El Ni{\~{n}}o-Southern Oscillation on the interannual variability of methane and tropospheric ozone}}, volume = {19}, year = {2019} } @article{Ru2018, abstract = {Simplified assumptions regarding the relationship between per capita income and emissions are oftentimes utilized to generate future emission scenarios in integrated assessment models (IAMs). One such relationship is an environmental Kuznets curve (EKC), where emissions first increase, then decline with income growth. However, current knowledge about this relationship lacks the specificity needed for each sector and pollutant pairing, which is important for future emission scenarios. To fill this knowledge gap, we analyze the historical relationship between per capita income and emissions of SO 2 , CO 2 , and black carbon (BC) utilizing widely-used global, country-level emission inventories for the following four sectors: power, industry, residential, and transportation. Based on a modeling setup using long-term growth rates, emissions of SO 2 from the power and industrial sectors, as well as CO 2 from the industrial and the residential sectors, largely follow an EKC pattern. Income-emission trajectories for SO 2 and CO 2 from other sectors, and those for BC from all sectors, do not show an EKC, however. Results across different global inventories were variable, indicating that uncertainties within historical emission trajectories persist. Nonetheless, these results demonstrate that long-term income-emission trajectories of air pollutants are both sector and pollutant specific. Future reference trajectories of SO 2 and BC from three IAMs show earlier estimates of turnover incomes and faster rates of emission declines when compared to historical data. Users of future emission scenarios derived using EKC assumptions should consider the underlying uncertainties in such projections in light of this historical analysis.}, author = {Ru, Muye and Shindell, Drew T. and Seltzer, Karl M. and Tao, Shu and Zhong, Qirui}, doi = {10.1088/1748-9326/aaece2}, issn = {17489326}, journal = {Environmental Research Letters}, keywords = {black carbon,economic growth,emission,environmental Kuznets curve,integrated assessment models,trajectory}, number = {12}, pages = {124021}, publisher = {IOP Publishing}, title = {{The long-term relationship between emissions and economic growth for SO2, CO2, and BC}}, url = {http://dx.doi.org/10.1088/1748-9326/aaece2}, volume = {13}, year = {2018} } @article{Ryder2018, abstract = {1 µm. Within the SAL, particles larger than 20 µm diameter were always present up to 5 km altitude, in concentrations over 10−5 cm−3, constituting up to 40 {\%} of total dust mass. Mean deff and VMD were 4.0 and 5.5 µm respectively. Larger particles were detected in the SAL than can be explained by sedimentation theory alone. Coarse-mode composition was dominated by quartz and alumino-silicates; the accumulation mode showed a strong contribution from sulfate-rich and sea salt particles. In the SAL, measured single scattering albedos (SSAs) at 550 nm representing d}, author = {Ryder, Claire L and Marenco, Franco and Brooke, Jennifer K and Estelles, Victor and Cotton, Richard and Formenti, Paola and McQuaid, James B and Price, Hannah C and Liu, Dantong and Ausset, Patrick and Rosenberg, Phil D and Taylor, Jonathan W and Choularton, Tom and Bower, Keith and Coe, Hugh and Gallagher, Martin and Crosier, Jonathan and Lloyd, Gary and Highwood, Eleanor J and Murray, Benjamin J}, doi = {10.5194/acp-18-17225-2018}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {dec}, number = {23}, pages = {17225--17257}, publisher = {Copernicus Publications}, title = {{Coarse-mode mineral dust size distributions, composition and optical properties from AER-D aircraft measurements over the tropical eastern Atlantic}}, url = {https://acp.copernicus.org/articles/18/17225/2018/}, volume = {18}, year = {2018} } @article{doi:10.1080/10962247.2014.959139, annote = {PMID: 25946960}, author = {Saari, Rebecca K and Selin, Noelle E and Rausch, Sebastian and Thompson, Tammy M}, doi = {10.1080/10962247.2014.959139}, journal = {Journal of the Air {\&} Waste Management Association}, number = {1}, pages = {74--89}, publisher = {Taylor {\&} Francis}, title = {{A self-consistent method to assess air quality co-benefits from U.S. climate policies}}, url = {https://doi.org/10.1080/10962247.2014.959139}, volume = {65}, year = {2015} } @article{Sadiq2017, abstract = {{\textless}p{\textgreater}Abstract. Tropospheric ozone is one of the most hazardous air pollutants as it harms both human health and plant productivity. Foliage uptake of ozone via dry deposition damages photosynthesis and causes stomatal closure. These foliage changes could lead to a cascade of biogeochemical and biogeophysical effects that not only modulate the carbon cycle, regional hydrometeorology and climate, but also cause feedbacks onto surface ozone concentration itself. In this study, we implement a semi-empirical parameterization of ozone damage on vegetation in the Community Earth System Model to enable online ozone–vegetation coupling, so that for the first time ecosystem structure and ozone concentration can coevolve in fully coupled land–atmosphere simulations. With ozone–vegetation coupling, present-day surface ozone is simulated to be higher by up to 4–6 ppbv over Europe, North America and China. Reduced dry deposition velocity following ozone damage contributes to ∼ 40–100 {\%} of those increases, constituting a significant positive biogeochemical feedback on ozone air quality. Enhanced biogenic isoprene emission is found to contribute to most of the remaining increases, and is driven mainly by higher vegetation temperature that results from lower transpiration rate. This isoprene-driven pathway represents an indirect, positive meteorological feedback. The reduction in both dry deposition and transpiration is mostly associated with reduced stomatal conductance following ozone damage, whereas the modification of photosynthesis and further changes in ecosystem productivity are found to play a smaller role in contributing to the ozone–vegetation feedbacks. Our results highlight the need to consider two-way ozone–vegetation coupling in Earth system models to derive a more complete understanding and yield more reliable future predictions of ozone air quality.{\textless}/p{\textgreater}}, author = {Sadiq, Mehliyar and Tai, Amos P. K. and Lombardozzi, Danica and {Val Martin}, Maria}, doi = {10.5194/acp-17-3055-2017}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {feb}, number = {4}, pages = {3055--3066}, title = {{Effects of ozone–vegetation coupling on surface ozone air quality via biogeochemical and meteorological feedbacks}}, url = {https://acp.copernicus.org/articles/17/3055/2017/}, volume = {17}, year = {2017} } @article{Saiz-Lopez2012, abstract = {{\textless}p{\textgreater}Abstract. We have integrated observations of tropospheric ozone, very short-lived (VSL) halocarbons and reactive iodine and bromine species from a wide variety of tropical data sources with the global CAM-Chem chemistry-climate model and offline radiative transfer calculations to compute the contribution of halogen chemistry to ozone loss and associated radiative impact in the tropical marine troposphere. The inclusion of tropospheric halogen chemistry in CAM-Chem leads to an annually averaged depletion of around 10{\%} ({\~{}}2.5 Dobson units) of the tropical tropospheric ozone column, with largest effects in the middle to upper troposphere. This depletion contributes approximately −0.10 W m−2 to the radiative flux at the tropical tropopause. This negative flux is of similar magnitude to the {\~{}}0.33 W m−2 contribution of tropospheric ozone to present-day radiative balance as recently estimated from satellite observations. We find that the implementation of oceanic halogen sources and chemistry in climate models is an important component of the natural background ozone budget and we suggest that it needs to be considered when estimating both preindustrial ozone baseline levels and long term changes in tropospheric ozone.{\textless}/p{\textgreater}}, author = {Saiz-Lopez, A. and Lamarque, J.-F. and Kinnison, D. E. and Tilmes, S. and Ord{\'{o}}{\~{n}}ez, C. and Orlando, J. J. and Conley, A. J. and Plane, J. M. C. and Mahajan, A. S. and {Sousa Santos}, G. and Atlas, E. L. and Blake, D. R. and Sander, S. P. and Schauffler, S. and Thompson, A. M. and Brasseur, G.}, doi = {10.5194/acp-12-3939-2012}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {9}, pages = {3939--3949}, title = {{Estimating the climate significance of halogen-driven ozone loss in the tropical marine troposphere}}, url = {https://acp.copernicus.org/articles/12/3939/2012/}, volume = {12}, year = {2012} } @article{Sajeev2018, author = {Sajeev, Erangu Purath Mohankumar and Amon, Barbara and Ammon, Christian and Zollitsch, Werner and Winiwarter, Wilfried}, doi = {10.1007/s10705-017-9893-3}, issn = {1385-1314, 1573-0867}, journal = {Nutrient Cycling in Agroecosystems}, language = {en}, month = {feb}, number = {1}, pages = {161--175}, title = {{Evaluating the potential of dietary crude protein manipulation in reducing ammonia emissions from cattle and pig manure: A meta-analysis}}, url = {http://link.springer.com/10.1007/s10705-017-9893-3}, volume = {110}, year = {2018} } @article{Saliba2019, abstract = {Four North Atlantic Aerosol and Marine Ecosystems Study (NAAMES) field campaigns from winter 2015 through spring 2018 sampled an extensive set of oceanographic and atmospheric parameters during the annual phytoplankton bloom cycle. This unique dataset provides four seasons of open-ocean observations of wind speed, sea surface temperature (SST), seawater particle attenuation at 660 nm (cp,660, a measure of ocean particulate organic carbon), bacterial production rates, and sea-spray aerosol size distributions and number concentrations (NSSA). The NAAMES measurements show moderate to strong correlations (0.56 {\textless} R {\textless} 0.70) between NSSA and local wind speeds in the marine boundary layer on hourly timescales, but this relationship weakens in the campaign averages that represent each season, in part because of the reduction in range of wind speed by multiday averaging. NSSA correlates weakly with seawater cp,660 (R = 0.36, P {\textless}{\textless} 0.01), but the correlation with cp,660, is improved (R = 0.51, P {\textless} 0.05) for periods of low wind speeds. In addition, NAAMES measurements provide observational dependence of SSA mode diameter (dm) on SST, with dm increasing to larger sizes at higher SST (R = 0.60, P {\textless}{\textless} 0.01) on hourly timescales. These results imply that climate models using bimodal SSA parameterizations to wind speed rather than a single SSA mode that varies with SST may overestimate SSA number concentrations (hence cloud condensation nuclei) by a factor of 4 to 7 and may underestimate SSA scattering (hence direct radiative effects) by a factor of 2 to 5, in addition to overpredicting variability in SSA scattering from wind speed by a factor of 5.}, author = {Saliba, Georges and Chen, Chia Li and Lewis, Savannah and Russell, Lynn M. and Rivellini, Laura Helena and Lee, Alex K.Y. and Quinn, Patricia K. and Bates, Timothy S. and Ha{\"{e}}ntjens, Nils and Boss, Emmanuel S. and Karp-Boss, Lee and Baetge, Nicholas and Carlson, Craig A. and Behrenfeld, Michael J.}, doi = {10.1073/pnas.1907574116}, issn = {10916490}, journal = {Proceedings of the National Academy of Sciences}, keywords = {NAAMES,Phytoplankton bloom,Radiative impacts,Sea spray aerosol}, number = {41}, pages = {20309--20314}, title = {{Factors driving the seasonal and hourly variability of sea-spray aerosol number in the North Atlantic}}, volume = {116}, year = {2019} } @article{Salter2014, abstract = {Breaking waves on the ocean surface produce bubbles which, upon bursting, deliver seawater constituents into the atmosphere as sea spray aerosol particles. One way of investigating this process in the laboratory is to generate a bubble plume by a continuous plunging jet. We performed a series of laboratory experiments to elucidate the role of seawater temperature on aerosol production from artificial seawater free from organic contamination using a plunging jet. The seawater temperature was varied from −1.3° C to 30.1° C, while the volume of air entrained by the jet, surface bubble size distributions, and size distribution of the aerosol particles produced was monitored. We observed that the volume of air entrained decreased as the seawater temperature was increased. The number of surface bubbles with film radius smaller than 2 mm decreased nonlinearly with seawater temperature. This decrease was coincident with a substantial reduction in particle production. The number concentrations of particles with dry diameter less than ∼1 $\mu$m decreased substantially as the seawater temperature was increased from −1.3° C to ∼9° C. With further increase in seawater temperature (up to 30° C), a small increase in the number concentration of larger particles (dry diameter {\textgreater}∼0.3 $\mu$m) was observed. Based on these observations, we infer that as seawater temperature increases, the process of bubble fragmentation changes, resulting in decreased air entrainment by the plunging jet, as well as the number of bubbles with film radius smaller than 2 mm. This again results in decreased particle production with increasing seawater temperature.}, author = {Salter, M. E. and Nilsson, E. D. and Butcher, A. and Bilde, M.}, doi = {10.1002/2013JD021376}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {jul}, number = {14}, pages = {9052--9072}, title = {{On the seawater temperature dependence of the sea spray aerosol generated by a continuous plunging jet}}, url = {https://onlinelibrary.wiley.com/doi/10.1002/2013JD021376}, volume = {119}, year = {2014} } @article{Samset2016a, abstract = {Precipitation is expected to respond differently to various drivers of anthropogenic climate change. We present the first results from the Precipitation Driver and Response Model Intercomparison Project (PDRMIP), where nine global climate models have perturbed CO2, CH4, black carbon, sulfate, and solar insolation. We divide the resulting changes to global mean and regional precipitation into fast responses that scale with changes in atmospheric absorption and slow responses scaling with surface temperature change. While the overall features are broadly similar between models, we find significant regional intermodel variability, especially over land. Black carbon stands out as a component that may cause significant model diversity in predicted precipitation change. Processes linked to atmospheric absorption are less consistently modeled than those linked to top-of-atmosphere radiative forcing. We identify a number of land regions where the model ensemble consistently predicts that fast precipitation responses to climate perturbations dominate over the slow, temperature-driven responses.}, author = {Samset, B. H. and Myhre, G. and Forster, P. M. and Hodnebrog and Andrews, T. and Faluvegi, G. and Fl{\"{i}}¿½schner, D. and Kasoar, M. and Kharin, V. and Kirkev{\"{i}}¿½g, A. and Lamarque, J. F. and Olivi{\"{i}}¿½, D. and Richardson, T. and Shindell, D. and Shine, K. P. and Takemura, T. and Voulgarakis, A.}, doi = {10.1002/2016GL068064}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {PDRMIP,climate drivers,precipitation}, month = {mar}, number = {6}, pages = {2782--2791}, title = {{Fast and slow precipitation responses to individual climate forcers: A PDRMIP multimodel study}}, url = {http://doi.wiley.com/10.1002/2016GL068064}, volume = {43}, year = {2016} } @article{Samset2018, abstract = {Limiting global warming to 1.5 or 2.0°C requires strong mitigation of anthropogenic greenhouse gas (GHG) emissions. Concurrently, emissions of anthropogenic aerosols will decline, due to coemission with GHG, and measures to improve air quality. However, the combined climate effect of GHG and aerosol emissions over the industrial era is poorly constrained. Here we show the climate impacts from removing present-day anthropogenic aerosol emissions and compare them to the impacts from moderate GHG-dominated global warming. Removing aerosols induces a global mean surface heating of 0.5–1.1°C, and precipitation increase of 2.0–4.6{\%}. Extreme weather indices also increase. We find a higher sensitivity of extreme events to aerosol reductions, per degree of surface warming, in particular over the major aerosol emission regions. Under near-term warming, we find that regional climate change will depend strongly on the balance between aerosol and GHG forcing.}, annote = {doi: 10.1002/2017GL076079}, author = {Samset, B. H. and Sand, M. and Smith, C. J. and Bauer, S. E. and Forster, P. M. and Fuglestvedt, J. S. and Osprey, S. and Schleussner, C. F.}, doi = {10.1002/2017GL076079}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {aerosols,black carbon,climate change,extreme weather,organic carbon,sulfate}, month = {jan}, number = {2}, pages = {1020--1029}, publisher = {Wiley-Blackwell}, title = {{Climate Impacts From a Removal of Anthropogenic Aerosol Emissions}}, url = {https://doi.org/10.1002/2017GL076079}, volume = {45}, year = {2018} } @article{Samset2013, abstract = {The impact of black carbon (BC) aerosols on the global radiation balance is not well constrained. Here twelve global aerosol models are used to show that at least 20{\%} of the present uncertainty in modeled BC direct radiative forcing (RF) is due to diversity in the simulated vertical profile of BC mass. Results are from phases 1 and 2 of the global aerosol model intercomparison project (AeroCom). Additionally, a significant fraction of the variability is shown to come from high altitudes, as, globally, more than 40{\%} of the total BC RF is exerted above 5 km. BC emission regions and areas with transported BC are found to have differing characteristics. These insights into the importance of the vertical profile of BC lead us to suggest that observational studies are needed to better characterize the global distribution of BC, including in the upper troposphere. {\textcopyright} 2013 Author(s).}, author = {Samset, B. H. and Myhre, G. and Schulz, M. and Balkanski, Y. and Bauer, S. and Berntsen, T. K. and Bian, H. and Bellouin, N. and Diehl, T. and Easter, R. C. and Ghan, S. J. and Iversen, T. and Kinne, S. and Kirkev{\"{a}}g, A. and Lamarque, J. F. and Lin, G. and Liu, X. and Penner, J. E. and Seland, O. and Skeie, R. B. and Stier, P. and Takemura, T. and Tsigaridis, K. and Zhang, K.}, doi = {10.5194/acp-13-2423-2013}, isbn = {1324232013}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {5}, pages = {2423--2434}, title = {{Black carbon vertical profiles strongly affect its radiative forcing uncertainty}}, volume = {13}, year = {2013} } @article{Samset2020, abstract = {A major step towards achieving the goals of the Paris agreement would be a measurable change in the evolution of global warming in response to mitigation of anthropogenic emissions. The inertia and internal variability of the climate system, however, will delay the emergence of a discernible response even to strong, sustained mitigation. Here, we investigate when we could expect a significant change in the evolution of global mean surface temperature after strong mitigation of individual climate forcers. Anthropogenic CO 2 has the highest potential for a rapidly measurable influence, combined with long term benefits, but the required mitigation is very strong. Black Carbon (BC) mitigation could be rapidly discernible, but has a low net gain in the longer term. Methane mitigation combines rapid effects on surface temperature with long term effects. For other gases or aerosols, even fully removing anthropogenic emissions is unlikely to have a discernible impact before mid-century.}, author = {Samset, B H and Fuglestvedt, J S and Lund, M T}, doi = {10.1038/s41467-020-17001-1}, issn = {2041-1723}, journal = {Nature Communications}, month = {dec}, number = {1}, pages = {3261}, pmid = {32636367}, publisher = {Nature Research}, title = {{Delayed emergence of a global temperature response after emission mitigation}}, url = {http://www.nature.com/articles/s41467-020-17001-1}, volume = {11}, year = {2020} } @article{Samyn2012, abstract = {Sulfate and nitrate records from 5 ice cores spread across Svalbard were compared and revealed strong temporal similarities with previously published global estimates of SO2 and NOx anthropogenic emissions during the 20th century. A significant departure from the early century sulfate and nitrate levels was evident at all drilling sites starting from the mid-1940s. A steady increase was observed in both sulfate and nitrate profiles at most sites until the late 1960s, when the annual concentrations started to increase at a higher rate. This peak activity lasted for about a decade, and was observed to decrease steadily from the early 1980s on, when sulfate levels declined significantly and when nitrate levels finally reached sulfate levels for the first time in 20th century. The timing of these trends in Svalbard with global SO2 and NOx concentration profiles was best appraised when considering composite concentration profiles of all Svalbard ice cores for sulfate and nitrate, respectively. Composite profiles were also found to provide a convenient mean for distinguishing between the most important world source regions. Based on correlation analysis, the major pollutant sources appeared to be Western Europe and North America for both sulfate and nitrate, followed by Central Europe and former U.S.S.R. in generally similar proportions.}, author = {Samyn, D. and Vega, C. and Motoyama, H. and Pohjola, V.}, doi = {10.1657/1938-4246-44.4.490}, issn = {15230430}, journal = {Arctic, Antarctic, and Alpine Research}, number = {4}, pages = {490--499}, title = {{Nitrate and Sulfate Anthropogenic Trends in the 20th Century from Five Svalbard Ice Cores}}, volume = {44}, year = {2012} } @article{Sand2013a, author = {Sand, Maria and Berntsen, Terje Koren and Seland, {\O}yvind and Kristj{\'{a}}nsson, J{\'{o}}n Egill}, doi = {10.1002/jgrd.50613}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {Arctic,Black carbon,Climate modeling,Climate sensitivity,Emissions}, month = {jul}, number = {14}, pages = {7788--7798}, publisher = {Wiley-Blackwell}, title = {{Arctic surface temperature change to emissions of black carbon within Arctic or midlatitudes}}, url = {http://doi.wiley.com/10.1002/jgrd.50613}, volume = {118}, year = {2013} } @article{Sand2013, abstract = {Recent studies suggest that the Arctic temperature response to black carbon (BC) forcing depend strongly on the location of the forcing. We investigate how atmospheric BC in the mid-latitudes remotely influence the Arctic climate, and compare this with the response to atmospheric BC located in the Arctic itself. In this study, idealized climate simulations are carried out with a fully coupled Earth System Model, which includes a comprehensive treatment of aerosol microphysics. In order to determine how BC transported to the Arctic and BC sources not reaching the Arctic impact the Arctic climate, atmospheric BC concentrations are scaled up in the mid-latitudes (28-60 N) and in the Arctic (60-90 N), respectively. Estimates of the impact on the Arctic energy budget are represented by analyzing radiation fluxes at the top of the atmosphere and at the surface, surface turbulent fluxes, and meridional heat transport in the atmosphere. Our calculations show that increased BC forcing in the Arctic atmosphere reduces the surface air temperature in the Arctic with a corresponding increase in the sea-ice fraction, despite the increased planetary absorption of sunlight. The analysis indicates that this effect is due to a combination of a weakening of the northward heat transport caused by a reduction in the meridional temperature gradient and a dimming at the surface. On the other hand we find that BC forcing at the mid-latitudes warms the Arctic surface significantly and decreases the sea-ice fraction. Our model calculations indicate that atmospheric BC forcing outside the Arctic may be more important for the Arctic climate change than the forcing in the Arctic itself. These results suggest that mitigation strategies for the Arctic climate should also address BC sources in locations outside the Arctic even if they do not contribute much to BC in the Arctic. {\textcopyright} 2013 Author(s).}, author = {Sand, M. and Berntsen, T. K. and Kay, J. E. and Lamarque, J. F. and Seland and Kirkev{\"{a}}g, A.}, doi = {10.5194/acp-13-211-2013}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, month = {jan}, number = {1}, pages = {211--224}, title = {{The arctic response to remote and local forcing of black carbon}}, url = {https://www.atmos-chem-phys.net/13/211/2013/}, volume = {13}, year = {2013} } @article{Sand2016a, abstract = {There is growing scientific and political interest in the impacts of climate change and anthropogenic emissions on the Arctic. Over recent decades temperatures in the Arctic have increased at twice the global rate, largely as a result of ice-albedo and temperature feedbacks. Although deep cuts in global CO2 emissions are required to slow this warming, there is also growing interest in the potential for reducing short-lived climate forcers (SLCFs; refs,). Politically, action on SLCFs may be particularly promising because the benefits of mitigation are seen more quickly than for mitigation of CO2 and there are large co-benefits in terms of improved air quality. This Letter is one of the first to systematically quantify the Arctic climate impact of regional SLCFs emissions, taking into account black carbon (BC), sulphur dioxide (SO 2), nitrogen oxides (NO x), volatile organic compounds (VOCs), organic carbon (OC) and tropospheric ozone (O3), and their transport processes and transformations in the atmosphere. This study extends the scope of previous works by including more detailed calculations of Arctic radiative forcing and quantifying the Arctic temperature response. We find that the largest Arctic warming source is from emissions within the Asian nations owing to the large absolute amount of emissions. However, the Arctic is most sensitive, per unit mass emitted, to SLCFs emissions from a small number of activities within the Arctic nations themselves. A stringent, but technically feasible mitigation scenario for SLCFs, phased in from 2015 to 2030, could cut warming by 0.2 (±0.17) K in 2050.}, annote = {From Duplicate 2 (Response of Arctic temperature to changes in emissions of short-lived climate forcers - Sand, M.; Berntsen, T. K.; Von Salzen, K.; Flanner, M. G.; Langner, J.; Victor, D. G.) From Duplicate 1 (Response of Arctic temperature to changes in emissions of short-lived climate forcers - Sand, M.; Berntsen, T. K.; Von Salzen, K.; Flanner, M. G.; Langner, J.; Victor, D. G.) And Duplicate 2 (Response of Arctic temperature to changes in emissions of short-lived climate forcers - Sand, M.; Berntsen, T. K.; Von Salzen, K.; Flanner, M. G.; Langner, J.; Victor, D. G.) And Duplicate 3 (Response of Arctic temperature to changes in emissions of short-lived climate forcers - Sand, M.; Berntsen, T. K.; Von Salzen, K.; Flanner, M. G.; Langner, J.; Victor, D. G.) And Duplicate 4 (Response of Arctic temperature to changes in emissions of short-lived climate forcers - Sand, M.; Berntsen, T. K.; Von Salzen, K.; Flanner, M. G.; Langner, J.; Victor, D. G.) From Duplicate 1 (Response of Arctic temperature to changes in emissions of short-lived climate forcers - Sand, M.; Berntsen, T. K.; Von Salzen, K.; Flanner, M. G.; Langner, J.; Victor, D. G.) From Duplicate 1 (Response of Arctic temperature to changes in emissions of short-lived climate forcers - Sand, M; Berntsen, T K; von Salzen, K; Flanner, M G; Langner, J; Victor, D G) Times Cited: 32 Flanner, Mark/C-6139-2011; Sand, Maria/J-8822-2016 Flanner, Mark/0000-0003-4012-174X; Sand, Maria/0000-0003-0256-7468 0 32 1758-6798 From Duplicate 2 (Response of Arctic temperature to changes in emissions of short-lived climate forcers - Sand, M.; Berntsen, T. K.; von Salzen, K.; Flanner, M. G.; Langner, J.; Victor, D. G.) From Duplicate 2 (Response of Arctic temperature to changes in emissions of short-lived climate forcers - Sand, M.; Berntsen, T. K.; Von Salzen, K.; Flanner, M. G.; Langner, J.; Victor, D. G.) From Duplicate 1 (Response of Arctic temperature to changes in emissions of short-lived climate forcers - Sand, M; Berntsen, T K; von Salzen, K; Flanner, M G; Langner, J; Victor, D G) Times Cited: 32 Flanner, Mark/C-6139-2011; Sand, Maria/J-8822-2016 Flanner, Mark/0000-0003-4012-174X; Sand, Maria/0000-0003-0256-7468 0 32 1758-6798 From Duplicate 5 (Response of Arctic temperature to changes in emissions of short-lived climate forcers - Sand, M.; Berntsen, T. K.; Von Salzen, K.; Flanner, M. G.; Langner, J.; Victor, D. G.) Times Cited: 32 Flanner, Mark/C-6139-2011; Sand, Maria/J-8822-2016 Flanner, Mark/0000-0003-4012-174X; Sand, Maria/0000-0003-0256-7468 0 32 1758-6798}, author = {Sand, M. and Berntsen, T. K. and {Von Salzen}, K. and Flanner, M. G. and Langner, J. and Victor, D. G.}, doi = {10.1038/nclimate2880}, isbn = {1758-678X}, issn = {17586798}, journal = {Nature Climate Change}, month = {mar}, number = {3}, pages = {286--289}, publisher = {Nature Publishing Group}, title = {{Response of Arctic temperature to changes in emissions of short-lived climate forcers}}, url = {http://dx.doi.org/10.1038/nclimate2880 http://www.nature.com/articles/nclimate2880}, volume = {6}, year = {2016} } @article{Sand2020a, author = {Sand, Maria and Berntsen, Terje K and Ekman, Annica M L and Hansson, Hans-Christen and Lewinschal, Anna}, doi = {10.5194/acp-20-3079-2020}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {5}, pages = {3079--3089}, publisher = {Copernicus Publications}, title = {{Surface temperature response to regional black carbon emissions: do location and magnitude matter?}}, url = {https://acp.copernicus.org/articles/20/3079/2020/}, volume = {20}, year = {2020} } @article{acp-16-10879-2016, abstract = {The aerosol size-segregated chemical composition was analyzed at an urban (Bologna) and a rural (San Pietro Capofiume) site in the Po Valley, Italy, during June and July 2012, by ion-chromatography (major water-soluble ions and organic acids) and evolved gas analysis (total and water-soluble carbon), to investigate sources and mechanisms of secondary aerosol formation during the summer. A significant enhancement of secondary organic and inorganic aerosol mass was observed under anticyclonic conditions with recirculation of planetary boundary layer air but with substantial differences between the urban and the rural site. The data analysis, including a principal component analysis (PCA) on the size-resolved dataset of chemical concentrations, indicated that the photochemical oxidation of inorganic and organic gaseous precursors was an important mechanism of secondary aerosol formation at both sites. In addition, at the rural site a second formation process, explaining the largest fraction (22 {\%}) of the total variance, was active at nighttime, especially under stagnant conditions. Nocturnal chemistry in the rural Po Valley was associated with the formation of ammonium nitrate in large accumulation-mode (0.42–1.2 µm) aerosols favored by local thermodynamic conditions (higher relative humidity and lower temperature compared to the urban site). Nocturnal concentrations of fine nitrate were, in fact, on average 5 times higher at the rural site than in Bologna. The water uptake by this highly hygroscopic compound under high RH conditions provided the medium for increased nocturnal aerosol uptake of water-soluble organic gases and possibly also for aqueous chemistry, as revealed by the shifting of peak concentrations of secondary compounds (water-soluble organic carbon (WSOC) and sulfate) toward the large accumulation mode (0.42–1.2 µm). Contrarily, the diurnal production of WSOC (proxy for secondary organic aerosol) by photochemistry was similar at the two sites but mostly affected the small accumulation mode of particles (0.14–0.42 µm) in Bologna, while a shift to larger accumulation mode was observed at the rural site. A significant increment in carbonaceous aerosol concentration (for both WSOC and water-insoluble carbon) at the urban site was recorded mainly in the quasi-ultrafine fraction (size range 0.05–0.14 µm), indicating a direct influence of traffic emissions on the mass concentrations of this range of particles.}, author = {Sandrini, S and van Pinxteren, D and Giulianelli, L and Herrmann, H and Poulain, L and Facchini, M C and Gilardoni, S and Rinaldi, M and Paglione, M and Turpin, B J and Pollini, F and Bucci, S and Zanca, N and Decesari, S}, doi = {10.5194/acp-16-10879-2016}, journal = {Atmospheric Chemistry and Physics}, number = {17}, pages = {10879--10897}, title = {{Size-resolved aerosol composition at an urban and a rural site in the Po Valley in summertime: implications for secondary aerosol formation}}, url = {https://acp.copernicus.org/articles/16/10879/2016/}, volume = {16}, year = {2016} } @article{Sarkar2019, abstract = {A first-ever long-term (2009–2015) study on the fine particulate matter (PM 2.5 ) and black carbon (BC) aerosol were conducted over Himalaya in order to investigate the characteristics, temporal variations and the important factors regulating the long-term trend. The study was conducted over a high altitude station, Darjeeling (27°01′N, 88°15′E, 2200 m asl) representing a typical high altitude urban atmosphere at eastern Himalaya in India. The average concentrations of PM 2.5 and BC over a period of seven years were 25.2 ± 5.6 $\mu$g m −3 (ranging between 2.2 and 220.4 $\mu$g m −3 ) and 3.4 ± 0.7 $\mu$g m −3 (0.4 to 15.6 $\mu$g m −3 ) respectively. We observed decreasing trends in both PM 2.5 (49{\%} at a rate of 170 ng m −3 month −1 ) and BC (34{\%} at the rate of 20 ng m −3 month −1 ) mass concentration over this region from 2009 to 2015. We extensively studied the impact of micrometeorological parameters on the long-term trend in PM 2.5 and BC through the correlation analysis. The significant changes in boundary layer dynamics over this region played a major role in the decreasing trend of aerosols. The concentration weighted trajectory analysis revealed that the important contributory long-distant source regions for PM 2.5 and BC over eastern Himalaya were Indo Gangetic Plane and Nepal. The contributions from these regions were found to be decreased significantly from 2009 to 2015. Investigations on the fire counts associated with the forest fire, and open burning activities through the satellite observations revealed that the decreasing trend in PM 2.5 and BC over eastern Himalaya is well correlated to the decreasing trend in the fire counts over IGP and Nepal. We also explored that the changes and up gradation of the domestic fuel at the Indo Gangetic Plane regions in recent years not only improved the regional air quality but also affected the atmospheric environment over the eastern part of Himalaya.}, author = {Sarkar, Chirantan and Roy, Arindam and Chatterjee, Abhijit and Ghosh, Sanjay K. and Raha, Sibaji}, doi = {10.1016/j.scitotenv.2018.11.367}, issn = {18791026}, journal = {Science of the Total Environment}, keywords = {Black carbon,Eastern Himalaya,PM 2.5,Trend analysis}, pages = {280--296}, title = {{Factors controlling the long-term (2009–2015) trend of PM 2.5 and black carbon aerosols at eastern Himalaya, India}}, volume = {656}, year = {2019} } @article{Sarwar2015, abstract = {Fate of ozone in marine environments has been receiving increased attention due to the tightening of ambient air quality standards. The role of deposition and halogen chemistry is examined through incorporation of an enhanced ozone deposition algorithm and inclusion of halogen chemistry in a comprehensive atmospheric modeling system. The enhanced ozone deposition treatment accounts for the interaction of iodide in seawater with ozone and increases deposition velocities by 1 order of magnitude. Halogen chemistry includes detailed chemical reactions of organic and inorganic bromine and iodine species. Two different simulations are completed with the halogen chemistry: without and with photochemical reactions of higher iodine oxides. Enhanced deposition reduces mean summer-time surface ozone by ∼3{\%} over marine regions in the Northern Hemisphere. Halogen chemistry without the photochemical reactions of higher iodine oxides reduces surface ozone by ∼15{\%} whereas simulations with the photochemical reactions of higher iodine oxides indicate ozone reductions of ∼48{\%}. The model without these processes overpredicts ozone compared to observations whereas the inclusion of these processes improves predictions. The inclusion of photochemical reactions for higher iodine oxides leads to ozone predictions that are lower than observations, underscoring the need for further refinement of the halogen emissions and chemistry scheme in the model.}, annote = {doi: 10.1021/acs.est.5b01657}, author = {Sarwar, Golam and Gantt, Brett and Schwede, Donna and Foley, Kristen and Mathur, Rohit and Saiz-Lopez, Alfonso}, doi = {10.1021/acs.est.5b01657}, issn = {0013-936X}, journal = {Environmental Science {\&} Technology}, month = {aug}, number = {15}, pages = {9203--9211}, publisher = {American Chemical Society}, title = {{Impact of Enhanced Ozone Deposition and Halogen Chemistry on Tropospheric Ozone over the Northern Hemisphere}}, url = {https://doi.org/10.1021/acs.est.5b01657}, volume = {49}, year = {2015} } @article{Saunois2016a, abstract = {Abstract. The global methane (CH4) budget is becoming an increasingly important component for managing realistic pathways to mitigate climate change. This relevance, due to a shorter atmospheric lifetime and a stronger warming potential than carbon dioxide, is challenged by the still unexplained changes of atmospheric CH4 over the past decade. Emissions and concentrations of CH4 are continuing to increase, making CH4 the second most important human-induced greenhouse gas after carbon dioxide. Two major difficulties in reducing uncertainties come from the large variety of diffusive CH4 sources that overlap geographically, and from the destruction of CH4 by the very short-lived hydroxyl radical (OH). To address these difficulties, we have established a consortium of multi-disciplinary scientists under the umbrella of the Global Carbon Project to synthesize and stimulate research on the methane cycle, and producing regular (∼ biennial) updates of the global methane budget. This consortium includes atmospheric physicists and chemists, biogeochemists of surface and marine emissions, and socio-economists who study anthropogenic emissions. Following Kirschke et al. (2013), we propose here the first version of a living review paper that integrates results of top-down studies (exploiting atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up models, inventories and data-driven approaches (including process-based models for estimating land surface emissions and atmospheric chemistry, and inventories for anthropogenic emissions, data-driven extrapolations). For the 2003–2012 decade, global methane emissions are estimated by top-down inversions at 558 Tg CH4 yr−1, range 540–568. About 60 {\%} of global emissions are anthropogenic (range 50–65 {\%}). Since 2010, the bottom-up global emission inventories have been closer to methane emissions in the most carbon-intensive Representative Concentrations Pathway (RCP8.5) and higher than all other RCP scenarios. Bottom-up approaches suggest larger global emissions (736 Tg CH4 yr−1, range 596–884) mostly because of larger natural emissions from individual sources such as inland waters, natural wetlands and geological sources. Considering the atmospheric constraints on the top-down budget, it is likely that some of the individual emissions reported by the bottom-up approaches are overestimated, leading to too large global emissions. Latitudinal data from top-down emissions indicate a predominance of tropical emissions (∼ 64 {\%} of the global budget,}, author = {Saunois, Marielle and Bousquet, Philippe and Poulter, Ben and Peregon, Anna and Ciais, Philippe and Canadell, Josep G. and Dlugokencky, Edward J. and Etiope, Giuseppe and Bastviken, David and Houweling, Sander and Janssens-Maenhout, Greet and Tubiello, Francesco N. and Castaldi, Simona and Jackson, Robert B. and Alexe, Mihai and Arora, Vivek K. and Beerling, David J. and Bergamaschi, Peter and Blake, Donald R. and Brailsford, Gordon and Brovkin, Victor and Bruhwiler, Lori and Crevoisier, Cyril and Crill, Patrick and Covey, Kristofer and Curry, Charles and Frankenberg, Christian and Gedney, Nicola and H{\"{o}}glund-Isaksson, Lena and Ishizawa, Misa and Ito, Akihiko and Joos, Fortunat and Kim, Heon-Sook and Kleinen, Thomas and Krummel, Paul and Lamarque, Jean-Fran{\c{c}}ois and Langenfelds, Ray and Locatelli, Robin and Machida, Toshinobu and Maksyutov, Shamil and McDonald, Kyle C. and Marshall, Julia and Melton, Joe R. and Morino, Isamu and Naik, Vaishali and O'Doherty, Simon and Parmentier, Frans-Jan W. and Patra, Prabir K. and Peng, Changhui and Peng, Shushi and Peters, Glen P. and Pison, Isabelle and Prigent, Catherine and Prinn, Ronald and Ramonet, Michel and Riley, William J. and Saito, Makoto and Santini, Monia and Schroeder, Ronny and Simpson, Isobel J. and Spahni, Renato and Steele, Paul and Takizawa, Atsushi and Thornton, Brett F. and Tian, Hanqin and Tohjima, Yasunori and Viovy, Nicolas and Voulgarakis, Apostolos and van Weele, Michiel and van der Werf, Guido R. and Weiss, Ray and Wiedinmyer, Christine and Wilton, David J. and Wiltshire, Andy and Worthy, Doug and Wunch, Debra and Xu, Xiyan and Yoshida, Yukio and Zhang, Bowen and Zhang, Zhen and Zhu, Qiuan}, doi = {10.5194/essd-8-697-2016}, isbn = {1866-3508}, issn = {1866-3516}, journal = {Earth System Science Data}, month = {dec}, number = {2}, pages = {697--751}, title = {{The global methane budget 2000–2012}}, url = {https://essd.copernicus.org/articles/8/697/2016/}, volume = {8}, year = {2016} } @article{Saunois2020, abstract = {Abstract. Understanding and quantifying the global methane (CH4) budget is important for assessing realistic pathways to mitigate climate change. Atmospheric emissions and concentrations of CH4 continue to increase, making CH4 the second most important human-influenced greenhouse gas in terms of climate forcing, after carbon dioxide (CO2). The relative importance of CH4 compared to CO2 depends on its shorter atmospheric lifetime, stronger warming potential, and variations in atmospheric growth rate over the past decade, the causes of which are still debated. Two major challenges in reducing uncertainties in the atmospheric growth rate arise from the variety of geographically overlapping CH4 sources and from the destruction of CH4 by short-lived hydroxyl radicals (OH). To address these challenges, we have established a consortium of multidisciplinary scientists under the umbrella of the Global Carbon Project to synthesize and stimulate new research aimed at improving and regularly updating the global methane budget. Following Saunois et al. (2016), we present here the second version of the living review paper dedicated to the decadal methane budget, integrating results of top-down studies (atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up estimates (including process-based models for estimating land surface emissions and atmospheric chemistry, inventories of anthropogenic emissions, and data-driven extrapolations). For the 2008–2017 decade, global methane emissions are estimated by atmospheric inversions (a top-down approach) to be 576 Tg CH4 yr−1 (range 550–594, corresponding to the minimum and maximum estimates of the model ensemble). Of this total, 359 Tg CH4 yr−1 or ∼ 60 {\%} is attributed to anthropogenic sources, that is emissions caused by direct human activity (i.e. anthropogenic emissions; range 336–376 Tg CH4 yr−1 or 50 {\%}–65 {\%}). The mean annual total emission for the new decade (2008–2017) is 29 Tg CH4 yr−1 larger than our estimate for the previous decade (2000–2009), and 24 Tg CH4 yr−1 larger than the one reported in the previous budget for 2003–2012 (Saunois et al., 2016). Since 2012, global CH4 emissions have been tracking the warmest scenarios assessed by the Intergovernmental Panel on Climate Change. Bottom-up methods suggest almost 30 {\%} larger global emissions (737 Tg CH4 yr−1, range 594–881) than top-down inversion methods. Indeed, bottom-up estimates for natural sources such as natural wetlands, other inland water systems, and geological sources are higher than top-down estimates. The atmospheric constraints on the top-down budget suggest that at least some of these bottom-up emissions are overestimated. The latitudinal distribution of atmospheric observation-based emissions indicates a predominance of tropical emissions (∼ 65 {\%} of the global budget,}, author = {Saunois, Marielle and Stavert, Ann R and Poulter, Ben and Bousquet, Philippe and Canadell, Josep G and Jackson, Robert B and Raymond, Peter A and Dlugokencky, Edward J and Houweling, Sander and Patra, Prabir K and Ciais, Philippe and Arora, Vivek K and Bastviken, David and Bergamaschi, Peter and Blake, Donald R and Brailsford, Gordon and Bruhwiler, Lori and Carlson, Kimberly M and Carrol, Mark and Castaldi, Simona and Chandra, Naveen and Crevoisier, Cyril and Crill, Patrick M and Covey, Kristofer and Curry, Charles L and Etiope, Giuseppe and Frankenberg, Christian and Gedney, Nicola and Hegglin, Michaela I and H{\"{o}}glund-Isaksson, Lena and Hugelius, Gustaf and Ishizawa, Misa and Ito, Akihiko and Janssens-Maenhout, Greet and Jensen, Katherine M and Joos, Fortunat and Kleinen, Thomas and Krummel, Paul B and Langenfelds, Ray L and Laruelle, Goulven G and Liu, Licheng and Machida, Toshinobu and Maksyutov, Shamil and McDonald, Kyle C and McNorton, Joe and Miller, Paul A and Melton, Joe R and Morino, Isamu and M{\"{u}}ller, Jurek and Murguia-Flores, Fabiola and Naik, Vaishali and Niwa, Yosuke and Noce, Sergio and O'Doherty, Simon and Parker, Robert J and Peng, Changhui and Peng, Shushi and Peters, Glen P and Prigent, Catherine and Prinn, Ronald and Ramonet, Michel and Regnier, Pierre and Riley, William J and Rosentreter, Judith A and Segers, Arjo and Simpson, Isobel J and Shi, Hao and Smith, Steven J and Steele, L Paul and Thornton, Brett F and Tian, Hanqin and Tohjima, Yasunori and Tubiello, Francesco N and Tsuruta, Aki and Viovy, Nicolas and Voulgarakis, Apostolos and Weber, Thomas S and van Weele, Michiel and van der Werf, Guido R and Weiss, Ray F and Worthy, Doug and Wunch, Debra and Yin, Yi and Yoshida, Yukio and Zhang, Wenxin and Zhang, Zhen and Zhao, Yuanhong and Zheng, Bo and Zhu, Qing and Zhu, Qiuan and Zhuang, Qianlai}, doi = {10.5194/essd-12-1561-2020}, issn = {1866-3516}, journal = {Earth System Science Data}, month = {jul}, number = {3}, pages = {1561--1623}, publisher = {Copernicus Publications}, title = {{The Global Methane Budget 2000–2017}}, url = {https://essd.copernicus.org/articles/12/1561/2020/}, volume = {12}, year = {2020} } @article{Schiferl2016, abstract = {The variability of atmospheric ammonia (NH3), emitted largely from agricultural sources, is an important factor when considering how inorganic fine particulate matter (PM2.5) concentrations and nitrogen cycling are changing over the United States. This study combines new observations of ammonia concentration from the surface, aboard aircraft, and retrieved by satellite to both evaluate the simulation of ammonia in a chemical transport model (GEOS-Chem) and identify which processes control the variability of these concentrations over a 5-year period (2008-2012). We find that the model generally underrepresents the ammonia concentration near large source regions (by 26{\%} at surface sites) and fails to reproduce the extent of interannual variability observed at the surface during the summer (JJA). Variability in the base simulation surface ammonia concentration is dominated by meteorology (64{\%}) as compared to reductions in SO2 and NOx emissions imposed by regulation (32{\%}) over this period. Introduction of year-to-year varying ammonia emissions based on animal population, fertilizer application, and meteorologically driven volatilization does not substantially improve the model comparison with observed ammonia concentrations, and these ammonia emissions changes have little effect on the simulated ammonia concentration variability compared to those caused by the variability of meteorology and acid-precursor emissions. There is also little effect on the PM2.5 concentration due to ammonia emissions variability in the summer when gas-phase changes are favored, but variability in wintertime emissions, as well as in early spring and late fall, will have a larger impact on PM2.5 formation. This work highlights the need for continued improvement in both satellite-based and in situ ammonia measurements to better constrain the magnitude and impacts of spatial and temporal variability in ammonia concentrations.}, author = {Schiferl, Luke D. and Heald, Colette L. and Damme, Martin Van and Clarisse, Lieven and Clerbaux, Cathy and Coheur, Pierre Fran{\c{c}}ois and Nowak, John B. and Neuman, J. Andrew and Herndon, Scott C. and Roscioli, Joseph R. and Eilerman, Scott J.}, doi = {10.5194/acp-16-12305-2016}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {sep}, number = {18}, pages = {12305--12328}, publisher = {Copernicus {\{}GmbH{\}}}, title = {{Interannual variability of ammonia concentrations over the United States: Sources and implications}}, volume = {16}, year = {2016} } @misc{Schmale2014, abstract = {The article discusses the aspects of air pollution that causes to severe environmental damages and focuses on the need to improve the air quality and mitigation of short-lived climate-forcing pollutants (SLCPs). Topics include interaction between air pollution and urban heat-island effect, damages ecosystems and agriculture, climate change mitigation, and global mean temperature rise. Chart depicting several air pollutants that influence climate like black carbon and methane is included.}, author = {Schmale, Julia and Shindell, Drew and {Von Schneidemesser}, Erika and Chabay, Ilan and Lawrence, Mark}, booktitle = {Nature}, doi = {10.1038/515335a}, isbn = {00280836}, issn = {14764687}, number = {7527}, pages = {335--337}, pmid = {25409811}, title = {{Air pollution: Clean up our skies}}, volume = {515}, year = {2014} } @misc{Schmale2014a, author = {Schmale, Julia and van Aardenne, John and {Von Schneidemesser}, Erika}, booktitle = {Atmospheric Environment}, doi = {10.1016/j.atmosenv.2014.03.016}, isbn = {13522310}, issn = {18732844}, keywords = {Air quality,Climate change,Co-benefits,Integrated policy,Metrics}, pages = {146--148}, title = {{New Directions: Support for integrated decision-making in air and climate policies – Development of a metrics-based information portal}}, volume = {90}, year = {2014} } @article{Schneider2015, abstract = {Trends in tropospheric nitrogen dioxide (NO2) columns over 66 large urban agglomerations worldwide have been computed using data from the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument onboard the Envisat platform for the period August 2002 to March 2012. A seasonal model including a∼linear trend was fitted to the satellite-based time series over each site. The results indicate distinct spatial patterns in trends. While agglomerations in Europe, North America, and some locations in East Asia/Oceania show decreasing tropospheric NO2 levels on the order of g'5{\%} yr-1, rapidly increasing levels of tropospheric NO2 are found for agglomerations in large parts of Asia, Africa, and South America. The site with the most rapidly increasing absolute levels of tropospheric NO2 was found to be Tianjin in China with a trend of 3.04 (±0.47)× 1015 molecules cm-2yr-1, whereas the site with the most rapidly increasing relative trend was Kabul in Afghanistan with 14.3 (±2.2) {\%} yr-1. In total, 34 sites exhibited increasing trends of tropospheric NO2 throughout the study period, 24 of which were found to be statistically significant. A total of 32 sites showed decreasing levels of tropospheric NO2 during the study period, of which 20 sites did so at statistically significant magnitudes. Overall, going beyond the relatively small set of megacities investigated previously, this study provides the first consistent analysis of recent changes in tropospheric NO2 levels over most large urban agglomerations worldwide, and indicates that changes in urban NO2 levels are subject to substantial regional differences as well as influenced by economic and demographic factors.}, annote = {ACP}, author = {Schneider, P. and Lahoz, W. A. and {Van Der A}, R.}, doi = {10.5194/acp-15-1205-2015}, isbn = {1680-7324}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {3}, pages = {1205--1220}, publisher = {Copernicus Publications}, title = {{Recent satellite-based trends of tropospheric nitrogen dioxide over large urban agglomerations worldwide}}, url = {https://www.atmos-chem-phys.net/15/1205/2015/}, volume = {15}, year = {2015} } @article{ISI:000438945300003, abstract = {Northern India (23{\&}ndash;31°N, 68{\&}ndash;90°E) is one of the most densely populated and polluted regions in world. Accurately modeling pollution in the region is difficult due to the extreme conditions with respect to emissions, meteorology, and topography, but it is paramount in order to understand how future changes in emissions and climate may alter the region's pollution regime. We evaluate the ability of a developmental version of the new-generation NOAA GFDL Atmospheric Model, version 4 (AM4) to simulate observed wintertime fine particulate matter (PM2.5) and its relationship to meteorology over Northern India. We compare two simulations of GFDL-AM4 nudged to observed meteorology for the period 1980{\&}ndash;2016 driven by pollutant emissions from two global inventories developed in support of the Coupled Model Intercomparison Project Phases 5 (CMIP5) and 6 (CMIP6), and compare results with ground-based observations from India's Central Pollution Control Board (CPCB) for the period 1 October 2015{\&}ndash;31 March 2016. Overall, our results indicate that the simulation with CMIP6 emissions produces improved concentrations of pollutants over the region relative to the CMIP5-driven simulation. While the particulate concentrations simulated by AM4 are biased low overall, the model generally simulates the magnitude and daily variability of observed total PM2.5. Nitrate and organic matter are the primary components of PM2.5 over Northern India in the model. On the basis of correlations of the individual model components with total observed PM2.5 and correlations between the two simulations, meteorology is the primary driver of daily variability. The model correctly reproduces the shape and magnitude of the seasonal cycle of PM2.5, but the simulated diurnal cycle misses the early evening rise and secondary maximum found in the observations. Observed PM2.5 abundances are by far the highest within the densely populated Indo-Gangetic Plain, where they are closely related to boundary layer meteorology, specifically relative humidity, wind speed, boundary layer height, and inversion strength. The GFDL AM4 model reproduces the overall observed pollution gradient over Northern India as well as the strength of the meteorology–PM2.5 relationship in most locations.}, author = {Schnell, Jordan L and Naik, Vaishali and Horowitz, Larry W and Paulot, Fabien and Mao, Jingqiu and Ginoux, Paul and Zhao, Ming and Ram, Kirpa}, doi = {10.5194/acp-18-10157-2018}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jul}, number = {14}, pages = {10157--10175}, title = {{Exploring the relationship between surface PM2.5 and meteorology in Northern India}}, url = {https://www.atmos-chem-phys.net/18/10157/2018/}, volume = {18}, year = {2018} } @article{ISI:000396094200037, abstract = {Heat waves and air pollution episodes pose a serious threat to human health and may worsen under future climate change. In this paper, we use 15 years (1999–2013) of commensurately gridded (1° x 1°) surface observations of extended summer (April–September) surface ozone (O3), fine particulate matter (PM2.5), and maximum temperature (TX) over the eastern United States and Canada to construct a climatology of the coincidence, overlap, and lag in space and time of their extremes. Extremes of each quantity are defined climatologically at each grid cell as the 50 d with the highest values in three 5-y windows (∼95th percentile). Any two extremes occur on the same day in the same grid cell more than 50{\%} of the time in the northeastern United States, but on a domain average, co-occurrence is approximately 30{\%}. Although not exactly co-occurring, many of these extremes show connectedness with consistent offsets in space and in time, which often defy traditional mechanistic explanations. All three extremes occur primarily in large-scale, multiday, spatially connected episodes with scales of {\textgreater}1,000 km and clearly coincide with large-scale meteorological features. The largest, longest-lived episodes have the highest incidence of co-occurrence and contain extreme values well above their local 95th percentile threshold, by +7 ppb for O3, +6 µg m−3 for PM2.5, and +1.7 °C for TX. Our results demonstrate the need to evaluate these extremes as synergistic costressors to accurately quantify their impacts on human health.}, author = {Schnell, Jordan L. and Prather, Michael J.}, doi = {10.1073/pnas.1614453114}, isbn = {0027-8424}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, month = {mar}, number = {11}, pages = {2854--2859}, pmid = {28242682}, title = {{Co-occurrence of extremes in surface ozone, particulate matter, and temperature over eastern North America}}, url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1614453114}, volume = {114}, year = {2017} } @article{Schnell2016, author = {Schnell, Jordan L. and Prather, Michael J. and Josse, Beatrice and Naik, Vaishali and Horowitz, Larry W. and Zeng, Guang and Shindell, Drew T. and Faluvegi, Greg}, doi = {10.1002/2016GL068060}, issn = {0094-8276}, journal = {Geophysical Research Letters}, month = {apr}, number = {7}, pages = {3509--3518}, title = {{Effect of climate change on surface ozone over North America, Europe, and East Asia}}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2016GL068060}, volume = {43}, year = {2016} } @article{Schroder2015, abstract = {Abstract. Size-resolved observations of aerosol particles and cloud droplet residuals were studied at a marine boundary layer site (251 m a.m.s.l.) in La Jolla, San Diego, California, during 2012. A counterflow virtual impactor (CVI) was used as the inlet to sample cloud residuals while a total inlet was used to sample both cloud residuals and interstitial particles. Two cloud events totaling 10 h of in-cloud sampling were analyzed. Based on bulk aerosol particle concentrations, mass concentrations of refractory black carbon (rBC), and back trajectories, the two air masses sampled were classified as polluted marine air. Since the fraction of cloud droplets sampled by the CVI was less than 100{\%}, the measured activated fractions of rBC should be considered as lower limits to the total fraction of rBC activated during the two cloud events. Size distributions of rBC and a coating analysis showed that sub-100 nm rBC cores with relatively thick coatings were incorporated into the cloud droplets (i.e., 95 nm rBC cores with median coating thicknesses of at least 65 nm were incorporated into the cloud droplets). Measurements also show that the coating volume fraction of rBC cores is relatively large for sub-100 nm rBC cores. For example, the median coating volume fraction of 95 nm rBC cores incorporated into cloud droplets was at least 0.9, a result that is consistent with $\kappa$-K{\"{o}}hler theory. Measurements of the total diameter of the rBC-containing particles (rBC core and coating) suggest that the total diameter of rBC-containing particles needed to be at least 165 nm to be incorporated into cloud droplets when the core rBC diameter is ≥ 85 nm. This result is consistent with previous work that has shown that particle diameter is important for activation of non-rBC particles. The activated fractions of rBC determined from the measurements ranged from 0.01 to 0.1 for core rBC diameters ranging from 70 to 220 nm. This type of data is useful for constraining models used for predicting rBC concentrations in the atmosphere.}, author = {Schroder, J. C. and Hanna, S. J. and Modini, R. L. and Corrigan, A. L. and Kreidenwies, S. M. and Macdonald, A. M. and Noone, K. J. and Russell, L. M. and Leaitch, W. R. and Bertram, A. K.}, doi = {10.5194/acp-15-1367-2015}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {feb}, number = {3}, pages = {1367--1383}, title = {{Size-resolved observations of refractory black carbon particles in cloud droplets at a marine boundary layer site}}, url = {https://acp.copernicus.org/articles/15/1367/2015/}, volume = {15}, year = {2015} } @article{Schultz2015, abstract = {Long-term observations of reactive gases in the troposphere are important for understanding trace gas cycles and the oxidation capacity of the atmosphere, assessing impacts of emission changes, verifying numerical model simulations, and quantifying the interactions between short-lived compounds and climate change. The World Meteorological Organization's (WMO) Global Atmosphere Watch (GAW) program coordinates a global network of surface stations some of which have measured reactive gases for more than 40 years. Gas species included under this umbrella are ozone, carbon monoxide, nitrogen oxides, and volatile organic compounds (VOCs). There are many challenges involved in setting-up and maintaining such a network over many decades and to ensure that data are of high quality, regularly updated and made easily accessible to users. This overview describes the GAW surface station network of reactive gases, its unique quality management framework, and discusses the data that are available from the central archive. Highlights of data use from the published literature are reviewed, and a brief outlook into the future of GAW is given. This manuscript constitutes the overview of a special feature on GAW reactive gases observations with individual papers reporting on research and data analysis of particular substances being covered by the program.}, author = {Schultz, Martin G. and Akimoto, Hajime and Bottenheim, Jan and Buchmann, Brigitte and Galbally, Ian E. and Gilge, Stefan and Helmig, Detlev and Koide, Hiroshi and Lewis, Alastair C. and Novelli, Paul C. and Plass-D{\"{u}}lmer, Christian and Ryerson, Thomas B. and Steinbacher, Martin and Steinbrecher, Rainer and Tarasova, Oksana and T{\o}rseth, Kjetil and Thouret, Valerie and Zellweger, Christoph}, doi = {10.12952/journal.elementa.000067}, issn = {2325-1026}, journal = {Elementa: Science of the Anthropocene}, month = {oct}, pages = {000067}, publisher = {University of California Press}, title = {{The Global Atmosphere Watch reactive gases measurement network}}, url = {http://www.elementascience.org/articles/10.12952/journal.elementa.000067/}, volume = {3}, year = {2015} } @article{Schulz2019a, abstract = {The vertical distribution of black carbon (BC) particles in the Arctic atmosphere is one of the key parameters controlling their radiative forcing and thus role in Arctic climate change. This work investigates the presence and properties of these light-absorbing aerosols over the High Canadian Arctic ( {\textgreater} 70°N). Airborne campaigns were performed as part of the NETCARE project (Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments) and provided insights into the variability of the vertical distributions of BC particles in summer 2014 and spring 2015. The observation periods covered evolutions of cyclonic disturbances at the polar front, which favoured the transport of air pollution into the High Canadian Arctic, as otherwise this boundary between the air masses largely impedes entrainment of pollution from lower latitudes. A total of 48 vertical profiles of refractory BC (rBC) mass concentration and particle size, extending from 0.1 to 5.5 km altitude were obtained with a Single-Particle Soot Photometer (SP2). Generally, the rBC mass concentration decreased from spring to summer by a factor of 10. Such depletion was associated with a decrease in the mean rBC particle diameter, from approximately 200 to 130 nm at low altitude. Due to the very low number fraction, rBC particles did not substantially contribute to the total aerosol population in summer. The analysis of profiles with potential temperature as vertical coordinate revealed characteristic variability patterns within specific levels of the cold and stably stratified, domelike, atmosphere over the polar region. The associated history of transport trajectories into each of these levels showed that the variability was induced by changing rates and efficiencies of rBC import. Generally, the source areas affecting the polar dome extended southward with increasing potential temperature (i.e. altitude) level in the dome. While the lower dome was mostly only influenced by low-level transport from sources within the cold central and marginal Arctic, for the mid-dome and upper dome during spring it was found that a cold air outbreak over eastern Europe caused intensified northward transport of air from a corridor over western Russia to central Asia. This sector was affected by emissions from gas flaring, industrial activity and wildfires. The development of transport caused rBC concentrations in the second lowest level to gradually increase from 32 to 49 ngm-3. In the{\ldots}}, author = {Schulz, Hannes and Zanatta, Marco and Bozem, Heiko and {Richard Leaitch}, W. and Herber, Andreas B. and Burkart, Julia and Willis, Megan D. and Kunkel, Daniel and Hoor, Peter M. and Abbatt, Jonathan P.D. and Gerdes, R{\"{u}}diger}, doi = {10.5194/acp-19-2361-2019}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {feb}, number = {4}, pages = {2361--2384}, publisher = {Copernicus GmbH}, title = {{High Arctic aircraft measurements characterising black carbon vertical variability in spring and summer}}, volume = {19}, year = {2019} } @article{esd-10-729-2019, author = {Schwarber, A K and Smith, S J and Hartin, C A and Vega-Westhoff, B A and Sriver, R}, doi = {10.5194/esd-10-729-2019}, journal = {Earth System Dynamics}, number = {4}, pages = {729--739}, title = {{Evaluating climate emulation: fundamental impulse testing of simple climate models}}, url = {https://esd.copernicus.org/articles/10/729/2019/}, volume = {10}, year = {2019} } @article{Schwarz2013, abstract = {Black carbon (BC) aerosol loadings were measured during the High-performance Instrumented Airborne Platform for Environmental Research Pole-to-Pole Observations (HIPPO) campaign above the remote Pacific from 85°N to 67°S. Over 700 vertical profiles extending from near the surface to max ∼14 km altitude were obtained with a single-particle soot photometer between early 2009 and mid-2011. The data provides a climatology of BC in the remote regions that reveals gradients of BC concentration reflecting global-scale transport and removal of pollution. BC is identified as a sensitive tracer of extratropical mixing into the lower tropical tropopause layer and trends toward surprisingly uniform loadings in the lower stratosphere of ∼1 ng/kg. The climatology is compared to predictions from the AeroCom global model intercomparison initiative. The AeroCom model suite overestimates loads in the upper troposphere/lower stratosphere (∼10×) more severely than at lower altitudes (∼3×), with bias roughly independent of season or geographic location; these results indicate that it overestimates BC lifetime. Key Points A BC climatology is provided for the remote Pacific and Polar regions AeroCom overestimates remote BC with strong altitude dependence Extratropical mixing into the TTL is estimated from BC latitudinal gradients {\textcopyright}2013 The Authors. Geophysical Research Letters published by Wiley on behalf of the American Geophysical Union.}, author = {Schwarz, J. P. and Samset, B. H. and Perring, A. E. and Spackman, J. R. and Gao, R. S. and Stier, P. and Schulz, M. and Moore, F. L. and Ray, Eric A. and Fahey, D. W.}, doi = {10.1002/2013GL057775}, issn = {00948276}, journal = {Geophysical Research Letters}, keywords = {AeroCom,HIPPO,aerosol,black carbon,remote,tropical tropopause layer}, month = {oct}, number = {20}, pages = {5542--5547}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Global-scale seasonally resolved black carbon vertical profiles over the Pacific}}, volume = {40}, year = {2013} } @article{Schwinger2017, abstract = {We estimate the additional transient surface warming $\Delta$T s caused by a potential reduction of marine dimethyl sulfide (DMS) production due to ocean acidification under the high-emission scenario RCP8.5 until the year 2200. Since we use a fully coupled Earth system model, our results include a range of feedbacks, such as the response of marine DMS production to the additional changes in temperature and sea ice cover. Our results are broadly consistent with the findings of a previous study that employed an offline model set-up. Assuming a medium (strong) sensitivity of DMS production to pH, we find an additional transient global warming of 0.30 K (0.47 K) towards the end of the 22nd century when DMS emissions are reduced by 7.3 Tg S yr -1 or 31 {\%} (11.5 Tg S yr -1 or 48 {\%}). The main mechanism behind the additional warming is a reduction of cloud albedo, but a change in shortwave radiative fluxes under clear-sky conditions due to reduced sulfate aerosol load also contributes significantly. We find an approximately linear relationship between reduction of DMS emissions and changes in top of the atmosphere radiative fluxes as well as changes in surface temperature for the range of DMS emissions considered here. For example, global average T s changes by -0. 041 K per 1 Tg S yr -1 change in sea-air DMS fluxes. The additional warming in our model has a pronounced asymmetry between northern and southern high latitudes. It is largest over the Antarctic continent, where the additional temperature increase of 0.56 K (0.89 K) is almost twice the global average. We find that feedbacks are small on the global scale due to opposing regional contributions. The most pronounced feedback is found for the Southern Ocean, where we estimate that the additional climate change enhances sea-air DMS fluxes by about 9 {\%} (15 {\%}), which counteracts the reduction due to ocean acidification.}, author = {Schwinger, J{\"{o}}rg and Tjiputra, Jerry and Goris, Nadine and Six, Katharina D. and Kirkev{\aa}g, Alf and Seland, {\O}yvind and Heinze, Christoph and Ilyina, Tatiana}, doi = {10.5194/bg-14-3633-2017}, issn = {17264189}, journal = {Biogeosciences}, number = {15}, pages = {3633--3648}, publisher = {Copernicus GmbH on behalf of the European Geosciences Union}, title = {{Amplification of global warming through pH dependence of DMS production simulated with a fully coupled Earth system model}}, volume = {14}, year = {2017} } @article{Scott2017a, abstract = {More than one quarter of natural forests have been cleared by humans to make way for other land-uses, with changes to forest cover projected to continue. The climate impact of land-use change (LUC) is dependent upon the relative strength of several biogeophysical and biogeochemical effects. In addition to affecting the surface albedo and exchanging carbon dioxide (CO2) and moisture with the atmosphere, vegetation emits biogenic volatile organic compounds (BVOCs), altering the formation of short-lived climate forcers (SLCFs) including aerosol, ozone (O3) and methane (CH4). Once emitted, BVOCs are rapidly oxidised by O3, and the hydroxyl (OH) and nitrate (NO3) radicals. These oxidation reactions yield secondary organic products which are implicated in the formation and growth of aerosol particles and are estimated to have a negative radiative effect on the climate (i.e. a cooling). These reactions also deplete OH, increasing the atmospheric lifetime of CH4, and directly affect concentrations of O3; the latter two being greenhouse gases which impose a positive radiative effect (i.e. a warming) on the climate. Our previous work assessing idealised deforestation scenarios found a positive radiative effect due to changes in SLCFs; however, since the radiative effects associated with changes to SLCFs result from a combination of non-linear processes it may not be appropriate to scale radiative effects from complete deforestation scenarios according to the deforestation extent. Here we combine a land-surface model, a chemical transport model, a global aerosol model, and a radiative transfer model to assess the net radiative effect of changes in SLCFs due to historical LUC between the years 1850 and 2000.}, annote = {Times Cited: 1 Rap, Alexandru/G-7532-2016; Forster, Piers/F-9829-2010; Manager, CSD Publications/B-2789-2015; Chipperfield, Martyn/H-6359-2013; Carslaw, Ken/C-8514-2009 Rap, Alexandru/0000-0002-2319-6769; Forster, Piers/0000-0002-6078-0171; Chipperfield, Martyn/0000-0002-6803-4149; Carslaw, Ken/0000-0002-6800-154X 0 1 1364-5498}, author = {Scott, C. E. and Monks, S. A. and Spracklen, D. V. and Arnold, S. R. and Forster, P. M. and Rap, A. and Carslaw, K. S. and Chipperfield, M. P. and Reddington, C. L.S. and Wilson, C.}, doi = {10.1039/c7fd00028f}, isbn = {1359-6640}, issn = {13645498}, journal = {Faraday Discussions}, pages = {101--120}, pmid = {28585973}, title = {{Impact on short-lived climate forcers (SLCFs) from a realistic land-use change scenario: Via changes in biogenic emissions}}, url = {http://pubs.rsc.org/en/Content/ArticleLanding/2017/FD/C7FD00028F http://xlink.rsc.org/?DOI=C7FD00028F}, volume = {200}, year = {2017} } @article{Scott2018, abstract = {The terrestrial biosphere is an important source of natural aerosol. Natural aerosol sources alter climate, but are also strongly controlled by climate, leading to the potential for natural aerosol-climate feedbacks. Here we use a global aerosol model to make an assessment of terrestrial natural aerosol-climate feedbacks, constrained by observations of aerosol number. We find that warmer-than-average temperatures are associated with higher-than-average number concentrations of large ({\textgreater}100 nm diameter) particles, particularly during the summer. This relationship is well reproduced by the model and is driven by both meteorological variability and variability in natural aerosol from biogenic and landscape fire sources. We find that the calculated extratropical annual mean aerosol radiative effect (both direct and indirect) is negatively related to the observed global temperature anomaly, and is driven by a positive relationship between temperature and the emission of natural aerosol. The extratropical aerosol-climate feedback is estimated to be -0.14 W m-2 K-1 for landscape fire aerosol, greater than the -0.03 W m-2 K-1 estimated for biogenic secondary organic aerosol. These feedbacks are comparable in magnitude to other biogeochemical feedbacks, highlighting the need for natural aerosol feedbacks to be included in climate simulations.}, author = {Scott, C. E. and Arnold, S. R. and Monks, S. A. and Asmi, A. and Paasonen, P. and Spracklen, D. V.}, doi = {10.1038/s41561-017-0020-5}, issn = {17520908}, journal = {Nature Geoscience}, month = {jan}, number = {1}, pages = {44--48}, title = {{Substantial large-scale feedbacks between natural aerosols and climate}}, volume = {11}, year = {2018} } @article{doi:10.1002/2013JD020838, abstract = {This study investigates ozone changes and the individual impacts of transport and chemistry on those changes. We specifically examine (1) variation related to El Ni{\~{n}}o Southern Oscillation (ENSO), which is a dominant mode of interannual variation of tropospheric ozone, and (2) long-term change between the 2000s and 2100 s. During El Ni{\~{n}}o, the simulated ozone shows an increase (1 ppbv/K) over Indonesia, a decrease (2–10 ppbv/K) over the eastern Pacific in the tropical troposphere, and an increase (50 ppbv/K) over the eastern Pacific in the midlatitude lower stratosphere. These variations fundamentally agree with those observed by MLS/TES instruments. The model demonstrates that tropospheric chemistry has a strong impact on the variation over the eastern Pacific in the tropical lower troposphere, and that transport dominates the variation in the midlatitude lower stratosphere. Between the 2000s and 2100 s, the model predicts an increase in the global burden of stratospheric ozone (0.24{\%}/decade) and a decrease in the global burden of tropospheric ozone (0.82{\%}/decade). The increase in the stratospheric burden is controlled by stratospheric chemistry. Tropospheric chemistry reduces the tropospheric burden by 1.07{\%}/decade. However, transport (i.e., stratosphere–troposphere exchange and tropospheric circulation) causes an increase in the burden (0.25{\%}/decade). Additionally we test the sensitivity of ozone changes to increased horizontal resolution of the representation of atmospheric circulation and advection apart from any aspects of the nonlinearity of chemistry sensitivity to horizontal resolution. No marked difference is found in medium-resolution or high-resolution simulations, suggesting that the increased horizontal resolution of transport has a minor impact.}, author = {Sekiya, T. and Sudo, K.}, doi = {10.1002/2013JD020838}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {ENSO,chemistry-climate model,climate change,ozone}, month = {apr}, number = {8}, pages = {4903--4921}, title = {{Roles of transport and chemistry processes in global ozone change on interannual and multidecadal time scales}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2013JD020838 http://doi.wiley.com/10.1002/2013JD020838}, volume = {119}, year = {2014} } @article{Serrano2019, abstract = {To protect human health and the environment (namely ecosystems), international air quality protocols and guidelines, like the Gothenburg protocol (1999) and the 2001 EU Air Quality Directive (NECD), conveyed national emission ceilings for atmospheric pollutants (Directive 2001/81/EC), including the reduction of sulfur (S) and nitrogen (N) emissions by 2010. However, to what degree this expected reduction in emissions had reflections at the ecosystem level (i.e. pollutant levels reaching and impacting ecosystems and their organisms) remains unknown. Here, we used lichens as ecological indicators, together with reported air and precipitation pollutant concentrations, to determine and map the consequences of the S and N atmospheric emission's reduction, during the implementation of the 2001 Directive (in 2002 and 2011), due primarily to the industrial-sector. The study area is a mixed-land-use industrialized Mediterranean agroforest ecosystem, in southwest Europe. The reduction of S emissions (2002−2011) was reflected at the ecosystem level, as the same S-declining trend was observed in atmospheric measurement stations and lichens alike (−70{\%}), indicating that most S deposited to the ecosystem had an industrial origin. However, this was not the case for N with a slight N-reduction near industrial facilities, but mostly N-deposition in lichens increased in areas dominated by agricultural land-uses. Taken together, these results highlight the importance of going beyond emissions estimation and modeling, to assess the success of the implementation of the NECD in lowering pollutant accumulation in living organisms and their environment. This can only be achieved by measuring pollutant deposition at the ecosystem level (e.g. living organisms). By doing so, we were able to show that the 2001 NECD was successful in reducing S concentrations from Industry, whereas N remains a challenge. Despite the small reduction in N-emissions, deposition into ecosystems did not reflect these changes as agriculture and transport sectors must reduce NH3 and NOx emissions.}, author = {Serrano, Helena Cristina and Oliveira, Maria Alexandra and Barros, Ceres and Augusto, Ana Sofia and Pereira, Maria Jo{\~{a}}o and Pinho, Pedro and Branquinho, Cristina}, doi = {10.1016/j.scitotenv.2018.08.059}, issn = {18791026}, journal = {Science of the Total Environment}, keywords = {Air Quality Directive,Deposition,Ecological indicator,Emission,Nitrogen,Sulfur}, pages = {1531--1538}, title = {{Measuring and mapping the effectiveness of the European Air Quality Directive in reducing N and S deposition at the ecosystem level}}, url = {http://www.sciencedirect.com/science/article/pii/S0048969718330262}, volume = {647}, year = {2019} } @techreport{Shah2015, abstract = {https://ies.lbl.gov/sites/default/files/lbnl-1003671.pdf}, address = {Berkeley, CA, USA}, author = {Shah, Nihar and Wei, Max and Letschert, Virginie and Phadke, Amol}, doi = {10.2172/1397235}, pages = {39}, publisher = {Ernest Orlando Lawrence Berkeley National Laboratory (LBNL)}, series = {Report No. LBNL-1003671}, title = {{Benefits of Leapfrogging to Superefficiency and Low Global Warming Potential Refrigerants in Room Air Conditioning}}, url = {http://www.osti.gov/servlets/purl/1397235/}, year = {2015} } @article{Sharma2017, abstract = {Absorption of sunlight by black carbon (BC) warms the atmosphere, which may be important for Arctic climate. The measurement of BC is complicated by the lack of a simple definition of BC and the absence of techniques that are uniquely sensitive to BC (e.g., Petzold et al., 2013). At the Global Atmosphere Watch baseline observatory in Alert, Nunavut (82.5° N), BC mass is estimated in three ways, none of which fully represent BC: conversion of light absorption measured with an Aethalometer to give equivalent black carbon (EBC), thermal desorption of elemental carbon (EC) from weekly integrated filter samples to give EC, and measurement of incandescence from the refractory black carbon (rBC) component of individual particles using a single particle soot photometer (SP2). Based on measurements between March 2011 and December 2013, EBC and EC are 2.7 and 3.1 times higher than rBC, respectively. The EBC and EC measurements are influenced by factors other than just BC, and higher estimates of BC are expected from these techniques. Some bias in the rBC measurement may result from calibration uncertainties that are difficult to estimate here. Considering a number of factors, our best estimate of BC mass in Alert, which may be useful for evaluation of chemical transport models, is an average of the rBC and EC measurements with a range bounded by the rBC and EC combined with the respective measurement uncertainties. Winter-, spring-, summer-, and fall-averaged (± atmospheric variability) estimates of BC mass in Alert for this study period are 49 ± 28, 30 ± 26, 22 ± 13, and 29 ± 9 ng m-3, respectively. Average coating thicknesses estimated from the SP2 are 25 to 40 {\%} of the 160-180 nm diameter rBC core sizes. For particles of approximately 200-400 nm optical diameter, the fraction containing rBC cores is estimated to be between 10 and 16 {\%}, but the possibility of smaller undetectable rBC cores in some of the particles cannot be excluded. Mass absorption coefficients (MACs) ± uncertainty at 550 nm wavelength, calculated from light absorption measurements divided by the best estimates of the BC mass concentrations, are 8.0 ± 4.0, 8.0 ± 4.0, 5.0 ± 2.5 and 9.0 ± 4.5 m2 g-1, for winter, spring, summer, and fall, respectively. Adjusted to better estimate absorption by BC only, the winter and spring values of MACs are 7.6 ± 3.8 and 7.7 ± 3.8 m2 g-1. There is evidence that the MAC values increase with coating thickness.}, author = {Sharma, Sangeeta and {Richard Leaitch}, W. and Huang, Lin and Veber, Daniel and Kolonjari, Felicia and Zhang, Wendy and Hanna, Sarah J. and Bertram, Allan K. and Ogren, John A.}, doi = {10.5194/acp-17-15225-2017}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {dec}, number = {24}, pages = {15225--15243}, publisher = {Copernicus GmbH}, title = {{An evaluation of three methods for measuring black carbon in Alert, Canada}}, url = {https://acp.copernicus.org/articles/17/15225/2017/}, volume = {17}, year = {2017} } @article{Sharma2013, abstract = {Arctic regional climate is influenced by the radiative impact of aerosol black carbon (BC) both in the atmosphere and deposited on the snow and ice covered surfaces. The NIES (National Institute for Environmental Studies) global atmospheric transport model was used, with BC emissions from mid-latitude fossil fuel and biomass burning source regions, to simulate BC concentrations with 16 year period. The model-simulated BC agreed well with the BC observations, including the trends and seasonality, at three Arctic sites: Alert (Nunavut, Canada), Barrow (Alaska, USA), and Zepplin, Ny-{\AA}lesund (Svalbard, Norway). The equivalent black carbon (EBC, absorption inferred BC) observations at the three Arctic locations showed an overall decline of 40{\%} from 1990 to 2009; with most change occurring during early 1990s. Model simulations confirmed declining influence on near surface BC contribution by 70{\%} , and atmospheric BC burden by one half from the Former Soviet Union (FSU) BC source region over 16 years. In contrast, the BC contribution from the East Asia (EA) region has little influence at the surface but atmospheric Arctic BC burden increased by 3 folds. Modelled dry deposition is dominant in the Arctic during wintertime, while wet deposition prevails at all latitudes during summer. Sensitivity analyses on the dry and wet deposition schemes indicate that parameterizations need to be refined to improve on the model performance. There are limitations in the model due to simplified parameterizations and remaining model uncertainties, which requires further exploration of source region contributions, especially from growing EA source region to Arctic BC levels in the future is warranted. {\textcopyright} 2012. American Geophysical Union.}, author = {Sharma, S. and Ishizawa, M. and Chan, D. and Lavou{\'{e}}, D. and Andrews, E. and Eleftheriadis, K. and Maksyutov, S.}, doi = {10.1029/2012JD017774}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {jan}, number = {2}, pages = {943--964}, title = {{16-year simulation of Arctic black carbon: Transport, source contribution, and sensitivity analysis on deposition}}, url = {http://doi.wiley.com/10.1029/2012JD017774}, volume = {118}, year = {2013} } @article{Shen20174355, abstract = {We use a statistical model to investigate the effect of 2000–2050 climate change on fine particulate matter (PM2. 5) air quality across the contiguous United States. By applying observed relationships of PM2. 5 and meteorology to the IPCC Coupled Model Intercomparision Project Phase 5 (CMIP5) archives, we bypass some of the uncertainties inherent in chemistry-climate models. Our approach uses both the relationships between PM2. 5 and local meteorology as well as the synoptic circulation patterns, defined as the singular value decomposition (SVD) pattern of the spatial correlations between PM2. 5 and meteorological variables in the surrounding region. Using an ensemble of 19 global climate models (GCMs) under the RCP4.5 scenario, we project an increase of 0.4–1.4 µg m−3 in annual mean PM2. 5 in the eastern US and a decrease of 0.3–1.2 µg m−3 in the Intermountain West by the 2050s, assuming present-day anthropogenic sources of PM2. 5. Mean summertime PM2. 5 increases as much as 2–3 µg m−3 in the eastern United States due to faster oxidation rates and greater mass of organic aerosols from biogenic emissions. Mean wintertime PM2. 5 decreases by 0.3–3 µg m−3 over most regions in the United States, likely due to the volatilization of ammonium nitrate. Our approach provides an efficient method to calculate the potential climate penalty on air quality across a range of models and scenarios. We find that current atmospheric chemistry models may underestimate or even fail to capture the strongly positive sensitivity of monthly mean PM2. 5 to temperature in the eastern United States in summer, and they may underestimate future changes in PM2. 5 in a warmer climate. In GEOS-Chem, the underestimate in monthly mean PM2. 5–temperature relationship in the east in summer is likely caused by overly strong negative sensitivity of monthly mean low cloud fraction to temperature in the assimilated meteorology ( ∼ −0.04 K−1) compared to the weak sensitivity implied by satellite observations (±0.01 K−1). The strong negative dependence of low cloud cover on temperature in turn causes the modeled rates of sulfate aqueous oxidation to diminish too rapidly as temperatures rise, leading to the underestimate of sulfate–temperature slopes, especially in the south. Our work underscores the importance of evaluating the sensitivity of PM2. 5 to its key controlling meteorological variables in climate-chemistry models on multiple timescales before they are applied to project future air quality.}, annote = {cited By 9}, author = {Shen, Lu and Mickley, Loretta J. and Murray, Lee T.}, doi = {10.5194/acp-17-4355-2017}, isbn = {1743552017}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {6}, pages = {4355--4367}, title = {{Influence of 2000–2050 climate change on particulate matter in the United States: Results from a new statistical model}}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016582916{\&}doi=10.5194{\%}2Facp-17-4355-2017{\&}partnerID=40{\&}md5=b002b58d0da81bff254d518513472755}, volume = {17}, year = {2017} } @article{Shen2019, abstract = {We use 2005–2016 observations of formaldehyde (HCHO) columns over China from the OMI, GOME-2, and SCIAMACHY satellite instruments to evaluate long-term trends in emission inventories of volatile organic compounds (VOCs) that affect air quality. The observations show large increases over 2005–2016 in the North China Plain (+1.1 ± 0.5{\%} a−1 relative to 2005) and the Yangtze River Delta region (+1.5 ± 0.4{\%} a−1 relative to 2005), consistent with the trend of anthropogenic VOC emissions in the Multi-resolution Emission Inventory for China (MEIC). Unlike other pollutants, VOC emissions have not been decreasing in recent years. An exception is the Huai River Basin in rural eastern China where the satellite data show rapidly decreasing VOC emissions since the early 2010s that appear to reflect bans on agricultural fires.}, author = {Shen, Lu and Jacob, Daniel J. and Zhu, Lei and Zhang, Qiang and Zheng, Bo and Sulprizio, Melissa P. and Li, Ke and {De Smedt}, Isabelle and {Gonz{\'{a}}lez Abad}, Gonzalo and Cao, Hansen and Fu, Tzung May and Liao, Hong}, doi = {10.1029/2019GL082172}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {OMI,VOC,formaldehyde}, number = {8}, pages = {4468--4475}, title = {{The 2005–2016 Trends of Formaldehyde Columns Over China Observed by Satellites: Increasing Anthropogenic Emissions of Volatile Organic Compounds and Decreasing Agricultural Fire Emissions}}, volume = {46}, year = {2019} } @article{Shephard2015, abstract = {Observations of atmospheric ammonia are important in understanding and modelling the impact of ammonia on both human health and the natural environment. We present a detailed description of a robust retrieval algorithm that demonstrates the capabilities of utilizing Cross-track Infrared Sounder (CrIS) satellite observations to globally retrieval ammonia concentrations. Initial ammonia retrieval results using both simulated and real observations show that (i) CrIS is sensitive to ammonia in the boundary layer with peak vertical sensitivity typically around ∼ 850-750 hPa (∼ 1.5 to 2.5 km), which can dip down close to the surface (∼ 900 hPa) under ideal conditions, (ii) it has a minimum detection limit of ∼ 1 ppbv (peak profile value typically at the surface), and (iii) the information content can vary significantly with maximum values of ∼ 1 degree-of-freedom for signal. Comparisons of the retrieval with simulated "true" profiles show a small positive retrieval bias of 6{\%} with a standard deviation of ∼ ± 20{\%} (ranging from ± 12 to ± 30{\%} over the vertical profile). Note that these uncertainty estimates are considered as lower bound values as no potential systematic errors are included in the simulations. The CrIS NH3 retrieval applied over the Central Valley in CA, USA, demonstrates that CrIS correlates well with the spatial variability of the boundary layer ammonia concentrations seen by the nearby Quantum Cascade-Laser (QCL) in situ surface and the Tropospheric Emission Spectrometer (TES) satellite observations as part of the DISCOVER-AQ campaign. The CrIS and TES ammonia observations show quantitatively similar retrieved boundary layer values that are often within the uncertainty of the two observations. Also demonstrated is CrIS's ability to capture the expected spatial distribution in the ammonia concentrations, from elevated values in the Central Valley from anthropogenic agriculture emissions, to much lower values in the unpolluted or clean surrounding mountainous regions. These initial results demonstrate the capabilities of the CrIS satellite to measure ammonia.}, author = {Shephard, M. W. and Cady-Pereira, K. E.}, doi = {10.5194/amt-8-1323-2015}, issn = {18678548}, journal = {Atmospheric Measurement Techniques}, month = {mar}, number = {3}, pages = {1323--1336}, publisher = {Copernicus {\{}GmbH{\}}}, title = {{Cross-track Infrared Sounder (CrIS) satellite observations of tropospheric ammonia}}, volume = {8}, year = {2015} } @article{Sheppard2011, abstract = {Although the effects of atmospheric nitrogen deposition on species composition are relatively well known, the roles of the different forms of nitrogen, in particular gaseous ammonia (NH3), have not been tested in the field. Since 2002, we have manipulated the form of N deposition to an ombrotrophic bog, Whim, on deep peat in southern Scotland, with low ambient N (wet + dry = 8 kg N ha−1 yr−1) and S (4 kg S ha−1 yr−1) deposition. A gradient of ammonia (NH3, dry N), from 70 kg N ha−1 yr−1 down to background, 3--4 kg N ha−1 yr−1 was generated by free air release. Wet ammonium (NH4+, wet N) was provided to replicate plots in a fine rainwater spray (NH4Cl at +8, +24, +56 kg N ha−1 yr−1). Automated treatments are coupled to meteorological conditions, in a globally unique, field experiment. Ammonia concentrations were converted to NH3-N deposition (kg N ha−1) using a site/vegetation specific parameterization. Within 3 years, exposure to relatively modest deposition of NH3, 20--56 kg NH3-N ha−1 yr−1 led to dramatic reductions in species cover, with almost total loss of Calluna vulgaris, Sphagnum capillifolium and Cladonia portentosa. These effects appear to result from direct foliar uptake and interaction with abiotic and biotic stresses, rather than via effects on the soil. Additional wet N by contrast, significantly increased Calluna cover after 5 years at the 56 kg N dose, but reduced cover of Sphagnum and Cladonia. Cover reductions caused by wet N were significantly different from and much smaller than those caused by equivalent dry N doses. The effects of gaseous NH3 described here, highlight the potential for ammonia to destroy acid heathland and peat bog ecosystems. Separating the effects of gaseous ammonia and wet ammonium deposition, for a peat bog, has significant implications for regulatory bodies and conservation agencies.}, author = {Sheppard, Lucy J and Leith, Ian D and Mizunuma, Toshie and {Neil Cape}, John and Crossley, Alan and Leeson, Sarah and Sutton, Mark A and Dijk, Netty and Fowler, David}, doi = {10.1111/j.1365-2486.2011.02478.x}, issn = {13541013}, journal = {Global Change Biology}, month = {dec}, number = {12}, pages = {3589--3607}, shorttitle = {Dry deposition of ammonia gas drives species chang}, title = {{Dry deposition of ammonia gas drives species change faster than wet deposition of ammonium ions: evidence from a long-term field manipulation}}, url = {http://doi.wiley.com/10.1111/j.1365-2486.2011.02478.x}, volume = {17}, year = {2011} } @article{acp-16-12239-2016, abstract = {We present a simulation of the global present-day composition of the troposphere which includes the chemistry of halogens (Cl, Br, I). Building on previous work within the GEOS-Chem model we include emissions of inorganic iodine from the oceans, anthropogenic and biogenic sources of halogenated gases, gas phase chemistry, and a parameterised approach to heterogeneous halogen chemistry. Consistent with Schmidt et al. (2016) we do not include sea-salt debromination. Observations of halogen radicals (BrO, IO) are sparse but the model has some skill in reproducing these. Modelled IO shows both high and low biases when compared to different datasets, but BrO concentrations appear to be modelled low. Comparisons to the very sparse observations dataset of reactive Cl species suggest the model represents a lower limit of the impacts of these species, likely due to underestimates in emissions and therefore burdens. Inclusion of Cl, Br, and I results in a general improvement in simulation of ozone (O3) concentrations, except in polar regions where the model now underestimates O3 concentrations. Halogen chemistry reduces the global tropospheric O3 burden by 18.6 {\%}, with the O3 lifetime reducing from 26 to 22 days. Global mean OH concentrations of 1.28 × 106 molecules cm−3 are 8.2 {\%} lower than in a simulation without halogens, leading to an increase in the CH4 lifetime (10.8 {\%}) due to OH oxidation from 7.47 to 8.28 years. Oxidation of CH4 by Cl is small (∼ 2 {\%}) but Cl oxidation of other VOCs (ethane, acetone, and propane) can be significant (∼ 15–27 {\%}). Oxidation of VOCs by Br is smaller, representing 3.9 {\%} of the loss of acetaldehyde and 0.9 {\%} of the loss of formaldehyde.}, author = {Sherwen, T and Schmidt, J A and Evans, M J and Carpenter, L J and Gro{\ss}mann, K and Eastham, S D and Jacob, D J and Dix, B and Koenig, T K and Sinreich, R and Ortega, I and Volkamer, R and Saiz-Lopez, A and Prados-Roman, C and Mahajan, A S and Ord{\'{o}}{\~{n}}ez, C}, doi = {10.5194/acp-16-12239-2016}, journal = {Atmospheric Chemistry and Physics}, number = {18}, pages = {12239--12271}, title = {{Global impacts of tropospheric halogens (Cl, Br, I) on oxidants and composition in GEOS-Chem}}, url = {https://www.atmos-chem-phys.net/16/12239/2016/}, volume = {16}, year = {2016} } @article{Sherwood2020, abstract = {Abstract We assess evidence relevant to Earth's equilibrium climate sensitivity per doubling of atmospheric CO2, characterized by an effective sensitivity S. This evidence includes feedback process understanding, the historical climate record, and the paleoclimate record. An S value lower than 2 K is difficult to reconcile with any of the three lines of evidence. The amount of cooling during the Last Glacial Maximum provides strong evidence against values of S greater than 4.5 K. Other lines of evidence in combination also show that this is relatively unlikely. We use a Bayesian approach to produce a probability density function (PDF) for S given all the evidence, including tests of robustness to difficult-to-quantify uncertainties and different priors. The 66{\%} range is 2.6?3.9 K for our Baseline calculation and remains within 2.3?4.5 K under the robustness tests; corresponding 5?95{\%} ranges are 2.3?4.7 K, bounded by 2.0?5.7 K (although such high-confidence ranges should be regarded more cautiously). This indicates a stronger constraint on S than reported in past assessments, by lifting the low end of the range. This narrowing occurs because the three lines of evidence agree and are judged to be largely independent and because of greater confidence in understanding feedback processes and in combining evidence. We identify promising avenues for further narrowing the range in S, in particular using comprehensive models and process understanding to address limitations in the traditional forcing-feedback paradigm for interpreting past changes.}, author = {Sherwood, S C and Webb, M J and Annan, J D and Armour, K C and Forster, P M and Hargreaves, J C and Hegerl, G and Klein, S A and Marvel, K D and Rohling, E J and Watanabe, M and Andrews, T and Braconnot, P and Bretherton, C S and Foster, G L and Hausfather, Z and von der Heydt, A S and Knutti, R and Mauritsen, T and Norris, J R and Proistosescu, C and Rugenstein, M and Schmidt, G A and Tokarska, K B and Zelinka, M D}, doi = {10.1029/2019RG000678}, file = {::}, issn = {8755-1209}, journal = {Reviews of Geophysics}, month = {dec}, number = {4}, pages = {e2019RG000678}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{An Assessment of Earth's Climate Sensitivity Using Multiple Lines of Evidence}}, volume = {58}, year = {2020} } @article{shi2017thermoACS, abstract = {Acidity (pH) plays a key role in the physical and chemical behavior of PM 2.5 . However, understanding of how specific PM sources impact aerosol pH is rarely considered. Performing source apportionment of PM 2.5 allows a unique link of sources pH of aerosol from the polluted city. Hourly water-soluble (WS) ions of PM 2.5 were measured online from December 25th, 2014 to June 19th, 2015 in a northern city in China. Five sources were resolved including secondary nitrate (41{\%}), secondary sulfate (26{\%}), coal combustion (14{\%}), mineral dust (11{\%}), and vehicle exhaust (9{\%}). The influence of source contributions to pH was estimated by ISORROPIA-II. The lowest aerosol pH levels were found at low WS-ion levels and then increased with increasing total ion levels, until high ion levels occur, at which point the aerosol becomes more acidic as both sulfate and nitrate increase. Ammonium levels increased nearly linearly with sulfate and nitrate until approximately 20 $\mu$g m -3 , supporting that the ammonium in the aerosol was more limited by thermodynamics than source limitations, and aerosol pH responded more to the contributions of sources such as dust than levels of sulfate. Commonly used pH indicator ratios were not indicative of the pH estimated using the thermodynamic model.}, annote = {doi: 10.1021/acs.est.6b05736}, author = {Shi, Guoliang and Xu, Jiao and Peng, Xing and Xiao, Zhimei and Chen, Kui and Tian, Yingze and Guan, Xinbei and Feng, Yinchang and Yu, Haofei and Nenes, Athanasios and Russell, Armistead G.}, doi = {10.1021/acs.est.6b05736}, isbn = {0013-936X}, issn = {0013-936X}, journal = {Environmental Science {\&} Technology}, month = {apr}, number = {8}, pages = {4289--4296}, publisher = {American Chemical Society}, title = {{pH of Aerosols in a Polluted Atmosphere: Source Contributions to Highly Acidic Aerosol}}, url = {https://doi.org/10.1021/acs.est.6b05736 https://pubs.acs.org/doi/10.1021/acs.est.6b05736}, volume = {51}, year = {2017} } @article{Shi2021, abstract = {The COVID-19 lockdowns led to major reductions in air pollutant emissions. Here, we quantitatively evaluate changes in ambient NO 2 , O 3 , and PM 2.5 concentrations arising from these emission changes in 11 cities globally by applying a deweathering machine learning technique. Sudden decreases in deweathered NO 2 concentrations and increases in O 3 were observed in almost all cities. However, the decline in NO 2 concentrations attributable to the lockdowns was not as large as expected, at reductions of 10 to 50{\%}. Accordingly, O 3 increased by 2 to 30{\%} (except for London), the total gaseous oxidant (O x = NO 2 + O 3 ) showed limited change, and PM 2.5 concentrations decreased in most cities studied but increased in London and Paris. Our results demonstrate the need for a sophisticated analysis to quantify air quality impacts of interventions and indicate that true air quality improvements were notably more limited than some earlier reports or observational data suggested.}, author = {Shi, Zongbo and Song, Congbo and Liu, Bowen and Lu, Gongda and Xu, Jingsha and {Van Vu}, Tuan and Elliott, Robert J. R. and Li, Weijun and Bloss, William J. and Harrison, Roy M.}, doi = {10.1126/sciadv.abd6696}, issn = {2375-2548}, journal = {Science Advances}, month = {jan}, number = {3}, pages = {eabd6696}, title = {{Abrupt but smaller than expected changes in surface air quality attributable to COVID-19 lockdowns}}, url = {https://www.science.org/doi/10.1126/sciadv.abd6696}, volume = {7}, year = {2021} } @article{Shindell2017, abstract = {The Paris Climate Agreement under the United Nations Framework Convention on Climate Change (UNFCCC) explicitly links the world's long-term climate and near-term sustainable development and poverty eradication agendas. Urgent action is needed, but there are many paths toward the agreement's long-term, end-of-century, 1.5° to 2°C climate target. We propose that reducing short-lived climate pollutants (SLCPs) enough to slow projected global warming by 0.5°C over the next 25 years be adopted as a near-term goal, with many potential benefits toward achieving Sustainable Development Goals (SDGs). As countries' climate commitments are formally adopted under the agreement and they prepare for its 2018 stocktaking, there is a need for them to pledge and report progress toward reductions not just in CO2 but in the full range of greenhouse gases (GHGs) and black carbon (BC) (plus co-emissions) in order to track progress toward long-term goals.}, author = {Shindell, D.T. and Borgford-Parnell, N. and Brauer, M. and Haines, A. and Kuylenstierna, J.C.I. and Leonard, S. A. and Ramanathan, V. and Ravishankara, A. and Amann, M. and Srivastava, L.}, doi = {10.1126/science.aak9521}, isbn = {0036-8075 1095-9203}, issn = {10959203}, journal = {Science}, month = {may}, number = {6337}, pages = {493--494}, pmid = {28473553}, title = {{A climate policy pathway for near- and long-term benefits}}, volume = {356}, year = {2017} } @article{Shindell2015b, abstract = {Examination of effective radiative forcing (ERF), a measure of changes in Earth's energy balance, facilitates understanding the role of various drivers of climate change. For short-lived compounds, ERF can be highly inhomogeneous geographically. The relationship between the spatial patterns of ERF and surface temperature response is poorly characterized, however. We examine that relationship in the latest generation of global climate models. We find that the uneven distribution of historical aerosol, ozone and land-use forcing leads to substantial differences compared to the well-mixed greenhouse gases (WMGHG). There is a stronger response per unit global mean forcing to historical inhomogeneous forcing than to WMGHG both globally and in much of the Northern Hemisphere (NH) extratropics, in fairly good agreement with results inferred from observations. Our results indicate that the enhanced global mean response is attributable to the concentration of inhomogeneous forcing in the NH extratropics, where there is strongest sensitivity to forcing, rather than to processes specific to the inhomogeneous forcers. In many regions, inclusion of inhomogeneous forcing greatly increases the spread in historical temperature changes simulated by the models, suggesting that better forcing characterization could play an important role in improving modeling of decadal scale regional climate change. Finally, incorporating observed temperatures, the results provide estimates of global historical aerosol forcing (-1.00.4 W m -2) consistent with other studies (though with narrower uncertainties), and also provide constraints on NH and NH extratropical historical aerosol forcing (-1.40.6 and -1.20.6 W m -2 , respectively) and aerosol+ozone forcing.}, author = {Shindell, Drew T. and Faluvegi, Greg and Rotstayn, Leon and Milly, George}, doi = {10.1002/2014JD022752}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {10.1002/2014JD022752 and aerosols,aerosol forcing,climate,regional climate}, month = {jun}, number = {11}, pages = {5385--5403}, title = {{Spatial patterns of radiative forcing and surface temperature response}}, url = {http://doi.wiley.com/10.1002/2014JD022752}, volume = {120}, year = {2015} } @article{ISI:000271233200034, abstract = {Evaluating multicomponent climate change mitigation strategies requires knowledge of the diverse direct and indirect effects of emissions. Methane, ozone, and aerosols are linked through atmospheric chemistry so that emissions of a single pollutant can affect several species. We calculated atmospheric composition changes, historical radiative forcing, and forcing per unit of emission due to aerosol and tropospheric ozone precursor emissions in a coupled composition-climate model. We found that gas-aerosol interactions substantially alter the relative importance of the various emissions. In particular, methane emissions have a larger impact than that used in current carbon-trading schemes or in the Kyoto Protocol. Thus, assessments of multigas mitigation policies, as well as any separate efforts to mitigate warming from short-lived pollutants, should include gas-aerosol interactions.}, annote = {Historical forcing 6.5.2 -- impacts of gas/aerosol interactions}, author = {Shindell, Drew T and Faluvegi, Greg and Koch, Dorothy M and Schmidt, Gavin A and Unger, Nadine and Bauer, Susanne E}, doi = {10.1126/science.1174760}, issn = {0036-8075}, journal = {Science}, month = {oct}, number = {5953}, pages = {716--718}, title = {{Improved Attribution of Climate Forcing to Emissions}}, type = {Article}, volume = {326}, year = {2009} } @article{Shindell2016b, author = {Shindell, Drew T and Lee, Yunha and Faluvegi, Greg}, doi = {10.1038/nclimate2935}, issn = {1758-678X}, journal = {Nature Climate Change}, month = {may}, number = {5}, pages = {503--507}, publisher = {Nature Publishing Group}, title = {{Climate and health impacts of US emissions reductions consistent with 2°C}}, url = {http://www.nature.com/articles/nclimate2935}, volume = {6}, year = {2016} } @article{Shindell2009, abstract = {The relative importance of regional and global changes in atmospheric greenhouse gas and aerosol concentrations for regional changes in climate is not well known. A climate model analysis of tropical, mid-latitude and polar regions shows that the extratropics and, in particular, the Arctic region are sensitive to local changes in radiative forcing.}, author = {Shindell, Drew T and Faluvegi, Greg}, doi = {10.1038/ngeo473}, issn = {1752-0894}, journal = {Nature Geoscience}, month = {apr}, number = {4}, pages = {294--300}, publisher = {Nature Publishing Group}, title = {{Climate response to regional radiative forcing during the twentieth century}}, url = {http://www.nature.com/articles/ngeo473}, volume = {2}, year = {2009} } @article{Shindell2017a, abstract = {Methane emissions contribute to global warming, damage public health and reduce the yield of agricultural and forest ecosystems. Quantifying these damages to the planetary commons by calculating the social cost of methane (SCM) facilitates more comprehensive cost-benefit analyses of methane emissions control measures and is the first step to potentially incorporating them into the marketplace. Use of a broad measure of social welfare is also an attractive alternative or supplement to emission metrics focused on a temperature target in a given year as it incentivizes action to provide benefits over a broader range of impacts and timescales. Calculating the SCM using consistent temporal treatment of physical and economic processes and incorporating climate- and air quality-related impacts, we find large SCM values, e.g. ∼{\$}2400 per ton and ∼{\$}3600 per ton with 5{\%} and 3{\%} discount rates respectively. These values are ∼100 and 50 times greater than corresponding social costs for carbon dioxide. Our results suggest that ∼110 of 140 Mt of identified methane abatement via scaling up existing technology and policy options provide societal benefits that outweigh implementation costs. Within the energy sector, renewables compare far better against use of natural gas in electricity generation when incorporating these social costs for methane. In the agricultural sector, changes in livestock management practices, promoting healthy diets including reduced beef and dairy consumption, and reductions in food waste have been promoted as ways to mitigate emissions, and these are shown here to indeed have the potential to provide large societal benefits (∼{\$}50–150 billion per year). Examining recent trends in methane and carbon dioxide, we find that increases in methane emissions may have offset much of the societal benefits from a slowdown in the growth rate of carbon dioxide emissions. The results indicate that efforts to reduce methane emissions via policies spanning a wide range of technical, regulatory and behavioural options provide benefits at little or negative net cost. Recognition of the full SCM, which has typically been undervalued, may help catalyze actions to reduce emissions and thereby provide a broad set of societal benefit}, author = {Shindell, D T and Fuglestvedt, J S and Collins, W J}, doi = {10.1039/C7FD00009J}, issn = {1359-6640}, journal = {Faraday Discussions}, pages = {429--451}, publisher = {The Royal Society of Chemistry}, title = {{The social cost of methane: theory and applications}}, url = {http://dx.doi.org/10.1039/C7FD00009J}, volume = {200}, year = {2017} } @article{acp-13-2939-2013, abstract = {{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) examined the short-lived drivers of climate change in current climate models. Here we evaluate the 10 ACCMIP models that included aerosols, 8 of which also participated in the Coupled Model Intercomparison Project phase 5 (CMIP5). {\textless}br{\textgreater}{\textless}br{\textgreater} The models reproduce present-day total aerosol optical depth (AOD) relatively well, though many are biased low. Contributions from individual aerosol components are quite different, however, and most models underestimate east Asian AOD. The models capture most 1980–2000 AOD trends well, but underpredict increases over the Yellow/Eastern Sea. They strongly underestimate absorbing AOD in many regions. {\textless}br{\textgreater}{\textless}br{\textgreater} We examine both the direct radiative forcing (RF) and the forcing including rapid adjustments (effective radiative forcing; ERF, including direct and indirect effects). The models' all-sky 1850 to 2000 global mean annual average total aerosol RF is (mean; range) −0.26 W m{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater}; −0.06 to −0.49 W m{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater}. Screening based on model skill in capturing observed AOD yields a best estimate of −0.42 W m{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater}; −0.33 to −0.50 W m{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater}, including adjustment for missing aerosol components in some models. Many ACCMIP and CMIP5 models appear to produce substantially smaller aerosol RF than this best estimate. Climate feedbacks contribute substantially (35 to −58{\%}) to modeled historical aerosol RF. The 1850 to 2000 aerosol ERF is −1.17 W m{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater}; −0.71 to −1.44 W m{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater}. Thus adjustments, including clouds, typically cause greater forcing than direct RF. Despite this, the multi-model spread relative to the mean is typically the same for ERF as it is for RF, or even smaller, over areas with substantial forcing. The largest 1850 to 2000 negative aerosol RF and ERF values are over and near Europe, south and east Asia and North America. ERF, however, is positive over the Sahara, the Karakoram, high Southern latitudes and especially the Arctic. {\textless}br{\textgreater}{\textless}br{\textgreater} Global aerosol RF peaks in most models around 1980, declining thereafter with only weak sensitivity to the Representative Concentration Pathway (RCP). One model, however, projects approximately stable RF levels, while two show increasingly negative RF due to nitrate (not included in most models). Aerosol ERF, in contrast, becomes more negative during 1980 to 2000. During this period, increased Asian emissions appear to have a larger impact on aerosol ERF than European and North American decreases due to their being upwind of the large, relatively pristine Pacific Ocean. There is no clear relationship between historical aerosol ERF and climate sensitivity in the CMIP5 subset of ACCMIP models. In the ACCMIP/CMIP5 models, historical aerosol ERF of about −0.8 to −1.5 W m{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater} is most consistent with observed historical warming. Aerosol ERF masks a large portion of greenhouse forcing during the late 20th and early 21st century at the global scale. Regionally, aerosol ERF is so large that net forcing is negative over most industrialized and biomass burning regions through 1980, but remains strongly negative only over east and southeast Asia by 2000. Net forcing is strongly positive by 1980 over most deserts, the Arctic, Australia, and most tropical oceans. Both the magnitude of and area covered by positive forcing expand steadily thereafter.{\textless}/p{\textgreater}}, author = {Shindell, D. T. and Lamarque, J. F. and Schulz, M. and Flanner, M. and Jiao, C. and Chin, M. and Young, P. J. and Lee, Y. H. and Rotstayn, L. and Mahowald, N. and Milly, G. and Faluvegi, G. and Balkanski, Y. and Collins, W. J. and Conley, A. J. and Dalsoren, S. and Easter, R. and Ghan, S. and Horowitz, L. and Liu, X. and Myhre, G. and Nagashima, T. and Naik, V. and Rumbold, S. T. and Skeie, R. and Sudo, K. and Szopa, S. and Takemura, T. and Voulgarakis, A. and Yoon, J. H. and Lo, F.}, doi = {10.5194/acp-13-2939-2013}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {6}, pages = {2939--2974}, title = {{Radiative forcing in the ACCMIP historical and future climate simulations}}, url = {https://www.atmos-chem-phys.net/13/2939/2013/}, volume = {13}, year = {2013} } @article{Shindell2018, abstract = {Societal risks increase as Earth warms, and increase further for emissions trajectories accepting relatively high levels of near-term emissions while assuming future negative emissions will compensate, even if they lead to identical warming as trajectories with reduced near-term emissions 1 . Accelerating carbon dioxide (CO 2 ) emissions reductions, including as a substitute for negative emissions, hence reduces long-term risks but requires dramatic near-term societal transformations 2 . A major barrier to emissions reductions is the difficulty of reconciling immediate, localized costs with global, long-term benefits 3,4 . However, 2 °C trajectories not relying on negative emissions or 1.5 °C trajectories require elimination of most fossil-fuel-related emissions. This generally reduces co-emissions that cause ambient air pollution, resulting in near-term, localized health benefits. We therefore examine the human health benefits of increasing 21st-century CO 2 reductions by 180 GtC, an amount that would shift a ‘standard' 2 °C scenario to 1.5 °C or could achieve 2 °C without negative emissions. The decreased air pollution leads to 153 ± 43 million fewer premature deaths worldwide, with {\~{}}40{\%} occurring during the next 40 years, and minimal climate disbenefits. More than a million premature deaths would be prevented in many metropolitan areas in Asia and Africa, and {\textgreater}200,000 in individual urban areas on every inhabited continent except Australia.}, author = {Shindell, Drew T. and Faluvegi, Greg and Seltzer, Karl and Shindell, Cary}, doi = {10.1038/s41558-018-0108-y}, edition = {2018/03/19}, issn = {17586798}, journal = {Nature Climate Change}, language = {eng}, number = {4}, pages = {1--5}, title = {{Quantified, localized health benefits of accelerated carbon dioxide emissions reductions}}, url = {https://www.ncbi.nlm.nih.gov/pubmed/29623109 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5880221/}, volume = {8}, year = {2018} } @article{Shindell2019a, abstract = {The combustion of fossil fuels produces emissions of the long-lived greenhouse gas carbon dioxide and of short-lived pollutants, including sulfur dioxide, that contribute to the formation of atmospheric aerosols1. Atmospheric aerosols can cool the climate, masking some of the warming effect that results from the emission of greenhouse gases1. However, aerosol particulates are highly toxic when inhaled, leading to millions of premature deaths per year2,3. The phasing out of unabated fossil-fuel combustion will therefore provide health benefits, but will also reduce the extent to which the warming induced by greenhouse gases is masked by aerosols. Because aerosol levels respond much more rapidly to changes in emissions relative to carbon dioxide, large near-term increases in the magnitude and rate of climate warming are predicted in many idealized studies that typically assume an instantaneous removal of all anthropogenic or fossil-fuel-related emissions1,4–9. Here we show that more realistic modelling scenarios do not produce a substantial near-term increase in either the magnitude or the rate of warming, and in fact can lead to a decrease in warming rates within two decades of the start of the fossil-fuel phase-out. Accounting for the time required to transform power generation, industry and transportation leads to gradually increasing and largely offsetting climate impacts of carbon dioxide and sulfur dioxide, with the rate of warming further slowed by reductions in fossil-methane emissions. Our results indicate that even the most aggressive plausible transition to a clean-energy society provides benefits for climate change mitigation and air quality at essentially all decadal to centennial timescales.}, author = {Shindell, Drew T. and Smith, Christopher J.}, doi = {10.1038/s41586-019-1554-z}, issn = {14764687}, journal = {Nature}, number = {7774}, pages = {408--411}, title = {{Climate and air-quality benefits of a realistic phase-out of fossil fuels}}, url = {https://doi.org/10.1038/s41586-019-1554-z}, volume = {573}, year = {2019} } @article{Shindell2012, abstract = {Tropospheric ozone and black carbon (BC) contribute to both degraded air quality and global warming. We considered ∼400 emission control measures to reduce these pollutants by using current technology and experience. We identified 14 measures targeting methane and BC emissions that reduce projected global mean warming ∼0.5°C by 2050. This strategy avoids 0.7 to 4.7 million annual premature deaths from outdoor air pollution and increases annual crop yields by 30 to 135 million metric tons due to ozone reductions in 2030 and beyond. Benefits of methane emissions reductions are valued at {\$}700 to {\$}5000 per metric ton, which is well above typical marginal abatement costs (less than {\$}250). The selected controls target different sources and influence climate on shorter time scales than those of carbon dioxide-reduction measures. Implementing both substantially reduces the risks of crossing the 2°C threshold.}, author = {Shindell, Drew T. and Kuylenstierna, Johan C.I. and Vignati, Elisabetta and {Van Dingenen}, Rita and Amann, Markus and Klimont, Zbigniew and Anenberg, Susan C. and Muller, Nicholas and Janssens-Maenhout, Greet and Raes, Frank and Schwartz, Joel and Faluvegi, Greg and Pozzoli, Luca and Kupiainen, Kaarle and H{\"{o}}glund-Isaksson, Lena and Emberson, Lisa and Streets, David and Ramanathan, V. and Hicks, Kevin and Oanh, N. T.Kim and Milly, George and Williams, Martin and Demkine, Volodymyr and Fowler, David}, doi = {10.1126/science.1210026}, isbn = {0036-8075}, issn = {10959203}, journal = {Science}, number = {6065}, pages = {183--189}, pmid = {22246768}, title = {{Simultaneously mitigating near-term climate change and improving human health and food security}}, volume = {335}, year = {2012} } @misc{Shoemaker2013, abstract = {Parallel strategies must focus on long- and short-lived pollutants, but not at the cost of reducing pressure for action on CO2 Short-lived climate pollutants (SLCPs) include methane (CH4), black carbon (BC), tropospheric ozone, and hydrofluorocarbons (HFCs). They are important contributors to anthropogenic climate change, responsible for as much as one-third of the current total greenhouse forcing (1). An emerging strategy, which we refer to as hybrid climate mitigation (HCM), emphasizes reducing SLCPs in parallel with long-lived carbon dioxide (CO2) so as to achieve climate goals, as well as health and food security benefits, associated with some of the SLCPs. Proponents of HCM argue that we should focus substantial effort on reducing SLCPs now, as we wait for sufficient political will to reduce CO2 emissions (2–4). But others (5) worry that any strategy involving SLCPs risks delaying efforts to reduce CO2, the main greenhouse gas most important for long-term warming if emissions continue as projected.}, author = {Shoemaker, J. K. and Schrag, D. P. and Molina, M. J. and Ramanathan, V.}, booktitle = {Science}, doi = {10.1126/science.1240162}, isbn = {00368075 (ISSN)}, issn = {10959203}, number = {6164}, pages = {1323--1324}, pmid = {24337280}, title = {{What role for short-lived climate pollutants in mitigation policy?}}, volume = {342}, year = {2013} } @article{ISI:000405304200008, abstract = {Anthropogenic emissions and land use changes have modified atmospheric aerosol concentrations and size distributions over time. Understanding preindustrial conditions and changes in organic aerosol due to anthropogenic activities is important because these features (1) influence estimates of aerosol radiative forcing and (2) can confound estimates of the historical response of climate to increases in greenhouse gases. Secondary organic aerosol (SOA), formed in the atmosphere by oxidation of organic gases, represents a major fraction of global submicron-sized atmospheric organic aerosol. Over the past decade, significant advances in understanding SOA properties and formation mechanisms have occurred through measurements, yet current climate models typically do not comprehensively include all important processes. This review summarizes some of the important developments during the past decade in understanding SOA formation. We highlight the importance of some processes that influence the growth of SOA particles to sizes relevant for clouds and radiative forcing, including formation of extremely low volatility organics in the gas phase, acid-catalyzed multiphase chemistry of isoprene epoxydiols, particle-phase oligomerization, and physical properties such as volatility and viscosity. Several SOA processes highlighted in this review are complex and interdependent and have nonlinear effects on the properties, formation, and evolution of SOA. Current global models neglect this complexity and nonlinearity and thus are less likely to accurately predict the climate forcing of SOA and project future climate sensitivity to greenhouse gases. Efforts are also needed to rank the most influential processes and nonlinear process-related interactions, so that these processes can be accurately represented in atmospheric chemistry-climate models.}, annote = {From Duplicate 1 (Recent advances in understanding secondary organic aerosol: Implications for global climate forcing - Shrivastava, Manish; Cappa, Christopher D.; Fan, Jiwen; Goldstein, Allen H.; Guenther, Alex B.; Jimenez, Jose L.; Kuang, Chongai; Laskin, Alexander; Martin, Scot T.; Ng, Nga Lee; Petaja, Tuukka; Pierce, Jeffrey R.; Rasch, Philip J.; Roldin, Pontus; Seinfeld, John H.; Shilling, John; Smith, James N.; Thornton, Joel A.; Volkamer, Rainer; Wang, Jian; Worsnop, Douglas R.; Zaveri, Rahul A.; Zelenyuk, Alla; Zhang, Qi) RF (both direct and indirect) for SOA -- section 6.5 From Duplicate 2 (Recent advances in understanding secondary organic aerosol: Implications for global climate forcing - Shrivastava, Manish; Cappa, Christopher D.; Fan, Jiwen; Goldstein, Allen H.; Guenther, Alex B.; Jimenez, Jose L.; Kuang, Chongai; Laskin, Alexander; Martin, Scot T.; Ng, Nga Lee; Petaja, Tuukka; Pierce, Jeffrey R.; Rasch, Philip J.; Roldin, Pontus; Seinfeld, John H.; Shilling, John; Smith, James N.; Thornton, Joel A.; Volkamer, Rainer; Wang, Jian; Worsnop, Douglas R.; Zaveri, Rahul A.; Zelenyuk, Alla; Zhang, Qi) ACP}, author = {Shrivastava, Manish and Cappa, Christopher D. and Fan, Jiwen and Goldstein, Allen H. and Guenther, Alex B. and Jimenez, Jose L. and Kuang, Chongai and Laskin, Alexander and Martin, Scot T. and Ng, Nga Lee and Petaja, Tuukka and Pierce, Jeffrey R. and Rasch, Philip J. and Roldin, Pontus and Seinfeld, John H. and Shilling, John and Smith, James N. and Thornton, Joel A. and Volkamer, Rainer and Wang, Jian and Worsnop, Douglas R. and Zaveri, Rahul A. and Zelenyuk, Alla and Zhang, Qi}, doi = {10.1002/2016RG000540}, isbn = {1680-7316}, issn = {87551209}, journal = {Reviews of Geophysics}, keywords = {secondary organic aerosol}, month = {jun}, number = {2}, pages = {509--559}, publisher = {Copernicus Publications}, title = {{Recent advances in understanding secondary organic aerosol: Implications for global climate forcing}}, type = {Review}, url = {https://www.atmos-chem-phys.net/15/8217/2015/ http://doi.wiley.com/10.1002/2016RG000540}, volume = {55}, year = {2017} } @article{Sicard2020, abstract = {The effect of lockdown due to coronavirus disease (COVID-19) pandemic on air pollution in four Southern European cities (Nice, Rome, Valencia and Turin) and Wuhan (China) was quantified, with a focus on ozone (O3). Compared to the same period in 2017–2019, the daily O3 mean concentrations increased at urban stations by 24{\%} in Nice, 14{\%} in Rome, 27{\%} in Turin, 2.4{\%} in Valencia and 36{\%} in Wuhan during the lockdown in 2020. This increase in O3 concentrations is mainly explained by an unprecedented reduction in NOx emissions leading to a lower O3 titration by NO. Strong reductions in NO2 mean concentrations were observed in all European cities, {\~{}}53{\%} at urban stations, comparable to Wuhan (57{\%}), and {\~{}}65{\%} at traffic stations. NO declined even further, {\~{}}63{\%} at urban stations and {\~{}}78{\%} at traffic stations in Europe. Reductions in PM2.5 and PM10 at urban stations were overall much smaller both in magnitude and relative change in Europe ({\~{}}8{\%}) than in Wuhan ({\~{}}42{\%}). The PM reductions due to limiting transportation and fuel combustion in institutional and commercial buildings were partly offset by increases of PM emissions from the activities at home in some of the cities. The NOx concentrations during the lockdown were on average 49{\%} lower than those at weekends of the previous years in all cities. The lockdown effect on O3 production was {\~{}}10{\%} higher than the weekend effect in Southern Europe and 38{\%} higher in Wuhan, while for PM the lockdown had the same effect as weekends in Southern Europe ({\~{}}6{\%} of difference). This study highlights the challenge of reducing the formation of secondary pollutants such as O3 even with strict measures to control primary pollutant emissions. These results are relevant for designing abatement policies of urban pollution.}, author = {Sicard, Pierre and {De Marco}, Alessandra and Agathokleous, Evgenios and Feng, Zhaozhong and Xu, Xiaobin and Paoletti, Elena and Rodriguez, Jos{\'{e}} Jaime Di{\'{e}}guez and Calatayud, Vicent}, doi = {10.1016/j.scitotenv.2020.139542}, issn = {00489697}, journal = {Science of The Total Environment}, keywords = {Air quality,Coronavirus,Lockdown,Ozone,Risk assessment}, month = {sep}, pages = {139542}, pmid = {32447070}, publisher = {Elsevier B.V.}, title = {{Amplified ozone pollution in cities during the COVID-19 lockdown}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S004896972033059X}, volume = {735}, year = {2020} } @article{Sickles2015, abstract = {Data collected in the eastern US between 1990 and 2009 at 34 paired dry and wet monitoring sites are examined. A goal is to evaluate the air quality impacts occurring between 1990 and 2009 that are associated with concurrent legislatively mandated changes in emissions. Four 5-year periods, 1990-1994 (P1), 1995-1999 (P2), 2000-2004 (P3), and 2005-2009 (P4) are considered, with a primary focus on P1-to-P4 changes. Results suggest that legislatively mandated air pollution mitigation strategies have been successful in improving air quality and reducing atmospheric deposition in the eastern US. Respective P1-to-P4 reductions of estimated sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions in the eastern US are 50 and 42{\%}. Corresponding behavior of the following metrics associated with these emissions reductions is examined: monitored atmospheric concentrations of SO2, aerosol sulfate (SO4), and oxidized sulfur (S); dry, wet, and total deposition of S; monitored atmospheric concentrations of nitric acid (HNO3), aerosol nitrate (NO3), and their sum, oxidized nitrogen (OxN); dry, wet, and total deposition of OxN; monitored atmospheric concentration of aerosol ammonium (NH4); dry, wet, and total deposition of NH4; summed monitored atmospheric concentration of oxidized and reduced nitrogen (N); dry, wet, and total deposition of N; wet deposition of hydrogen ion (H+); monitored atmospheric concentration of ozone (O3); dry deposition of O3; and the summed monitored atmospheric concentration of aerosol NO3, SO4, and NH4 (Clean Air Status and Trends Network particulate matter-CASTNET PM). Other metrics (e.g., ratios of dry to total deposition) are also considered. Selected period-to-period changes of air quality and deposition metrics at site, regional, and seasonal scales are discussed. As an example, despite P1-to-P3 reductions in estimated emissions of both SO2 and NOx, aerosol NO3 concentration increased in the east, with widespread wintertime numerical increases in both aerosol NO3 concentration and CASTNET PM. However, a reversal of this behavior is associated with continuing P3-to-P4 reductions of SO2 and NOx emissions. Thus, additional P3-to-P4 reductions of these emissions, especially NOx, appear to have made progress in altering the chemical regime of the wintertime eastern US atmosphere so that future emissions reductions and their resulting reductions in aerosol concentrations may no longer be accompanied by sub-linear changes (or actual increases) in CASTNET PM.}, author = {{Sickles II}, J. E. and Shadwick, D. S.}, doi = {10.5194/acp-15-173-2015}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {1}, pages = {173--197}, title = {{Air quality and atmospheric deposition in the eastern US: 20 years of change}}, volume = {15}, year = {2015} } @article{Silva2016, abstract = {Background: Exposure to ozone and fine particulate matter (PM2.5) can cause adverse health effects, including premature mortality due to cardiopulmonary diseases and lung cancer. Recent studies quantify global air pollution mortality but not the contribution of different emissions sectors, or they focus on a specific sector. Objectives: We estimated the global mortality burden of anthropogenic ozone and PM2.5, and the impact of five emissions sectors, using a global chemical transport model at a finer horizontal resolution (0.67° × 0.5°) than previous studies. Methods: We performed simulations for 2005 using the Model for Ozone and Related Chemical Tracers, version 4 (MOZART-4), zeroing out all anthropogenic emissions and emissions from specific sectors (All Transportation, Land Transportation, Energy, Industry, and Residential and Commercial). We estimated premature mortality using a log-linear concentration-response function for ozone and an integrated exposure-response model for PM2.5. Results: We estimated 2.23 (95{\%} CI: 1.04, 3.33) million deaths/year related to anthropogenic PM2.5, with the highest mortality in East Asia (48{\%}). The Residential and Commercial sector had the greatest impact globally-675 (95{\%} CI: 428, 899) thousand deaths/year-and in most regions. Land Transportation dominated in North America (32{\%} of total anthropogenic PM2.5 mortality), and it had nearly the same impact (24{\%}) as Residential and Commercial (27{\%}) in Europe. Anthropogenic ozone was associated with 493 (95{\%} CI: 122, 989) thousand deaths/year, with the Land Transportation sector having the greatest impact globally (16{\%}). Conclusions: The contributions of emissions sectors to ambient air pollution-related mortality differ among regions, suggesting region-specific air pollution control strategies. Global sectorspecific actions targeting Land Transportation (ozone) and Residential and Commercial (PM2.5) sectors would particularly benefit human health.}, author = {Silva, Raquel A. and Adelman, Zachariah and Fry, Meridith M. and West, J. Jason}, doi = {10.1289/EHP177}, issn = {0091-6765}, journal = {Environmental Health Perspectives}, month = {nov}, number = {11}, pages = {1776--1784}, title = {{The Impact of Individual Anthropogenic Emissions Sectors on the Global Burden of Human Mortality due to Ambient Air Pollution}}, url = {https://ehp.niehs.nih.gov/doi/10.1289/EHP177}, volume = {124}, year = {2016} } @article{Silver2018, abstract = {China's rapid industrialisation and urbanisation has led to poor air quality. The Chinese government have responded by introducing policies to reduce emissions and setting ambitious targets for ambient PM2.5, SO2, NO2 and O3 concentrations. Previous satellite and modelling studies indicate that concentrations of these pollutants have begun to decline within the last decade. However, prior to 2012, air quality data from ground-based monitoring stations were difficult to obtain, limited to a few locations in major cities, and often unreliable. Since then, a comprehensive monitoring network, with over 1000 stations across China has been established by the Ministry of Ecology and Environment (MEE). We use a three-year (2015–2017) dataset consisting of hourly PM2.5, O3, NO2 and SO2 concentrations obtained from the MEE, combined with similar data from Taiwan and Hong Kong. We find that at 53{\%} and 59{\%} of stations, PM2.5 and SO2 concentrations have decreased significantly, with median rates across all stations of −3.4 and −1.9 $\mu$g m−3 year−1 respectively. At 50{\%} of stations, O3 maximum daily 8 h mean (MDA8) concentrations have increased significantly, with median rates across all stations of 4.6 $\mu$g m−3 year−1. It will be important to understand the relative contribution of changing anthropogenic emissions and meteorology to the changes in air pollution reported here.}, author = {Silver, B and Reddington, C L and Arnold, S R and Spracklen, D V}, doi = {10.1088/1748-9326/aae718}, issn = {1748-9326}, journal = {Environmental Research Letters}, number = {11}, pages = {114012}, publisher = {IOP Publishing}, title = {{Substantial changes in air pollution across China during 2015–2017}}, url = {http://dx.doi.org/10.1088/1748-9326/aae718}, volume = {13}, year = {2018} } @article{Silvern2018, abstract = {Observations from the SEAC4RS aircraft campaign over the southeast United States in August–September 2013 show NO/NO2 concentration ratios in the upper troposphere that are approximately half of photochemical equilibrium values computed from Jet Propulsion Laboratory (JPL) kinetic data. One possible explanation is the presence of labile NOx reservoir species, presumably organic, decomposing thermally to NO2 in the instrument. The NO2 instrument corrects for this artifact from known labile HNO4 and CH3O2NO2 NOx reservoirs. To bridge the gap between measured and simulated NO2, additional unaccounted labile NOx reservoir species would have to be present at a mean concentration of {\~{}}40 ppt for the SEAC4RS conditions (compared with 197 ppt for NOx). An alternative explanation is error in the low-temperature rate constant for the NO + O3 reaction (30{\%} 1-$\sigma$ uncertainty in JPL at 240 K) and/or in the spectroscopic data for NO2 photolysis (20{\%} 1-$\sigma$ uncertainty). Resolving this discrepancy is important for understanding global budgets of tropospheric oxidants and for interpreting satellite observations of tropospheric NO2 columns.}, author = {Silvern, R. F. and Jacob, D. J. and Travis, K. R. and Sherwen, T. and Evans, M. J. and Cohen, R. C. and Laughner, J. L. and Hall, S. R. and Ullmann, K. and Crounse, J. D. and Wennberg, P. O. and Peischl, J. and Pollack, I. B.}, doi = {10.1029/2018GL077728}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {GEOS-Chem,NOx,SEAC4RS,kinetics,upper troposphere}, month = {may}, number = {9}, pages = {4466--4474}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Observed NO/NO2 Ratios in the Upper Troposphere Imply Errors in NO-NO2-O3 Cycling Kinetics or an Unaccounted NOx Reservoir}}, volume = {45}, year = {2018} } @article{Simpson2012, abstract = {After methane, ethane is the most abundant hydrocarbon in the remote atmosphere. It is a precursor to tropospheric ozone and it influences the atmosphere-s oxidative capacity through its reaction with the hydroxyl radical, ethane-s primary atmospheric sink. Here we present the longest continuous record of global atmospheric ethane levels. We show that global ethane emission rates decreased from 14.3 to 11.3 teragrams per year, or by 21 per cent, from 1984 to 2010. We attribute this to decreasing fugitive emissions from ethane-s fossil fuel source-most probably decreased venting and flaring of natural gas in oil fields-rather than a decline in its other major sources, biofuel use and biomass burning. Ethane-s major emission sources are shared with methane, and recent studies have disagreed on whether reduced fossil fuel or microbial emissions have caused methane-s atmospheric growth rate to slow. Our findings suggest that reduced fugitive fossil fuel emissions account for at least 10-21 teragrams per year (30-70 per cent) of the decrease in methane-s global emissions, significantly contributing to methane-s slowing atmospheric growth rate since the mid-1980s. {\textcopyright} 2012 Macmillan Publishers Limited. All rights reserved.}, author = {Simpson, Isobel J. and Andersen, Mads P.Sulbaek and Meinardi, Simone and Bruhwiler, Lori and Blake, Nicola J. and Helmig, Detlev and {Sherwood Rowland}, F. and Blake, Donald R.}, doi = {10.1038/nature11342}, issn = {00280836}, journal = {Nature}, number = {7412}, pages = {490--494}, title = {{Long-term decline of global atmospheric ethane concentrations and implications for methane}}, volume = {488}, year = {2012} } @article{Singh2018, abstract = {The continuous observations over a period of 7 years (2009–2016) available at 7 locations show declining trend of atmospheric BC in the UK. Among all the locations, the highest decrease of 8 ± 3 percent per year was observed at the Marylebone road in London. The detailed analysis performed at 21 locations during 2009–2011 shows that average annual mean atmospheric BC concentration were 0.45, 1.47 ± 0.58, 1.34 ± 0.31, 1.83 ± 0.46 and 9.72 $\mu$gm−3 at rural, suburban, urban background, urban centre and kerbside sites respectively. Around 1 $\mu$gm−3 of atmospheric BC could be attributed to urban emission, whereas traffic contributed up to 8 $\mu$g m−3 of atmospheric BC near busy roads. Seasonal pattern was also observed at all locations except rural and kerbside location, with maximum concentrations (1.2–4 $\mu$gm−3) in winter. Further, minimum concentrations (0.3–1.2 $\mu$gm−3) were observed in summer and similar concentrations in spring and fall. At suburban and urban background locations, similar diurnal pattern were observed with atmospheric BC concentration peaks (≈1.8 $\mu$g m−3) in the morning (around 9 a.m.) and evening (7–9 p.m.) rush hours, whereas minimum concentrations were during late night hours (peak at 5 a.m.) and the afternoon hours (peak at 2 p.m.). The urban centre values show a similar morning pattern (peak at 9 a.m.; concentration - 2.5 $\mu$gm−3) in relation to background locations but only a slight decrease in concentration in the afternoon which remained above 2 $\mu$gm−3 till midnight. It is concluded that the higher flow of traffic at urban centre locations results in higher atmospheric BC concentrations throughout the day. Comparison of weekday and weekend daily averaged atmospheric BC showed maximum concentrations on Friday having minimum levels on Sunday. This study will help to refine the atmospheric BC emission over Europe and also provide inputs for climate change models, which in turn will help policy makers to reduce atmospheric BC emissions, globally.}, author = {Singh, Vikas and Ravindra, Khaiwal and Sahu, Lokesh and Sokhi, Ranjeet}, doi = {10.1016/j.atmosenv.2018.01.030}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Atmospheric black carbon (BC),BC trends,Climate change,Diurnal pattern,Emissions,Temporal variations}, pages = {148--157}, title = {{Trends of atmospheric black carbon concentration over United Kingdom}}, volume = {178}, year = {2018} } @article{Sitch2007, annote = {NULL}, author = {Sitch, S. and Cox, P. M. and Collins, W. J. and Huntingford, C.}, doi = {10.1038/nature06059}, issn = {0028-0836}, journal = {Nature}, month = {aug}, number = {7155}, pages = {791--794}, title = {{Indirect radiative forcing of climate change through ozone effects on the land-carbon sink}}, url = {http://www.nature.com/doifinder/10.1038/nature06059}, volume = {448}, year = {2007} } @article{Six2013, abstract = {Climate change and decreasing seawater pH (ocean acidification) have widely been considered as uncoupled consequences of the anthropogenic CO 2 perturbation. Recently, experiments in seawater enclosures (mesocosms) showed that concentrations of dimethylsulphide (DMS), a biogenic sulphur compound, were markedly lower in a low-pH environment. Marine DMS emissions are the largest natural source of atmospheric sulphur and changes in their strength have the potential to alter the Earth's radiation budget. Here we establish observational-based relationships between pH changes and DMS concentrations to estimate changes in future DMS emissions with Earth system model climate simulations. Global DMS emissions decrease by about 18(±3){\%} in 2100 compared with pre-industrial times as a result of the combined effects of ocean acidification and climate change. The reduced DMS emissions induce a significant additional radiative forcing, of which 83{\%} is attributed to the impact of ocean acidification, tantamount to an equilibrium temperature response between 0.23 and 0.48 K. Our results indicate that ocean acidification has the potential to exacerbate anthropogenic warming through a mechanism that is not considered at present in projections of future climate change. {\textcopyright} 2013 Macmillan Publishers Limited. All rights reserved.}, author = {Six, Katharina D. and Kloster, Silvia and Ilyina, Tatiana and Archer, Stephen D. and Zhang, Kai and Maier-Reimer, Ernst}, doi = {10.1038/nclimate1981}, issn = {1758678X}, journal = {Nature Climate Change}, month = {aug}, number = {11}, pages = {975--978}, publisher = {Springer Nature}, title = {{Global warming amplified by reduced sulphur fluxes as a result of ocean acidification}}, volume = {3}, year = {2013} } @article{Skowron2021, abstract = {Aviation emissions of nitrogen oxides (NOx) alter the composition of the atmosphere, perturbing the greenhouse gases ozone and methane, resulting in positive and negative radiative forcing effects, respectively. In 1981, the International Civil Aviation Organization adopted a first certification standard for the regulation of aircraft engine NOx emissions with subsequent increases in stringency in 1992, 1998, 2004 and 2010 to offset the growth of the environmental impact of air transport, the main motivation being to improve local air quality with the assumed co-benefit of reducing NOx emissions at altitude and therefore their climate impacts. Increased stringency is an ongoing topic of discussion and more stringent standards are usually associated with their beneficial environmental impact. Here we show that this is not necessarily the right direction with respect to reducing the climate impacts of aviation (as opposed to local air quality impacts) because of the tradeoff effects between reducing NOx emissions and increased fuel usage, along with a revised understanding of the radiative forcing effects of methane. Moreover, the predicted lower surface air pollution levels in the future will be beneficial for reducing the climate impact of aviation NOx emissions. Thus, further efforts leading to greater fuel efficiency, and therefore lower CO2 emissions, may be preferable to reducing NOx emissions in terms of aviation's climate impacts.}, author = {Skowron, Agnieszka and Lee, David S and {De Le{\'{o}}n}, Rub{\'{e}}n Rodr{\'{i}}guez and Lim, Ling L and Owen, Bethan}, doi = {10.1038/s41467-020-20771-3}, issn = {2041-1723}, journal = {Nature Communications}, number = {1}, pages = {564}, title = {{Greater fuel efficiency is potentially preferable to reducing NOx emissions for aviation's climate impacts}}, url = {https://doi.org/10.1038/s41467-020-20771-3}, volume = {12}, year = {2021} } @article{Smith2013a, abstract = {Emissions reductions focused on anthropogenic climate-forcing agents with relatively short atmospheric lifetimes, such as methane (CH4) and black carbon, have been suggested as a strategy to reduce the rate of climate change over the next several decades. We find that reductions of methane and black carbon would likely have only a modest impact on near-term global climate warming. Even with maximally feasible reductions phased in from 2015 to 2035, global mean temperatures in 2050 would be reduced by 0.16 °C, with a range of 0.04-0.35 °C because of uncertainties in carbonaceous aerosol emissions and aerosol forcing per unit of emissions. The high end of this range is only possible if total historical aerosol forcing is relatively small. More realistic emission reductions would likely provide an even smaller climate benefit. We find that the climate benefit from reductions in short-lived forcing agents are smaller than previously estimated. These near-term climate benefits of targeted reductions in short-lived forcers are not substantially different in magnitude from the benefits from a comprehensive climate policy.}, author = {Smith, S. J. and Mizrahi, A.}, doi = {10.1073/pnas.1308470110}, isbn = {0027-8424}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, month = {aug}, number = {35}, pages = {14202--14206}, pmid = {23940357}, title = {{Near-term climate mitigation by short-lived forcers}}, url = {http://www.pnas.org/cgi/doi/10.1073/pnas.1308470110}, volume = {110}, year = {2013} } @article{Smith2018, abstract = {Abstract. Simple climate models can be valuable if they are able to replicate aspects of complex fully coupled earth system models. Larger ensembles can be produced, enabling a probabilistic view of future climate change. A simple emissions-based climate model, FAIR, is presented, which calculates atmospheric concentrations of greenhouse gases and effective radiative forcing (ERF) from greenhouse gases, aerosols, ozone and other agents. Model runs are constrained to observed temperature change from 1880 to 2016 and produce a range of future projections under the Representative Concentration Pathway (RCP) scenarios. The constrained estimates of equilibrium climate sensitivity (ECS), transient climate response (TCR) and transient climate response to cumulative CO2 emissions (TCRE) are 2.86 (2.01 to 4.22)K, 1.53 (1.05 to 2.41)K and 1.40 (0.96 to 2.23)K (1000GtC)−1 (median and 5–95{\%} credible intervals). These are in good agreement with the likely Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) range, noting that AR5 estimates were derived from a combination of climate models, observations and expert judgement. The ranges of future projections of temperature and ranges of estimates of ECS, TCR and TCRE are somewhat sensitive to the prior distributions of ECS∕TCR parameters but less sensitive to the ERF from a doubling of CO2 or the observational temperature dataset used to constrain the ensemble. Taking these sensitivities into account, there is no evidence to suggest that the median and credible range of observationally constrained TCR or ECS differ from climate model-derived estimates. The range of temperature projections under RCP8.5 for 2081–2100 in the constrained FAIR model ensemble is lower than the emissions-based estimate reported in AR5 by half a degree, owing to differences in forcing assumptions and ECS∕TCR distributions.}, author = {Smith, Christopher J. and Forster, Piers M. and Allen, Myles and Leach, Nicholas and Millar, Richard J. and Passerello, Giovanni A. and Regayre, Leighton A.}, doi = {10.5194/gmd-11-2273-2018}, issn = {1991-9603}, journal = {Geoscientific Model Development}, month = {jun}, number = {6}, pages = {2273--2297}, title = {{FAIR v1.3: a simple emissions-based impulse response and carbon cycle model}}, url = {https://www.geosci-model-dev.net/11/2273/2018/}, volume = {11}, year = {2018} } @article{Smith2019, abstract = {Committed warming describes how much future warming can be expected from historical emissions due to inertia in the climate system. It is usually defined in terms of the level of warming above the present for an abrupt halt of emissions. Owing to socioeconomic constraints, this situation is unlikely, so we focus on the committed warming from present-day fossil fuel assets. Here we show that if carbon-intensive infrastructure is phased out at the end of its design lifetime from the end of 2018, there is a 64{\%} chance that peak global mean temperature rise remains below 1.5 °C. Delaying mitigation until 2030 considerably reduces the likelihood that 1.5 °C would be attainable even if the rate of fossil fuel retirement was accelerated. Although the challenges laid out by the Paris Agreement are daunting, we indicate 1.5 °C remains possible and is attainable with ambitious and immediate emission reduction across all sectors.}, author = {Smith, Christopher J. and Forster, Piers M. and Allen, Myles and Fuglestvedt, Jan and Millar, Richard J. and Rogelj, Joeri and Zickfeld, Kirsten}, doi = {10.1038/s41467-018-07999-w}, issn = {20411723}, journal = {Nature Communications}, number = {1}, pages = {101}, title = {{Current fossil fuel infrastructure does not yet commit us to 1.5 °C warming}}, url = {https://doi.org/10.1038/s41467-018-07999-w}, volume = {10}, year = {2019} } @article{Smith2020b, abstract = {The relatively short atmospheric lifetimes of methane (CH 4 ) and black carbon (BC) have focused attention on the potential for reducing anthropogenic climate change by reducing Short-Lived Climate Forcer (SLCF) emissions. This paper examines radiative forcing and global mean temperature results from the Energy Modeling Forum (EMF)-30 multi-model suite of scenarios addressing CH 4 and BC mitigation, the two major short-lived climate forcers. Central estimates of temperature reductions in 2040 from an idealized scenario focused on reductions in methane and black carbon emissions ranged from 0.18–0.26 °C across the nine participating models. Reductions in methane emissions drive 60{\%} or more of these temperature reductions by 2040, although the methane impact also depends on auxiliary reductions that depend on the economic structure of the model. Climate model parameter uncertainty has a large impact on results, with SLCF reductions resulting in as much as 0.3–0.7 °C by 2040. We find that the substantial overlap between a SLCF-focused policy and a stringent and comprehensive climate policy that reduces greenhouse gas emissions means that additional SLCF emission reductions result in, at most, a small additional benefit of {\~{}} 0.1 °C in the 2030–2040 time frame.}, author = {Smith, Steven J and Chateau, Jean and Dorheim, Kalyn and Drouet, Laurent and Durand-Lasserve, Olivier and Fricko, Oliver and Fujimori, Shinichiro and Hanaoka, Tatsuya and Harmsen, Mathijs and Hilaire, J{\'{e}}r{\^{o}}me and Keramidas, Kimon and Klimont, Zbigniew and Luderer, Gunnar and Moura, Maria Cecilia P and Riahi, Keywan and Rogelj, Joeri and Sano, Fuminori and van Vuuren, Detlef P and Wada, Kenichi}, doi = {10.1007/s10584-020-02794-3}, issn = {0165-0009}, journal = {Climatic Change}, month = {dec}, number = {3}, pages = {1427--1442}, title = {{Impact of methane and black carbon mitigation on forcing and temperature: a multi-model scenario analysis}}, url = {https://doi.org/10.1007/s10584-020-02794-3 https://link.springer.com/10.1007/s10584-020-02794-3}, volume = {163}, year = {2020} } @article{Murdymootoo2016, abstract = {Abstract. The Surface PARTiculate mAtter Network (SPARTAN) is a long-term project that includes characterization of chemical and physical attributes of aerosols from filter samples collected worldwide. This paper discusses the ongoing efforts of SPARTAN to define and quantify major ions and trace metals found in fine particulate matter (PM2.5). Our methods infer the spatial and temporal variability of PM2.5 in a cost-effective manner. Gravimetrically weighed filters represent multi-day averages of PM2.5, with a collocated nephelometer sampling air continuously. SPARTAN instruments are paired with AErosol RObotic NETwork (AERONET) sun photometers to better understand the relationship between ground-level PM2.5 and columnar aerosol optical depth (AOD). We have examined the chemical composition of PM2.5 at 12 globally dispersed, densely populated urban locations and a site at Mammoth Cave (US) National Park used as a background comparison. So far, each SPARTAN location has been active between the years 2013 and 2016 over periods of 2–26 months, with an average period of 12 months per site. These sites have collectively gathered over 10 years of quality aerosol data. The major PM2.5 constituents across all sites (relative contribution±SD) are ammoniated sulfate (20{\%}±11{\%}), crustal material (13.4{\%}±9.9{\%}), equivalent black carbon (11.9{\%}±8.4{\%}), ammonium nitrate (4.7{\%}±3.0{\%}), sea salt (2.3{\%}±1.6{\%}), trace element oxides (1.0{\%}±1.1{\%}), water (7.2{\%}±3.3{\%}) at 35{\%} RH, and residual matter (40{\%}±24{\%}). Analysis of filter samples reveals that several PM2.5 chemical components varied by more than an order of magnitude between sites. Ammoniated sulfate ranges from 1.1µgm−3 (Buenos Aires, Argentina) to 17µgm−3 (Kanpur, India in the dry season). Ammonium nitrate ranged from 0.2µgm−3 (Mammoth Cave, in summer) to 6.8 µgm−3 (Kanpur, dry season). Equivalent black carbon ranged from 0.7µgm−3 (Mammoth Cave) to over 8µgm−3 (Dhaka, Bangladesh and Kanpur, India). Comparison of SPARTAN vs. coincident measurements from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network at Mammoth Cave yielded a high degree of consistency for daily PM2.5 (r2 = 0.76, slope = 1.12), daily sulfate (r2 = 0.86, slope = 1.03), and mean fractions of all major PM2.5 components (within 6{\%}). Major ions generally agree well with previous studies at the same urban locations (e.g. sulfate fractions agree within 4{\%} for 8 out of 11 collocation comparisons). Enhanced anthropogenic dust fractions in large urban areas (e.g. Singapore, Kanpur, Hanoi, and Dhaka) are apparent from high Zn:Al ratios. The expected water contribution to aerosols is calculated via the hygroscopicity parameter $\kappa$v for each filter. Mean aggregate values ranged from 0.15 (Ilorin) to 0.28 (Rehovot). The all-site parameter mean is 0.20±0.04. Chemical composition and water retention in each filter measurement allows inference of hourly PM2.5 at 35{\%} relative humidity by merging with nephelometer measurements. These hourly PM2.5 estimates compare favourably with a beta attenuation monitor (MetOne) at the nearby US embassy in Beijing, with a coefficient of variation r2 = 0.67 (n = 3167), compared to r2 = 0.62 when $\kappa$v was not considered. SPARTAN continues to provide an open-access database of PM2.5 compositional filter information and hourly mass collected from a global federation of instruments.}, author = {Snider, G. and Weagle, C. L. and Murdymootoo, K. K. and Ring, A. and Ritchie, Y. and Stone, E. and Walsh, A. and Akoshile, C. and Anh, N. X. and Balasubramanian, R. and Brook, J. and Qonitan, F. D. and Dong, J. and Griffith, D. and He, K. and Holben, B. N. and Kahn, R. and Lagrosas, N. and Lestari, P. and Ma, Z. and Misra, A. and Norford, L. K. and Quel, E. J. and Salam, A. and Schichtel, B. and Segev, L. and Tripathi, S. and Wang, C. and Yu, C. and Zhang, Q. and Zhang, Y. and Brauer, M. and Cohen, A. and Gibson, M. D. and Liu, Y. and Martins, J. V. and Rudich, Y. and Martin, R. V.}, doi = {10.5194/acp-16-9629-2016}, journal = {Atmospheric Chemistry and Physics}, number = {15}, pages = {9629--9653}, publisher = {Copernicus GmbH}, title = {{Variation in global chemical composition of PM2.5: emerging results from SPARTAN}}, volume = {16}, year = {2016} } @article{amt-8-505-2015, abstract = {Ground-based observations have insufficient spatial coverage to assess long-term human exposure to fine particulate matter (PM2.5) at the global scale. Satellite remote sensing offers a promising approach to provide information on both short- and long-term exposure to PM2.5 at local-to-global scales, but there are limitations and outstanding questions about the accuracy and precision with which ground-level aerosol mass concentrations can be inferred from satellite remote sensing alone. A key source of uncertainty is the global distribution of the relationship between annual average PM2.5 and discontinuous satellite observations of columnar aerosol optical depth (AOD). We have initiated a global network of ground-level monitoring stations designed to evaluate and enhance satellite remote sensing estimates for application in health-effects research and risk assessment. This Surface PARTiculate mAtter Network (SPARTAN) includes a global federation of ground-level monitors of hourly PM2.5 situated primarily in highly populated regions and collocated with existing ground-based sun photometers that measure AOD. The instruments, a three-wavelength nephelometer and impaction filter sampler for both PM2.5 and PM10, are highly autonomous. Hourly PM2.5 concentrations are inferred from the combination of weighed filters and nephelometer data. Data from existing networks were used to develop and evaluate network sampling characteristics. SPARTAN filters are analyzed for mass, black carbon, water-soluble ions, and metals. These measurements provide, in a variety of regions around the world, the key data required to evaluate and enhance satellite-based PM2.5 estimates used for assessing the health effects of aerosols. Mean PM2.5 concentrations across sites vary by more than 1 order of magnitude. Our initial measurements indicate that the ratio of AOD to ground-level PM2.5 is driven temporally and spatially by the vertical profile in aerosol scattering. Spatially this ratio is also strongly influenced by the mass scattering efficiency.}, author = {Snider, G and Weagle, C L and Martin, R V and van Donkelaar, A and Conrad, K and Cunningham, D and Gordon, C and Zwicker, M and Akoshile, C and Artaxo, P and Anh, N X and Brook, J and Dong, J and Garland, R M and Greenwald, R and Griffith, D and He, K and Holben, B N and Kahn, R and Koren, I and Lagrosas, N and Lestari, P and Ma, Z and {Vanderlei Martins}, J and Quel, E J and Rudich, Y and Salam, A and Tripathi, S N and Yu, C and Zhang, Q and Zhang, Y and Brauer, M and Cohen, A and Gibson, M D and Liu, Y}, doi = {10.5194/amt-8-505-2015}, journal = {Atmospheric Measurement Techniques}, number = {1}, pages = {505--521}, title = {{SPARTAN: a global network to evaluate and enhance satellite-based estimates of ground-level particulate matter for global health applications}}, url = {https://www.atmos-meas-tech.net/8/505/2015/}, volume = {8}, year = {2015} } @incollection{soares2016seasalt, address = {Cham, Switzerland}, author = {Soares, Joana and Sofiev., Mikhail and Geels., Camilla and Christensen., Jesper H. and Anderson., Camilla and Lagner., Joakim and Tsyro, Svetlana}, booktitle = {Air Pollution Modeling and its Application XXIV}, doi = {10.1007/978-3-319-24478-5_34}, editor = {Steyn, D. and Chaumerliac, N.}, isbn = {978-3-319-24478-5}, pages = {207--212}, publisher = {Springer}, series = {Springer Proceedings in Complexity}, title = {{Impact of Climate Change on the Production and Transport of Sea Salt Aerosol on European Seas}}, year = {2016} } @article{Sofiev2018, abstract = {We evaluate public health and climate impacts of low-sulphur fuels in global shipping. Using high-resolution emissions inventories, integrated atmospheric models, and health risk functions, we assess ship-related PM2.5 pollution impacts in 2020 with and without the use of low-sulphur fuels. Cleaner marine fuels will reduce ship-related premature mortality and morbidity by 34 and 54{\%}, respectively, representing a {\~{}} 2.6{\%} global reduction in PM2.5 cardiovascular and lung cancer deaths and a {\~{}}3.6{\%} global reduction in childhood asthma. Despite these reductions, low-sulphur marine fuels will still account for {\~{}}250k deaths and {\~{}}6.4 M childhood asthma cases annually, and more stringent standards beyond 2020 may provide additional health benefits. Lower sulphur fuels also reduce radiative cooling from ship aerosols by {\~{}}80{\%}, equating to a {\~{}}3{\%} increase in current estimates of total anthropogenic forcing. Therefore, stronger international shipping policies may need to achieve climate and health targets by jointly reducing greenhouse gases and air pollution.}, author = {Sofiev, Mikhail and Winebrake, James J. and Johansson, Lasse and Carr, Edward W. and Prank, Marje and Soares, Joana and Vira, Julius and Kouznetsov, Rostislav and Jalkanen, Jukka Pekka and Corbett, James J.}, doi = {10.1038/s41467-017-02774-9}, issn = {20411723}, journal = {Nature Communications}, number = {1}, pages = {406}, title = {{Cleaner fuels for ships provide public health benefits with climate tradeoffs}}, volume = {9}, year = {2018} } @article{doi:10.1080/10962247.2014.956904, abstract = {The U.S. Environmental Protection Agency (EPA) initiated the national PM2.5 Chemical Speciation Monitoring Network (CSN) in 2000 to support evaluation of long-term trends and to better quantify the impact of sources on particulate matter (PM) concentrations in the size range below 2.5 $\mu$m aerodynamic diameter (PM2.5; fine particles). The network peaked at more than 260 sites in 2005. In response to the 1999 Regional Haze Rule and the need to better understand the regional transport of PM, EPA also augmented the long-existing Interagency Monitoring of Protected Visual Environments (IMPROVE) visibility monitoring network in 2000, adding nearly 100 additional IMPROVE sites in rural Class 1 Areas across the country. Both networks measure the major chemical components of PM2.5 using historically accepted filter-based methods. Components measured by both networks include major anions, carbonaceous material, and a series of trace elements. CSN also measures ammonium and other cations directly, whereas IMPROVE estimates ammonium assuming complete neutralization of the measured sulfate and nitrate. IMPROVE also measures chloride and nitrite. In general, the field and laboratory approaches used in the two networks are similar; however, there are numerous, often subtle differences in sampling and chemical analysis methods, shipping, and quality control practices. These could potentially affect merging the two data sets when used to understand better the impact of sources on PM concentrations and the regional nature and long-range transport of PM2.5. This paper describes, for the first time in the peer-reviewed literature, these networks as they have existed since 2000, outlines differences in field and laboratory approaches, provides a summary of the analytical parameters that address data uncertainty, and summarizes major network changes since the inception of CSN.}, author = {Solomon, Paul A and Crumpler, Dennis and Flanagan, James B and Jayanty, R K M and Rickman, Ed E and McDade, Charles E}, doi = {10.1080/10962247.2014.956904}, journal = {Journal of the Air {\&} Waste Management Association}, number = {12}, pages = {1410--1438}, publisher = {Taylor {\&} Francis}, title = {{U.S. National PM2.5 Chemical Speciation Monitoring Networks – CSN and IMPROVE: Description of networks}}, url = {https://doi.org/10.1080/10962247.2014.956904}, volume = {64}, year = {2014} } @article{Conibear2018, abstract = {Exposure to ambient fine particulate matter (PM 2.5 ) is a leading contributor to diseases in India. Previous studies analysing emission source attributions were restricted by coarse model resolution and limited PM 2.5 observations. We use a regional model informed by new observations to make the first high-resolution study of the sector-specific disease burden from ambient PM 2.5 exposure in India. Observed annual mean PM 2.5 concentrations exceed 100 $\mu$g m -3 and are well simulated by the model. We calculate that the emissions from residential energy use dominate (52{\%}) population-weighted annual mean PM 2.5 concentrations, and are attributed to 511,000 (95UI: 340,000-697,000) premature mortalities annually. However, removing residential energy use emissions would avert only 256,000 (95UI: 162,000-340,000), due to the non-linear exposure-response relationship causing health effects to saturate at high PM 2.5 concentrations. Consequently, large reductions in emissions will be required to reduce the health burden from ambient PM 2.5 exposure in India.}, author = {Spracklen, Dominick V. and Arnold, Stephen R. and Conibear, Luke and Butt, Edward W. and Knote, Christoph}, doi = {10.1038/s41467-018-02986-7}, issn = {20411723}, journal = {Nature Communications}, number = {1}, pages = {617}, title = {{Residential energy use emissions dominate health impacts from exposure to ambient particulate matter in India}}, volume = {9}, year = {2018} } @article{Squire2015, abstract = {Isoprene is a precursor to tropospheric ozone, a key pollutant and greenhouse gas. Anthropogenic activity over the coming century is likely to cause large changes in atmospheric CO2 levels, climate and land use, all of which will alter the global vegetation distribution leading to changes in isoprene emissions. Previous studies have used global chemistry-climate models to assess how possible changes in climate and land use could affect isoprene emissions and hence tropospheric ozone. The chemistry of isoprene oxidation, which can alter the concentration of ozone, is highly complex, therefore it must be parameterised in these models. In this work, we compare the effect of four different reduced isoprene chemical mechanisms, all currently used in Earth system models, on tropospheric ozone. Using a box model we compare ozone in these reduced schemes to that in a more explicit scheme (the Master Chemical Mechanism) over a range of NOx and isoprene emissions, through the use of O3 isopleths. We find that there is some variability, especially at high isoprene emissions, caused by differences in isoprene-derived NOx reservoir species. A global model is then used to examine how the different reduced schemes respond to potential future changes in climate, isoprene emissions, anthropogenic emissions and land use change. We find that, particularly in isoprene-rich regions, the response of the schemes varies considerably. The wide-ranging response is due to differences in the model descriptions of the peroxy radical chemistry, particularly their relative rates of reaction towards NO, leading to ozone formation, or HO2, leading to termination. Also important is the yield of isoprene nitrates and peroxyacyl nitrate precursors from isoprene oxidation. Those schemes that produce less of these NOx reservoir species, tend to produce more ozone locally and less away from the source region. We also note changes in other key oxidants such as NO3 and OH (due to the inclusion of additional isoprene-derived HOx recycling pathways). These have implications for secondary organic aerosol formation, as does the inclusion of an epoxide formation pathway in one of the mechanisms. By combining the emissions and O3 data from all of the global model integrations, we are able to construct isopleth plots comparable to those from the box model analysis. We find that the global and box model isopleths show good qualitative agreement, suggesting that comparing chemical mechanisms with a box model in this framework is a useful tool for assessing mechanistic performance in complex global models. We conclude that as the choice of reduced isoprene mechanism may alter both the magnitude and sign of the ozone response, how isoprene chemistry is parameterised in perturbation experiments such as these is a crucially important consideration. More measurements and laboratory studies are needed to validate these reduced mechanisms especially under high-volatile-organiccompound, low-NOx conditions.}, author = {Squire, O. J. and Archibald, A. T. and Griffiths, P. T. and Jenkin, M. E. and Smith, D. and Pyle, J. A.}, doi = {10.5194/acp-15-5123-2015}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {9}, pages = {5123--5143}, title = {{Influence of isoprene chemical mechanism on modelled changes in tropospheric ozone due to climate and land use over the 21st century}}, url = {https://www.atmos-chem-phys.net/15/5123/2015/}, volume = {15}, year = {2015} } @article{ISI:000346907100027, abstract = {We investigate the relative importance of climate change (CC) and anthropogenic land cover change (ALCC) for the dust emissions and burden changes between the late nineteenth century and today. For this purpose, the climate-aerosol model ECHAM6-HAM2 is complemented by a new scheme to derive potential dust sources at runtime using the vegetation cover provided by the land component JSBACH of ECHAM6. Dust emissions are computed online using information from the ECHAM6 atmospheric component. This allows us to account for changes in land cover and climate interactively and to distinguish between emissions from natural and agricultural dust sources. For today's climate we find that nearly 10{\%} of dust particles are emitted from agricultural areas. According to our simulations, global annual dust emissions have increased by 25{\%} between the late nineteenth century and today (e. g., from 729 Tg/a to 912 Tg/a). Globally, CC and ALCC (e. g., agricultural expansion) have both contributed to this change (56{\%} and 40{\%}, respectively). There are however large regional differences. For example, change in dust emissions in Africa are clearly dominated by CC. Global dust burden have increased by 24.5{\%} since the late nineteenth century, which results in a clear-sky radiative forcing at top of the atmosphere of similar to 0.14W/m(2). Based on these findings, we recommend that both climate changes and anthropogenic land cover changes should be considered when investigating long-term changes in dust emissions.}, annote = {Forcing by dust from PI to PD -- section 6.5}, author = {Stanelle, Tanja and Bey, Isabelle and Raddatz, Thomas and Reick, Christian and Tegen, Ina}, doi = {10.1002/2014JD022062}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {dec}, number = {23}, pages = {13,526--13,546}, title = {{Anthropogenically induced changes in twentieth century mineral dust burden and the associated impact on radiative forcing}}, type = {Article}, url = {http://doi.wiley.com/10.1002/2014JD022062}, volume = {119}, year = {2014} } @article{Stavrakou2014a, abstract = {Abstract. Due to the scarcity of observational constraints and the rapidly changing environment in East and Southeast Asia, isoprene emissions predicted by models are expected to bear substantial uncertainties. The aim of this study is to improve upon the existing bottom-up estimates, and to investigate the temporal evolution of the fluxes in Asia over 1979–2012. To this purpose, we calculate the hourly emissions at 0.5°×0.5° resolution using the MEGAN–MOHYCAN model driven by ECMWF ERA-Interim climatology. In order to remedy for known biases identified in previous studies, and to improve the simulation of interannual variability and trends in emissions, this study incorporates (i) changes in land use, including the rapid expansion of oil palms, (ii) meteorological variability according to ERA-Interim, (iii) long-term changes in solar radiation (dimming/brightening) constrained by surface network radiation measurements, and (iv) recent experimental evidence that South Asian tropical forests are much weaker isoprene emitters than previously assumed, and on the other hand, that oil palms have a strong isoprene emission capacity. These effects lead to a significant lowering (factor of 2) in the total isoprene fluxes over the studied domain, and to emission reductions reaching a factor of 3.5 in Southeast Asia. The bottom-up annual isoprene emissions for 2005 are estimated at 7.0, 4.8, 8.3, and 2.9 Tg in China, India, Indonesia and Malaysia, respectively. The isoprene flux anomaly over the whole domain and studied period is found to be strongly correlated with the Oceanic Ni{\~{n}}o Index (r = 0.73), with positive (negative) anomalies related to El Ni{\~{n}}o (La Ni{\~{n}}a) years. Changes in temperature and solar radiation are the major drivers of the interannual variability and trends in the emissions, except over semi-arid areas such as northwestern China, Pakistan and Kazakhstan, where soil moisture is by far the main cause of interannual emission changes. In our base simulation, annual positive flux trends of 0.2{\%} and 0.52{\%} throughout the entire period are found in Asia and China, respectively, related to a positive trend in temperature and solar radiation. The impact of oil palm expansion in Indonesia and Malaysia is to enhance the trends over that region, e.g., from 1.17{\%} to 1.5{\%} in 1979–2005 in Malaysia. A negative emission trend is derived in India (−0.4{\%}), owing to the negative trend in solar radiation data associated with the strong dimming effect likely due to inc{\ldots}}, author = {Stavrakou, T. and M{\"{u}}ller, J.-F. and Bauwens, M. and {De Smedt}, I. and {Van Roozendael}, M. and Guenther, A. and Wild, M. and Xia, X.}, doi = {10.5194/acp-14-4587-2014}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {9}, pages = {4587--4605}, title = {{Isoprene emissions over Asia 1979–2012: impact of climate and land-use changes}}, volume = {14}, year = {2014} } @article{Stechow2016, author = {Stechow, Christoph and Minx, Jan and Riahi, Keywan and Jewell, Jessica and McCollum, David and Callaghan, Max and Bertram, Christoph and Luderer, Gunnar and Baiocchi, Giovanni}, doi = {10.1088/1748-9326/11/3/034022}, journal = {Environmental Research Letters}, month = {mar}, pages = {34022}, title = {{2°C and SDGs: United they stand, divided they fall?}}, volume = {11}, year = {2016} } @article{Stein2014, abstract = {Abstract. Despite the developments in the global modelling of chemistry and of the parameterization of the physical processes, carbon monoxide (CO) concentrations remain underestimated during Northern Hemisphere (NH) winter by most state-of-the-art chemistry transport models. The consequential model bias can in principle originate from either an underestimation of CO sources or an overestimation of its sinks. We address both the role of surface sources and sinks with a series of MOZART (Model for Ozone And Related Tracers) model sensitivity studies for the year 2008 and compare our results to observational data from ground-based stations, satellite observations, and vertical profiles from measurements on passenger aircraft. In our base case simulation using MACCity (Monitoring Atmospheric Composition and Climate project) anthropogenic emissions, the near-surface CO mixing ratios are underestimated in the Northern Hemisphere by more than 20 ppb from December to April, with the largest bias of up to 75 ppb over Europe in January. An increase in global biomass burning or biogenic emissions of CO or volatile organic compounds (VOCs) is not able to reduce the annual course of the model bias and yields concentrations over the Southern Hemisphere which are too high. Raising global annual anthropogenic emissions with a simple scaling factor results in overestimations of surface mixing ratios in most regions all year round. Instead, our results indicate that anthropogenic CO and, possibly, VOC emissions in the MACCity inventory are too low for the industrialized countries only during winter and spring. Reasonable agreement with observations can only be achieved if the CO emissions are adjusted seasonally with regionally varying scaling factors. A part of the model bias could also be eliminated by exchanging the original resistance-type dry deposition scheme with a parameterization for CO uptake by oxidation from soil bacteria and microbes, which reduces the boreal winter dry deposition fluxes. The best match to surface observations, satellite retrievals, and aircraft observations was achieved when the modified dry deposition scheme was combined with increased wintertime road traffic emissions over Europe and North America (factors up to 4.5 and 2, respectively). One reason for the apparent underestimation of emissions may be an exaggerated downward trend in the Representative Concentration Pathway (RCP) 8.5 scenario in these regions between 2000 and 2010, as this scenario was used to extrapolate the MACCity emissions from their base year 2000. This factor is potentially amplified by a lack of knowledge about the seasonality of emissions. A methane lifetime of 9.7 yr for our basic model and 9.8 yr for the optimized simulation agrees well with current estimates of global OH, but we cannot fully exclude a potential effect from errors in the geographical and seasonal distribution of OH concentrations on the modelled CO.}, author = {Stein, O. and Schultz, M. G. and Bouarar, I. and Clark, H. and Huijnen, V. and Gaudel, A. and George, M. and Clerbaux, C.}, doi = {10.5194/acp-14-9295-2014}, isbn = {1680-7375}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {sep}, number = {17}, pages = {9295--9316}, title = {{On the wintertime low bias of Northern Hemisphere carbon monoxide found in global model simulations}}, url = {https://acp.copernicus.org/articles/14/9295/2014/}, volume = {14}, year = {2014} } @article{Stevens2017, abstract = {Abstract. A simple plume implementation of the second version (v2) of the Max Planck Institute Aerosol Climatology, MACv2-SP, is described. MACv2-SP provides a prescription of anthropogenic aerosol optical properties and an associated Twomey effect. It was created to provide a harmonized description of post-1850 anthropogenic aerosol radiative forcing for climate modeling studies. MACv2-SP has been designed to be easy to implement, change and use, and thereby enable studies exploring the climatic effects of different patterns of aerosol radiative forcing, including a Twomey effect. MACv2-SP is formulated in terms of nine spatial plumes associated with different major anthropogenic source regions. The shape of the plumes is fit to the Max Planck Institute Aerosol Climatology, version 2, whose present-day (2005) distribution is anchored by surface-based observations. Two types of plumes are considered: one predominantly associated with biomass burning, the other with industrial emissions. These differ in the prescription of their annual cycle and in their optical properties, thereby implicitly accounting for different contributions of absorbing aerosol to the different plumes. A Twomey effect for each plume is prescribed as a change in the host model's background cloud-droplet population density using relationships derived from satellite data. Year-to-year variations in the amplitude of the plumes over the historical period (1850–2016) are derived by scaling the plumes with associated national emission sources of SO2 and NH3. Experiments using MACv2-SP are performed with the Max Planck Institute Earth System Model. The globally and annually averaged instantaneous and effective aerosol radiative forcings are estimated to be −0.6 and −0.5 W m−2, respectively. Forcing from aerosol–cloud interactions (the Twomey effect) offsets the reduction of clear-sky forcing by clouds, so that the net effect of clouds on the aerosol forcing is small; hence, the clear-sky forcing, which is more readily measurable, provides a good estimate of the total aerosol forcing.}, author = {Stevens, Bjorn and Fiedler, Stephanie and Kinne, Stefan and Peters, Karsten and Rast, Sebastian and M{\"{u}}sse, Jobst and Smith, Steven J and Mauritsen, Thorsten}, doi = {10.5194/gmd-10-433-2017}, issn = {1991-9603}, journal = {Geoscientific Model Development}, month = {feb}, number = {1}, pages = {433--452}, title = {{MACv2-SP: a parameterization of anthropogenic aerosol optical properties and an associated Twomey effect for use in CMIP6}}, url = {https://gmd.copernicus.org/articles/10/433/2017/}, volume = {10}, year = {2017} } @article{Stevenson2006, abstract = {Global tropospheric ozone distributions, budgets, and radiative forcings from an ensemble of 26 state-of-the-art atmospheric chemistry models have been intercompared and synthesized as part of a wider study into both the air quality and climate roles of ozone. Results from three 2030 emissions scenarios, broadly representing ?optimistic,? ?likely,? and ?pessimistic? options, are compared to a base year 2000 simulation. This base case realistically represents the current global distribution of tropospheric ozone. A further set of simulations considers the influence of climate change over the same time period by forcing the central emissions scenario with a surface warming of around 0.7K. The use of a large multimodel ensemble allows us to identify key areas of uncertainty and improves the robustness of the results. Ensemble mean changes in tropospheric ozone burden between 2000 and 2030 for the 3 scenarios range from a 5{\%} decrease, through a 6{\%} increase, to a 15{\%} increase. The intermodel uncertainty (±1 standard deviation) associated with these values is about ±25{\%}. Model outliers have no significant influence on the ensemble mean results. Combining ozone and methane changes, the three scenarios produce radiative forcings of ?50, 180, and 300 mW m?2, compared to a CO2 forcing over the same time period of 800?1100 mW m?2. These values indicate the importance of air pollution emissions in short- to medium-term climate forcing and the potential for stringent/lax control measures to improve/worsen future climate forcing. The model sensitivity of ozone to imposed climate change varies between models but modulates zonal mean mixing ratios by ±5 ppbv via a variety of feedback mechanisms, in particular those involving water vapor and stratosphere-troposphere exchange. This level of climate change also reduces the methane lifetime by around 4{\%}. The ensemble mean year 2000 tropospheric ozone budget indicates chemical production, chemical destruction, dry deposition and stratospheric input fluxes of 5100, 4650, 1000, and 550 Tg(O3) yr?1, respectively. These values are significantly different to the mean budget documented by the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (TAR). The mean ozone burden (340 Tg(O3)) is 10{\%} larger than the IPCC TAR estimate, while the mean ozone lifetime (22 days) is 10{\%} shorter. Results from individual models show a correlation between ozone burden and lifetime, and each model's ozone burden and lifetime respond in similar ways across the emissions scenarios. The response to climate change is much less consistent. Models show more variability in the tropics compared to midlatitudes. Some of the most uncertain areas of the models include treatments of deep tropical convection, including lightning NOx production; isoprene emissions from vegetation and isoprene's degradation chemistry; stratosphere-troposphere exchange; biomass burning; and water vapor concentrations.}, annote = {doi: 10.1029/2005JD006338}, author = {Stevenson, D S and Dentener, F J and Schultz, M G and Ellingsen, K and van Noije, T P C and Wild, O and Zeng, G and Amann, M and Atherton, C S and Bell, N and Bergmann, D J and Bey, I and Butler, T and Cofala, J and Collins, W J and Derwent, R G and Doherty, R M and Drevet, J and Eskes, H J and Fiore, A M and Gauss, M and Hauglustaine, D A and Horowitz, L W and Isaksen, I S A and Krol, M C and Lamarque, J.-F. and Lawrence, M G and Montanaro, V and M{\"{u}}ller, J.-F. and Pitari, G and Prather, M J and Pyle, J A and Rast, S and Rodriguez, J M and Sanderson, M G and Savage, N H and Shindell, D T and Strahan, S E and Sudo, K and Szopa, S}, doi = {10.1029/2005JD006338}, issn = {0148-0227}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {intercomparison,modeling,tropospheric ozone}, month = {apr}, number = {D8}, pages = {D08301}, publisher = {Wiley-Blackwell}, title = {{Multimodel ensemble simulations of present-day and near-future tropospheric ozone}}, url = {https://doi.org/10.1029/2005JD006338}, volume = {111}, year = {2006} } @article{Stevenson2013, abstract = {Abstract. Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP) scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 410 mW m−2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation) in RFs of ±17{\%}. Three different radiation schemes were used – we find differences in RFs between schemes (for the same ozone fields) of ±10{\%}. Applying two different tropopause definitions gives differences in RFs of ±3{\%}. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30{\%} for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44±12{\%}), nitrogen oxides (31 ± 9{\%}), carbon monoxide (15 ± 3{\%}) and non-methane volatile organic compounds (9 ± 2{\%}); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m−2 DU−1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m−2; relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030), and 200, 300, 280 and 600 (in 2100). Models show some coherent responses of ozone to climate change: decreases in the tropical lower troposphere, associated with increases in water vapour; and increases in the sub-tropical to mid-latitude upper troposphere, associated with increases in lightning and stratosphere-to-troposphere transport. Climate change has relatively small impacts on global mean tropospheric ozone RF.}, author = {Stevenson, D. S. and Young, P. J. and Naik, V. and Lamarque, J.-F. and Shindell, D. T. and Voulgarakis, A. and Skeie, R. B. and Dalsoren, S. B. and Myhre, G. and Berntsen, T. K. and Folberth, G. A. and Rumbold, S. T. and Collins, W. J. and MacKenzie, I. A. and Doherty, R. M. and Zeng, G. and van Noije, T. P. C. and Strunk, A. and Bergmann, D. and Cameron-Smith, P. and Plummer, D. A. and Strode, S. A. and Horowitz, L. and Lee, Y. H. and Szopa, S. and Sudo, K. and Nagashima, T. and Josse, B. and Cionni, I. and Righi, M. and Eyring, V. and Conley, A. and Bowman, K. W. and Wild, O. and Archibald, A.}, doi = {10.5194/acp-13-3063-2013}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {6}, pages = {3063--3085}, title = {{Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)}}, url = {https://www.atmos-chem-phys.net/13/3063/2013/}, volume = {13}, year = {2013} } @article{Stevenson2019, author = {Stevenson, David S. and Zhao, Alcide and Naik, Vaishali and O'Connor, Fiona M. and Tilmes, Simone and Zeng, Guang and Murray, Lee T. and Collins, William J. and Griffiths, Paul T. and Shim, Sungbo and Horowitz, Larry W. and Sentman, Lori T. and Emmons, Louisa}, doi = {10.5194/acp-20-12905-2020}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {nov}, number = {21}, pages = {12905--12920}, title = {{Trends in global tropospheric hydroxyl radical and methane lifetime since 1850 from AerChemMIP}}, url = {https://acp.copernicus.org/articles/20/12905/2020/}, volume = {20}, year = {2020} } @article{Stjern2017a, abstract = {We investigate the climate response to increased concentrations of black carbon (BC), as part of the Precipitation Driver Response Model Intercomparison Project (PDRMIP). A tenfold increase in BC is simulated by nine global coupled-climate models, producing a model median effective radiative forcing of 0.82 (ranging from 0.41 to 2.91) W m −2 , and a warming of 0.67 (0.16 to 1.66) K globally and 1.24 (0.26 to 4.31) K in the Arctic. A strong positive instantaneous radiative forcing (median of 2.10 W m −2 based on five of the models) is countered by negative rapid adjustments (−0.64 W m −2 for the same five models), which dampen the total surface temperature signal. Unlike other drivers of climate change, the response of temperature and cloud profiles to the BC forcing is dominated by rapid adjustments. Low-level cloud amounts increase for all models, while higher-level clouds are diminished. The rapid temperature response is particularly strong above 400 hPa, where increased atmospheric stabilization and reduced cloud cover contrast the response pattern of the other drivers. In conclusion, we find that this substantial increase in BC concentrations does have considerable impacts on important aspects of the climate system. However, some of these effects tend to offset one another, leaving a relatively small median global warming of 0.47 K per W m −2 —about 20{\%} lower than the response to a doubling of CO 2 . Translating the tenfold increase in BC to the present-day impact of anthropogenic BC (given the emissions used in this work) would leave a warming of merely 0.07 K.}, annote = {doi: 10.1002/2017JD027326}, author = {Stjern, Camilla Weum and Samset, Bj{\o}rn Hallvard and Myhre, Gunnar and Forster, Piers M. and Hodnebrog, {\O}ivind and Andrews, Timothy and Boucher, Olivier and Faluvegi, Gregory and Iversen, Trond and Kasoar, Matthew and Kharin, Viatcheslav and Kirkev{\aa}g, Alf and Lamarque, Jean Fran{\c{c}}ois and Olivi{\'{e}}, Dirk and Richardson, Thomas and Shawki, Dilshad and Shindell, Drew and Smith, Christopher J. and Takemura, Toshihiko and Voulgarakis, Apostolos}, doi = {10.1002/2017JD027326}, issn = {21698996}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {black carbon,climate,rapid adjustments,semidirect}, month = {nov}, number = {21}, pages = {11462--11481}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Rapid Adjustments Cause Weak Surface Temperature Response to Increased Black Carbon Concentrations}}, url = {https://doi.org/10.1002/2017JD027326}, volume = {122}, year = {2017} } @article{Stockwell2020, annote = {doi: 10.1080/10962247.2019.1694605}, author = {Stockwell, William R and Saunders, Emily and Goliff, Wendy S and Fitzgerald, Rosa M}, doi = {10.1080/10962247.2019.1694605}, issn = {1096-2247}, journal = {Journal of the Air {\&} Waste Management Association}, month = {jan}, number = {1}, pages = {44--70}, publisher = {Taylor {\&} Francis}, title = {{A perspective on the development of gas-phase chemical mechanisms for Eulerian air quality models}}, url = {https://doi.org/10.1080/10962247.2019.1694605}, volume = {70}, year = {2020} } @article{Stohl2015c, abstract = {This paper presents a summary of the work done within the European Union's Seventh Framework Programme project ECLIPSE (Evaluating the Climate and Air Quality Impacts of Short-Lived Pollutants). ECLIPSE had a unique systematic concept for designing a realistic and effective mitigation scenario for short-lived climate pollutants (SLCPs; methane, aerosols and ozone, and their precursor species) and quantifying its climate and air quality impacts, and this paper presents the results in the context of this overarching strategy. The first step in ECLIPSE was to create a new emission inventory based on current legislation (CLE) for the recent past and until 2050. Substantial progress compared to previous work was made by including previously unaccounted types of sources such as flaring of gas associated with oil production, and wick lamps. These emission data were used for present-day reference simulations with four advanced Earth system models (ESMs) and six chemistry transport models (CTMs). The model simulations were compared with a variety of ground-based and satellite observational data sets from Asia, Europe and the Arctic. It was found that the models still underestimate the measured seasonality of aerosols in the Arctic but to a lesser extent than in previous studies. Problems likely related to the emissions were identified for northern Russia and India, in particular. To estimate the climate impacts of SLCPs, ECLIPSE followed two paths of research: the first path calculated radiative forcing (RF) values for a large matrix of SLCP species emissions, for different seasons and regions independently. Based on these RF calculations, the Global Temperature change Potential metric for a time horizon of 20 years (GTP20) was calculated for each SLCP emission type. This climate metric was then used in an integrated assessment model to identify all emission mitigation measures with a beneficial air quality and short-term (20-year) climate impact. These measures together defined a SLCP mitigation (MIT) scenario. Compared to CLE, the MIT scenario would reduce global methane (CH4) and black carbon (BC) emissions by about 50 and 80 {\%}, respectively. For CH4, measures on shale gas production, waste management and coal mines were most important. For non-CH4 SLCPs, elimination of high-emitting vehicles and wick lamps, as well as reducing emissions from gas flaring, coal and biomass stoves, agricultural waste, solvents and diesel engines were most important. These measures lead to large reductions in calculated surface concentrations of ozone and particulate matter. We estimate that in the EU, the loss of statistical life expectancy due to air pollution was 7.5 months in 2010, which will be reduced to 5.2 months by 2030 in the CLE scenario. The MIT scenario would reduce this value by another 0.9 to 4.3 months. Substantially larger reductions due to the mitigation are found for China (1.8 months) and India (11-12 months). The climate metrics cannot fully quantify the climate response. Therefore, a second research path was taken. Transient climate ensemble simulations with the four ESMs were run for the CLE and MIT scenarios, to determine the climate impacts of the mitigation. In these simulations, the CLE scenario resulted in a surface temperature increase of 0.70 ± 0.14 K between the years 2006 and 2050. For the decade 2041-2050, the warming was reduced by 0.22 ± 0.07 K in the MIT scenario, and this result was in almost exact agreement with the response calculated based on the emission metrics (reduced warming of 0.22 ± 0.09 K). The metrics calculations suggest that non-CH4 SLCPs contribute ∼ 22 {\%} to this response and CH4 78 {\%}. This could not be fully confirmed by the transient simulations, which attributed about 90 {\%} of the temperature response to CH4 reductions. Attribution of the observed temperature response to non-CH4 SLCP emission reductions and BC specifically is hampered in the transient simulations by small forcing and co-emitted species of the emission basket chosen. Nevertheless, an important conclusion is that our mitigation basket as a whole would lead to clear benefits for both air quality and climate. The climate response from BC reductions in our study is smaller than reported previously, possibly because our study is one of the first to use fully coupled climate models, where unforced variability and sea ice responses cause relatively strong temperature fluctuations that may counteract (and, thus, mask) the impacts of small emission reductions. The temperature responses to the mitigation were generally stronger over the continents than over the oceans, and with a warming reduction of 0.44 K (0.39-0.49) K the largest over the Arctic. Our calculations suggest particularly beneficial climate responses in southern Europe, where surface warming was reduced by about 0.3 K and precipitation rates were increased by about 15 (6-21) mm yrg'1 (more than 4 {\%} of total precipitation) from spring to autumn. Thus, the mitigation could help to alleviate expected future drought and water shortages in the Mediterranean area. We also report other important results of the ECLIPSE project.}, author = {Stohl, A. and Aamaas, B. and Amann, M. and Baker, L. H. and Bellouin, N. and Berntsen, T. K. and Boucher, O. and Cherian, R. and Collins, W. and Daskalakis, N. and Dusinska, M. and Eckhardt, S. and Fuglestvedt, J. S. and Harju, M. and Heyes, C. and Hodnebrog and Hao, J. and Im, U. and Kanakidou, M. and Klimont, Z. and Kupiainen, K. and Law, K. S. and Lund, M. T. and Maas, R. and MacIntosh, C. R. and Myhre, G. and Myriokefalitakis, S. and Olivi{\'{e}}, D. and Quaas, J. and Quennehen, B. and Raut, J. C. and Rumbold, S. T. and Samset, B. H. and Schulz, M. and Seland and Shine, K. P. and Skeie, R. B. and Wang, S. and Yttri, K. E. and Zhu, T.}, doi = {10.5194/acp-15-10529-2015}, isbn = {1680-7324}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {sep}, number = {18}, pages = {10529--10566}, title = {{Evaluating the climate and air quality impacts of short-lived pollutants}}, volume = {15}, year = {2015} } @article{Stohl2013, abstract = {Abstract. Arctic haze is a seasonal phenomenon with high concentrations of accumulation-mode aerosols occurring in the Arctic in winter and early spring. Chemistry transport models and climate chemistry models struggle to reproduce this phenomenon, and this has recently prompted changes in aerosol removal schemes to remedy the modeling problems. In this paper, we show that shortcomings in current emission data sets are at least as important. We perform a 3 yr model simulation of black carbon (BC) with the Lagrangian particle dispersion model FLEXPART. The model is driven with a new emission data set ("ECLIPSE emissions") which includes emissions from gas flaring. While gas flaring is estimated to contribute less than 3{\%} of global BC emissions in this data set, flaring dominates the estimated BC emissions in the Arctic (north of 66° N). Putting these emissions into our model, we find that flaring contributes 42{\%} to the annual mean BC surface concentrations in the Arctic. In March, flaring even accounts for 52{\%} of all Arctic BC near the surface. Most of the flaring BC remains close to the surface in the Arctic, so that the flaring contribution to BC in the middle and upper troposphere is small. Another important factor determining simulated BC concentrations is the seasonal variation of BC emissions from residential combustion (often also called domestic combustion, which is used synonymously in this paper). We have calculated daily residential combustion emissions using the heating degree day (HDD) concept based on ambient air temperature and compare results from model simulations using emissions with daily, monthly and annual time resolution. In January, the Arctic-mean surface concentrations of BC due to residential combustion emissions are 150{\%} higher when using daily emissions than when using annually constant emissions. While there are concentration reductions in summer, they are smaller than the winter increases, leading to a systematic increase of annual mean Arctic BC surface concentrations due to residential combustion by 68{\%} when using daily emissions. A large part (93{\%}) of this systematic increase can be captured also when using monthly emissions; the increase is compensated by a decreased BC burden at lower latitudes. In a comparison with BC measurements at six Arctic stations, we find that using daily-varying residential combustion emissions and introducing gas flaring emissions leads to large improvements of the simulated Arctic BC, both in terms of mean concentration levels and simulated seasonality. Case studies based on BC and carbon monoxide (CO) measurements from the Zeppelin observatory appear to confirm flaring as an important BC source that can produce pollution plumes in the Arctic with a high BC / CO enhancement ratio, as expected for this source type. BC measurements taken during a research ship cruise in the White, Barents and Kara seas north of the region with strong flaring emissions reveal very high concentrations of the order of 200–400 ng m−3. The model underestimates these concentrations substantially, which indicates that the flaring emissions (and probably also other emissions in northern Siberia) are rather under- than overestimated in our emission data set. Our results suggest that it may not be "vertical transport that is too strong or scavenging rates that are too low" and "opposite biases in these processes" in the Arctic and elsewhere in current aerosol models, as suggested in a recent review article (Bond et al., Bounding the role of black carbon in the climate system: a scientific assessment, J. Geophys. Res., 2013), but missing emission sources and lacking time resolution of the emission data that are causing opposite model biases in simulated BC concentrations in the Arctic and in the mid-latitudes.}, author = {Stohl, A. and Klimont, Z. and Eckhardt, S. and Kupiainen, K. and Shevchenko, V. P. and Kopeikin, V. M. and Novigatsky, A. N.}, doi = {10.5194/acp-13-8833-2013}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {sep}, number = {17}, pages = {8833--8855}, title = {{Black carbon in the Arctic: the underestimated role of gas flaring and residential combustion emissions}}, url = {https://acp.copernicus.org/articles/13/8833/2013/}, volume = {13}, year = {2013} } @article{Storelvmo2013, abstract = {Cirrus clouds, thin ice clouds in the upper troposphere, have a net warming effect on Earth's climate. Consequently, a reduction in cirrus cloud amount or optical thickness would cool the climate. Recent research indicates that by seeding cirrus clouds with particles that promote ice nucleation, their lifetimes and coverage could be reduced. We have tested this hypothesis in a global climate model with a state-of-the-art representation of cirrus clouds and find that cirrus cloud seeding has the potential to cancel the entire warming caused by human activity from pre-industrial times to present day. However, the desired effect is only obtained for seeding particle concentrations that lie within an optimal range. With lower than optimal particle concentrations, a seeding exercise would have no effect. Moreover, a higher than optimal concentration results in an over-seeding that could have the deleterious effect of prolonging cirrus lifetime and contributing to global warming. {\textcopyright} 2013. American Geophysical Union. All Rights Reserved.}, author = {Storelvmo, T. and Kristjansson, J. E. and Muri, H. and Pfeffer, M. and Barahona, D. and Nenes, A.}, doi = {10.1029/2012GL054201}, issn = {00948276}, journal = {Geophysical Research Letters}, month = {jan}, number = {1}, pages = {178--182}, title = {{Cirrus cloud seeding has potential to cool climate}}, url = {http://doi.wiley.com/10.1029/2012GL054201}, volume = {40}, year = {2013} } @article{Strada2016, abstract = {Abstract. A global Earth system model is applied to quantify the impacts of direct anthropogenic aerosol effective radiative forcing on gross primary productivity (GPP) and isoprene emission. The impacts of different pollution aerosol sources (anthropogenic, biomass burning, and non-biomass burning) are investigated by performing sensitivity experiments. The model framework includes all known light and meteorological responses of photosynthesis, but uses fixed canopy structures and phenology. On a global scale, our results show that global land carbon fluxes (GPP and isoprene emission) are not sensitive to pollution aerosols, even under a global decline in surface solar radiation (direct + diffuse) by ∼ 9 {\%}. At a regional scale, GPP and isoprene emission show a robust but opposite sensitivity to pollution aerosols in regions where forested canopies dominate. In eastern North America and Eurasia, anthropogenic pollution aerosols (mainly from non-biomass burning sources) enhance GPP by +5–8 {\%} on an annual average. In the northwestern Amazon Basin and central Africa, biomass burning aerosols increase GPP by +2–5 {\%} on an annual average, with a peak in the northwestern Amazon Basin during the dry-fire season (+5–8 {\%}). The prevailing mechanism varies across regions: light scattering dominates in eastern North America, while a reduction in direct radiation dominates in Europe and China. Aerosol-induced GPP productivity increases in the Amazon and central Africa include an additional positive feedback from reduced canopy temperatures in response to increases in canopy conductance. In Eurasia and northeastern China, anthropogenic pollution aerosols drive a decrease in isoprene emission of −2 to −12 {\%} on an annual average. Future research needs to incorporate the indirect effects of aerosols and possible feedbacks from dynamic carbon allocation and phenology.}, author = {Strada, Susanna and Unger, Nadine}, doi = {10.5194/acp-16-4213-2016}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {apr}, number = {7}, pages = {4213--4234}, title = {{Potential sensitivity of photosynthesis and isoprene emission to direct radiative effects of atmospheric aerosol pollution}}, url = {https://acp.copernicus.org/articles/16/4213/2016/}, volume = {16}, year = {2016} } @article{Strefler2014, abstract = {In this paper we analyze the interaction between climate and air pollution policies using the integrated assessment model REMIND coupled to the reduced-form climate model MAGICC. Since overall, aerosols tend to cool the atmosphere, there is a concern that a reduction of pollutant emissions could accelerate global warming and offset the climate benefits of carbon dioxide emission reductions.We investigate scenarios which independently reduce emissions from either large-scale sources, such as power plants, or small-scale sources, such as cooking and heating stoves. Large-scale sources are likely to be easier to control, but their aerosol emissions are characterized by a relatively high sulfur content, which tends to result in atmospheric cooling. Pollution from small-scale sources, by contrast, is characterized by a high share of carbonaceous aerosol, which is an important contributor to global warming.We find that air pollution policies can significantly reduce aerosol emissions when no climate policies are in place. Stringent climate policies lead to a large reduction of fossil fuel use, and therefore result in a concurrent reduction of air pollutant emissions. These reductions partly reduce aerosol masking, thus initially counteracting the reduction of greenhouse gas forcing, however not overcompensating it. If climate policies are in place, air pollution policies have almost no impacts on medium- and long-term radiative forcing. Therefore there is no conflict of objectives between clean air and limiting global warming. We find that the stringency of air pollution policies may influence the rate of global temperature change in the first decade. Afterwards climate change mitigation policies are of greater importance. {\textcopyright} 2014 Elsevier Ltd.}, author = {Strefler, Jessica and Luderer, Gunnar and Kriegler, Elmar and Meinshausen, Malte}, doi = {10.1016/j.envsci.2014.04.009}, isbn = {14629011}, issn = {18736416}, journal = {Environmental Science {\&} Policy}, keywords = {Aerosols,Air pollution,Climate change,Integrated assessment modeling}, pages = {33--43}, title = {{Can air pollutant controls change global warming?}}, url = {http://dx.doi.org/10.1016/j.envsci.2014.04.009}, volume = {41}, year = {2014} } @article{Strode2015a, abstract = {Abstract. A low bias in carbon monoxide (CO) at northern high and mid-latitudes is a common feature of chemistry climate models (CCMs) that may indicate or contribute to a high bias in simulated OH and corresponding low bias in methane lifetime. We use simulations with CO tagged by source type to investigate the sensitivity of the CO bias to CO emissions, transport, global mean OH, and the hemispheric asymmetry of OH. We also investigate how each of these possible contributors to the CO bias affects the methane lifetime. We find that the use of specified meteorology alters the distribution of CO compared to a free-running CCM simulation, improving the comparison with surface observations in summer. Our results also show that reducing the hemispheric asymmetry of OH improves the agreement of simulated CO with observations. We use simulations with parameterized OH to quantify the impact of known model biases on simulated OH. Removing biases in ozone and water vapor as well as reducing Northern Hemisphere NOx does not remove the hemispheric asymmetry in OH, but it reduces global mean OH by 18 {\%}, bringing the simulated methane lifetime into agreement with observation-based estimates.}, author = {Strode, S. A. and Duncan, B. N. and Yegorova, E. A. and Kouatchou, J. and Ziemke, J. R. and Douglass, A. R.}, doi = {10.5194/acp-15-11789-2015}, isbn = {1680-7316}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {oct}, number = {20}, pages = {11789--11805}, title = {{Implications of carbon monoxide bias for methane lifetime and atmospheric composition in chemistry climate models}}, url = {https://acp.copernicus.org/articles/15/11789/2015/}, volume = {15}, year = {2015} } @article{Strode2016, abstract = {We use a series of chemical transport model and chemistry climate model simulations to investigate the observed negative trends in MOPITT CO over several regions of the world, and to examine the consistency of time-dependent emission inventories with observations. We find that simulations driven by the MACCity inventory, used for the Chemistry Climate Modeling Initiative (CCMI), reproduce the negative trends in the CO column observed by MOPITT for 2000-2010 over the eastern United States and Europe. However, the simulations have positive trends over eastern China, in contrast to the negative trends observed by MOPITT. The model bias in CO, after applying MOPITT averaging kernels, contributes to the model-observation discrepancy in the trend over eastern China. This demonstrates that biases in a model's average concentrations can influence the interpretation of the temporal trend compared to satellite observations. The total ozone column plays a role in determining the simulated tropospheric CO trends. A large positive anomaly in the simulated total ozone column in 2010 leads to a negative anomaly in OH and hence a positive anomaly in CO, contributing to the positive trend in simulated CO. These results demonstrate that accurately simulating variability in the ozone column is important for simulating and interpreting trends in CO.}, author = {Strode, Sarah A. and Worden, Helen M. and Damon, Megan and Douglass, Anne R. and Duncan, Bryan N. and Emmons, Louisa K. and Lamarque, Jean Francois and Manyin, Michael and Oman, Luke D. and Rodriguez, Jose M. and Strahan, Susan E. and Tilmes, Simone}, doi = {10.5194/acp-16-7285-2016}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {jun}, number = {11}, pages = {7285--7294}, publisher = {Copernicus GmbH}, title = {{Interpreting space-based trends in carbon monoxide with multiple models}}, url = {https://acp.copernicus.org/articles/16/7285/2016/}, volume = {16}, year = {2016} } @article{struthers2013, abstract = {AbstractGlobal climate model output is combined with an emission parameterization to estimate the change in the global and regional sea salt aerosol number emission from 1870 to 2100. Global average results suggest a general increase in sea salt aerosol number emission due to increasing surface wind speed. However, the emission changes are not uniform over the aerosol size spectrum due to an increase in sea surface temperature. From 1870 to 2100 the emission of coarse mode particles (dry diameter DP{\textgreater}655 nm) increase by approximately 10 {\%} (global average), whereas no significant change in the emission of ultrafine mode aerosols (dry diameter Dp{\textless}76 nm) was found over the same period. Significant regional differences in the number emission trends were also found. Based on CAM-Oslo global climate model output, no straight-forward relationship was found between the change in the number emissions and changes in the sea salt aerosol burden or optical thickness. This is attributed to a change in the simulated residence time of the sea salt aerosol. For the 21st century, a decrease in the residence time leads to a weaker sea salt aerosol-climate feedback that what would be inferred based on changes in number emissions alone. Finally, quantifying any potential impact on marine stratocumulus cloud microphysical and radiative properties due to changes in sea salt aerosol number emissions is likely to be complicated by commensurate changes in anthropogenic aerosol emissions and changes in meteorology.}, author = {Struthers, H and Ekman, A M L and Glantz, P and Iversen, T and Kirkev{\aa}g, A and Seland, {\O} and M{\aa}rtensson, E M and Noone, K and Nilsson, E D}, doi = {10.1002/jgrd.50129}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {climate,emissions,sea salt aerosol}, number = {2}, pages = {670--682}, title = {{Climate-induced changes in sea salt aerosol number emissions: 1870 to 2100}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/jgrd.50129}, volume = {118}, year = {2013} } @article{Stuber2001, abstract = {The climate response to a set of idealized ozone perturbations is investigated by integrations with a coupled atmosphere-ocean model. Although all perturbations, including a homogeneous CO2 increase, induce the same stratosphere adjusted, tropopause radiative forcing, the climate response is quite variable within the set of experiments. Except for an upper tropospheric ozone increase, our model is more sensitive to ozone perturbations than to an equivalent CO2 perturbation. This applies in particular to a lower stratospheric ozone increase. The accompanying changes in the stratospheric water vapor (SWV) distribution are found to impose additional forcings on climate that may well exceed the forcings due to the original perturbations. Without SWV feedback on radiation the climate sensitivity to a lower stratospheric ozone increase draws remarkably near the respective value for equivalent CO2. This emphasizes the crucial role SWV may have in the forcing-response relationship.}, author = {Stuber, Nicola and Ponater, Michael and Sausen, Robert}, doi = {10.1029/2001GL013000}, issn = {0094-8276}, journal = {Geophysical Research Letters}, month = {aug}, number = {15}, pages = {2887--2890}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Is the climate sensitivity to ozone perturbations enhanced by stratospheric water vapor feedback?}}, volume = {28}, year = {2001} } @article{ISI:000396115000042, abstract = {CASTNET (Clean Air Status and Trends Network) ozone and temperature data and large-scale meteorological analysis are used to quantify the extent to which meteorological events and their persistence impact ozone with an emphasis on the high end of the ozone distribution (greater than the 90th percentile). Ozone increases with each successive stagnation day in all regions of the U.S., with the highest increase in the Northeastern U.S. (0.4 standard deviation or similar to 4.7 ppb per successive stagnation day). Ozone increases with days since cyclone passage only in the Northeastern and Mid-Atlantic regions of the U.S., but on average not enough to reach the 90th percentile concentration. Persistent high temperature does not result in further ozone increases in any region. On the interannual timescale there is little evidence that summers with large numbers of the above events increase ozone preferentially on the high end of the ozone distribution.}, author = {Sun, Wenxiu and Hess, Peter and Liu, Chengji}, doi = {10.1002/2016GL071731}, issn = {00948276}, journal = {Geophysical Research Letters}, month = {feb}, number = {3}, pages = {1545--1553}, title = {{The impact of meteorological persistence on the distribution and extremes of ozone}}, url = {http://doi.wiley.com/10.1002/2016GL071731}, volume = {44}, year = {2017} } @article{doi:10.1111/j.1365-2486.2012.02787.x, abstract = {Abstract The capacity of forests to mitigate global climate change can be negatively influenced by tropospheric ozone that impairs both photosynthesis and stomatal control of plant transpiration, thus affecting ecosystem productivity and watershed hydrology. We have evaluated individual and interactive effects of ozone and climate on late season streamflow for six forested watersheds (38–970 000 ha) located in the Southeastern United States. Models were based on 18–26 year data records for each watershed and involved multivariate analysis of interannual variability of late season streamflow in response to physical and chemical climate during the growing season. In all cases, some combination of ozone variables significantly improved model performance over climate-only models. Effects of ozone and ozone × climate interactions were also consistently negative and were proportional to variations in actual ozone exposures, both spatially across the region and over time. Conservative estimates of the influence of ozone on the variability (R2) of observed flow ranged from 7{\%} in the area of lowest ozone exposure in West Virginia to 23{\%} in the areas of highest exposure in Tennessee. Our results are supported by a controlled field study using free-air concentration enrichment methodology which indicated progressive ozone-induced loss of stomatal control over tree transpiration during the summer in mixed aspen-birch stands. Despite the frequent assumption that ozone reduces tree water loss, our findings support increasing evidence that ozone at near ambient concentrations can reduce stomatal control of leaf transpiration, and increase water use. Increases in evapotranspiration and associated streamflow reductions in response to ambient ozone exposures are expected to episodically increase the frequency and severity of drought and affect flow-dependent aquatic biota in forested watersheds. Regional and global models of hydrologic cycles and related ecosystem functions should consider potential interactions of ozone with climate under both current and future warmer and ozone-enriched climatic conditions.}, author = {Sun, G E and McLaughlin, Samuel B and Porter, John H and Uddling, Johan and Mulholland, Patrick J and Adams, Mary B and Pederson, Neil}, doi = {10.1111/j.1365-2486.2012.02787.x}, journal = {Global Change Biology}, keywords = {climate,drought enhancement,forest water use,ozone,streamflow}, number = {11}, pages = {3395--3409}, title = {{Interactive influences of ozone and climate on streamflow of forested watersheds}}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2012.02787.x}, volume = {18}, year = {2012} } @article{Sun2018, abstract = {Studies reporting the historical trends of SO2, NOx, CO, and nonmethane volatile organic compounds emissions in China using unified approaches and sources are limited. Here we established 66-year emission trends of these four species in China. Six primary anthropogenic sources were included, and we made a series of improvements to the few existing inventories based on detailed statistical data, recently published emission factors, and technology renewal to reduce the uncertainties. National SO2, NOx, CO, and nonmethane volatile organic compounds emissions in 2015 were 27.1, 20.6, 188, and 28.4 Mt, with annual growth rates of 5.8{\%}, 5.9{\%}, 3.8{\%}, and 4.6{\%} since 1949, respectively. In recent years, fossil fuel combustion was the major contributor to SO2, NOx, and CO emissions, whereas industrial process contributed most to VOCs emissions. Our results revealed a 10{\%} decrease in the SO2 emissions from 2005 to 2010 as a result of improvements in the flue gas desulfurization installation rate. NOx emissions stopped rising and started falling in 2011, with technology renewal and the penetration of end-of-pipe control measures in industrial boilers and cement production. Furthermore, we calculated future speciated VOCs emissions and ozone formation potential under alternative policy scenarios and projected to reduce emissions by 10{\%} (compared with 2013 levels) with stringent control measures in 2020. A reactivity-based control strategy was proposed to achieve greater ozone formation potential reductions while requiring less VOCs emissions reduction.}, author = {Sun, W. and Shao, M. and Granier, C. and Liu, Y. and Ye, C. S. and Zheng, J. Y.}, doi = {10.1029/2018EF000822}, issn = {23284277}, journal = {Earth's Future}, keywords = {China,air pollutants,emission inventory,long-term trends,reactivity control,scenario analysis}, number = {8}, pages = {1112--1133}, title = {{Long-Term Trends of Anthropogenic SO2, NOx, CO, and NMVOCs Emissions in China}}, volume = {6}, year = {2018} } @article{Sutton2013, abstract = {Existing descriptions of bi-directional ammonia (NH 3 ) land–atmosphere exchange incorporate temperature and moisture controls, and are beginning to be used in regional chemical transport models. However, such models have typically applied simpler emission factors to upscale the main NH 3 emission terms. While this approach has successfully simulated the main spatial patterns on local to global scales, it fails to address the environment- and climate-dependence of emissions. To handle these issues, we outline the basis for a new modelling paradigm where both NH 3 emissions and deposition are calculated online according to diurnal, seasonal and spatial differences in meteorology. We show how measurements reveal a strong, but complex pattern of climatic dependence, which is increasingly being characterized using ground-based NH 3 monitoring and satellite observations, while advances in process-based modelling are illustrated for agricultural and natural sources, including a global application for seabird colonies. A future architecture for NH 3 emission–deposition modelling is proposed that integrates the spatio-temporal interactions, and provides the necessary foundation to assess the consequences of climate change. Based on available measurements, a first empirical estimate suggests that 5°C warming would increase emissions by 42 per cent (28–67{\%}). Together with increased anthropogenic activity, global NH 3 emissions may increase from 65 (45–85) Tg N in 2008 to reach 132 (89–179) Tg by 2100.}, author = {Sutton, Mark A and Reis, Stefan and Riddick, Stuart N and Dragosits, Ulrike and Nemitz, Eiko and Theobald, Mark R and Tang, Y Sim and Braban, Christine F and Vieno, Massimo and Dore, Anthony J and Mitchell, Robert F and Wanless, Sarah and Daunt, Francis and Fowler, David and Blackall, Trevor D and Milford, Celia and Flechard, Chris R and Loubet, Benjamin and Massad, Raia and Cellier, Pierre and Personne, Erwan and Coheur, Pierre F and Clarisse, Lieven and {Van Damme}, Martin and Ngadi, Yasmine and Clerbaux, Cathy and Skj{\o}th, Carsten Ambelas and Geels, Camilla and Hertel, Ole and {Wichink Kruit}, Roy J. and Pinder, Robert W and Bash, Jesse O and Walker, John T and Simpson, David and Horv{\'{a}}th, L{\'{a}}szl{\'{o}} and Misselbrook, Tom H and Bleeker, Albert and Dentener, Frank and de Vries, Wim}, doi = {10.1098/rstb.2013.0166}, issn = {0962-8436}, journal = {Philosophical Transactions of the Royal Society B: Biological Sciences}, month = {jul}, number = {1621}, pages = {20130166}, title = {{Towards a climate-dependent paradigm of ammonia emission and deposition}}, url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2013.0166}, volume = {368}, year = {2013} } @article{Szogs2017a, author = {Szogs, Sebastian and Arneth, Almut and Anthoni, Peter and Doelman, Jonathan C. and Humpen{\"{o}}der, Florian and Popp, Alexander and Pugh, Thomas A.M. and Stehfest, Elke}, doi = {10.1016/j.atmosenv.2017.06.025}, issn = {13522310}, journal = {Atmospheric Environment}, month = {sep}, pages = {73--87}, title = {{Impact of LULCC on the emission of BVOCs during the 21st century}}, volume = {165}, year = {2017} } @article{Te2016, abstract = {{\textless}p{\textgreater}Carbon monoxide (CO) is an atmospheric key species due to its toxicity and its impact on the atmospheric oxidizing capacity, both factors affecting air quality. The paper studies the altitude dependent seasonal variability of CO at the three different sites Paris, Jungfraujoch and Wollongong, with an emphasis on establishing a link between the CO vertical distribution and the nature of CO emission sources. The CO seasonal variability obtained from the total columns and from the free tropospheric partial columns shows a maximum around March-April and a minimum around September-October in the Northern Hemisphere (Paris and Jungfraujoch). In the Southern Hemisphere (Wollongong) this seasonal variability is shifted by about 6 months. Satellite observations by IASI-MetOp and MOPITT instruments confirm this seasonality. Ground-based FTIR is demonstrated to provide useful complementary information due to good sensitivity in the boundary layer. In situ surface measurements of CO volume mixing ratios in Paris and at Jungfraujoch reveal a time-lag of the near surface seasonal variability of about 2 months with respect to the total column variability at the same sites. The chemical transport model GEOS-Chem is employed to interpret our observations. GEOS-Chem sensitivity runs allow identifying the emission sources influencing the seasonal cycle of CO. In Paris and on top of Jungfraujoch, the surface seasonality is mainly driven by anthropogenic emissions, while the total column seasonality is also controlled by air masses transported from distant sources. In the case of Wollongong, where the CO seasonality is mainly affected by biomass burning, no time shift is observed between surface and above the boundary layer.{\textless}/p{\textgreater}}, author = {T{\'{e}}, Yao and Jeseck, Pascal and Franco, Bruno and Mahieu, Emmanuel and Jones, Nicholas and Paton-Walsh, Clare and Griffith, David W.T. and Buchholz, Rebecca R. and Hadji-Lazaro, Juliette and Hurtmans, Daniel and Janssen, Christof}, doi = {10.5194/acp-16-10911-2016}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {17}, pages = {10911--10925}, title = {{Seasonal variability of surface and column carbon monoxide over the megacity Paris, high-altitude Jungfraujoch and Southern Hemispheric Wollongong stations}}, volume = {16}, year = {2016} } @article{Tan2018, abstract = {Abstract. This study uses multi-model ensemble results of 11 models from the second phase of Task Force Hemispheric Transport of Air Pollution (HTAP II) to calculate the global sulfur (S) and nitrogen (N) deposition in 2010. Modeled wet deposition is evaluated with observation networks in North America, Europe and East Asia. The modeled results agree well with observations, with 76–83{\&}thinsp;{\%} of stations being predicted within ±50{\&}thinsp;{\%} of observations. The models underestimate SO42-, NO3- and NH4+ wet depositions in some European and East Asian stations but overestimate NO3- wet deposition in the eastern United States. Intercomparison with previous projects (PhotoComp, ACCMIP and HTAP I) shows that HTPA II has considerably improved the estimation of deposition at European and East Asian stations. Modeled dry deposition is generally higher than the “inferential” data calculated by observed concentration and modeled velocity in North America, but the inferential data have high uncertainty, too. The global S deposition is 84{\&}thinsp;Tg(S) in 2010, with 49{\&}thinsp;{\%} in continental regions and 51{\&}thinsp;{\%} in the ocean (19{\&}thinsp;{\%} of which coastal). The global N deposition consists of 59{\&}thinsp;Tg(N) oxidized nitrogen (NOy) deposition and 64{\&}thinsp;Tg(N) reduced nitrogen (NHx) deposition in 2010. About 65{\&}thinsp;{\%} of N is deposited in continental regions, and 35{\&}thinsp;{\%} in the ocean (15{\&}thinsp;{\%} of which coastal). The estimated outflow of pollution from land to ocean is about 4{\&}thinsp;Tg(S) for S deposition and 18{\&}thinsp;Tg(N) for N deposition. Comparing our results to the results in 2001 from HTAP I, we find that the global distributions of S and N deposition have changed considerably during the last 10 years. The global S deposition decreases 2{\&}thinsp;Tg(S) (3{\&}thinsp;{\%}) from 2001 to 2010, with significant decreases in Europe (5{\&}thinsp;Tg(S) and 55{\&}thinsp;{\%}), North America (3{\&}thinsp;Tg(S) and 29{\&}thinsp;{\%}) and Russia (2{\&}thinsp;Tg(S) and 26{\&}thinsp;{\%}), and increases in South Asia (2{\&}thinsp;Tg(S) and 42{\&}thinsp;{\%}) and the Middle East (1{\&}thinsp;Tg(S) and 44{\&}thinsp;{\%}). The global N deposition increases by 7{\&}thinsp;Tg(N) (6{\&}thinsp;{\%}), mainly contributed by South Asia (5{\&}thinsp;Tg(N) and 39{\&}thinsp;{\%}), East Asia (4{\&}thinsp;Tg(N) and 21{\&}thinsp;{\%}) and Southeast Asia (2{\&}thinsp;Tg(N) and 21{\&}thinsp;{\%}). The NHx deposition increases with no control policy on NH3 emission in North America. On the other hand, NOy deposition has started to dominate in East Asia (especially China) due to boosted NOx emission. ]]{\textgreater}}, author = {Tan, Jiani and Fu, Joshua S. and Dentener, Frank and Sun, Jian and Emmons, Louisa and Tilmes, Simone and Sudo, Kengo and Flemming, Johannes and Jonson, Jan Eiof and Gravel, Sylvie and Bian, Huisheng and Davila, Yanko and Henze, Daven K. and Lund, Marianne T. and Kucsera, Tom and Takemura, Toshihiko and Keating, Terry}, doi = {10.5194/acp-18-6847-2018}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {9}, pages = {6847--6866}, title = {{Multi-model study of HTAP II on sulfur and nitrogen deposition}}, url = {https://www.atmos-chem-phys.net/18/6847/2018/}, volume = {18}, year = {2018} } @article{Tanaka2018, abstract = {On-road operations of Volkswagen light-duty diesel vehicles equipped with defeat devices cause emissions of NOx up to 40 times above emission standards. Higher on-road NOx emissions are a widespread problem not limited to Volkswagen vehicles, but the Volkswagen violations brought this issue under the spotlight. While several studies investigated the health impacts of high NOx emissions, the climatic impacts have not been quantified. Here we show that such diesel cars generate a larger warming on the time scale of several years but a smaller warming on the decadal time scale during actual on-road operations than in vehicle certification tests. The difference in longer-term warming levels, however, depends on underlying driving conditions. Furthermore, in the presence of defeat devices, the climatic advantage of ‘clean diesel' cars over gasoline cars, in terms of global-mean temperature change, is in our view not necessarily the case.}, author = {Tanaka, Katsumasa and Lund, Marianne T and Aamaas, Borgar and Berntsen, Terje}, doi = {10.1088/1748-9326/aab18c}, issn = {1748-9326}, journal = {Environmental Research Letters}, number = {4}, pages = {44020}, publisher = {IOP Publishing}, title = {{Climate effects of non-compliant Volkswagen diesel cars}}, url = {http://dx.doi.org/10.1088/1748-9326/aab18c}, volume = {13}, year = {2018} } @article{Tang2018, abstract = {A unique long-term dataset from the UK National Ammonia Monitoring Network (NAMN) is used here to assess spatial, seasonal and long-term variability in atmospheric ammonia (NH3: 1998-2014) and particulate ammonium (NH4+: 1999-2014) across the UK. Extensive spatial heterogeneity in NH3 concentrations is observed, with lowest annual mean concentrations at remote sites ({\textless} 0.2 $\mu$g m-3) and highest in the areas with intensive agriculture (up to 22 $\mu$g m-3), while NH4+ concentrations show less spatial variability (e.g. range of 0.14 to 1.8 $\mu$g m-3 annual mean in 2005). Temporally, NH3 concentrations are influenced by environmental conditions and local emission sources. In particular, peak NH3 concentrations are observed in summer at background sites (defined by 5 km grid average NH3 emissions {\textless} 1 kg N ha-1 yr-1) and in areas dominated by sheep farming, driven by increased volatilization of NH3 in warmer summer temperatures. In areas where cattle, pig and poultry farming is dominant, the largest NH3 concentrations are in spring and autumn, matching periods of manure application to fields. By contrast, peak concentrations of NH4+ aerosol occur in spring, associated with long-range transboundary sources. An estimated decrease in NH3 emissions by 16 {\%} between 1998 and 2014 was reported by the UK National Atmospheric Emissions Inventory. Annually averaged NH3 data from NAMN sites operational over the same period (n Combining double low line 59) show an indicative downward trend, although the reduction in NH3 concentrations is smaller and non-significant: Mann-Kendall (MK), -6.3 {\%}; linear regression (LR), -3.1 {\%}. In areas dominated by pig and poultry farming, a significant reduction in NH3 concentrations between 1998 and 2014 (MK: -22 {\%}; LR: -21 {\%}, annually averaged NH3) is consistent with, but not as large as the decrease in estimated NH3 emissions from this sector over the same period (-39 {\%}). By contrast, in cattle-dominated areas there is a slight upward trend (non-significant) in NH3 concentrations (MK: +12 {\%}; LR: +3.6 {\%}, annually averaged NH3), despite the estimated decline in NH3 emissions from this sector since 1998 (-11 {\%}). At background and sheep-dominated sites, NH3 concentrations increased over the monitoring period. These increases (non-significant) at background (MK: +17 {\%}; LR: +13 {\%}, annually averaged data) and sheep-dominated sites (MK: +15 {\%}; LR: +19 {\%}, annually averaged data) would be consistent with the concomitant reduction in SO2 emissions over the same period, leading to a longer atmospheric lifetime of NH3, thereby increasing NH3 concentrations in remote areas. The observations for NH3 concentrations not decreasing as fast as estimated emission trends are consistent with a larger downward trend in annual particulate NH4+ concentrations (1999-2014: MK: -47 {\%}; LR: -49 {\%}, p {\textless} 0.01, n Combining double low line 23), associated with a lower formation of particulate NH4+ in the atmosphere from gas phase NH3.}, author = {Tang, Yuk S. and Braban, Christine F. and Dragosits, Ulrike and Dore, Anthony J. and Simmons, Ivan and {Van Dijk}, Netty and Poskitt, Janet and {Dos Santos Pereira}, Gloria and Keenan, Patrick O. and Conolly, Christopher and Vincent, Keith and Smith, Rognvald I. and Heal, Mathew R. and Sutton, Mark A.}, doi = {10.5194/acp-18-705-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {jan}, number = {2}, pages = {705--733}, publisher = {Copernicus {\{}GmbH{\}}}, title = {{Drivers for spatial, temporal and long-term trends in atmospheric ammonia and ammonium in the UK}}, volume = {18}, year = {2018} } @article{Garivait2015a, abstract = {Past studies suggest that forest fires contribute significantly to the formation of ozone in the troposphere. However, the emissions of ozone precursors from wildfires, and the mechanisms involved in ozone production from boreal fires, are very complicated. Moreover, an evaluation of the role of forest fires is prevented by the lack of direct observations of the ozone precursor, nitrogen oxides (NO x ), and large uncertainties exist in the emissions inventories currently used for modelling. A comprehensive understanding of the important processes and factors involving wildfires has thus been unobtainable. We made 16 year consistent analyses of NO x emissions from boreal wildfires by using satellite observations of tropospheric nitrogen dioxides (NO 2 ) from 1996 to 2011. We report substantial interannual variability of tropospheric NO 2 originating from large boreal fires over Siberia in 1998, 2002, 2003, 2006, and 2008; and over Alaska in 2004, 2005, and 2009. Monthly comparisons of NO 2 enhancements with fire radiative power (FRP) show reasonably strong correlation, suggesting that FRP is a better proxy than burned area for boreal fire NO x emissions. We provide space-based constraints on NO x emission factors (EFs) for Siberian and Alaskan fires. Although the associated uncertainty is relatively large, the derived EFs fall into a in reasonably agreeable range with those previously determined by in situ ground-based and airborne observations over these regions.}, author = {Tanimoto, Hiroshi and Ikeda, Kohei and Boersma, K Folkert and van der A, Ronald J and Garivait, Savitri}, doi = {10.1088/1748-9326/10/6/065004}, issn = {1748-9326}, journal = {Environmental Research Letters}, number = {6}, pages = {65004}, title = {{Interannual variability of nitrogen oxides emissions from boreal fires in Siberia and Alaska during 1996–2011 as observed from space}}, url = {http://stacks.iop.org/1748-9326/10/i=6/a=065004}, volume = {10}, year = {2015} } @article{Taylor2014, abstract = {Abstract. Wet deposition is the dominant mechanism for removing black carbon (BC) from the atmosphere and is key in determining its atmospheric lifetime, vertical gradient and global transport. Despite the importance of BC in the climate system, especially in terms of its ability to modulate the radiative energy budget, there are few quantitative case studies of wet removal in ambient environments. We present a case study of BC wet removal by examining aerosol size distributions and BC coating properties sampled in three Canadian boreal biomass burning plumes, one of which passed through a precipitating cloud. This depleted the majority of the plume's BC mass, and the largest and most coated BC-containing particles were found to be preferentially removed, suggesting that nucleation scavenging was likely the dominant mechanism. Calculated single-scattering albedo (SSA) showed little variation, as a large number of non-BC particles were also present in the precipitation-affected plume. The remaining BC cores were smaller than those observed in previous studies of BC in post-precipitation outflow over Asia, possibly due to the thick coating by hydrophilic compounds associated with the Canadian biomass burning particles. This study provides measurements of BC size, mixing state and removal efficiency to constrain model parameterisations of BC wet removal in biomass burning regions, which will help to reduce uncertainty in radiative forcing calculations.}, author = {Taylor, J. W. and Allan, J. D. and Allen, G. and Coe, H. and Williams, P. I. and Flynn, M. J. and {Le Breton}, M. and Muller, J. B. A. and Percival, C. J. and Oram, D. and Forster, G. and Lee, J. D. and Rickard, A. R. and Parrington, M. and Palmer, P. I.}, doi = {10.5194/acp-14-13755-2014}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {dec}, number = {24}, pages = {13755--13771}, title = {{Size-dependent wet removal of black carbon in Canadian biomass burning plumes}}, url = {https://acp.copernicus.org/articles/14/13755/2014/}, volume = {14}, year = {2014} } @article{Theobald2019, abstract = {The wet deposition of nitrogen and sulfur in Europe for the period 1990-2010 was estimated by six atmospheric chemistry transport models (CHIMERE, CMAQ, EMEP MSC-W, LOTOS-EUROS, MATCH and MINNI) within the framework of the EURODELTA-Trends model intercomparison. The simulated wet deposition and its trends for two 11-year periods (1990-2000 and 2000-2010) were evaluated using data from observations from the EMEP European monitoring network. For annual wet deposition of oxidised nitrogen (WNOx), model bias was within 30{\%} of the average of the observations for most models. There was a tendency for most models to underestimate annual wet deposition of reduced nitrogen (WNHx), although the model bias was within 40{\%} of the average of the observations. Model bias for WNHx was inversely correlated with model bias for atmospheric concentrations of NH 3 + NH 4+ , suggesting that an underestimation of wet deposition partially contributed to an overestimation of atmospheric concentrations. Model bias was also within about 40{\%} of the average of the observations for the annual wet deposition of sulfur (WSOx) for most models. Decreasing trends in WNOx were observed at most sites for both 11-year periods, with larger trends, on average, for the second period. The models also estimated predominantly decreasing trends at the monitoring sites and all but one of the models estimated larger trends, on average, for the second period. Decreasing trends were also observed at most sites for WNHx, although larger trends, on average, were observed for the first period. This pattern was not reproduced by the models, which estimated smaller decreasing trends, on average, than those observed or even small increasing trends. The largest observed trends were for WSOx, with decreasing trends at more than 80{\%} of the sites. On average, the observed trends were larger for the first period. All models were able to reproduce this pattern, although some models underestimated the trends (by up to a factor of 4) and others overestimated them (by up to 40 {\%}), on average. These biases in modelled trends were directly related to the tendency of the models to under-or overestimate annual wet deposition and were smaller for the relative trends (expressed as {\%}yr -1 relative to the deposition at the start of the period). The fact that model biases were fairly constant throughout the time series makes it possible to improve the predictions of wet deposition for future scenarios by adjusting the model estimates using a bias correction calculated from past observations. An analysis of the contributions of various factors to the modelled trends suggests that the predominantly decreasing trends in wet deposition are mostly due to reductions in emissions of the precursors NO x , NH 3 and SO x . However, changes in meteorology (e.g. precipitation) and other (nonlinear) interactions partially offset the decreasing trends due to emission reductions during the first period but not the second. This suggests that the emission reduction measures had a relatively larger effect on wet deposition during the second period, at least for the sites with observations.}, author = {Theobald, Mark R. and Vivanco, Marta G. and Aas, Wenche and Andersson, Camilla and Ciarelli, Giancarlo and Couvidat, Florian and Cuvelier, Kees and Manders, Astrid and Mircea, Mihaela and Pay, Maria Teresa and Tsyro, Svetlana and Adani, Mario and Bergstr{\"{o}}m, Robert and Bessagnet, Bertrand and Briganti, Gino and Cappelletti, Andrea and D'Isidoro, Massimo and Fagerli, Hilde and Mar, Kathleen and Otero, Noelia and Raffort, Valentin and Roustan, Yelva and Schaap, Martijn and Wind, Peter and Colette, Augustin}, doi = {10.5194/acp-19-379-2019}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {jan}, number = {1}, pages = {379--405}, publisher = {Copernicus Publications}, title = {{An evaluation of European nitrogen and sulfur wet deposition and their trends estimated by six chemistry transport models for the period 1990–2010}}, volume = {19}, year = {2019} } @article{doi:10.1080/10962247.2016.1192071, annote = {PMID: 27216236}, author = {Thompson, Tammy M and Rausch, Sebastian and Saari, Rebecca K and Selin, Noelle E}, doi = {10.1080/10962247.2016.1192071}, journal = {Journal of the Air {\&} Waste Management Association}, number = {10}, pages = {988--1002}, publisher = {Taylor {\&} Francis}, title = {{Air quality co-benefits of subnational carbon policies}}, url = {https://doi.org/10.1080/10962247.2016.1192071}, volume = {66}, year = {2016} } @article{acp-21-1105-2021, abstract = {Feedbacks play a fundamental role in determining the magnitude of the response of the climate system to exter- nal forcing, such as from anthropogenic emissions. The lat- est generation of Earth system models includes aerosol and chemistry components that interact with each other and with the biosphere. These interactions introduce a complex web of feedbacks that is important to understand and quantify. This paper addresses multiple pathways for aerosol and chemical feedbacks in Earth system models. These focus on changes in natural emissions (dust, sea salt, dimethyl sulfide, biogenic volatile organic compounds (BVOCs) and light- ning) and changes in reaction rates for methane and ozone chemistry. The feedback terms are then given by the sensitiv- ity of a pathway to climate change multiplied by the radiative effect of the change. We find that the overall climate feedback through chem- istry and aerosols is negative in the sixth Coupled Model Intercomparison Project (CMIP6) Earth system models due to increased negative forcing from aerosols in a climate with warmer surface temperatures following a quadrupling of CO2 concentrations. This is principally due to increased emissions of sea salt and BVOCs which are sensitive to cli- mate change and cause strong negative radiative forcings. Increased chemical loss of ozone and methane also con- tributes to a negative feedback. However, overall methane lifetime is expected to increase in a warmer climate due to increased BVOCs. Increased emissions of methane from wetlands would also offset some of the negative feedbacks. The CMIP6 experimental design did not allow the methane lifetime or methane emission changes to affect climate, so we found a robust negative contribution from interactive aerosols and chemistry to climate sensitivity in CMIP6 Earth system models.}, author = {Thornhill, G D and Collins, W and Olivi{\'{e}}, D and Skeie, R B and Archibald, A and Bauer, S and Checa-Garcia, R and Fiedler, S and Folberth, G and Gjermundsen, A and Horowitz, L and Lamarque, J.-F. and Michou, M and Mulcahy, J and Nabat, P and Naik, V and O'Connor, F M and Paulot, F and Schulz, M and Scott, C E and S{\'{e}}f{\'{e}}rian, R and Smith, C and Takemura, T and Tilmes, S and Tsigaridis, K and Weber, J}, doi = {10.5194/acp-21-1105-2021}, journal = {Atmospheric Chemistry and Physics}, number = {2}, pages = {1105--1126}, title = {{Climate-driven chemistry and aerosol feedbacks in CMIP6 Earth system models}}, url = {https://acp.copernicus.org/articles/21/1105/2021/}, volume = {21}, year = {2021} } @article{Thornhill2021a, author = {Thornhill, Gillian D and Collins, William J and Kramer, Ryan J and Olivi{\'{e}}, Dirk and Skeie, Ragnhild B. and O'Connor, Fiona M. and Abraham, Nathan Luke and Checa-Garcia, Ramiro and Bauer, Susanne E and Deushi, Makoto and Emmons, Louisa K. and Forster, Piers M. and Horowitz, Larry W. and Johnson, Ben and Keeble, James and Lamarque, Jean-Francois and Michou, Martine and Mills, Michael J. and Mulcahy, Jane P. and Myhre, Gunnar and Nabat, Pierre and Naik, Vaishali and Oshima, Naga and Schulz, Michael and Smith, Christopher J. and Takemura, Toshihiko and Tilmes, Simone and Wu, Tongwen and Zeng, Guang and Zhang, Jie}, doi = {10.5194/acp-21-853-2021}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jan}, number = {2}, pages = {853--874}, publisher = {Copernicus Publications}, title = {{Effective radiative forcing from emissions of reactive gases and aerosols – a multi-model comparison}}, url = {https://acp.copernicus.org/articles/21/853/2021/}, volume = {21}, year = {2021} } @article{Tilmes2019, abstract = {The Community Earth System Model version 2 (CESM2) includes three main atmospheric configurations: the Community Atmosphere Model version 6 (CAM6) with simplified chemistry and a simplified organic aerosol (OA) scheme, CAM6 with comprehensive tropospheric and stratospheric chemistry representation (CAM6-chem), and the Whole Atmosphere Community Climate Model version 6 (WACCM6). Both, CAM6-chem and WACCM6 include a more comprehensive secondary organic aerosols (SOA) approach using the Volatility Basis Set (VBS) scheme and prognostic stratospheric aerosols. This paper describes the different OA schemes available in the different atmospheric configurations of CESM2 and discusses differences in aerosol burden and resulting climate forcings. Derived OA burden and trends differ due to differences in OA formation using the different approaches. Regional differences in Aerosol Optical Depth with larger values using the comprehensive approach occur over SOA source regions. Stronger increasing SOA trends between 1960 and 2015 in WACCM6 compared to CAM6 are due to increasing biogenic emissions aligned with increasing surface temperatures. Using the comprehensive SOA approach further leads to improved comparisons to aircraft observations and SOA formation of ≈143 Tg/yr. We further use WACCM6 to identify source contributions of OA from biogenic, fossil fuel, and biomass burning emissions, to quantify SOA amounts and trends from these sources. Increasing SOA trends between 1960 and 2015 are the result of increasing biogenic emissions aligned with increasing surface temperatures. Biogenic emissions are at least two thirds of the total SOA burden. In addition, SOA source contributions from fossil fuel emissions become more important, with largest values over Southeast Asia. The estimated total anthropogenic forcing of OA in WACCM6 for 1995–2010 conditions is −0.43 W/m2, mostly from the aerosol direct effect.}, author = {Tilmes, S. and Hodzic, A. and Emmons, L. K. and Mills, M. J. and Gettelman, A. and Kinnison, D. E. and Park, M. and Lamarque, J. F. and Vitt, F. and Shrivastava, M. and Campuzano-Jost, P. and Jimenez, J. L. and Liu, X.}, doi = {10.1029/2019MS001827}, issn = {19422466}, journal = {Journal of Advances in Modeling Earth Systems}, keywords = {CESM2,WACCM6,organic aerosols}, month = {dec}, number = {12}, pages = {4323--4351}, publisher = {Blackwell Publishing Ltd}, title = {{Climate Forcing and Trends of Organic Aerosols in the Community Earth System Model (CESM2)}}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019MS001827}, volume = {11}, year = {2019} } @article{Tohjima2020, abstract = {The COVID-19 pandemic caused drastic reductions in carbon dioxide (CO 2 ) emissions, but due to its large atmospheric reservoir and long lifetime, no detectable signal has been observed in the atmospheric CO 2 growth rate. Using the variabilities in CO 2 ($\Delta$CO 2 ) and methane ($\Delta$CH 4 ) observed at Hateruma Island, Japan during 1997–2020, we show a traceable CO 2 emission reduction in China during February–March 2020. The monitoring station at Hateruma Island observes the outflow of Chinese emissions during winter and spring. A systematic increase in the $\Delta$CO 2 /$\Delta$CH 4 ratio, governed by synoptic wind variability, well corroborated the increase in China's fossil-fuel CO 2 (FFCO 2 ) emissions during 1997–2019. However, the $\Delta$CO 2 /$\Delta$CH 4 ratios showed significant decreases of 29 ± 11 and 16 ± 11 mol mol −1 in February and March 2020, respectively, relative to the 2011–2019 average of 131 ± 11 mol mol −1 . By projecting these observed $\Delta$CO 2 /$\Delta$CH 4 ratios on transport model simulations, we estimated reductions of 32 ± 12{\%} and 19 ± 15{\%} in the FFCO 2 emissions in China for February and March 2020, respectively, compared to the expected emissions. Our data are consistent with the abrupt decrease in the economic activity in February, a slight recovery in March, and return to normal in April, which was calculated based on the COVID-19 lockdowns and mobility restriction datasets.}, author = {Tohjima, Yasunori and Patra, Prabir K. and Niwa, Yosuke and Mukai, Hitoshi and Sasakawa, Motoki and Machida, Toshinobu}, doi = {10.1038/s41598-020-75763-6}, issn = {2045-2322}, journal = {Scientific Reports}, keywords = {Tohjima2020}, month = {dec}, number = {1}, pages = {18688}, title = {{Detection of fossil-fuel CO2 plummet in China due to COVID-19 by observation at Hateruma}}, url = {http://www.nature.com/articles/s41598-020-75763-6}, volume = {10}, year = {2020} } @article{Tong2020, author = {Tong, D and Cheng, J and Liu, Y and Yu, S and Yan, L and Hong, C and Qin, Y and Zhao, H and Zheng, Y and Geng, G and Li, M and Liu, F and Zhang, Y and Zheng, B and Clarke, L and Zhang, Q}, doi = {doi.org/10.5194/acp-20-5729-2020}, journal = {Atmospheric Chemistry and Physics}, number = {9}, pages = {5729--5757}, title = {{Dynamic projection of anthropogenic emissions in China: methodology and 2015–2050 emission pathways under a range of socioeconomic, climate policy, and pollution control scenarios}}, volume = {20}, year = {2020} } @article{Tsigaridis2014a, abstract = {This paper evaluates the current status of global modeling of the organic aerosol (OA) in the troposphere and analyzes the differences between models as well as between models and observations. Thirty-one global chemistry transport models (CTMs) and general circulation models (GCMs) have participated in this intercomparison, in the framework of AeroCom phase II. The simulation of OA varies greatly between models in terms of the magnitude of primary emissions, secondary OA (SOA) formation, the number of OA species used (2 to 62), the complexity of OA parameterizations (gas-particle partitioning, chemical aging, multiphase chemistry, aerosol microphysics), and the OA physical, chemical and optical properties. The diversity of the global OA simulation results has increased since earlier AeroCom experiments, mainly due to the increasing complexity of the SOA parameterization in models, and the implementation of new, highly uncertain, OA sources. Diversity of over one order of magnitude exists in the modeled vertical distribution of OA concentrations that deserves a dedicated future study. Furthermore, although the OA / OC ratio depends on OA sources and atmospheric processing, and is important for model evaluation against OA and OC observations, it is resolved only by a few global models. The median global primary OA (POA) source strength is 56 Tg a−1 (range 34–144 Tg a−1) and the median SOA source strength (natural and anthropogenic) is 19 Tg a−1 (range 13–121 Tg a−1). Among the models that take into account the semi-volatile SOA nature, the median source is calculated to be 51 Tg a−1 (range 16–121 Tg a−1), much larger than the median value of the models that calculate SOA in a more simplistic way (19 Tg a−1; range 13–20 Tg a−1, with one model at 37 Tg a−1). The median atmospheric burden of OA is 1.4 Tg (24 models in the range of 0.6–2.0 Tg and 4 between 2.0 and 3.8 Tg), with a median OA lifetime of 5.4 days (range 3.8–9.6 days). In models that reported both OA and sulfate burdens, the median value of the OA/sulfate burden ratio is calculated to be 0.77; 13 models calculate a ratio lower than 1, and 9 models higher than 1. For 26 models that reported OA deposition fluxes, the median wet removal is 70 Tg a−1 (range 28–209 Tg a−1), which is on average 85{\%} of the total OA deposition. Fine aerosol organic carbon (OC) and OA observations from continuous monitoring networks and individual field campaigns have been used for model evaluation. At urban locations, t{\ldots}}, author = {Tsigaridis, K. and Daskalakis, N. and Kanakidou, M. and Adams, P. J. and Artaxo, P. and Bahadur, R. and Balkanski, Y. and Bauer, S. E. and Bellouin, N. and Benedetti, A. and Bergman, T. and Berntsen, T. K. and Beukes, J. P. and Bian, H. and Carslaw, K. S. and Chin, M. and Curci, G. and Diehl, T. and Easter, R. C. and Ghan, S. J. and Gong, S. L. and Hodzic, A. and Hoyle, C. R. and Iversen, T. and Jathar, S. and Jimenez, J. L. and Kaiser, J. W. and Kirkev{\"{a}}g, A. and Koch, D. and Kokkola, H. and {H Lee}, Y. and Lin, G. and Liu, X. and Luo, G. and Ma, X. and Mann, G. W. and Mihalopoulos, N. and Morcrette, J. J. and M{\"{u}}ller, J. F. and Myhre, G. and Myriokefalitakis, S. and Ng, N. L. and O'donnell, D. and Penner, J. E. and Pozzoli, L. and Pringle, K. J. and Russell, L. M. and Schulz, M. and Sciare, J. and Seland and Shindell, D. T. and Sillman, S. and Skeie, R. B. and Spracklen, D. and Stavrakou, T. and Steenrod, S. D. and Takemura, T. and Tiitta, P. and Tilmes, S. and Tost, H. and {Van Noije}, T. and {Van Zyl}, P. G. and {Von Salzen}, K. and Yu, F. and Wang, Z. and Wang, Z. and Zaveri, R. A. and Zhang, H. and Zhang, K. and Zhang, Q. and Zhang, X.}, doi = {10.5194/acp-14-10845-2014}, isbn = {1680-7375}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {19}, pages = {10845--10895}, title = {{The AeroCom evaluation and intercomparison of organic aerosol in global models}}, volume = {14}, year = {2014} } @article{Turner2018, abstract = {The hydroxyl radical (OH) is the primary oxidant in the troposphere, and the impact of its fluctuations on the methane budget has been disputed in recent years, however measurements of OH are insufficient to characterize global interannual fluctuations relevant for methane. Here, we use a 6,000-y control simulation of preindustrial conditions with a chemistry-climate model to quantify the natural variability in OH and internal feedbacks governing that variability. We find that, even in the absence of external forcing, maximum OH changes are 3.8 ± 0.8{\%} over a decade, which is large in the context of the recent methane growth from 2007–2017. We show that the OH variability is not a white-noise process. A wavelet analysis indicates that OH variability exhibits significant feedbacks with the same periodicity as the El Ni{\~{n}}o–Southern Oscillation (ENSO). We find intrinsically generated modulation of the OH variability, suggesting that OH may show periods of rapid or no change in future decades that are solely due to the internal climate dynamics (as opposed to external forcings). An empirical orthogonal function analysis further indicates that ENSO is the dominant mode of OH variability, with the modulation of OH occurring primarily through lightning N O x . La Ni{\~{n}}a is associated with an increase in convection in the Tropical Pacific, which increases the simulated occurrence of lightning and allows for more OH production. Understanding this link between OH and ENSO may improve the predictability of the oxidative capacity of the troposphere and assist in elucidating the causes of current and historical trends in methane.}, author = {Turner, Alexander J and Fung, Inez and Naik, Vaishali and Horowitz, Larry W and Cohen, Ronald C}, doi = {10.1073/pnas.1807532115}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, month = {sep}, number = {36}, pages = {8931--8936}, title = {{Modulation of hydroxyl variability by ENSO in the absence of external forcing}}, url = {http://www.pnas.org/content/early/2018/08/16/1807532115.abstract http://www.pnas.org/lookup/doi/10.1073/pnas.1807532115}, volume = {115}, year = {2018} } @article{Turner2017, abstract = {Methane is the second strongest anthropogenic greenhouse gas and its atmospheric burden has more than doubled since 1850. Methane concentrations stabilized in the early 2000s and began increasing again in 2007. Neither the stabilization nor the recent growth are well understood, as evidenced by multiple competing hypotheses in recent literature. Here we use a multispecies two-box model inversion to jointly constrain 36 y of methane sources and sinks, using ground-based measurements of methane, methyl chloroform, and the C 13 /C 12 ratio in atmospheric methane ($\delta$ 13 CH 4 ) from 1983 through 2015. We find that the problem, as currently formulated, is underdetermined and solutions obtained in previous work are strongly dependent on prior assumptions. Based on our analysis, the mathematically most likely explanation for the renewed growth in atmospheric methane, counterintuitively, involves a 25-Tg/y decrease in methane emissions from 2003 to 2016 that is offset by a 7{\%} decrease in global mean hydroxyl (OH) concentrations, the primary sink for atmospheric methane, over the same period. However, we are still able to fit the observations if we assume that OH concentrations are time invariant (as much of the previous work has assumed) and we then find solutions that are largely consistent with other proposed hypotheses for the renewed growth of atmospheric methane since 2007. We conclude that the current surface observing system does not allow unambiguous attribution of the decadal trends in methane without robust constraints on OH variability, which currently rely purely on methyl chloroform data and its uncertain emissions estimates.}, annote = {10.1073/pnas.1616020114}, author = {Turner, Alexander J and Frankenberg, Christian and Wennberg, Paul O and Jacob, Daniel J}, doi = {10.1073/pnas.1616020114}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, month = {may}, number = {21}, pages = {5367--5372}, title = {{Ambiguity in the causes for decadal trends in atmospheric methane and hydroxyl}}, url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1616020114}, volume = {114}, year = {2017} } @article{TurnockSub, author = {Turnock, Steven T. and Allen, Robert J. and Andrews, Martin and Bauer, Susanne E. and Deushi, Makoto and Emmons, Louisa and Good, Peter and Horowitz, Larry and John, Jasmin G. and Michou, Martine and Nabat, Pierre and Naik, Vaishali and Neubauer, David and O'Connor, Fiona M. and Olivi{\'{e}}, Dirk and Oshima, Naga and Schulz, Michael and Sellar, Alistair and Shim, Sungbo and Takemura, Toshihiko and Tilmes, Simone and Tsigaridis, Kostas and Wu, Tongwen and Zhang, Jie}, doi = {10.5194/acp-20-14547-2020}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {nov}, number = {23}, pages = {14547--14579}, title = {{Historical and future changes in air pollutants from CMIP6 models}}, url = {https://doi.org/10.5194/acp-20-14547-2020 https://acp.copernicus.org/articles/20/14547/2020/}, volume = {20}, year = {2020} } @article{Turnock2016, abstract = {European air quality legislation has reduced emissions of air pollutants across Europe since the 1970s, affecting air quality, human health and regional climate. We used a coupled composition-climate model to simulate the impacts of European air quality legislation and technology measures implemented between 1970 and 2010. We contrast simulations using two emission scenarios; one with actual emissions in 2010 and the other with emissions that would have occurred in 2010 in the absence of technological improvements and end-of-pipe treatment measures in the energy, industrial and road transport sectors. European emissions of sulphur dioxide, black carbon (BC) and organic carbon in 2010 are 53{\%}, 59{\%} and 32{\%} lower respectively compared to emissions that would have occurred in 2010 in the absence of legislative and technology measures. These emission reductions decreased simulated European annual mean concentrations of fine particulate matter (PM 2.5 ) by 35{\%}, sulphate by 44{\%}, BC by 56{\%} and particulate organic matter by 23{\%}. The reduction in PM 2.5 concentrations is calculated to have prevented 80 000 (37 000–116 000, at 95{\%} confidence intervals) premature deaths annually across the European Union, resulting in a perceived financial benefit to society of US{\$}232 billion annually (1.4{\%} of 2010 EU GDP). The reduction in aerosol concentrations due to legislative and technology measures caused a positive change in the aerosol radiative effect at the top of atmosphere, reduced atmospheric absorption and also increased the amount of solar radiation incident at the surface over Europe. We used an energy budget approximation to estimate that these changes in the radiative balance have increased European annual mean surface temperatures and precipitation by 0.45 ± 0.11 °C and by 13 ± 0.8 mm yr −1 respectively. Our results show that the implementation of European legislation and technological improvements to reduce the emission of air pollutants has improved air quality and human health over Europe, as well as having an unintended impact on the regional radiative balance and climate.}, author = {Turnock, S. T. and Butt, E. W. and Richardson, T. B. and Mann, G. W. and Reddington, C. L. and Forster, P. M. and Haywood, J. and Crippa, M. and Janssens-Maenhout, G. and Johnson, C. E. and Bellouin, N. and Carslaw, K. S. and Spracklen, D. V.}, doi = {10.1088/1748-9326/11/2/024010}, isbn = {1748-9326}, issn = {17489326}, journal = {Environmental Research Letters}, keywords = {aerosols,air quality,climate,emissions,health,mitigation}, number = {2}, pages = {024010}, title = {{The impact of European legislative and technology measures to reduce air pollutants on air quality, human health and climate}}, volume = {11}, year = {2016} } @article{Turnock2019, abstract = {Abstract Oxidation of sulfur dioxide (SO2) in cloud water by reaction with ozone is an important sulfate aerosol formation mechanism and strongly dependent on the acidity of cloud water. Decadal reductions in Northern Hemisphere sulfur emissions have contributed to higher cloud water pH, thereby altering sulfate formation rates. Here we use a global composition-climate model to show that changes in cloud water pH over the 1970?2009 period strongly affects the aerosol particle size distribution, cloud condensation nuclei concentrations, and the magnitude of aerosol radiative forcing. The simulated all-sky aerosol radiative forcing (1970?2009) over the North Atlantic is +1.2 W m?2 if pH remains constant at 5.0, as in many climate models. However, the forcing increases to +5.2 W m?2 if pH is assumed to increase by 1.0 unit over this period. Global composition climate models need to account for variations in cloud water pH to improve the representation of sulfate aerosol formation and aerosol radiative effects.}, author = {Turnock, S T and Mann, G W and Woodhouse, M T and Dalvi, M and O'Connor, F M and Carslaw, K S and Spracklen, D V}, doi = {10.1029/2019GL082067}, issn = {0094-8276}, journal = {Geophysical Research Letters}, month = {apr}, number = {7}, pages = {4039--4048}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{The Impact of Changes in Cloud Water pH on Aerosol Radiative Forcing}}, volume = {46}, year = {2019} } @article{Twomey1977, abstract = {By increasing droplet concentration and thereby the optical thickness of a cloud, pollution acts to increase the reflectance (albedo) of clouds; by increasing the absorption coefficient it acts to decrease the reflectance. Calculations suggest that the former effect (brightening of the clouds in reflection, hence climatically a cooling effect) dominates for thin to moderately thick clouds, whereas for sufficiently thick clouds the latter effect (climatically a warming effect) can become dominant.}, author = {Twomey, S.}, doi = {10.1175/1520-0469(1977)034<1149:TIOPOT>2.0.CO;2}, issn = {0022-4928}, journal = {Journal of the Atmospheric Sciences}, month = {jul}, number = {7}, pages = {1149--1152}, title = {{The Influence of Pollution on the Shortwave Albedo of Clouds}}, url = {http://journals.ametsoc.org/doi/10.1175/1520-0469(1977)034{\%}3C1149:TIOPOT{\%}3E2.0.CO;2}, volume = {34}, year = {1977} } @article{Tzompa-Sosa2019, abstract = {Emissions of C 2 -C 5 alkanes from the U.S. oil and gas sector have changed rapidly over the last decade. We use a nested GEOS-Chem simulation driven by updated 2011NEI emissions with aircraft, surface, and column observations to (1) examine spatial patterns in the emissions and observed atmospheric abundances of C 2 -C 5 alkanes over the United States and (2) estimate the contribution of emissions from the U.S. oil and gas industry to these patterns. The oil and gas sector in the updated 2011NEI contributes over 80{\%} of the total U.S. emissions of ethane (C 2 H 6 ) and propane (C 3 H 8 ), and emissions of these species are largest in the central United States. Observed mixing ratios of C 2 -C 5 alkanes show enhancements over the central United States below 2 km. A nested GEOS-Chem simulation underpredicts observed C 3 H 8 mixing ratios in the boundary layer over several U.S. regions, and the relative underprediction is not consistent, suggesting C 3 H 8 emissions should receive more attention moving forward. Our decision to consider only C 4 -C 5 alkane emissions as a single lumped species produces a geographic distribution similar to observations. Due to the increasing importance of oil and gas emissions in the United States, we recommend continued support of existing long-term measurements of C 2 -C 5 alkanes. We suggest additional monitoring of C 2 -C 5 alkanes downwind of northeastern Colorado, Wyoming, and western North Dakota to capture changes in these regions. The atmospheric chemistry modeling community should also evaluate whether chemical mechanisms that lump larger alkanes are sufficient to understand air quality issues in regions with large emissions of these species.}, author = {Tzompa‐Sosa, Z. A. and Henderson, B. H. and Keller, C. A. and Travis, K. and Mahieu, E. and Franco, B. and Estes, M. and Helmig, D. and Fried, A. and Richter, D. and Weibring, P. and Walega, J. and Blake, D. R. and Hannigan, J. W. and Ortega, I. and Conway, S. and Strong, K. and Fischer, E. V.}, doi = {10.1029/2018JD028955}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {2011NEI,alkanes,butanes and pentanes,ethane,oil and gas,propane}, month = {jan}, number = {2}, pages = {1148--1169}, title = {{Atmospheric Implications of Large C2‐C5 Alkane Emissions From the U.S. Oil and Gas Industry}}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2018JD028955}, volume = {124}, year = {2019} } @article{Uherek2010, abstract = {Emissions from land transport, and from road transport in particular, have significant impacts on the atmosphere and on climate change. This assessment gives an overview of past, present and future emissions from land transport, of their impacts on the atmospheric composition and air quality, on human health and climate change and on options for mitigation. In the past vehicle exhaust emission control has successfully reduced emissions of nitrogen oxides, carbon monoxide, volatile organic compounds and particulate matter. This contributed to improved air quality and reduced health impacts in industrialised countries. In developing countries however, pollutant emissions have been growing strongly, adversely affecting many populations. In addition, ozone and particulate matter change the radiative balance and hence contribute to global warming on shorter time scales. Latest knowledge on the magnitude of land transport's impact on global warming is reviewed here. In the future, road transport's emissions of these pollutants are expected to stagnate and then decrease globally. This will then help to improve the air quality notably in developing countries. On the contrary, emissions of carbon dioxide and of halocarbons from mobile air conditioners have been globally increasing and are further expected to grow. Consequently, road transport's impact on climate is gaining in importance. The expected efficiency improvements of vehicles and the introduction of biofuels will not be sufficient to offset the expected strong growth in both, passenger and freight transportation. Technical measures could offer a significant reduction potential, but strong interventions would be needed as markets do not initiate the necessary changes. Further reductions would need a resolute expansion of low-carbon fuels, a tripling of vehicle fuel efficiency and a stagnation in absolute transport volumes. Land transport will remain a key sector in climate change mitigation during the next decades.}, author = {Uherek, Elmar and Halenka, Tomas and Borken-Kleefeld, Jens and Balkanski, Yves and Berntsen, Terje and Borrego, Carlos and Gauss, Michael and Hoor, Peter and Juda-Rezler, Katarzyna and Lelieveld, Jos and Melas, Dimitrios and Rypdal, Kristin and Schmid, Stephan}, doi = {https://doi.org/10.1016/j.atmosenv.2010.01.002}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Air pollution,Climate impacts,Emission scenarios,Emissions,Health impacts,Mitigation scenarios,Mobile air conditioners,Radiative forcing,Transport: road, rail, inland shipping,Vehicle technologies}, number = {37}, pages = {4772--4816}, title = {{Transport impacts on atmosphere and climate: Land transport}}, url = {https://www.sciencedirect.com/science/article/pii/S1352231010000099}, volume = {44}, year = {2010} } @incollection{UN1987a, author = {UN}, booktitle = {United Nations – Treaty Series No. 26369}, pages = {29--111}, publisher = {United Nations (UN)}, title = {{The Montreal Protocol on Substances that Deplete the Ozone Layer}}, url = {https://treaties.un.org/doc/publication/unts/volume 1522/volume-1522-i-26369-english.pdf}, year = {1989} } @techreport{Dentener2010, address = {New York, NY, USA and Geneva, Switzerland}, author = {UNECE}, doi = {https://unece.org/hemispheric-transport-air-pollution}, editor = {Dentener, Frank J. and Keating, Terry J. and Akimoto, Hajime}, isbn = {978-92-1-117043-6}, pages = {278}, publisher = {United Nations Economic Commission for Europe (UNECE). United Nations (UN)}, series = {Air Pollution Studies No. 17}, title = {{Hemispheric Transport of Air Pollution. Part A: Ozone and Particulate Matter}}, url = {https://unece.org/hemispheric-transport-air-pollution}, year = {2010} } @techreport{CCAC2019, abstract = {This report identifies 25 clean air measures that can positively impact human health, crop yields, climate change and socio-economic development, as well as contribute to achieving the Sustainable Development Goals. Implementing these measures could help 1 billion people breathe cleaner air by 2030 and reduce global warming by a third of a degree Celsius by 2050.}, address = {Nairobi, Kenya}, author = {UNEP}, doi = {https://www.ccacoalition.org/en/resources/air-pollution-asia-and-pacific-science-based-solutions-summary-full-report}, isbn = {978-92-807-3725-7}, pages = {232}, publisher = {United Nations Environment Program (UNEP)}, title = {{Air Pollution in Asia and the Pacific: Science-Based Solutions}}, url = {https://www.ccacoalition.org/en/resources/air-pollution-asia-and-pacific-science-based-solutions-summary-full-report}, year = {2019} } @techreport{UNEP/WMO2011, abstract = {Scientific evidence and new analyses demonstrate that control of black carbon particles and tropospheric ozone through rapid implementation of proven emission reduction measures would have immediate and multiple benefits for human well-being. Black carbon exists as particles in the atmosphere and is a major component of soot; it has significant human health and climate impacts. At ground level, ozone is an air pollutant harmful to human health and ecosystems, and throughout the troposphere, or lower atmosphere, is also a significant greenhouse gas. Ozone is not directly emitted, but is produced from emissions of precursors of which methane and carbon monoxide are of particular interest here. THE CHALLENGE 1. The climate is changing now, warming at the highest rate in polar and}, address = {Nairobi, Kenya}, author = {UNEP and WMO}, doi = {http://hdl.handle.net/20.500.11822/8028}, isbn = {978-92-807-3142-2}, pages = {30}, publisher = {United Nations Environment Programme (UNEP) and World Meteorological Organization (WMO). UNEP}, series = {UNEP/GC/26/INF/20}, title = {{Integrated Assessment of Black Carbon and Tropospheric Ozone. Summary for Decision Makers}}, url = {http://hdl.handle.net/20.500.11822/8028}, year = {2011} } @techreport{UNEP-CCAC2018, address = {Nairobi, Kenya}, author = {UNEP and CCAC}, doi = {https://www.ccacoalition.org/en/resources/integrated-assessment-short-lived-climate-pollutants-latin-america-and-caribbean}, pages = {101}, publisher = {United Nations Environment Programme (UNEP) and Climate and Clean Air Coalition (CCAC). UNEP}, title = {{Integrated Assessment of Short-lived Climate Pollutants in Latin America and the Caribbean: improving air quality while mitigating climate change}}, url = {https://www.ccacoalition.org/en/resources/integrated-assessment-short-lived-climate-pollutants-latin-america-and-caribbean}, year = {2018} } @incollection{UNEP2016, address = {Nairobi, Kenya}, author = {UNEP}, booktitle = {Report of the Twenty-Eighth Meeting of the Parties to the Montreal Protocol on Substances that Deplete the Ozone Layer}, doi = {https://undocs.org/pdf?symbol=en/UNEP/OzL.Pro.28/12}, pages = {46--53}, publisher = {United Nations Environment Programme (UNEP)}, series = {UNEP/OzL.Pro.28/12}, title = {{Amendment to the Montreal Protocol on Substances that Deplete the Ozone Layer}}, url = {https://undocs.org/pdf?symbol=en/UNEP/OzL.Pro.28/12}, year = {2016} } @article{Unger2017, abstract = {A coupled global aerosol–carbon–climate model is applied to assess the impacts of aerosol physical climate change on the land ecosystem services gross primary productivity (GPP) and net primary productivity (NPP) in the 1996–2005 period. Aerosol impacts are quantified on an annual mean basis relative to the hypothetical aerosol-free world in 1996–2005, the global climate state in the absence of the historical rise in aerosol pollution. We examine the separate and combined roles of fast feedbacks associated with the land and slow feedbacks associated with the ocean. We consider all fossil fuel, biofuel and biomass burning aerosol emission sources as anthropogenic. The effective radiative forcing for aerosol–radiation interactions is −0.44 W m −2 and aerosol–cloud interactions is −1.64 W m −2 . Aerosols cool and dry the global climate system by −0.8 °C and −0.08 mm per day relative to the aerosol-free world. Without aerosol pollution, human-induced global warming since the preindustrial would have already exceeded the 1.5 °C aspirational limit set in the Paris Agreement by the 1996–2005 decade. Aerosol climate impacts on the global average land ecosystem services are small due to large opposite sign effects in the tropical and boreal biomes. Aerosol slow feedbacks associated with the ocean strongly dominate impacts in the Amazon and North American Boreal. Aerosol cooling of the Amazon by −1.2 °C drives NPP increases of 8{\%} or +0.76 ± 0.61 PgC per year, a 5–10 times larger impact than estimates of diffuse radiation fertilization by biomass burning aerosol in this region. The North American Boreal suffers GPP and NPP decreases of 35{\%} due to aerosol-induced cooling and drying (−1.6 °C, −0.14 mm per day). Aerosol–land feedbacks play a larger role in the eastern US and Central Africa. Our study identifies an eco-climate teleconnection in the polluted earth system: the rise of the northern hemisphere mid-latitude reflective aerosol pollution layer causes long range cooling that protects Amazon NPP by 8{\%} and suppresses boreal NPP by 35{\%}.}, author = {Unger, N. and Yue, X. and Harper, K. L.}, doi = {10.1039/C7FD00033B}, issn = {1359-6640}, journal = {Faraday Discussions}, pages = {121--142}, title = {{Aerosol climate change effects on land ecosystem services}}, url = {http://xlink.rsc.org/?DOI=C7FD00033B}, volume = {200}, year = {2017} } @article{Unger2014, abstract = {Human conversion of forest ecosystems to agriculture is a major driver of global change. Conventionally, the impacts of the historical cropland expansion on Earth's radiation balance have been quantified through two opposing effects: the release of stored carbon to the atmosphere as CO2 (warming) versus the increase in surface albedo (cooling)1 . Changing forest cover has a third effect on the global radiation balance by altering emissions of biogenic volatile organic compounds (BVOCs) that control the loadings of multiple warming and cooling climate pollutants: tropospheric ozone (O3 ), methane (CH4 ) and aerosols. Although human land cover change has dominated BVOC emission variability over the past century2–4 , the net effect on global climate has not been quantified. Here, I showthat the effects of the global cropland expansion between the 1850s and 2000s on BVOC emissions and atmospheric chemistry have imposed an additional net global radiative impact of −0.11 ± 0.17Wm−2 (cooling). This magnitude is comparable to that of the surface albedo and land carbon release effects. I conclude that atmospheric chemistry must be considered in climate impact assessments of anthropogenic land cover change and in forestry for climate protection strategies.}, author = {Unger, Nadine}, doi = {10.1038/nclimate2347}, issn = {1758-678X}, journal = {Nature Climate Change}, month = {oct}, number = {10}, pages = {907--910}, title = {{Human land-use-driven reduction of forest volatiles cools global climate}}, url = {http://www.nature.com/articles/nclimate2347}, volume = {4}, year = {2014} } @article{Unger2013, abstract = {A biochemical model of isoprene emission embedded within a global chemistry-climate simulation framework is applied to investigate the transient response to environmental change over the past century. In the model, the isoprene production is directly coupled to photosynthesis and depends on intercellular carbon dioxide concentration (CO2), atmospheric CO 2, and canopy temperature. Sensitivity runs are performed to isolate the relative roles of individual global change drivers: CO2, physical climate, and anthropogenic land cover change (ALCC). Between 1880 and 2000, atmospheric CO2 increased by {\~{}}30{\%} from 291 to 370 ppmv, global average surface air temperature increased by 0.7°C, and the crop cover fraction of vegetated land area more than doubled from 15 to 37{\%}. Over the past century, isoprene emission has decreased globally by 20{\%} from 534 to 449 Tg C/yr, while gross primary productivity has increased by 15{\%} from 107 to 124 Pg C/yr mostly due to CO2 fertilization. In terms of individual drivers, the global isoprene source increased by 7{\%} due to the atmospheric CO 2 concentration rise (including the opposing effects of CO 2 fertilization and CO2 inhibition), decreased by 22{\%} due to ALCC, and increased by only 3{\%} due to physical climate change. Thus, ALCC is the dominant driver of isoprene emission change. Modeled global isoprene emissions were higher in the preindustrial than in the present day. In the industrial era, isoprene emission change represents a human-induced climate forcing, analogous to land use-driven CO2 emission, not a climate feedback because temperature-driven increase was a relatively weak driver of isoprene emission change from 1880 to 2000. Key Points Isoprene emission was 20{\%} higher in 1880 than in 2000 Human land use is dominant driver of twentieth century isoprene change Twentieth century isoprene emission change is a climate forcing not a feedback {\textcopyright}2013. American Geophysical Union. All Rights Reserved.}, author = {Unger, N.}, doi = {10.1002/2013JD020978}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {biogenic emissions,chemistry climate,land use}, month = {dec}, number = {24}, pages = {13606--13613}, publisher = {Blackwell Publishing Ltd}, title = {{Isoprene emission variability through the twentieth century}}, url = {http://doi.wiley.com/10.1002/2013JD020978}, volume = {118}, year = {2013} } @article{Unger2010, abstract = {A much-cited bar chart provided by the Intergovernmental Panel on Climate Change displays the climate impact, as expressed by radiative forcing in watts per meter squared, of individual chemical species. The organization of the chart reflects the history of atmospheric chemistry, in which investigators typically focused on a single species of interest. However, changes in pollutant emissions and concentrations are a symptom, not a cause, of the primary driver of anthropogenic climate change: human activity. In this paper, we suggest organizing the bar chart according to drivers of change—that is, by economic sector. Climate impacts of tropospheric ozone, fine aerosols, aerosol-cloud interactions, methane, and long-lived greenhouse gases are considered. We quantify the future evolution of the total radiative forcing due to perpetual constant year 2000 emissions by sector, most relevant for the development of climate policy now, and focus on two specific time points, near-term at 2020 and long-term at 2100. Because sector profiles differ greatly, this approach fosters the development of smart climate policy and is useful to identify effective opportunities for rapid mitigation of anthropogenic radiative forcing.}, author = {Unger, Nadine and Bond, Tami C and Wang, James S and Koch, Dorothy M and Menon, Surabi and Shindell, Drew T and Bauer, Susanne}, doi = {10.1073/pnas.0906548107}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, month = {feb}, number = {8}, pages = {3382--3387}, publisher = {National Academy of Sciences}, title = {{Attribution of climate forcing to economic sectors}}, url = {http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2816198/}, volume = {107}, year = {2010} } @article{Unger2013a, abstract = {Abstract. We describe the implementation of a biochemical model of isoprene emission that depends on the electron requirement for isoprene synthesis into the Farquhar–Ball–Berry leaf model of photosynthesis and stomatal conductance that is embedded within a global chemistry-climate simulation framework. The isoprene production is calculated as a function of electron transport-limited photosynthesis, intercellular and atmospheric carbon dioxide concentration, and canopy temperature. The vegetation biophysics module computes the photosynthetic uptake of carbon dioxide coupled with the transpiration of water vapor and the isoprene emission rate at the 30 min physical integration time step of the global chemistry-climate model. In the model, the rate of carbon assimilation provides the dominant control on isoprene emission variability over canopy temperature. A control simulation representative of the present-day climatic state that uses 8 plant functional types (PFTs), prescribed phenology and generic PFT-specific isoprene emission potentials (fraction of electrons available for isoprene synthesis) reproduces 50{\%} of the variability across different ecosystems and seasons in a global database of 28 measured campaign-average fluxes. Compared to time-varying isoprene flux measurements at 9 select sites, the model authentically captures the observed variability in the 30 min average diurnal cycle (R2 = 64–96{\%}) and simulates the flux magnitude to within a factor of 2. The control run yields a global isoprene source strength of 451 TgC yr−1 that increases by 30{\%} in the artificial absence of plant water stress and by 55{\%} for potential natural vegetation.}, author = {Unger, N. and Harper, K. and Zheng, Y. and Kiang, N. Y. and Aleinov, I. and Arneth, A. and Schurgers, G. and Amelynck, C. and Goldstein, A. and Guenther, A. and Heinesch, B. and Hewitt, C. N. and Karl, T. and Laffineur, Q. and Langford, B. and {A. McKinney}, K. and Misztal, P. and Potosnak, M. and Rinne, J. and Pressley, S. and Schoon, N. and Ser{\c{c}}a, D.}, doi = {10.5194/acp-13-10243-2013}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {oct}, number = {20}, pages = {10243--10269}, title = {{Photosynthesis-dependent isoprene emission from leaf to planet in a global carbon–chemistry–climate model}}, url = {https://acp.copernicus.org/articles/13/10243/2013/}, volume = {13}, year = {2013} } @article{Unger2020, author = {Unger, Nadine and Zheng, Yiqi and Yue, Xu and Harper, Kandice L.}, doi = {10.1038/s41558-019-0678-3}, issn = {1758-678X}, journal = {Nature Climate Change}, month = {feb}, number = {2}, pages = {134--137}, title = {{Mitigation of ozone damage to the world's land ecosystems by source sector}}, url = {http://www.nature.com/articles/s41558-019-0678-3}, volume = {10}, year = {2020} } @article{acp-15-2805-2015, author = {{Val Martin}, M and Heald, C L and Lamarque, J.-F. and Tilmes, S and Emmons, L K and Schichtel, B A}, doi = {10.5194/acp-15-2805-2015}, journal = {Atmospheric Chemistry and Physics}, number = {5}, pages = {2805--2823}, title = {{How emissions, climate, and land use change will impact mid-century air quality over the United States: a focus on effects at national parks}}, url = {https://www.atmos-chem-phys.net/15/2805/2015/}, volume = {15}, year = {2015} } @article{VanDamme2018, abstract = {Through its important role in the formation of particulate matter, atmospheric ammonia affects air quality and has implications for human health and life expectancy1,2. Excess ammonia in the environment also contributes to the acidification and eutrophication of ecosystems3–5 and to climate change6. Anthropogenic emissions dominate natural ones and mostly originate from agricultural, domestic and industrial activities7. However, the total ammonia budget and the attribution of emissions to specific sources remain highly uncertain across different spatial scales7–9. Here we identify, categorize and quantify the world's ammonia emission hotspots using a high-resolution map of atmospheric ammonia obtained from almost a decade of daily IASI satellite observations. We report 248 hotspots with diameters smaller than 50 kilometres, which we associate with either a single point source or a cluster of agricultural and industrial point sources—with the exception of one hotspot, which can be traced back to a natural source. The state-of-the-art EDGAR emission inventory10 mostly agrees with satellite-derived emission fluxes within a factor of three for larger regions. However, it does not adequately represent the majority of point sources that we identified and underestimates the emissions of two-thirds of them by at least one order of magnitude. Industrial emitters in particular are often found to be displaced or missing. Our results suggest that it is necessary to completely revisit the emission inventories of anthropogenic ammonia sources and to account for the rapid evolution of such sources over time. This will lead to better health and environmental impact assessments of atmospheric ammonia and the implementation of suitable nitrogen management strategies.}, author = {{Van Damme}, Martin and Clarisse, Lieven and Whitburn, Simon and Hadji-Lazaro, Juliette and Hurtmans, Daniel and Clerbaux, Cathy and Coheur, Pierre-Fran{\c{c}}ois}, doi = {10.1038/s41586-018-0747-1}, issn = {1476-4687}, journal = {Nature}, number = {7734}, pages = {99--103}, title = {{Industrial and agricultural ammonia point sources exposed}}, volume = {564}, year = {2018} } @article{VanDamme2015, abstract = {We exploit 6 years of measurements from the Infrared Atmospheric Sounding Interferometer (IASI)/MetOp-A instrument to identify seasonal patterns and interannual variability of atmospheric NH3. This is achieved by analyzing the time evolution of the monthly mean NH3 columns in 12 subcontinental areas around the world, simultaneously considering measurements from IASI morning and evening overpasses. For most regions, IASI has a sufficient sensitivity throughout the years to capture the seasonal patterns of NH3 columns, and we show that each region is characterized by a well-marked and distinctive cycle, with maxima mainly related to underlying emission processes. The largest column abundances and seasonal amplitudes throughout the years are found in southwestern Asia, with maxima twice as large as what is observed in southeastern China. The relation between emission sources and retrieved NH3 columns is emphasized at a smaller regional scale by inferring a climatology of the month of maximum columns. Key Points Six years of NH3 morning and evening IASI measurements are analyzed Seasonal cycles of atmospheric NH3 are characterized for subcontinental areas Source processes are attributed from a climatology of the month of NH3 maximum}, author = {{Van Damme}, M. and Erisman, J. W. and Clarisse, L. and Dammers, E. and Whitburn, S. and Clerbaux, C. and Dolman, A. J. and Coheur, P. F.}, doi = {10.1002/2015GL065496}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {IASI satellite,N cycle,NH3 source processes,ammonia (NH3),seasonality,spatiotemporal variability}, number = {20}, pages = {8660--8668}, title = {{Worldwide spatiotemporal atmospheric ammonia (NH3) columns variability revealed by satellite}}, volume = {42}, year = {2015} } @article{acp-18-16173-2018, abstract = {This paper describes, documents, and validates the TM5-FAst Scenario Screening Tool (TM5-FASST), a global reduced-form air quality source–receptor model that has been designed to compute ambient pollutant concentrations as well as a broad range of pollutant-related impacts on human health, agricultural crop production, and short-lived pollutant climate metrics, taking as input annual pollutant emission data aggregated at the national or regional level. The TM5-FASST tool, providing a trade-off between accuracy and applicability, is based on linearized emission-concentration sensitivities derived with the full chemistry-transport model TM5. The tool has been extensively applied in various recent critical studies. Although informal and fragmented validation has already been performed in various publications, this paper provides a comprehensive documentation of all components of the model and a validation against the full TM5 model. We find that the simplifications introduced in order to generate immediate results from emission scenarios do not compromise the validity of the output and as such TM5-FASST is proven to be a useful tool in science-policy analysis. Furthermore, it constitutes a suitable architecture for implementing the ensemble of source–receptor relations obtained in the frame of the HTAP modelling exercises, thus creating a link between the scientific community and policy-oriented users.}, author = {{Van Dingenen}, R and Dentener, F and Crippa, M and Leitao, J and Marmer, E and Rao, S and Solazzo, E and Valentini, L}, doi = {10.5194/acp-18-16173-2018}, journal = {Atmospheric Chemistry and Physics}, number = {21}, pages = {16173--16211}, title = {{TM5-FASST: a global atmospheric source-receptor model for rapid impact analysis of emission changes on air quality and short-lived climate pollutants}}, url = {https://www.atmos-chem-phys.net/18/16173/2018/}, volume = {18}, year = {2018} } @article{VanDingenen2009, abstract = {In this paper we evaluate the global impact of surface ozone on four types of agricultural crop. The study is based on modelled global hourly ozone fields for the year 2000 and 2030, using the global 1°×1° 2-way nested atmospheric chemical transport model (TM5). Projections for the year 2030 are based on the relatively optimistic "current legislation (CLE) scenario", i.e. assuming that currently approved air quality legislation will be fully implemented by the year 2030, without a further development of new abatement policies. For both runs, the relative yield loss due to ozone damage is evaluated based on two different indices (accumulated concentration above a 40 ppbV threshold and seasonal mean daytime ozone concentration respectively) on a global, regional and national scale. The cumulative metric appears to be far less robust than the seasonal mean, while the seasonal mean shows satisfactory agreement with measurements in Europe, the US, China and Southern India and South-East Asia. Present day global relative yield losses are estimated to range between 7{\%} and 12{\%} for wheat, between 6{\%} and 16{\%} for soybean, between 3{\%} and 4{\%} for rice, and between 3{\%} and 5{\%} for maize (range resulting from different metrics used). Taking into account possible biases in our assessment, introduced through the global application of "western" crop exposure-response functions, and through model performance in reproducing ozone-exposure metrics, our estimates may be considered as being conservative. Under the 2030 CLE scenario, the global situation is expected to deteriorate mainly for wheat (additional 2-6{\%} loss globally) and rice (additional 1-2{\%} loss globally). India, for which no mitigation measures have been assumed by 2030, accounts for 50{\%} of these global increase in crop yield loss. On a regional-scale, significant reductions in crop losses by CLE-2030 are only predicted in Europe (soybean) and China (wheat). Translating these assumed yield losses into total global economic damage for the four crops considered, using world market prices for the year 2000, we estimate an economic loss in the range {\$}14-{\$}26 billion. About 40{\%} of this damage is occurring in China and India. Considering the recent upward trends in food prices, the ozone-induced damage to crops is expected to offset a significant portion of the GDP growth rate, especially in countries with an economy based on agricultural production. {\textcopyright} 2008 Elsevier Ltd. All rights reserved.}, author = {{Van Dingenen}, Rita and Dentener, Frank J. and Raes, Frank and Krol, Maarten C. and Emberson, Lisa and Cofala, Janusz}, doi = {10.1016/j.atmosenv.2008.10.033}, isbn = {1352-2310}, issn = {13522310}, journal = {Atmospheric Environment}, keywords = {Crop damage,Global,Impact assessment,Model,Ozone}, number = {3}, pages = {604--618}, title = {{The global impact of ozone on agricultural crop yields under current and future air quality legislation}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231008009424}, volume = {43}, year = {2009} } @article{VanHeerwaarden2021, abstract = {Spring 2020 broke sunshine duration records across Western Europe. The Netherlands recorded the highest surface irradiance since 1928, exceeding the previous extreme of 2011 by 13{\%}, and the diffuse fraction of the irradiance measured a record low percentage (38{\%}). The coinciding irradiance extreme and a reduction in anthropogenic pollution due to COVID-19 measures triggered the hypothesis that cleaner-than-usual air contributed to the record. Based on analyses of ground-based and satellite observations and experiments with a radiative transfer model, we estimate a 1.3{\%} (2.3 W m−2) increase in surface irradiance with respect to the 2010–2019 mean due to a low median aerosol optical depth, and a 17.6{\%} (30.7 W m−2) increase due to several exceptionally dry days and a very low cloud fraction overall. Our analyses show that the reduced aerosols and contrails due to the COVID-19 measures are far less important in the irradiance record than the dry and particularly cloud-free weather.}, author = {van Heerwaarden, Chiel C and Mol, Wouter B and Veerman, Menno A and Benedict, Imme and Heusinkveld, Bert G and Knap, Wouter H and Kazadzis, Stelios and Kouremeti, Natalia and Fiedler, Stephanie}, doi = {10.1038/s43247-021-00110-0}, issn = {2662-4435}, journal = {Communications Earth {\&} Environment}, number = {1}, pages = {37}, title = {{Record high solar irradiance in Western Europe during first COVID-19 lockdown largely due to unusual weather}}, url = {https://doi.org/10.1038/s43247-021-00110-0}, volume = {2}, year = {2021} } @article{gmd-10-3329-2017, abstract = {Abstract. Fires have influenced atmospheric composition and climate since the rise of vascular plants, and satellite data have shown the overall global extent of fires. Our knowledge of historic fire emissions has progressively improved over the past decades due mostly to the development of new proxies and the improvement of fire models. Currently, there is a suite of proxies including sedimentary charcoal records, measurements of fire-emitted trace gases and black carbon stored in ice and firn, and visibility observations. These proxies provide opportunities to extrapolate emission estimates back in time based on satellite data starting in 1997, but each proxy has strengths and weaknesses regarding, for example, the spatial and temporal extents over which they are representative. We developed a new historic biomass burning emissions dataset starting in 1750 that merges the satellite record with several existing proxies and uses the average of six models from the Fire Model Intercomparison Project (FireMIP) protocol to estimate emissions when the available proxies had limited coverage. According to our approach, global biomass burning emissions were relatively constant, with 10-year averages varying between 1.8 and 2.3 Pg C yr−1. Carbon emissions increased only slightly over the full time period and peaked during the 1990s after which they decreased gradually. There is substantial uncertainty in these estimates, and patterns varied depending on choices regarding data representation, especially on regional scales. The observed pattern in fire carbon emissions is for a large part driven by African fires, which accounted for 58 {\%} of global fire carbon emissions. African fire emissions declined since about 1950 due to conversion of savanna to cropland, and this decrease is partially compensated for by increasing emissions in deforestation zones of South America and Asia. These global fire emission estimates are mostly suited for global analyses and will be used in the Coupled Model Intercomparison Project Phase 6 (CMIP6) simulations.}, author = {van Marle, Margreet J. E. and Kloster, Silvia and Magi, Brian I. and Marlon, Jennifer R. and Daniau, Anne-Laure and Field, Robert D. and Arneth, Almut and Forrest, Matthew and Hantson, Stijn and Kehrwald, Natalie M. and Knorr, Wolfgang and Lasslop, Gitta and Li, Fang and Mangeon, St{\'{e}}phane and Yue, Chao and Kaiser, Johannes W. and van der Werf, Guido R.}, doi = {10.5194/gmd-10-3329-2017}, issn = {1991-9603}, journal = {Geoscientific Model Development}, month = {sep}, number = {9}, pages = {3329--3357}, title = {{Historic global biomass burning emissions for CMIP6 (BB4CMIP) based on merging satellite observations with proxies and fire models (1750–2015)}}, url = {https://www.geosci-model-dev.net/10/3329/2017/}, volume = {10}, year = {2017} } @article{vanVuuren2011, abstract = {This paper summarizes the development process and main characteristics of the Representative Concentration Pathways (RCPs), a set of four new pathways developed for the climate modeling community as a basis for long-term and near-term modeling experiments. The four RCPs together span the range of year 2100 radiative forcing values found in the open literature, i.e. from 2.6 to 8.5 W/m2. The RCPs are the product of an innovative collaboration between integrated assessment modelers, climate modelers, terrestrial ecosystem modelers and emission inventory experts. The resulting product forms a comprehensive data set with high spatial and sectoral resolutions for the period extending to 2100. Land use and emissions of air pollutants and greenhouse gases are reported mostly at a 0.5{\{}$\backslash$thinspace{\}}{\{}$\backslash$texttimes{\}}{\{}$\backslash$thinspace{\}}0.5 degree spatial resolution, with air pollutants also provided per sector (for well-mixed gases, a coarser resolution is used). The underlying integrated assessment model outputs for land use, atmospheric emissions and concentration data were harmonized across models and scenarios to ensure consistency with historical observations while preserving individual scenario trends. For most variables, the RCPs cover a wide range of the existing literature. The RCPs are supplemented with extensions (Extended Concentration Pathways, ECPs), which allow climate modeling experiments through the year 2300. The RCPs are an important development in climate research and provide a potential foundation for further research and assessment, including emissions mitigation and impact analysis.}, author = {van Vuuren, Detlef P and Edmonds, Jae and Kainuma, Mikiko and Riahi, Keywan and Thomson, Allison and Hibbard, Kathy and Hurtt, George C and Kram, Tom and Krey, Volker and Lamarque, Jean-Francois and Masui, Toshihiko and Meinshausen, Malte and Nakicenovic, Nebojsa and Smith, Steven J and Rose, Steven K}, doi = {10.1007/s10584-011-0148-z}, issn = {1573-1480}, journal = {Climatic Change}, month = {aug}, number = {1}, pages = {5--31}, title = {{The representative concentration pathways: an overview}}, url = {https://doi.org/10.1007/s10584-011-0148-z}, volume = {109}, year = {2011} } @article{VanZanten2017, abstract = {We present measurements of atmospheric concentrations of ammonia and ammonium in the Netherlands over the period 1993–2014 and measurements of wet deposition of ammonium for 1985–2014. The various time series have been obtained at 16 monitoring stations from the Dutch National Air Quality Monitoring Network. The monitoring stations are geographically homogenously spread over the Netherlands and are equally distributed over regions with relatively low, moderate and high ammonia emission. During the period covered, changes in the monitoring have occurred. To obtain consistent time series, data are revalidated or corrected when necessary, according to current validation procedures or latest technical insights. The time series of ammonia concentrations are gap filled and time series corrected for meteorological influences are constructed. The course in the ammonia concentrations shows roughly two periods. For 1993–2004, the ammonia concentrations show a downward trend of 36{\%}, which is statistically significant with a confidence interval (CI) of 99{\%}. For 2005–2014, an upward trend of 19{\%} (CI 90{\%}) is reported. Correcting time series of ammonia concentrations for meteorological influences enhances the statistical reliability of the derived trends. This resulted in trends of −40{\%} (CI 99{\%}) and 24{\%} (CI 95{\%}) respectively. For the full period there exists no trend in ammonia concentrations due to a trend in atmospheric conditions. For 2005–2014 ammonia concentrations increased especially in springtime, while showing no change in winter months. After correcting for meteorological influences, all seasons in this period show an increase in ammonia concentrations although the increase in the spring months is still the largest. For 1993–2014 the reported ammonia emissions in the Netherlands declined in both periods with respectively 51{\%} and 22{\%}. The trends in emissions and ammonia concentrations correspond in the period 1993–2004 whilst over the period 2005–2014, the trends in emissions and concentrations of ammonia diverge. This divergence is for roughly a third accounted for by processes related to changes in chemical climate (see accompanying modelling paper by Wichink Kruit et al., 2016) but it is not clear what explains the remaining difference in trends. For 1993–2014, downward trends of wet deposition of ammonium and ammonium in aerosol are found to be 47{\%} and 68{\%}, respectively. A split into two periods is not found as is the case with the ammonia concentration. However, although statistically not significant, both wet deposition of ammonium and ammonium in aerosol show a leveling off in decline between 2005 and 2014.}, author = {van Zanten, M. C. and {Wichink Kruit}, R. J. and Hoogerbrugge, R. and {Van der Swaluw}, E. and van Pul, W. A.J.}, doi = {10.1016/j.atmosenv.2016.11.007}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Ammonia,Ammonium aerosol,Emissions,Measurements,Trends,Wet deposition}, month = {jan}, pages = {352--360}, publisher = {Elsevier {\{}BV{\}}}, title = {{Trends in ammonia measurements in the Netherlands over the period 1993–2014}}, volume = {148}, year = {2017} } @article{Vandyck2018, abstract = {Local air quality co-benefits can provide complementary support for ambitious climate action and can enable progress on related Sustainable Development Goals. Here we show that the transformation of the energy system implied by the emission reduction pledges brought forward in the context of the Paris Agreement on climate change (Nationally Determined Contributions or NDCs) substantially reduces local air pollution across the globe. The NDCs could avoid between 71 and 99 thousand premature deaths annually in 2030 compared to a reference case, depending on the stringency of direct air pollution controls. A more ambitious 2 °C-compatible pathway raises the number of avoided premature deaths from air pollution to 178–346 thousand annually in 2030, and up to 0.7–1.5 million in the year 2050. Air quality co-benefits on morbidity, mortality, and agriculture could globally offset the costs of climate policy. An integrated policy perspective is needed to maximise benefits for climate and health.}, author = {Vandyck, Toon and Keramidas, Kimon and Kitous, Alban and Spadaro, Joseph V and {Van Dingenen}, Rita and Holland, Mike and Saveyn, Bert}, doi = {10.1038/s41467-018-06885-9}, issn = {2041-1723}, journal = {Nature Communications}, number = {1}, pages = {4939}, title = {{Air quality co-benefits for human health and agriculture counterbalance costs to meet Paris Agreement pledges}}, url = {https://doi.org/10.1038/s41467-018-06885-9}, volume = {9}, year = {2018} } @article{doi:10.1111/j.1469-8137.2012.04152.x, abstract = {Summary • Here, we investigated the effects of increasing concentrations of ozone ([O3]) on soybean canopy-scale fluxes of heat and water vapor, as well as water use efficiency (WUE), at the Soybean Free Air Concentration Enrichment (SoyFACE) facility. • Micrometeorological measurements were made to determine the net radiation (Rn), sensible heat flux (H), soil heat flux (G0) and latent heat flux ($\lambda$ET) of a commercial soybean (Glycine max) cultivar (Pioneer 93B15), exposed to a gradient of eight daytime average ozone concentrations ranging from approximately current (c. 40 ppb) to three times current (c. 120 ppb) levels. • As [O3] increased, soybean canopy fluxes of $\lambda$ET decreased and H increased, whereas Rn and G0 were not altered significantly. Exposure to increased [O3] also resulted in warmer canopies, especially during the day. The lower $\lambda$ET decreased season total evapotranspiration (ET) by c. 26{\%}. The [O3]-induced relative decline in ET was half that of the relative decline in seed yield, driving a 50{\%} reduction in seasonal WUE. • These results suggest that rising [O3] will alter the canopy energy fluxes that drive regional climate and hydrology, and have a negative impact on productivity and WUE, key ecosystem services.}, author = {VanLoocke, Andy and Betzelberger, Amy M and Ainsworth, Elizabeth A and Bernacchi, Carl J}, doi = {10.1111/j.1469-8137.2012.04152.x}, journal = {New Phytologist}, keywords = {evapotranspiration,free air concentration enrichment (FACE),surface energy balance,tropospheric ozone,vegetation–climate interactions,water use efficiency (WUE)}, number = {1}, pages = {164--171}, title = {{Rising ozone concentrations decrease soybean evapotranspiration and water use efficiency whilst increasing canopy temperature}}, url = {https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-8137.2012.04152.x}, volume = {195}, year = {2012} } @article{Vattioni2019, author = {Vattioni, Sandro and Weisenstein, Debra and Keith, David and Feinberg, Aryeh and Peter, Thomas and Stenke, Andrea}, doi = {10.5194/acp-19-4877-2019}, journal = {Atmospheric Chemistry and Physics}, month = {apr}, number = {7}, pages = {4877--4897}, title = {{Exploring accumulation-mode H2SO4 versus SO2 stratospheric sulfate geoengineering in a sectional aerosol–chemistry–climate model}}, volume = {19}, year = {2019} } @article{Veira2016, abstract = {Abstract Global warming is expected to considerably impact wildfire activity and aerosol emission release in the future. Due to their complexity, the future interactions between climate change, wildfire activity, emission release, and atmospheric aerosol processes are still uncertain. Here we use the process-based fire model SPITFIRE within the global vegetation model JSBACH to simulate wildfire activity for present-day climate conditions and future Representative Concentration Pathways (RCPs). The modeled fire emission fluxes and fire radiative power serve as input for the aerosol-climate model ECHAM6-HAM2, which has been extended by a semiempirical plume height parametrization. Our results indicate a general increase in extratropical and a decrease in tropical wildfire activity at the end of the 21st century. Changes in emission fluxes are most pronounced for the strongest warming scenario RCP8.5 (+49{\%} in the extratropics, ?37{\%} in the tropics). Tropospheric black carbon (BC) concentrations are similarly affected by changes in emission fluxes and changes in climate conditions with regional variations of up to ?50{\%} to +100{\%}. In the Northern Hemispheric extratropics, we attribute a mean increase in aerosol optical thickness of +0.031±0.002 to changes in wildfire emissions. Due to the compensating effects of fire intensification and more stable atmospheric conditions, global mean emission heights change by at most 0.3 km with only minor influence on BC long-range transport. The changes in wildfire emission fluxes for the RCP8.5 scenario, however, may largely compensate the projected reduction in anthropogenic BC emissions by the end of the 21st century.}, annote = {https://doi.org/10.1002/2015JD024142}, author = {Veira, A and Lasslop, G and Kloster, S}, doi = {https://doi.org/10.1002/2015JD024142}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {Earth System Modeling,aerosols,atmospheric transport,climate warming,emission heights,wildfires}, month = {apr}, number = {7}, pages = {3195--3223}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Wildfires in a warmer climate: Emission fluxes, emission heights, and black carbon concentrations in 2090–2099}}, url = {https://doi.org/10.1002/2015JD024142}, volume = {121}, year = {2016} } @article{Velders2015, abstract = {Hydrofluorocarbons (HFCs) are manufactured for use as substitutes for ozone-depleting substances that are being phased out globally under Montreal Protocol regulations. While HFCs do not deplete ozone, many are potent greenhouse gases that contribute to climate change. Here, new global scenarios show that baseline emissions of HFCs could reach 4.0-5.3 GtCO2-eq yr-1 in 2050. The new baseline (or business-as-usual) scenarios are formulated for 10 HFC compounds, 11 geographic regions, and 13 use categories. The scenarios rely on detailed data reported by countries to the United Nations; projections of gross domestic product and population; and recent observations of HFC atmospheric abundances. In the baseline scenarios, by 2050 China (31{\%}), India and the rest of Asia (23{\%}), the Middle East and northern Africa (11{\%}), and the USA (10{\%}) are the principal source regions for global HFC emissions; and refrigeration (40-58{\%}) and stationary air conditioning (21-40{\%}) are the major use sectors. The corresponding radiative forcing could reach 0.22-0.25 W m-2 in 2050, which would be 12-24{\%} of the increase from business-as-usual CO2 emissions from 2015 to 2050. National regulations to limit HFC use have already been adopted in the European Union, Japan and USA, and proposals have been submitted to amend the Montreal Protocol to substantially reduce growth in HFC use. Calculated baseline emissions are reduced by 90{\%} in 2050 by implementing the North America Montreal Protocol amendment proposal. Global adoption of technologies required to meet national regulations would be sufficient to reduce 2050 baseline HFC consumption by more than 50{\%} of that achieved with the North America proposal for most developed and developing countries.}, author = {Velders, Guus J M and Fahey, David W. and Daniel, John S. and Andersen, Stephen O. and McFarland, Mack}, doi = {10.1016/j.atmosenv.2015.10.071}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {CO2-eq emissions,Climate,HFC,Montreal Protocol,Radiative forcing}, pages = {200--209}, title = {{Future atmospheric abundances and climate forcings from scenarios of global and regional hydrofluorocarbon (HFC) emissions}}, url = {http://www.sciencedirect.com/science/article/pii/S135223101530488X}, volume = {123}, year = {2015} } @article{Velders2009, abstract = {The consumption and emissions of hydrofluorocarbons (HFCs) are projected to increase substantially in the coming decades in response to regulation of ozone depleting gases under the Montreal Protocol. The projected increases result primarily from sustained growth in demand for refrigeration, air-conditioning (AC) and insulating foam products in developing countries assuming no new regulation of HFC consumption or emissions. New HFC scenarios are presented based on current hydrochlorofluorocarbon (HCFC) consumption in leading applications, patterns of replacements of HCFCs by HFCs in developed countries, and gross domestic product (GDP) growth. Global HFC emissions significantly exceed previous estimates after 2025 with developing country emissions as much as 800{\%} greater than in developed countries in 2050. Global HFC emissions in 2050 are equivalent to 9-19{\%} (CO2-eq. basis) of projected global CO2 emissions in business-as-usual scenarios and contribute a radiative forcing equivalent to that from 6-13 years of CO2 emissions near 2050. This percentage increases to 28-45{\%} compared with projected CO 2 emissions in a 450-ppm CO2 stabilization scenario. In a hypothetical scenario based on a global cap followed by 4{\%} annual reductions in consumption, HFC radiative forcing is shown to peak and begin to decline before 2050.}, author = {Velders, Guus J.M. and Fahey, David W. and Daniel, John S. and McFarland, Mack and Andersen, Stephen O.}, doi = {10.1073/pnas.0902817106}, issn = {00278424}, journal = {Proceedings of the National Academy of Sciences}, keywords = {HCFC consumption,Radiative forcing,Scenarios}, number = {27}, pages = {10949--10954}, title = {{The large contribution of projected HFC emissions to future climate forcing}}, url = {http://www.pnas.org/content/106/27/10949.full.pdf{\#}page=1{\&}view=FitH}, volume = {106}, year = {2009} } @article{Venkataraman2018, abstract = {Abstract. India is currently experiencing degraded air quality, and future economic development will lead to challenges for air quality management. Scenarios of sectoral emissions of fine particulate matter and its precursors were developed and evaluated for 2015–2050, under specific pathways of diffusion of cleaner and more energy-efficient technologies. The impacts of individual source sectors on PM2.5 concentrations were assessed through systematic simulations of spatially and temporally resolved particulate matter concentrations, using the GEOS-Chem model, followed by population-weighted aggregation to national and state levels. We find that PM2.5 pollution is a pan-India problem, with a regional character, and is not limited to urban areas or megacities. Under present-day emissions, levels in most states exceeded the national PM2.5 annual standard (40 µg m−3). Sources related to human activities were responsible for the largest proportion of the present-day population exposure to PM2.5 in India. About 60 {\%} of India's mean population-weighted PM2.5 concentrations come from anthropogenic source sectors, while the remainder are from other sources, windblown dust and extra-regional sources. Leading contributors are residential biomass combustion, power plant and industrial coal combustion and anthropogenic dust (including coal fly ash, fugitive road dust and waste burning). Transportation, brick production and distributed diesel were other contributors to PM2.5. Future evolution of emissions under regulations set at current levels and promulgated levels caused further deterioration of air quality in 2030 and 2050. Under an ambitious prospective policy scenario, promoting very large shifts away from traditional biomass technologies and coal-based electricity generation, significant reductions in PM2.5 levels are achievable in 2030 and 2050. Effective mitigation of future air pollution in India requires adoption of aggressive prospective regulation, currently not formulated, for a three-pronged switch away from (i) biomass-fuelled traditional technologies, (ii) industrial coal-burning and (iii) open burning of agricultural residue. Future air pollution is dominated by industrial process emissions, reflecting larger expansion in industrial, rather than residential energy demand. However, even under the most active reductions envisioned, the 2050 mean exposure, excluding any impact from windblown mineral dust, is estimated to be nearly 3 times higher than the WHO Air Quality Guideline.}, author = {Venkataraman, Chandra and Brauer, Michael and Tibrewal, Kushal and Sadavarte, Pankaj and Ma, Qiao and Cohen, Aaron and Chaliyakunnel, Sreelekha and Frostad, Joseph and Klimont, Zbigniew and Martin, Randall V. and Millet, Dylan B. and Philip, Sajeev and Walker, Katherine and Wang, Shuxiao}, doi = {10.5194/acp-18-8017-2018}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jun}, number = {11}, pages = {8017--8039}, title = {{Source influence on emission pathways and ambient PM2.5 pollution over India (2015–2050)}}, url = {https://acp.copernicus.org/articles/18/8017/2018/}, volume = {18}, year = {2018} } @article{Venter2020, abstract = {The lockdown response to coronavirus disease 2019 (COVID-19) has caused an unprecedented reduction in global economic and transport activity. We test the hypothesis that this has reduced tropospheric and ground-level air pollution concentrations, using satellite data and a network of {\textgreater}10,000 air quality stations. After accounting for the effects of meteorological variability, we find declines in the population-weighted concentration of ground-level nitrogen dioxide (NO 2 : 60{\%} with 95{\%} CI 48 to 72{\%}), and fine particulate matter (PM 2.5 : 31{\%}; 95{\%} CI: 17 to 45{\%}), with marginal increases in ozone (O 3 : 4{\%}; 95{\%} CI: −2 to 10{\%}) in 34 countries during lockdown dates up until 15 May. Except for ozone, satellite measurements of the troposphere indicate much smaller reductions, highlighting the spatial variability of pollutant anomalies attributable to complex NO x chemistry and long-distance transport of fine particulate matter with a diameter less than 2.5 µm (PM 2.5 ). By leveraging Google and Apple mobility data, we find empirical evidence for a link between global vehicle transportation declines and the reduction of ambient NO 2 exposure. While the state of global lockdown is not sustainable, these findings allude to the potential for mitigating public health risk by reducing “business as usual” air pollutant emissions from economic activities. Explore trends here: https://nina.earthengine.app/view/lockdown-pollution .}, author = {Venter, Zander S and Aunan, Kristin and Chowdhury, Sourangsu and Lelieveld, Jos}, doi = {10.1073/pnas.2006853117}, isbn = {0000000246002}, issn = {0027-8424}, journal = {Proceedings of the National Academy of Sciences}, keywords = {04,10,1101,14,20060673,2020,a license to display,by peer review,covid-19,doi,funder,https,is the author,medrxiv preprint doi,mortality,nitrogen dioxide,org,ozone,particulate matter,pediatric asthma,the copyright holder for,the preprint in perpetuity,this preprint,this version posted april,which was not certified,who has granted medrxiv}, month = {aug}, number = {32}, pages = {18984--18990}, title = {{COVID-19 lockdowns cause global air pollution declines}}, url = {http://www.pnas.org/lookup/doi/10.1073/pnas.2006853117}, volume = {117}, year = {2020} } @article{Vereecken2015, annote = {doi: 10.1021/cr500488p}, author = {Vereecken, Luc and Glowacki, David R and Pilling, Michael J}, doi = {10.1021/cr500488p}, issn = {0009-2665}, journal = {Chemical Reviews}, month = {may}, number = {10}, pages = {4063--4114}, publisher = {American Chemical Society}, title = {{Theoretical Chemical Kinetics in Tropospheric Chemistry: Methodologies and Applications}}, url = {https://doi.org/10.1021/cr500488p}, volume = {115}, year = {2015} } @article{Vernier2018, abstract = {We describe and show results from a series of field campaigns that used balloonborne instruments launched from India and Saudi Arabia during the summers 2014–17 to study the nature, formation, and impacts of the Asian Tropopause Aerosol Layer (ATAL). The campaign goals were to i) characterize the optical, physical, and chemical properties of the ATAL; ii) assess its impacts on water vapor and ozone; and iii) understand the role of convection in its formation. To address these objectives, we launched 68 balloons from four locations, one in Saudi Arabia and three in India, with payload weights ranging from 1.5 to 50 kg. We measured meteorological parameters; ozone; water vapor; and aerosol backscatter, concentration, volatility, and composition in the upper troposphere and lower stratosphere (UTLS) region. We found peaks in aerosol concentrations of up to 25 cm–3 for radii {\textgreater} 94 nm, associated with a scattering ratio at 940 nm of ∼1.9 near the cold-point tropopause. During medium-duration balloon flights near the tropopause, we collected aerosols and found, after offline ion chromatography analysis, the dominant presence of nitrate ions with a concentration of about 100 ng m–3. Deep convection was found to influence aerosol loadings 1 km above the cold-point tropopause. The Balloon Measurements of the Asian Tropopause Aerosol Layer (BATAL) project will continue for the next 3–4 years, and the results gathered will be used to formulate a future National Aeronautics and Space Administration–Indian Space Research Organisation (NASA–ISRO) airborne campaign with NASA high-altitude aircraft.}, author = {Vernier, J.-P. and Fairlie, T D and Deshler, T and {Venkat Ratnam}, M and Gadhavi, H and Kumar, B S and Natarajan, M and Pandit, A K and {Akhil Raj}, S T and {Hemanth Kumar}, A and Jayaraman, A and Singh, A K and Rastogi, N and Sinha, P R and Kumar, S and Tiwari, S and Wegner, T and Baker, N and Vignelles, D and Stenchikov, G and Shevchenko, I and Smith, J and Bedka, K and Kesarkar, A and Singh, V and Bhate, J and Ravikiran, V and {Durga Rao}, M and Ravindrababu, S and Patel, A and Vernier, H and Wienhold, F G and Liu, H and Knepp, T N and Thomason, L and Crawford, J and Ziemba, L and Moore, J and Crumeyrolle, S and Williamson, M and Berthet, G and J{\'{e}}gou, F and Renard, J.-B.}, doi = {10.1175/BAMS-D-17-0014.1}, issn = {0003-0007}, journal = {Bulletin of the American Meteorological Society}, month = {jun}, number = {5}, pages = {955--973}, title = {{BATAL: The Balloon Measurement Campaigns of the Asian Tropopause Aerosol Layer}}, volume = {99}, year = {2018} } @article{Vet2014, author = {Vet, Robert and Artz, Richard S and Carou, Silvina and Shaw, Mike and Ro, Chul-Un and Aas, Wenche and Baker, Alex and Bowersox, Van C and Dentener, Frank and Galy-Lacaux, Corinne and Hou, Amy and Pienaar, Jacobus J and Gillett, Robert and Forti, M Cristina and Gromov, Sergey and Hara, Hiroshi and Khodzher, Tamara and Mahowald, Natalie M and Nickovic, Slobodan and Rao, P S P and Reid, Neville W}, doi = {https://doi.org/10.1016/j.atmosenv.2013.10.060}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {Assessment,Deposition,Emissions,Global Atmosphere Watch,Major ions,Precipitation chemistry,pH}, pages = {3--100}, title = {{A global assessment of precipitation chemistry and deposition of sulfur, nitrogen, sea salt, base cations, organic acids, acidity and pH, and phosphorus}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231013008133}, volume = {93}, year = {2014} } @misc{Victor2015, abstract = {Cutting levels of soot and other short-lived pollutants delivers tangible benefits and helps governments to build confidence that collective action on climate change is feasible. After the Paris climate meeting this December, actually reducing these pollutants will be essential to the credibility of the diplomatic process. O}, author = {Victor, David G. and Zaelke, Durwood and Ramanathan, Veerabhadran}, booktitle = {Nature Climate Change}, doi = {10.1038/nclimate2703}, isbn = {1758-6798}, issn = {17586798}, number = {9}, pages = {796--798}, title = {{Soot and short-lived pollutants provide political opportunity}}, volume = {5}, year = {2015} } @article{Vignesh2020, abstract = {Abstract The seasonal and regional variations of cloud fractions are compared across two generations of global climate model ensembles, specifically, the Coupled Model Intercomparison Project-5 (CMIP5) and CMIP6, through the historical period in terms of skills and multimodel agreement. We find a wider spread of historical cloud fraction changes in the CMIP6 than was simulated by the CMIP5. The global mean cloud fractions of CMIP6 increased by about 4.5{\%} from the CMIP5, which attributed to greater changes in the northern hemisphere than in the southern hemisphere. The CMIP6 cloud fractions in recent years are validated with the CALIPSO{\_}CLOUSAT observations to understand the cloud fraction uncertainties in CMIP6 models. The CMIP6 ensemble mean of cloud fractions compares well with the observations with a mean difference of 0.5{\%} in lower altitudes. The CMIP6 cloud fractions are higher than the observations at higher latitudes in both hemispheres in the upper troposphere, and the biases vary from one model to another. The spatial difference between the ensemble and observations is further revealed over the tropics: where the model displays a 3{\%} higher bias. In addition, we observed a significant trend occuring in the northern hemisphere since the mid-20th century using calculations of cloud fraction trends based on the robust regression technique. Finally, we reduce the differences between the model and observations by applying a simple regression technique. The results exemplify that the model and modified observations compare well, with the root mean square value decreased by nearly 28{\%}, and the correlation increased significantly.}, annote = {https://doi.org/10.1029/2019EA000975}, author = {Vignesh, P Preetham and Jiang, Jonathan H and Kishore, P and Su, Hui and Smay, Timothy and Brighton, Nicholas and Velicogna, Isabella}, doi = {https://doi.org/10.1029/2019EA000975}, issn = {2333-5084}, journal = {Earth and Space Science}, keywords = {CALIPSO,CMIP6,Cloudsat,cloud fraction,layered cloud fraction,trends}, month = {feb}, number = {2}, pages = {e2019EA000975}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Assessment of CMIP6 Cloud Fraction and Comparison with Satellite Observations}}, url = {https://doi.org/10.1029/2019EA000975}, volume = {7}, year = {2020} } @article{gmd-13-4459-2020, author = {Vira, J and Hess, P and Melkonian, J and Wieder, W R}, doi = {10.5194/gmd-13-4459-2020}, journal = {Geoscientific Model Development}, number = {9}, pages = {4459--4490}, title = {{An improved mechanistic model for ammonia volatilization in Earth system models: Flow of Agricultural Nitrogen version 2 (FANv2)}}, url = {https://gmd.copernicus.org/articles/13/4459/2020/}, volume = {13}, year = {2020} } @article{Virts2011a, address = {Boston MA, USA}, author = {Virts, Katrina S. and Wallace, John M. and Hutchins, Michael L. and Holzworth, Robert H.}, doi = {10.1175/BAMS-D-12-00082.1}, issn = {0003-0007}, journal = {Bulletin of the American Meteorological Society}, month = {sep}, number = {9}, pages = {1381--1391}, publisher = {American Meteorological Society}, title = {{Highlights of a New Ground-Based, Hourly Global Lightning Climatology}}, url = {http://journals.ametsoc.org/doi/10.1175/BAMS-D-12-00082.1}, volume = {94}, year = {2013} } @article{Visioni2019, abstract = {Simulations of stratospheric aerosol geoengineering have typically considered injections at a constant rate over the entire year. However, the seasonal variability of both sunlight and the stratospheric circulation suggests seasonally dependent injection strategies. We simulated single-point injections of the same amount of SO2 in each of the four seasons and at five different latitudes (30°S, 15°S, equator, 15°N, and 30°N), 5 km above the tropopause. Our findings suggest that injecting only during one season reduces the amount of SO2 needed to achieve a certain aerosol optical depth, thus potentially reducing some of the side effects of geoengineering. We find, in particular, that injections at 15°N or 15°S in spring of the corresponding hemisphere results in the largest reductions in incoming solar radiation. Compared to annual injections, by injecting in the different seasons we identify additional distinct spatiotemporal aerosol optical depth patterns, thanks to seasonal differences in the stratospheric circulation.}, author = {Visioni, Daniele and MacMartin, Douglas G. and Kravitz, Ben and Tilmes, Simone and Mills, Michael J. and Richter, Jadwiga H. and Boudreau, Matthew P.}, doi = {10.1029/2019GL083680}, issn = {0094-8276}, journal = {Geophysical Research Letters}, keywords = {climate engineering,stratospheric aerosol injection,stratospheric sulfate,sulfate geoengineering}, month = {jul}, number = {13}, pages = {7790--7799}, title = {{Seasonal Injection Strategies for Stratospheric Aerosol Geoengineering}}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2019GL083680}, volume = {46}, year = {2019} } @article{VonSchneidemesser2015, abstract = {Climate change and air pollution are critical environmental issues both in the here and now and for the coming decades. Many mitigation options offer the possibility to both improve air quality and mitigate climate change, such as improvements in energy efficiency, or a switch to wind or solar power, all of which reduce emissions across the board. The atmospheric chemistry of ozone is an important context to understand the linkages between air quality and climate change, because many indirect effects are linked to this chemistry. As an air pollutant, ozone has a variety of adverse effects on human health, including decreased pulmonary function, aggravation of pre-existing diseases such as asthma, increases in hospital admissions, especially respiratory ailments, and premature mortality.}, author = {von Schneidemesser, Erika and Monks, Paul S. and Allan, James D. and Bruhwiler, Lori and Forster, Piers and Fowler, David and Lauer, Axel and Morgan, William T. and Paasonen, Pauli and Righi, Mattia and Sindelarova, Katerina and Sutton, Mark A.}, doi = {10.1021/acs.chemrev.5b00089}, isbn = {0009-2665}, issn = {15206890}, journal = {Chemical Reviews}, number = {10}, pages = {3856--3897}, pmid = {25926133}, title = {{Chemistry and the Linkages between Air Quality and Climate Change}}, volume = {115}, year = {2015} } @article{Voulgarakis2013a, abstract = {Results from simulations performed for the Atmospheric Chemistry and Climate Modeling Intercomparison Project (ACCMIP) are analysed to examine how OH and methane lifetime may change from present day to the future, under different climate and emissions scenarios. Present day (2000) mean tropospheric chemical lifetime derived from the ACCMIP multi-model mean is 9.8±1.6 yr (9.3±0.9 yr when only including selected models), lower than a recent observationally-based estimate, but with a similar range to previous multi-model estimates. Future model projections are based on the four Representative Concentration Pathways (RCPs), and the results also exhibit a large range. Decreases in global methane lifetime of 4.5±9.1{\%} are simulated for the scenario with lowest radiative forcing by 2100 (RCP 2.6), while increases of 8.5±10.4{\%} are simulated for the scenario with highest radiative forcing (RCP 8.5). In this scenario, the key driver of the evolution of OH and methane lifetime is methane itself, since its concentration more than doubles by 2100 and it consumes much of the OH that exists in the troposphere. Stratospheric ozone recovery, which drives tropospheric OH decreases through photolysis modifications, also plays a partial role. In the other scenarios, where methane changes are less drastic, the interplay between various competing drivers leads to smaller and more diverse OH and methane lifetime responses, which are difficult to attribute. For all scenarios, regional OH changes are even more variable, with the most robust feature being the large decreases over the remote oceans in RCP8.5. Through a regression analysis, we suggest that differences in emissions of non-methane volatile organic compounds and in the simulation of photolysis rates may be the main factors causing the differences in simulated present day OH and methane lifetime. Diversity in predicted changes between present day and future OH was found to be associated more strongly with differences in modelled temperature and stratospheric ozone changes. Finally, through perturbation experiments we calculated an OH feedback factor (F) of 1.24 from present day conditions (1.50 from 2100 RCP8.5 conditions) and a climate feedback on methane lifetime of 0.33±0.13 yrK-1, on average. Models that did not include interactive stratospheric ozone effects on photolysis showed a stronger sensitivity to climate, as they did not account for negative effects of climate-driven stratospheric ozone recovery on tropospheric OH, which would have partly offset the overall OH/methane lifetime response to climate change. {\textcopyright} Author(s) 2013.}, annote = {From Duplicate 2 (Analysis of present day and future OH and methane lifetime in the ACCMIP simulations - Voulgarakis, A; Naik, V; Lamarque, J F; Shindell, D T; Young, P J; Prather, M J; Wild, O; Field, R D; Bergmann, D; Cameron-Smith, P; Cionni, I; Collins, W J; Dalsoren, S B; Doherty, R M; Eyring, V; Faluvegi, G; Folberth, G A; Horowitz, L W; Josse, B; MacKenzie, I A; Nagashima, T; Plummer, D A; Righi, M; Rumbold, S T; Stevenson, D S; Strode, S A; Sudo, K; Szopa, S; Zeng, G) Times Cited: 105 Collins, William/A-5895-2010; Lamarque, Jean-Francois/L-2313-2014; Righi, Mattia/I-5120-2013; Shindell, Drew/D-4636-2012; Naik, Vaishali/A-4938-2013; Bergmann, Daniel/F-9801-2011; mackenzie, ian/E-9320-2013; Eyring, Veronika/O-9999-2016; Wild, Oliver/A-4909-2009; CIONNI, Irene/E-8204-2017; Young, Paul/E-8739-2010; Horowitz, Larry/D-8048-2014; Szopa, Sophie/F-8984-2010; Cameron-Smith, Philip/E-2468-2011; Strode, Sarah/H-2248-2012; Manager, CSD Publications/B-2789-2015; Stevenson, David/C-8089-2012; Faluvegi, Gregory/; Dalsoren, Stig/; Zeng, Guang/; Righi, Mattia/; Folberth, Gerd/ Collins, William/0000-0002-7419-0850; Lamarque, Jean-Francois/0000-0002-4225-5074; Naik, Vaishali/0000-0002-2254-1700; Bergmann, Daniel/0000-0003-4357-6301; Eyring, Veronika/0000-0002-6887-4885; Wild, Oliver/0000-0002-6227-7035; CIONNI, Irene/0000-0002-0591-9193; Young, Paul/0000-0002-5608-8887; Horowitz, Larry/0000-0002-5886-3314; Szopa, Sophie/0000-0002-8641-1737; Cameron-Smith, Philip/0000-0002-8802-8627; Strode, Sarah/0000-0002-8103-1663; Stevenson, David/0000-0002-4745-5673; Faluvegi, Gregory/0000-0001-9011-3663; Dalsoren, Stig/0000-0002-6752-4728; Zeng, Guang/0000-0002-9356-5021; Righi, Mattia/0000-0003-3827-5950; Folberth, Gerd/0000-0002-1075-440X 0 106 1680-7324}, author = {Voulgarakis, A. and Naik, V. and Lamarque, J. F. and Shindell, D. T. and Young, P. J. and Prather, M. J. and Wild, O. and Field, R. D. and Bergmann, D. and Cameron-Smith, P. and Cionni, I. and Collins, W. J. and Dals{\o}ren, S. B. and Doherty, R. M. and Eyring, V. and Faluvegi, G. and Folberth, G. A. and Horowitz, L. W. and Josse, B. and MacKenzie, I. A. and Nagashima, T. and Plummer, D. A. and Righi, M. and Rumbold, S. T. and Stevenson, D. S. and Strode, S. A. and Sudo, K. and Szopa, S. and Zeng, G.}, doi = {10.5194/acp-13-2563-2013}, isbn = {1680-7316}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {5}, pages = {2563--2587}, title = {{Analysis of present day and future OH and methane lifetime in the ACCMIP simulations}}, url = {https://www.atmos-chem-phys.net/13/2563/2013/}, volume = {13}, year = {2013} } @article{Wang20181223, abstract = {Air quality is closely associated with climate change via the biosphere because plants release large quantities of volatile organic compounds (VOC) that mediate both gaseous pollutants and aerosol dynamics. Earlier studies, which considered only leaf physiology and simply scale up from leaf-level enhancements of emissions, suggest that climate warming enhances whole forest VOC emissions, and these increased VOC emissions aggravate ozone pollution and secondary organic aerosol formation. Using an individual-based forest VOC emissions model—UVAFME-VOC—that simulates system-level emissions by explicitly simulating forest community dynamics to the individual tree level, ecological competition among the individuals of differing size and age, and radioactive transfer and leaf function through the canopy, we find that climate warming only sometimes stimulates isoprene emissions (the single largest source of non-methane hydrocarbon) in a southeastern US forest. These complex patterns result from the combination of higher temperatures' stimulating emissions at the leaf level but decreasing the abundance of isoprene-emitting taxa at the community level by causing a decline in the abundance of isoprene-emitting species (Quercus spp.). This ecological effect eventually outweighs the physiological one, thus reducing overall emissions. Such reduced emissions have far-reaching implications for the climate-air quality relationships that have been established on the paradigm of warming-enhancement VOC emissions from vegetation. This local scale modelling study suggests that community ecology rather than only individual physiology should be integrated into future studies of biosphere- climate-chemistry interactions.}, annote = {cited By 0}, author = {Wang, Bin and Shuman, Jacquelyn and Shugart, Herman H. and Lerdau, Manuel T.}, doi = {10.1002/eap.1721}, issn = {19395582}, journal = {Ecological Applications}, keywords = {UVAFME-VOC,air quality,biodiversity,climate warming,individual-based model,isoprene}, number = {5}, pages = {1223--1231}, title = {{Biodiversity matters in feedbacks between climate change and air quality: a study using an individual-based model}}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049303704{\&}doi=10.1002{\%}2Feap.1721{\&}partnerID=40{\&}md5=a6f0bffa66b99d38c2bffb8c0e212c1d}, volume = {28}, year = {2018} } @article{Wang2014b, abstract = {Abstract. Emissions of air pollutants in East Asia play an important role in the regional and global atmospheric environment. In this study we evaluated the recent emission trends of sulfur dioxide (SO2), nitrogen oxides (NOx), particulate matter (PM), and non-methane volatile organic compounds (NMVOC) in East Asia, and projected their future emissions up until 2030 with six emission scenarios. The results will provide future emission projections for the modeling community of the model inter-comparison program for Asia (MICS-Asia). During 2005–2010, the emissions of SO2 and PM2.5 in East Asia decreased by 15 and 12{\%}, respectively, mainly attributable to the large-scale deployment of flue gas desulfurization (FGD) at China's power plants, and the promotion of highly efficient PM removal technologies in China's power plants and cement industry. During this period, the emissions of NOx and NMVOC increased by 25 and 15{\%}, driven by rapid increase in the emissions from China due to inadequate control strategies. In contrast, the NOx and NMVOC emissions in East Asia except China decreased by 13–17{\%}, mainly due to the implementation of stringent vehicle emission standards in Japan and South Korea. Under current regulations and current levels of implementation, NOx, SO2, and NMVOC emissions in East Asia are projected to increase by about one-quarter over 2010 levels by 2030, while PM2.5 emissions are expected to decrease by 7{\%}. Assuming enforcement of new energy-saving policies, emissions of NOx, SO2, PM2.5 and NMVOC in East Asia are expected to decrease by 28, 36, 28, and 15{\%}, respectively, compared with the baseline case. The implementation of "progressive" end-of-pipe control measures would lead to another one-third reduction of the baseline emissions of NOx, and about one-quarter reduction of SO2, PM2.5, and NMVOC. Assuming the full application of technically feasible energy-saving policies and end-of-pipe control technologies, the emissions of NOx, SO2, and PM2.5 in East Asia would account for only about one-quarter, and NMVOC for one-third, of the levels of the baseline projection. Compared with previous projections, this study projects larger reductions in NOx and SO2 emissions by considering aggressive governmental plans and standards scheduled to be implemented in the next decade, and quantifies the significant effects of detailed progressive control measures on NMVOC emissions up until 2030.}, author = {Wang, S. X. and Zhao, B. and Cai, S. Y. and Klimont, Z. and Nielsen, C. P. and Morikawa, T. and Woo, J. H. and Kim, Y. and Fu, X. and Xu, J. Y. and Hao, J. M. and He, K. B.}, doi = {10.5194/acp-14-6571-2014}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {13}, pages = {6571--6603}, title = {{Emission trends and mitigation options for air pollutants in East Asia}}, volume = {14}, year = {2014} } @article{Wang2014, abstract = {Black carbon (BC) plays an important role in both climate change and health impact. Still, BC emissions as well as the historical trends are associated with high uncertainties in existing inventories. In the present study, global BC emissions from 1960 to 2007 were estimated for 64 sources, by using recompiled fuel consumption and emission factor data sets. Annual BC emissions had increased from 5.3 (3.4-8.5 as an interquartile range) to 9.1 (5.6-14.4) teragrams during this period. Our estimations are 11-16{\%} higher than those in previous inventories. Over the period, we found that the BC emission intensity, defined as the amount of BC emitted per unit of energy production, had decreased for all the regions, especially China and India. Improvements in combustion technology and changes in fuel composition had led to an increase in energy use efficiency, and subsequently a decline of BC emission intensities in power plants, the residential sector, and transportation. On the other hand, the BC emission intensities had increased in the industrial and agricultural sectors, mainly due to an expansion of low-efficiency industry (coke and brick production) in developing countries and to an increasing usage of diesel in agriculture in developed countries. {\textcopyright} 2014 American Chemical Society.}, author = {Wang, Rong and Tao, Shu and Shen, Huizhong and Huang, Ye and Chen, Han and Balkanski, Yves and Boucher, Olivier and Ciais, Philippe and Shen, Guofeng and Li, Wei and Zhang, Yanyan and Chen, Yuanchen and Lin, Nan and Su, Shu and Li, Bengang and Liu, Junfeng and Liu, Wenxin}, doi = {10.1021/es5021422}, issn = {0013-936X}, journal = {Environmental Science {\&} Technology}, month = {jun}, number = {12}, pages = {6780--6787}, title = {{Trend in Global Black Carbon Emissions from 1960 to 2007}}, url = {https://pubs.acs.org/doi/10.1021/es5021422}, volume = {48}, year = {2014} } @article{Wang2014a, abstract = {We use a global chemical transport model (GEOS-Chem) to interpret aircraft curtain observations of black carbon (BC) aerosol over the Pacific from 85°N to 67°S during the 2009–2011 HIAPER (High-Performance Instrumented Airborne Platform for Environmental Research) Pole-to-Pole Observations (HIPPO) campaigns. Observed concentrations are very low, implying much more efficient scavenging than is usually implemented in models. Our simulation with a global source of 6.5 Tg a−1 and mean tropospheric lifetime of 4.2 days (versus 6.8 ± 1.8 days for the Aerosol Comparisons between Observations and Models (AeroCom) models) successfully simulates BC concentrations in source regions and continental outflow and captures the principal features of the HIPPO data but is still higher by a factor of 2 (1.48 for column loads) over the Pacific. It underestimates BC absorbing aerosol optical depths (AAODs) from the Aerosol Robotic Network by 32{\%} on a global basis. Only 8.7{\%} of global BC loading in GEOS-Chem is above 5 km, versus 21 ± 11{\%} for the AeroCom models, with important implications for radiative forcing estimates. Our simulation yields a global BC burden of 77 Gg, a global mean BC AAOD of 0.0017, and a top-of-atmosphere direct radiative forcing (TOA DRF) of 0.19 W m−2, with a range of 0.17–0.31 W m−2 based on uncertainties in the BC atmospheric distribution. Our TOA DRF is lower than previous estimates (0.27 ± 0.06 W m−2 in AeroCom, 0.65–0.9 W m−2 in more recent studies). We argue that these previous estimates are biased high because of excessive BC concentrations over the oceans and in the free troposphere.}, author = {Wang, Qiaoqiao and Jacob, Daniel J. and Spackman, J. Ryan and Perring, Anne E. and Schwarz, Joshua P. and Moteki, Nobuhiro and Marais, Elo{\"{i}}se A. and Ge, Cui and Wang, Jun and Barrett, Steven R. H.}, doi = {10.1002/2013JD020824}, isbn = {2169-897X}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {jan}, number = {1}, pages = {195--206}, title = {{Global budget and radiative forcing of black carbon aerosol: Constraints from pole-to-pole (HIPPO) observations across the Pacific}}, url = {http://doi.wiley.com/10.1002/2013JD020824}, volume = {119}, year = {2014} } @article{Wang2018, abstract = {Dimethyl sulfide (DMS), primarily produced by marine organisms, contributes significantly to sulfate aerosol loading over the ocean after being oxidized in the atmosphere. In addition to exerting a direct radiative effect, the resulting aerosol particles act as cloud condensation nuclei, modulating cloud properties and extent, with impacts on atmospheric radiative transfer and climate. Thus, changes in pelagic ecosystems, such as phytoplankton physiology and community structure, may influence organosulfur production, and subsequently affect climate via the sulfur cycle. A fully coupled Earth system model, including explicit marine ecosystems and the sulfur cycle, is used here to investigate the impacts of changes associated with individual phytoplankton groups on DMS emissions and climate. Simulations show that changes in phytoplankton community structure, DMS production efficiency, and interactions of multielement biogeochemical cycles can all lead to significant differences in DMS transfer to the atmosphere. Subsequent changes in sulfate aerosol burden, cloud condensation nuclei number, and radiative effect are examined. We find the global annual mean cloud radiative effect shifts up to 0.21 W/m2, and the mean surface temperature increases up to 0.1 °C due to DMS production changes associated with individual phytoplankton group in simulations with radiative effects at the 2,100 levels under an 8.5 scenario. However, changes in DMS emissions, radiative effect, and surface temperature are more intensive on regional scales. Hence, we speculate that major uncertainties associated with future marine sulfur cycling will involve strong region-to-region climate shifts. Further understanding of marine ecosystems and the relevant phytoplankton-aerosol-climate linkage are needed for improving climate projections.}, author = {Wang, Shanlin and Maltrud, Mathew E. and Burrows, Susannah M. and Elliott, Scott M. and Cameron-Smith, Philip}, doi = {10.1029/2017GB005862}, issn = {19449224}, journal = {Global Biogeochemical Cycles}, keywords = {climate impact,community composition change,dimethyl sulfide,phytoplankton}, month = {jun}, number = {6}, pages = {1005--1026}, publisher = {American Geophysical Union ({\{}AGU{\}})}, title = {{Impacts of Shifts in Phytoplankton Community on Clouds and Climate via the Sulfur Cycle}}, volume = {32}, year = {2018} } @misc{Wang2015, abstract = {Non-methane hydrocarbons (NMHCs) play a critical role in the photochemical production of ozone (O3) and organic aerosols. Obtaining an accurate understanding on temporal trends of NMHC emissions is essential for predicting air quality changes and evaluating the effectiveness of current control measures. In this study, we evaluated temporal trends of anthropogenic NMHC emissions during August in Beijing based on ambient measurements during selected summer periods at an urban site in Beijing from 2002 to 2013. In the contrast to the results from the most recent inventory (Multi-resolution Emission Inventory for China, MEIC), which reported that anthropogenic NMHC emissions during August increased by 28{\%} from 2004 to 2012, whereas mixing ratios of NMHCs measured at this urban site decreased by 37{\%} during the same time period. A positive matrix factorization (PMF) model was applied to these NMHC measurements for source apportionment. The results showed that the relative contributions of vehicular exhaust and gasoline evaporation to measured NMHC concentrations decreased by 66{\%} during August from 2004 to 2012, comparable to the relative decline of 67{\%} for transportation-related NMHC emissions reported by the MEIC inventory. This finding indicates that the implementation of stricter emissions standards for new vehicles and specific control measures for in-use vehicles has been effective for reducing transportation-related NMHC emissions. In addition, the PMF results suggested that there were no significant temporal changes in NMHC concentrations from solvent use and industry during August from 2004 to 2012, in contrast with the rapid rate of increase (8.8{\%} yr-1) reported by the MEIC inventory. To re-evaluate the NMHC emissions trends for solvent use and industry, annual variations in NMHC / NOx ratios were compared between ambient measurements at the PKU site and the MEIC inventory. In contrast to the significant rise in NMHC / NOx ratios from the MEIC inventory, the measured NMHC / NOx ratios declined by 14{\%} during August from 2005 to 2012. The inferred NMHC / NOx ratios based on PMF results exhibited a comparable decline of 11{\%} to measured ratios. These results indicate that the increase rate for NMHC emissions from solvent use and industry in Beijing might be overestimated in the current inventory; therefore, additional research is necessary to verify the NMHC emission trends for this source.}, author = {Wang, M. and Shao, M. and Chen, W. and Lu, S. and Liu, Y. and Yuan, B. and Zhang, Q. and Zhang, Q. and Chang, C. C. and Wang, B. and Zeng, L. and Hu, M. and Yang, Y. and Li, Y.}, booktitle = {Atmospheric Chemistry and Physics}, doi = {10.5194/acp-15-1489-2015}, issn = {16807324}, number = {3}, pages = {1489--1502}, title = {{Trends of non-methane hydrocarbons (NMHC) emissions in Beijing during 2002-2013}}, volume = {15}, year = {2015} } @article{Wang2011, abstract = {Abstract. We use a cloud-system-resolving model to study marine-cloud brightening. We examine how injected aerosol particles that act as cloud condensation nuclei (CCN) are transported within the marine boundary layer and how the additional particles in clouds impact cloud microphysical processes, and feedback on dynamics. Results show that the effectiveness of cloud brightening depends strongly on meteorological and background aerosol conditions. Cloud albedo enhancement is very effective in a weakly precipitating boundary layer and in CCN-limited conditions preceded by heavy and/or persistent precipitation. The additional CCN help sustain cloud water by weakening the precipitation substantially in the former case and preventing the boundary layer from collapse in the latter. For a given amount of injected CCN, the injection method (i.e., number and distribution of sprayers) is critical to the spatial distribution of these CCN. Both the areal coverage and the number concentration of injected particles are key players but neither one always emerges as more important than the other. The same amount of injected material is much less effective in either strongly precipitating clouds or polluted clouds, and it is ineffective in a relatively dry boundary layer that supports clouds of low liquid water path. In the polluted case and "dry" case, the CCN injection increases drop number concentration but lowers supersaturation and liquid water path. As a result, the cloud experiences very weak albedo enhancement, regardless of the injection method.}, author = {Wang, H. and Rasch, P. J. and Feingold, G.}, doi = {10.5194/acp-11-4237-2011}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {9}, pages = {4237--4249}, title = {{Manipulating marine stratocumulus cloud amount and albedo: a process-modelling study of aerosol–cloud–precipitation interactions in response to injection of cloud condensation nuclei}}, url = {https://acp.copernicus.org/articles/11/4237/2011/}, volume = {11}, year = {2011} } @article{Wang2019SCES, abstract = {Accurate determination of the atmospheric particulate matter mass concentration and chemical composition is helpful in exploring the causes and sources of atmospheric enthalpy pollution and in evaluating the rationality of environmental air quality control strategies. Based on the sampling and chemical composition data of PM2.5 in different key regions of China in the CARE-China observation network, this research analyzes the environmental air quality data released by the China National Environmental Monitoring Centre during the studied period to determine the changes in the particulate matter mass concentration in key regions and the evolution of the corresponding chemical compositions during the implementation of the Action Plan for Prevention and Control of Air Pollution from 2013--2017. The results show the following. (1) The particulate matter mass concentration in China showed a significant downward trend; however, the PM2.5 annual mass concentration in 64{\%} of cities exceeds the New Chinese Ambient Air Quality Standard (CAAQS) Grade II (GB3095-2012). The region to the east of the Taihang Mountains, the Fenhe and Weihe River Plain and the Urumqi-Changji regions in Xinjiang, all have PM2.5 concentration loading that is still high, and heavy haze pollution occurred frequently in the autumn and winter. (2) During the heavy pollution in the autumn and winter, the concentrations of sulfate and organic components decreased significantly. The mean {\$}{\$}{\{}$\backslash$rm{\{}SO{\}}{\}}{\_}4{\^{}}{\{}2-{\}}{\$}{\$}SO42−concentration in PM2.5 decreased by 76{\%}, 12{\%}, 81{\%} and 38{\%} in Beijing-Tianjin-Hebei (BTH), the Pearl River Delta (PRD), the Sichuan-Chongqing region (SC) and the Fenhe and Weihe River Plain, respectively. The mean organic matter (OM) concentration decreased by 70{\%}, 44{\%}, 48{\%} and 31{\%}, respectively, and the mean concentration of {\$}{\$}{\{}$\backslash$rm{\{}NH{\}}{\}}{\_}4{\^{}}+{\$}{\$}NH4+decreased by 68{\%}, 1.6{\%}, 38{\%} and 25{\%}, respectively. The mean elemental carbon (EC) concentration decreased by 84{\%} and 20{\%} in BTH and SC, respectively, and it increased by 61{\%} and 11{\%} in the PRD and Fenhe and Weihe River Plain, respectively. The mean concentration of mineral and unresolved chemical components (MI) dropped by 70{\%}, 24{\%} and 13{\%} in BTH, the PRD and the Fenhe and Weihe River Plain, respectively. The change in the PM2.5 chemical composition is consistent with the decrease of the PM2.5 mass concentration. (3) In 2015, the mean OM concentration contributions to fine particles and coarse particles were 13--46{\%} and 46--57{\%}, respectively, and the mean MI concentration contributions to fine particles and coarse and particles were 31--60{\%} and 39--73{\%}, respectively; these values are lower than the 2013 values from the key regions, which is the most important factor behind the decrease of the particulate matter mass concentration. From 2013 to 2015, among the chemical components of different particle size fractions, the peak value of the coarse particle size fraction decreased significantly, and the fine particle size fractions of {\$}{\$}{\{}$\backslash$rm{\{}SO{\}}{\}}{\_}4{\^{}}{\{}2-{\}},{\{}$\backslash$rm{\{}NO{\}}{\}}{\_}4{\^{}}-,$\backslash$;{\{}$\backslash$rm{\{}and{\}}{\}}$\backslash$;{\{}$\backslash$rm{\{}NH{\}}{\}}{\_}4{\^{}}+{\$}{\$}SO42−,NO4−,andNH4+decreased with the decrease of the particulate matter mass concentration in different particle size fractions. The fine-particle size peaks of {\$}{\$}{\{}$\backslash$rm{\{}SO{\}}{\}}{\_}4{\^{}}{\{}2-{\}},{\{}$\backslash$rm{\{}NO{\}}{\}}{\_}4{\^{}}-,$\backslash$;{\{}$\backslash$rm{\{}and{\}}{\}}$\backslash$;{\{}$\backslash$rm{\{}NH{\}}{\}}{\_}4{\^{}}+{\$}{\$}SO42−,NO4−,andNH4+ shifted from 0.65--1.1 {\$}\mu{\$}m to the finer size range of 0.43--0.65 {\$}\mu{\$}m during the same time frame.}, author = {Wang, Yuesi and Li, Wenjie and Gao, Wenkang and Liu, Zirui and Tian, Shili and Shen, Rongrong and Ji, Dongsheng and Wang, Shuai and Wang, Lili and Tang, Guiqian and Song, Tao and Cheng, Mengtian and Wang, Gehui and Gong, Zhengyu and Hao, Jiming and Zhang, Yuanhang}, doi = {10.1007/s11430-018-9373-1}, issn = {1869-1897}, journal = {Science China Earth Sciences}, month = {dec}, number = {12}, pages = {1857--1871}, title = {{Trends in particulate matter and its chemical compositions in China from 2013–2017}}, url = {https://doi.org/10.1007/s11430-018-9373-1}, volume = {62}, year = {2019} } @article{Wang2020a, abstract = {Due to the pandemic of coronavirus disease 2019 in China, almost all avoidable activities in China are prohibited since Wuhan announced lockdown on January 23, 2020. With reduced activities, severe air pollution events still occurred in the North China Plain, causing discussions regarding why severe air pollution was not avoided. The Community Multi-scale Air Quality model was applied during January 01 to February 12, 2020 to study PM2.5 changes under emission reduction scenarios. The estimated emission reduction case (Case 3) better reproduced PM2.5. Compared with the case without emission change (Case 1), Case 3 predicted that PM2.5 concentrations decreased by up to 20{\%} with absolute decreases of 5.35, 6.37, 9.23, 10.25, 10.30, 12.14, 12.75, 14.41, 18.00 and 30.79 {\$}\mu{\$}g/m3 in Guangzhou, Shanghai, Beijing, Shijiazhuang, Tianjin, Jinan, Taiyuan, Xi'an, Zhengzhou, Wuhan, respectively. In high-pollution days with PM2.5 greater than 75 {\$}\mu{\$}g/m3, the reductions of PM2.5 in Case 3 were 7.78, 9.51, 11.38, 13.42, 13.64, 14.15, 14.42, 16.95 and 22.08 {\$}\mu{\$}g/m3 in Shanghai, Jinan, Shijiazhuang, Beijing, Taiyuan, Xi'an, Tianjin, Zhengzhou and Wuhan, respectively. The reductions in emissions of PM2.5 precursors were {\~{}}2 times of that in concentrations, indicating that meteorology was unfavorable during simulation episode. A further analysis shows that benefits of emission reductions were overwhelmed by adverse meteorology and severe air pollution events were not avoided. This study highlights that large emissions reduction in transportation and slight reduction in industrial would not help avoid severe air pollution in China, especially when meteorology is unfavorable. More efforts should be made to completely avoid severe air pollution.}, author = {Wang, Pengfei and Chen, Kaiyu and Zhu, Shengqiang and Wang, Peng and Zhang, Hongliang}, doi = {10.1016/j.resconrec.2020.104814}, issn = {09213449}, journal = {Resources, Conservation and Recycling}, keywords = {COVID-19,China,Emission reduction,Meteorology,Severe air pollution}, month = {jul}, pages = {104814}, publisher = {Elsevier B.V.}, title = {{Severe air pollution events not avoided by reduced anthropogenic activities during COVID-19 outbreak}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S092134492030135X}, volume = {158}, year = {2020} } @article{Wang2021, abstract = {Anthropogenic aerosol (AA) forcing has been shown as a critical driver of climate change over Asia since the mid-20th century. Here we show that almost all Coupled Model Intercomparison Project Phase 6 (CMIP6) models fail to capture the observed dipole pattern of aerosol optical depth (AOD) trends over Asia during 2006–2014, last decade of CMIP6 historical simulation, due to an opposite trend over eastern China compared with observations. The incorrect AOD trend over China is attributed to problematic AA emissions adopted by CMIP6. There are obvious differences in simulated regional aerosol radiative forcing and temperature responses over Asia when using two different emissions inventories (one adopted by CMIP6; the other from Peking university, a more trustworthy inventory) to driving a global aerosol-climate model separately. We further show that some widely adopted CMIP6 pathways (after 2015) also significantly underestimate the more recent decline in AA emissions over China. These flaws may bring about errors to the CMIP6-based regional climate attribution over Asia for the last two decades and projection for the next few decades, previously anticipated to inform a wide range of impact analysis.}, author = {Wang, Zhili and Lin, Lei and Xu, Yangyang and Che, Huizheng and Zhang, Xiaoye and Zhang, Hua and Dong, Wenjie and Wang, Chense and Gui, Ke and Xie, Bing}, doi = {10.1038/s41612-020-00159-2}, issn = {2397-3722}, journal = {npj Climate and Atmospheric Science}, number = {1}, pages = {2}, title = {{Incorrect Asian aerosols affecting the attribution and projection of regional climate change in CMIP6 models}}, url = {https://doi.org/10.1038/s41612-020-00159-2}, volume = {4}, year = {2021} } @article{Wang2018b, author = {Wang, Xin and Wu, Jin and Chen, Min and Xu, Xiangtao and Wang, Zhenhua and Wang, Bin and Wang, Chengzhang and Piao, Shilong and Lin, Weili and Miao, Guofang and Deng, Meifeng and Qiao, Chunlian and Wang, Jing and Xu, Shan and Liu, Lingli}, doi = {10.1111/gcb.14339}, issn = {13541013}, journal = {Global Change Biology}, month = {oct}, number = {10}, pages = {4983--4992}, title = {{Field evidences for the positive effects of aerosols on tree growth}}, url = {http://doi.wiley.com/10.1111/gcb.14339}, volume = {24}, year = {2018} } @article{Warner2014, abstract = {This study tests a novel methodology to add value to satellite data sets. This methodology, data fusion, is similar to data assimilation, except that the background model-based field is replaced by a satellite data set, in this case AIRS (Atmospheric Infrared Sounder) carbon monoxide (CO) measurements. The observational information comes from CO measurements with lower spatial coverage than AIRS, namely, from TES (Tropospheric Emission Spectrometer) and MLS (Microwave Limb Sounder). We show that combining these data sets with data fusion uses the higher spectral resolution of TES to extend AIRS CO observational sensitivity to the lower troposphere, a region especially important for air quality studies. We also show that combined CO measurements from AIRS and MLS provide enhanced information in the UTLS (upper troposphere/lower stratosphere) region compared to each product individually. The combined AIRS-TES and AIRS-MLS CO products are validated against DACOM (differential absorption mid-IR diode laser spectrometer) in situ CO measurements from the INTEX-B (Intercontinental Chemical Transport Experiment: MILAGRO and Pacific phases) field campaign and in situ data from HIPPO (HIAPER Pole-to-Pole Observations) flights. The data fusion results show improved sensitivities in the lower and upper troposphere (20-30{\%} and above 20{\%}, respectively) as compared with AIRS-only version 5 CO retrievals, and improved daily coverage compared with TES and MLS CO data. {\textcopyright} 2014 Author(s).}, author = {Warner, J. X. and Yang, R. and Wei, Z. and Carminati, F. and Tangborn, A. and Sun, Z. and Lahoz, W. and Atti{\'{e}}, J. L. and {El Amraoui}, L. and Duncan, B.}, doi = {10.5194/acp-14-103-2014}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, number = {1}, pages = {103--114}, title = {{Global carbon monoxide products from combined AIRS, TES and MLS measurements on A-train satellites}}, volume = {14}, year = {2014} } @article{Warner2016, abstract = {Abstract. Ammonia (NH3) plays an increasingly important role in the global biogeochemical cycle of reactive nitrogen as well as in aerosol formation and climate. We present extensive and nearly continuous global ammonia measurements made by the Atmospheric Infrared Sounder (AIRS) from the Aqua satellite to identify and quantify major persistent and episodic sources as well as to characterize seasonality. We examine the 13-year period from September 2002 through August 2015 with a retrieval algorithm using an optimal estimation technique with a set of three, spatially and temporally uniform a priori profiles. Vertical profiles show good agreement (∼ 5–15 {\%}) between AIRS NH3 and the in situ profiles from the winter 2013 DISCOVER-AQ (DISCOVER-Air Quality) field campaign in central California, despite the likely biases due to spatial resolution differences between the two instruments. The AIRS instrument captures the strongest consistent NH3 concentrations due to emissions from the anthropogenic (agricultural) source regions, such as South Asia (India/Pakistan), China, the United States (US), parts of Europe, Southeast (SE) Asia (Thailand/Myanmar/Laos), the central portion of South America, as well as Western and Northern Africa. These correspond primarily to irrigated croplands, as well as regions with heavy precipitation, with extensive animal feeding operations and fertilizer applications where a summer maximum and a secondary spring maximum are reliably observable. In the Southern Hemisphere (SH) regular agricultural fires contribute to a spring maximum. Regions of strong episodic emissions include Russia and Alaska as well as parts of South America, Africa, and Indonesia. Biomass burning, especially wildfires, dominate these episodic NH3 high concentrations.}, author = {Warner, Juying X and Wei, Zigang and Strow, L Larrabee and Dickerson, Russell R and Nowak, John B}, doi = {10.5194/acp-16-5467-2016}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {may}, number = {8}, pages = {5467--5479}, publisher = {Copernicus {\{}GmbH{\}}}, title = {{The global tropospheric ammonia distribution as seen in the 13-year AIRS measurement record}}, url = {https://acp.copernicus.org/articles/16/5467/2016/}, volume = {16}, year = {2016} } @article{Warner2017, abstract = {This study provides evidence of substantial increases in atmospheric ammonia (NH3) concentrations (14 year) over several of the worlds major agricultural regions, using recently available retrievals from the Atmospheric Infrared Sounder (AIRS) aboard NASA's Aqua satellite. The main sources of atmospheric NH3 are farming and animal husbandry involving reactive nitrogen ultimately derived from fertilizer use; rates of emission are also sensitive to climate change. Significant increasing trends are seen over the U.S. (2.61{\%} yr−1), the European Union (EU) (1.83{\%} yr−1), and China (2.27{\%} yr−1). Over the EU, the trend results from decreased scavenging by acid aerosols. Over the U.S., the increase results from a combination of decreased chemical loss and increased soil temperatures. Over China, decreased chemical loss, increasing temperatures, and increased fertilizer use all play a role. Over South Asia, increased NH3 emissions are masked by increased SO2 and NOx emissions, leading to increased aerosol loading and adverse health effects.}, author = {Warner, J. X. and Dickerson, R. R. and Wei, Z. and Strow, L. L. and Wang, Y. and Liang, Q.}, doi = {10.1002/2016GL072305}, issn = {19448007}, journal = {Geophysical Research Letters}, keywords = {NH3,NO2,SO2,ammonia trends,ammonium aerosols}, month = {jan}, number = {6}, pages = {2875--2884}, title = {{Increased atmospheric ammonia over the world's major agricultural areas detected from space}}, volume = {44}, year = {2017} } @article{Weber2016, author = {Weber, Rodney J and Guo, Hongyu and Russell, Armistead G and Nenes, Athanasios}, doi = {10.1038/ngeo2665}, journal = {Nature Geoscience}, month = {feb}, number = {4}, pages = {282--285}, publisher = {Springer Nature}, title = {{High aerosol acidity despite declining atmospheric sulfate concentrations over the past 15 years}}, volume = {9}, year = {2016} } @article{Weber2020, abstract = {We present an assessment of the impacts on atmospheric composition and radiative forcing of short-lived pollutants following a worldwide decrease in anthropogenic activity and emissions comparable to what has occurred in response to the COVID-19 pandemic, using the global composition-climate model United Kingdom Chemistry and Aerosols Model (UKCA). Emission changes reduce tropospheric hydroxyl radical and ozone burdens, increasing methane lifetime. Reduced SO2 emissions and oxidizing capacity lead to a decrease in sulfate aerosol and increase in aerosol size, with accompanying reductions to cloud droplet concentration. However, large reductions in black carbon emissions increase aerosol albedo. Overall, the changes in ozone and aerosol direct effects (neglecting aerosol-cloud interactions which were statistically insignificant but whose response warrants future investigation) yield a radiative forcing of −33 to −78 mWm−2. Upon cessation of emission reductions, the short-lived climate forcers rapidly return to pre-COVID levels; meaning, these changes are unlikely to have lasting impacts on climate assuming emissions return to pre-intervention levels.}, author = {Weber, James and Shin, Youngsub M and {Staunton Sykes}, John and Archer‐Nicholls, Scott and Abraham, N Luke and Archibald, Alex T}, doi = {10.1029/2020GL090326}, issn = {0094-8276}, journal = {Geophysical Research Letters}, keywords = {COVID-19,aerosol,atmospheric chemistry,atmospheric composition,climate,climate change}, month = {oct}, number = {20}, pages = {e2020GL090326}, publisher = {Blackwell Publishing Ltd}, title = {{Minimal Climate Impacts From Short‐Lived Climate Forcers Following Emission Reductions Related to the COVID‐19 Pandemic}}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2020GL090326}, volume = {47}, year = {2020} } @article{WEINSTEIN2010980, abstract = {Background PM2.5 and PM10 levels were determined during Harmattan (West African wind blown dust) at a background site in Conakry, Guinea. The study was conducted from January to February, 2004 when Harmattan dust appeared to be most pronounced. PM2.5 concentrations at the Nongo American housing compound ranged from 38$\mu$gm−3 to 177$\mu$gm−3, and PM10 ranged from 80$\mu$gm−3 to 358$\mu$gm−3, exceeding standards set by EPA and European Commission Environment Directorate-General. PTFE filter samples were analyzed for insoluble and soluble inorganic constituents by XRF and IC, respectively. Sulfur and associated SO42- concentrations were notably consistent among PM2.5 and PM10 samples which marked a relatively stable S background signal from anthropogenic sources. Enrichment factor (EF) analysis and aerosol mass reconstruction (AMR) techniques were used to isolate potential PM source contributors. The EF's for SiO2, TiO2, Al2O3, Fe2O3, and MnO were near unity which suggests a crustal origin for these elements. EF's for Na2O and K2O were above unity and highly variable, these elements were elevated due to widespread mangrove wood combustion as a fuel source in Conakry. The EF's for Cr were notably high with a median of 7 and interquartile range from 5 to 16, the elevated levels were attributed to unregulated point source and mobile source emitters in and around Conakry.}, author = {Weinstein, Jason P and Hedges, Scott R and Kimbrough, Sue}, doi = {https://doi.org/10.1016/j.chemosphere.2009.12.022}, issn = {0045-6535}, journal = {Chemosphere}, keywords = {Conakry,Guinea,Harmattan,Particulate matter,XRF}, number = {8}, pages = {980--988}, title = {{Characterization and aerosol mass balance of PM2.5 and PM10 collected in Conakry, Guinea during the 2004 Harmattan period}}, url = {http://www.sciencedirect.com/science/article/pii/S0045653509014453}, volume = {78}, year = {2010} } @article{Weisenstein2015, abstract = {Abstract. Solid aerosol particles have long been proposed as an alternative to sulfate aerosols for solar geoengineering. Any solid aerosol introduced into the stratosphere would be subject to coagulation with itself, producing fractal aggregates, and with the natural sulfate aerosol, producing liquid-coated solids. Solid aerosols that are coated with sulfate and/or have formed aggregates may have very different scattering properties and chemical behavior than uncoated non-aggregated monomers do. We use a two-dimensional (2-D) chemistry–transport–aerosol model to capture the dynamics of interacting solid and liquid aerosols in the stratosphere. As an example, we apply the model to the possible use of alumina and diamond particles for solar geoengineering. For 240 nm radius alumina particles, for example, an injection rate of 4 Tg yr−1 produces a global-average shortwave radiative forcing of −1.2 W m−2 and minimal self-coagulation of alumina although almost all alumina outside the tropics is coated with sulfate. For the same radiative forcing, these solid aerosols can produce less ozone loss, less stratospheric heating, and less forward scattering than sulfate aerosols do. Our results suggest that appropriately sized alumina, diamond or similar high-index particles may have less severe technology-specific risks than sulfate aerosols do. These results, particularly the ozone response, are subject to large uncertainties due to the limited data on the rate constants of reactions on the dry surfaces.}, author = {Weisenstein, D. K. and Keith, D. W. and Dykema, J. A.}, doi = {10.5194/acp-15-11835-2015}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {oct}, number = {20}, pages = {11835--11859}, title = {{Solar geoengineering using solid aerosol in the stratosphere}}, url = {https://acp.copernicus.org/articles/15/11835/2015/}, volume = {15}, year = {2015} } @article{Wells2020a, author = {Wells, Kelley C. and Millet, Dylan B. and Payne, Vivienne H. and Deventer, M. Julian and Bates, Kelvin H. and de Gouw, Joost A. and Graus, Martin and Warneke, Carsten and Wisthaler, Armin and Fuentes, Jose D.}, doi = {10.1038/s41586-020-2664-3}, file = {::}, issn = {0028-0836}, journal = {Nature}, month = {sep}, number = {7824}, pages = {225--233}, title = {{Satellite isoprene retrievals constrain emissions and atmospheric oxidation}}, volume = {585}, year = {2020} } @article{acp-18-11261-2018, abstract = {Nitrate aerosol makes up a significant fraction of fine particles and plays a key role in regional air quality and climate. The North China Plain (NCP) is one of the most industrialized and polluted regions in China. To ob- tain a holistic understanding of the nitrate pollution and its formation mechanisms over the NCP region, intensive field observations were conducted at three sites during summer- time in 2014–2015. The measurement sites include an ur- ban site in downtown Jinan – the capital city of Shandong Province –, a rural site downwind of Jinan city, and a re- mote mountain site at Mt. Tai (1534 m a.s.l.). Elevated ni- trate concentrations were observed at all three sites despite distinct temporal and spatial variations. Using historical ob- servations, the nitrate / PM2.5 and nitrate / sulfate ratios have statistically significantly increased in Jinan (2005–2015) and at Mt. Tai (from 2007 to 2014), indicating the worsening situation of regional nitrate pollution. A multiphase chemi- cal box model (RACM–CAPRAM) was deployed and con- strained by observations to elucidate the nitrate formation mechanisms. The principal formation route is the partition- ing of gaseous HNO3 to the aerosol phase during the day, whilst the nocturnal nitrate formation is dominated by the heterogeneous hydrolysis of N2 O5 . The daytime nitrate pro- duction in the NCP region is mainly limited by the availabil- ity of NO2 and to a lesser extent by O3 and NH3. In com- parison, the nighttime formation is controlled by both NO2 and O3. The presence of NH3 contributes to the formation of nitrate aerosol during the day, while there is slightly de- creasing nitrate formation at night. Our analyses suggest that controlling NOx and O3 is an efficient way, at the moment, to mitigate nitrate pollution in the NCP region, where NH3 is usually in excess in summer. This study provides observa- tional evidence of a rising trend of nitrate aerosol as well as scientific support for formulating effective control strategies for regional haze in China.}, author = {Wen, Liang and Xue, Likun and Wang, Xinfeng and Xu, Caihong and Chen, Tianshu and Yang, Lingxiao and Wang, Tao and Zhang, Qingzhu and Wang, Wenxing}, doi = {10.5194/acp-18-11261-2018}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, month = {aug}, number = {15}, pages = {11261--11275}, publisher = {Copernicus {\{}GmbH{\}}}, title = {{Summertime fine particulate nitrate pollution in the North China Plain: increasing trends, formation mechanisms and implications for control policy}}, url = {https://www.atmos-chem-phys.net/18/11261/2018/}, volume = {18}, year = {2018} } @article{Wennberg2018a, abstract = {Isoprene carries approximately half of the flux of non-methane volatile organic carbon emitted to the atmosphere by the biosphere. Accurate representation of its oxidation rate and products is essential for quantifying its influence on the abundance of the hydroxyl radical (OH), nitrogen oxide free radicals (NOx), ozone (O3), and, via the formation of highly oxygenated compounds, aerosol. We present a review of recent laboratory and theoretical studies of the oxidation pathways of isoprene initiated by addition of OH, O3, the nitrate radical (NO3), and the chlorine atom. From this review, a recommendation for a nearly complete gas-phase oxidation mechanism of isoprene and its major products is developed. The mechanism is compiled with the aims of providing an accurate representation of the flow of carbon while allowing quantification of the impact of isoprene emissions on HOx and NOx free radical concentrations and of the yields of products known to be involved in condensed-phase processes. Finally, a simplified (reduced) mechanism is developed for use in chemical transport models that retains the essential chemistry required to accurately simulate isoprene oxidation under conditions where it occurs in the atmosphere - above forested regions remote from large NOx emissions.}, author = {Wennberg, Paul O. and Bates, Kelvin H. and Crounse, John D. and Dodson, Leah G. and McVay, Renee C. and Mertens, Laura A. and Nguyen, Tran B. and Praske, Eric and Schwantes, Rebecca H. and Smarte, Matthew D. and {St Clair}, Jason M. and Teng, Alexander P. and Zhang, Xuan and Seinfeld, John H.}, doi = {10.1021/acs.chemrev.7b00439}, file = {::}, issn = {15206890}, journal = {Chemical Reviews}, month = {apr}, number = {7}, pages = {3337--3390}, publisher = {American Chemical Society}, title = {{Gas-Phase Reactions of Isoprene and Its Major Oxidation Products}}, volume = {118}, year = {2018} } @article{West2013, author = {West, J Jason and Smith, Steven J and Silva, Raquel A and Naik, Vaishali and Zhang, Yuqiang and Adelman, Zachariah and Fry, Meridith M and Anenberg, Susan and Horowitz, Larry W and Lamarque, Jean-Francois}, doi = {10.1038/nclimate2009}, issn = {1758-678X}, journal = {Nature Climate Change}, month = {oct}, number = {10}, pages = {885--889}, publisher = {Nature Publishing Group}, title = {{Co-benefits of mitigating global greenhouse gas emissions for future air quality and human health}}, url = {http://www.nature.com/articles/nclimate2009}, volume = {3}, year = {2013} } @article{Westervelt201643, abstract = {Climate change can influence fine particulate matter concentrations (PM2.5) through changes in air pollution meteorology. Knowledge of the extent to which climate change can exacerbate or alleviate air pollution in the future is needed for robust climate and air pollution policy decision-making. To examine the influence of climate on PM2.5, we use the Geophysical Fluid Dynamics Laboratory Coupled Model version 3 (GFDL CM3), a fully-coupled chemistry-climate model, combined with future emissions and concentrations provided by the four Representative Concentration Pathways (RCPs). For each of the RCPs, we conduct future simulations in which emissions of aerosols and their precursors are held at 2005 levels while other climate forcing agents evolve in time, such that only climate (and thus meteorology) can influence PM2.5surface concentrations. We find a small increase in global, annual mean PM2.5of about 0.21 $\mu$g m−3(5{\%}) for RCP8.5, a scenario with maximum warming. Changes in global mean PM2.5are at a maximum in the fall and are mainly controlled by sulfate followed by organic aerosol with minimal influence of black carbon. RCP2.6 is the only scenario that projects a decrease in global PM2.5with future climate changes, albeit only by −0.06 $\mu$g m−3(1.5{\%}) by the end of the 21st century. Regional and local changes in PM2.5are larger, reaching upwards of 2 $\mu$g m−3for polluted (eastern China) and dusty (western Africa) locations on an annually averaged basis in RCP8.5. Using multiple linear regression, we find that future PM2.5concentrations are most sensitive to local temperature, followed by surface wind and precipitation. PM2.5concentrations are robustly positively associated with temperature, while negatively related with precipitation and wind speed. Present-day (2006–2015) modeled sensitivities of PM2.5to meteorological variables are evaluated against observations and found to agree reasonably well with observed sensitivities (within 10–50{\%} over the eastern United States for several variables), although the modeled PM2.5is less sensitive to precipitation than in the observations due to weaker convective scavenging. We conclude that the hypothesized “climate penalty” of future increases in PM2.5is relatively minor on a global scale compared to the influence of emissions on PM2.5concentrations.}, annote = {cited By 6}, author = {Westervelt, D. M. and Horowitz, L. W. and Naik, V. and Tai, A. P.K. and Fiore, A. M. and Mauzerall, D. L.}, doi = {10.1016/j.atmosenv.2016.07.040}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Climate change,Climate model,PM2.5,Sensitivity}, pages = {43--56}, title = {{Quantifying PM2.5-meteorology sensitivities in a global climate model}}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979220566{\&}doi=10.1016{\%}2Fj.atmosenv.2016.07.040{\&}partnerID=40{\&}md5=9db9b5a9e9cdafd2b9613bb643fb98cd}, volume = {142}, year = {2016} } @article{Westervelt2018a, abstract = {Abstract. The unintended climatic implications of aerosol and precursor emission reductions implemented to protect public health are poorly understood. We investigate the precipitation response to regional changes in aerosol emissions using three coupled chemistry–climate models: NOAA Geophysical Fluid Dynamics Laboratory Coupled Model 3 (GFDL-CM3), NCAR Community Earth System Model (CESM1), and NASA Goddard Institute for Space Studies ModelE2 (GISS-E2). Our approach contrasts a long present-day control simulation from each model (up to 400 years with perpetual year 2000 or 2005 emissions) with 14 individual aerosol emissions perturbation simulations (160–240 years each). We perturb emissions of sulfur dioxide and/or carbonaceous aerosol within six world regions and assess the significance of precipitation responses relative to internal variability determined by the control simulation and across the models. Global and regional precipitation mostly increases when we reduce regional aerosol emissions in the models, with the strongest responses occurring for sulfur dioxide emissions reductions from Europe and the United States. Precipitation responses to aerosol emissions reductions are largest in the tropics and project onto the El Ni{\~{n}}o–Southern Oscillation (ENSO). Regressing precipitation onto an Indo-Pacific zonal sea level pressure gradient index (a proxy for ENSO) indicates that the ENSO component of the precipitation response to regional aerosol removal can be as large as 20{\%} of the total simulated response. Precipitation increases in the Sahel in response to aerosol reductions in remote regions because an anomalous interhemispheric temperature gradient alters the position of the Intertropical Convergence Zone (ITCZ). This mechanism holds across multiple aerosol reduction simulations and models.}, author = {Westervelt, Daniel M. and Conley, Andrew J. and Fiore, Arlene M. and Lamarque, Jean-Fran{\c{c}}ois and Shindell, Drew T. and Previdi, Michael and Mascioli, Nora R. and Faluvegi, Greg and Correa, Gustavo and Horowitz, Larry W.}, doi = {10.5194/acp-18-12461-2018}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {aug}, number = {16}, pages = {12461--12475}, title = {{Connecting regional aerosol emissions reductions to local and remote precipitation responses}}, url = {https://www.atmos-chem-phys.net/18/12461/2018/}, volume = {18}, year = {2018} } @techreport{WHO2017, address = {Copenhagen, Denmark}, author = {WHO}, doi = {https://www.euro.who.int/__data/assets/pdf_file/0019/331660/Evolution-air-quality.pdf}, isbn = {9789289052306}, pages = {32}, publisher = {World Health Organization (WHO) Regional Office for Europe}, title = {{Evolution of WHO air quality guidelines: past, present and future}}, url = {https://www.euro.who.int/{\_}{\_}data/assets/pdf{\_}file/0019/331660/Evolution-air-quality.pdf}, year = {2017} } @article{WichinkKruit2017, abstract = {This study investigates to what extent emissions of ammonia, physicochemical processes and meteorology affect the trend in the atmospheric ammonia in the Netherlands between 1993 and 2014. Two distinct periods were distinguished: a period of declining ammonia concentrations between 1993 and 2004 and a period of slightly increasing ammonia concentrations between 2005 and 2014. In the first period, large emission reductions were reported, while the second period is characterized by smaller emission reductions. The Operational Priority Substances (OPS) model was used to quantify the effects of meteorology and physicochemical processes on atmospheric ammonia concentrations. The general performance of the OPS model for ammonia concentration, ammonium concentration and wet deposition of ammonia/ammonium is quite good when evaluated with observations over the whole period. For the period 1993–2004, model sensitivity runs show that the change in atmospheric chemical conditions and specific meteorological conditions can largely explain the smaller decline in ammonia concentrations compared with the decline in ammonia emissions. Uncertainties in emissions such as changes in the timing of manure applications and uncertainties in the estimated excretion and grazing emissions might partly explain remaining differences at the beginning of the period. Low-emission manure spreading techniques have an important reducing effect on the atmospheric ammonia concentration. Without these techniques, the ammonia concentrations at the measurement stations would have been about 3.5–4 $\mu$g m−3higher in recent years. In the period between 2005 and 2014 emissions declined at a much lower rate, but the observed concentrations increased slightly. One third of the observed difference in trends can again be explained by the changed chemical conditions while no explanation has yet been found for the rest.}, author = {{Wichink Kruit}, R. J. and Aben, J. and de Vries, W. and Sauter, F. and van der Swaluw, E. and van Zanten, M. C. and van Pul, W. A.J.}, doi = {10.1016/j.atmosenv.2017.01.031}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Ammonia,Codeposition,Emissions,Measurements,Modelling,Trends}, pages = {20--30}, title = {{Modelling trends in ammonia in the Netherlands over the period 1990–2014}}, volume = {154}, year = {2017} } @article{acp-20-11955-2020, author = {Wilcox, L J and Liu, Z and Samset, B H and Hawkins, E and Lund, M T and Nordling, K and Undorf, S and Bollasina, M and Ekman, A M L and Krishnan, S and Merikanto, J and Turner, A G}, doi = {10.5194/acp-20-11955-2020}, journal = {Atmospheric Chemistry and Physics}, number = {20}, pages = {11955--11977}, title = {{Accelerated increases in global and Asian summer monsoon precipitation from future aerosol reductions}}, url = {https://acp.copernicus.org/articles/20/11955/2020/}, volume = {20}, year = {2020} } @article{Wilcox2019a, abstract = {Abstract. Asian emissions of anthropogenic aerosols and their precursors have increased rapidly since 1980, with half of the increase since the pre-industrial era occurring in this period. Transient experiments with the HadGEM3-GC2 coupled model were designed to isolate the impact of Asian anthropogenic aerosols on global climate in boreal winter. It is found that this increase has resulted in local circulation changes, which in turn have driven decreases in precipitation over China, alongside an intensification of the offshore monsoon flow. No large temperature changes are seen over China. Over India, the opposite response is found, with decreasing temperatures and increasing precipitation. The dominant feature of the local circulation changes is an increase in low-level convergence, ascent, and precipitation over the Maritime Continent, which forms part of a tropical Pacific-wide La Ni{\~{n}}a-like response. HadGEM3-GC2 also simulates pronounced far-field responses. A decreased meridional temperature gradient in the North Pacific leads to a positive Pacific–North American circulation pattern, with associated temperature anomalies over the North Pacific and North America. Anomalous northeasterly flow over northeast Europe drives advection of cold air into central and western Europe, causing cooling in this region. An anomalous anticyclonic circulation over the North Atlantic causes drying over western Europe. Using a steady-state primitive equation model, LUMA, we demonstrate that these far-field midlatitude responses arise primarily as a result of Rossby waves generated over China, rather than in the equatorial Pacific.}, author = {Wilcox, Laura J and Dunstone, Nick and Lewinschal, Anna and Bollasina, Massimo and Ekman, Annica M L and Highwood, Eleanor J}, doi = {10.5194/acp-19-9081-2019}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jul}, number = {14}, pages = {9081--9095}, publisher = {Copernicus Publications}, title = {{Mechanisms for a remote response to Asian anthropogenic aerosol in boreal winter}}, url = {https://acp.copernicus.org/articles/19/9081/2019/}, volume = {19}, year = {2019} } @article{Wild2020, author = {Wild, Oliver and Voulgarakis, Apostolos and O'Connor, Fiona and Lamarque, Jean-Fran{\c{c}}ois and Ryan, Edmund M and Lee, Lindsay}, doi = {10.5194/acp-20-4047-2020}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {apr}, number = {7}, pages = {4047--4058}, publisher = {Copernicus Publications}, title = {{Global sensitivity analysis of chemistry–climate model budgets of tropospheric ozone and OH: exploring model diversity}}, url = {https://acp.copernicus.org/articles/20/4047/2020/ https://acp.copernicus.org/articles/20/4047/2020/acp-20-4047-2020.pdf}, volume = {20}, year = {2020} } @article{Wilkinson2009, abstract = {There is considerable interest in modeling isoprene emissions from terrestrial vegetation, because these emissions exert a principal control over the oxidative capacity of the troposphere. We used a unique field experiment that employs a continuous gradient in CO2 concentration from 240 to 520 ppmv to demonstrate that isoprene emissions in Eucalyptus globulus were enhanced at the lowest CO2 concentration, which was similar to the estimated CO2 concentrations during the last Glacial Maximum, compared with 380 ppmv, the current CO2 concentration. Leaves of Liquidambar styraciflua did not show an increase in isoprene emission at the lowest CO2 concentration. However, isoprene emission rates from both species were lower for trees grown at 520 ppmv CO2 compared with trees grown at 380 ppmv CO2. When grown in environmentally controlled chambers, trees of Populus deltoides and Populus tremuloides exhibited a 30-40{\%} reduction in isoprene emission rate when grown at 800 ppmv CO2, compared with 400 ppmv CO2. P. tremuloides exhibited a 33{\%} reduction when grown at 1200 ppmv CO2, compared with 600 ppmv CO2. We used current models of leaf isoprene emission to demonstrate that significant errors occur if the CO2 inhibition of isoprene is not taken into account. In order to alleviate these errors, we present a new model of isoprene emission that describes its response to changes in atmospheric CO2 concentration. The model logic is based on assumed competition between cytosolic and chloroplastic processes for pyruvate, one of the principal substrates of isoprene biosynthesis. {\textcopyright} Journal compilation {\textcopyright} 2009 Blackwell Publishing.}, author = {Wilkinson, Michael J. and Monson, Russell K. and Trahan, Nicole and Lee, Stanfield and Brown, Erin and Jackson, Robert B. and Polley, H. Wayne and Fay, Philip A. and Fall, Ray}, doi = {10.1111/j.1365-2486.2008.01803.x}, issn = {13541013}, journal = {Global Change Biology}, keywords = {Atmospheric chemistry,CH4,Climate change,Forests,Global change,O3}, month = {may}, number = {5}, pages = {1189--1200}, title = {{Leaf isoprene emission rate as a function of atmospheric CO2 concentration}}, volume = {15}, year = {2009} } @article{WILLIAMS2018e202, author = {Williams, Martin L and Lott, Melissa C and Kitwiroon, Nutthida and Dajnak, David and Walton, Heather and Holland, Mike and Pye, Steve and Fecht, Daniela and Toledano, Mireille B and Beevers, Sean D}, doi = {10.1016/S2542-5196(18)30067-6}, issn = {25425196}, journal = {The Lancet Planetary Health}, month = {may}, number = {5}, pages = {e202--e213}, title = {{The Lancet Countdown on health benefits from the UK Climate Change Act: a modelling study for Great Britain}}, url = {http://www.sciencedirect.com/science/article/pii/S2542519618300676 https://linkinghub.elsevier.com/retrieve/pii/S2542519618300676}, volume = {2}, year = {2018} } @article{doi:10.1111/j.1365-3040.2007.01717.x, abstract = {The surface concentration of ozone ([O3]) has risen from less than 10 ppb prior to the industrial revolution to a day-time mean concentration of approximately 40 ppb over much of the northern temperate zone. If current global emission trends continue, surface [O3] is projected to rise a further 50{\%} over this century, with larger increases in many locations including Northern Hemisphere forests. This review uses statistical meta-analysis to determine mean effects, and their confidence limits, of both the current and projected elevations of [O3] on light-saturated photosynthetic CO2 uptake (Asat) and stomatal conductance (gs) in trees. In total, 348 measurements of Asat from 61 studies and 266 measures of gs from 55 studies were reviewed. Results suggested that the elevation of [O3] that has occurred since the industrial revolution is depressing Asat and gs by 11{\%} (CI 9-13{\%}) and 13{\%} (CI 11-15{\%}), respectively, where CI is the 95{\%} confidence interval. In contrast to angiosperms, gymnosperms were not significantly affected. Both drought and elevated [CO2] significantly decreased the effect of ambient [O3]. Younger trees ({\textless}4 years) were affected less than older trees. Elevation of [O3] above current levels caused progressively larger losses of Asat and gs, including gymnosperms. Results are consistent with the expectation that damage to photosynthesis depends on the cumulative uptake of ozone (O3) into the leaf. Thus, factors that lower gs lessen damage. Where both gs and [O3] were recorded, an overall decline in A sat of 0.21{\%} per mmol m-2 of estimated cumulative O 3 uptake was calculated. These findings suggest that rising [O 3], an often overlooked aspect of global atmospheric change, is progressively depressing the ability of temperate and boreal forests to assimilate carbon and transfer water vapour to the atmosphere, with significant potential effects on terrestrial carbon sinks and regional hydrologies. {\textcopyright} 2007 The Authors.}, author = {Wittig, Victoria E. and Ainsworth, Elizabeth A. and Long, Stephen P.}, doi = {10.1111/j.1365-3040.2007.01717.x}, issn = {01407791}, journal = {Plant, Cell {\&} Environment}, keywords = {Air pollution,Atmospheric change,Cumulative ozone uptake,Forests,Global change,Stomata}, number = {9}, pages = {1150--1162}, title = {{To what extent do current and projected increases in surface ozone affect photosynthesis and stomatal conductance of trees? A meta-analytic review of the last 3 decades of experiments}}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-3040.2007.01717.x}, volume = {30}, year = {2007} } @techreport{ProjectReport2018, address = {Geneva, Switzerland}, author = {WMO}, doi = {https://csl.noaa.gov/assessments/ozone/2018/downloads/}, isbn = {978-1-7329317-1-8}, pages = {588}, publisher = {World Meteorological Organization (WMO)}, series = {Global Ozone Research and Monitoring Project – Report No. 58}, title = {{Scientific Assessment of Ozone Depletion: 2018}}, url = {https://csl.noaa.gov/assessments/ozone/2018/downloads/}, year = {2018} } @article{Woodward2005, abstract = {Vegetation and climate fields from a coupled carbon-cycle ? climate model integration, which included the feedback of vegetation on climate, have been used to drive the HadAM3 AGCM incorporating the Hadley Centre mineral dust scheme in experiments to investigate future dust concentration and forcing. Comparison of 2000 with 2100 simulations shows the global annual mean atmospheric dust load increases from 4 ? 104 to 1.3 ? 105 mg m?2, due to the combination of desertification and climate change. The global mean radiative forcing due to dust increases from 0.04 to 0.21 Wm?2 at the top of the atmosphere and from ?0.74 to ?1.82 Wm?2 at the surface.}, author = {Woodward, S and Roberts, D L and Betts, R A}, doi = {10.1029/2005GL023482}, issn = {00948276}, journal = {Geophysical Research Letters}, month = {sep}, number = {18}, pages = {L18810}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{A simulation of the effect of climate change-induced desertification on mineral dust aerosol}}, url = {http://doi.wiley.com/10.1029/2005GL023482}, volume = {32}, year = {2005} } @article{Worden2013, abstract = {Abstract. Atmospheric carbon monoxide (CO) distributions are controlled by anthropogenic emissions, biomass burning, transport and oxidation by reaction with the hydroxyl radical (OH). Quantifying trends in CO is therefore important for understanding changes related to all of these contributions. Here we present a comprehensive record of satellite observations from 2000 through 2011 of total column CO using the available measurements from nadir-viewing thermal infrared instruments: MOPITT, AIRS, TES and IASI. We examine trends for CO in the Northern and Southern Hemispheres along with regional trends for Eastern China, Eastern USA, Europe and India. We find that all the satellite observations are consistent with a modest decreasing trend {\~{}} −1 {\%} yr−1 in total column CO over the Northern Hemisphere for this time period and a less significant, but still decreasing trend in the Southern Hemisphere. Although decreasing trends in the United States and Europe have been observed from surface CO measurements, we also find a decrease in CO over E. China that, to our knowledge, has not been reported previously. Some of the interannual variability in the observations can be explained by global fire emissions, but the overall decrease needs further study to understand the implications for changes in anthropogenic emissions.}, author = {Worden, H. M. and Deeter, M. N. and Frankenberg, C. and George, M. and Nichitiu, F. and Worden, J. and Aben, I. and Bowman, K. W. and Clerbaux, C. and Coheur, P. F. and de Laat, A. T. J. and Detweiler, R. and Drummond, J. R. and Edwards, D. P. and Gille, J. C. and Hurtmans, D. and Luo, M. and Mart{\'{i}}nez-Alonso, S. and Massie, S. and Pfister, G. and Warner, J. X.}, doi = {10.5194/acp-13-837-2013}, isbn = {1680-7316}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jan}, number = {2}, pages = {837--850}, title = {{Decadal record of satellite carbon monoxide observations}}, url = {https://acp.copernicus.org/articles/13/837/2013/}, volume = {13}, year = {2013} } @article{Wu2008a, abstract = {We use a global chemical transport model (GEOS-Chem) driven by a general circulation model (NASA Goddard Institute for Space Studies GCM) to investigate the effects of 2000?2050 global change in climate and emissions (the Intergovernmental Panel on Climate Change A1B scenario) on the global tropospheric ozone budget and on the policy-relevant background (PRB) ozone in the United States. The PRB ozone, defined as the ozone that would be present in U.S. surface air in the absence of North American anthropogenic emissions, has important implications for setting national air quality standards. We examine separately and then together the effects of changes in climate and anthropogenic emissions of ozone precursors. We find that the 2000?2050 change in global anthropogenic emissions of ozone precursors increases the global tropospheric ozone burden by 17{\%}. The 2000?2050 climate change increases the tropospheric ozone burden by 1.6{\%}, due mostly to lightning in the upper troposphere, and also increases global tropospheric OH by 12{\%}. In the lower troposphere, by contrast, climate change generally decreases the background ozone. The 2000?2050 increase in global anthropogenic emissions of ozone precursors increases PRB ozone by 2?6 ppb in summer; the maximum effect is found in April (3?7 ppb). The summertime PRB ozone decreases by up to 2 ppb with 2000?2050 climate change, except over the Great Plains, where it increases slightly as a result of increasing soil NOx emission. Climate change cancels out the effect of rising global anthropogenic emissions on the summertime PRB ozone in the eastern United States, but there is still a 2?5 ppb increase in the west.}, annote = {doi: 10.1029/2007JD009639}, author = {Wu, Shiliang and Mickley, Loretta J and Jacob, Daniel J and Rind, David and Streets, David G}, doi = {10.1029/2007JD009639}, issn = {0148-0227}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {PRB ozone,global change,tropospheric ozone}, month = {sep}, number = {D18}, pages = {D18312}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Effects of 2000–2050 changes in climate and emissions on global tropospheric ozone and the policy-relevant background surface ozone in the United States}}, url = {https://doi.org/10.1029/2007JD009639}, volume = {113}, year = {2008} } @article{Wu2018, abstract = {Organic aerosols (OAs) account typically for 20–90{\%} of fine particles (PM2.5) in the lower troposphere. They contribute to a wide range of environmental problems, from local issues (e.g., urban haze) to global problems (e.g., climate change). Huge efforts have been dedicated to studying the composition, abundance, spatial and temporal distribution and sources of organic aerosols in China. This review aims to summarize recent studies on characteristics and sources of OAs and assesses the current state of understanding of the organic aerosol pollution in China. The OA constitutes ∼20–45{\%} of the PM2.5 with an annual mean value of 5.2–44.5 $\mu$g/m3 at sites across China, which is about five times higher than that reported in North America and Europe. There are thousands of different organic compounds in atmospheric aerosols, but only about 5–10{\%} of them have been identified and quantified. OAs show pronounced spatial variations with much higher concentrations in Northern than Southern China. Seasonally, the highest OA concentrations are observed in the winter, whereas the lowest are in the summer. This is due to higher emission rates from anthropogenic sources (e.g., biomass and coal combustion) and poorer dispersion conditions in the winter. Approximately 60–80{\%} of total OA is apportioned by receptor modeling (such as Chemical Mass Balance, CMB) and tracer-yield method, based on the source profiles of primary organic aerosols (POA) and secondary OA (SOA) derived from local emission sources. A number of OA sources are identified, including motor vehicles, industrial emissions, biomass combustion, food cooking, and coal combustion for POA and anthropogenic and biogenic emissions for SOA. Industrial emissions and motor vehicular exhaust are the dominant sources of organic aerosols in the industrialized areas of Northern China, as well as the Pearl River Delta and Eastern China, whereas in other urban areas, residential coal combustion and motor vehicular exhaust are the dominant sources in winter and summer respectively.}, author = {Wu, Xuefang and Vu, Tuan V and Shi, Zongbo and Harrison, Roy M and Liu, Di and Cen, Kuang}, doi = {https://doi.org/10.1016/j.atmosenv.2018.06.025}, issn = {1352-2310}, journal = {Atmospheric Environment}, keywords = {China,Organic aerosols,Source apportionment,Spatial distribution,Temporal variations}, pages = {187--212}, title = {{Characterization and source apportionment of carbonaceous PM2.5 particles in China – A review}}, url = {https://www.sciencedirect.com/science/article/pii/S1352231018304084}, volume = {189}, year = {2018} } @article{Xi2016, abstract = {A regional dust model system is applied to quantify the anthropogenic dust emission in the post-Soviet Central Asia from 2000 to 2014. Two physically based dust schemes suggest that a proportion of 18.3-32.8{\%} of total dust emissions is contributed by agricultural land use and the desiccation of Aral Sea, whereas a simplified dust scheme yields higher estimates in the range of 49.7-56.5{\%} depending on whether a static or dynamic preferential dust source function is used. The dust schemes also differ greatly in the spatial distribution of anthropogenic dust and the sensitivity to the use of land use intensity in separating natural and human-made source areas, suggesting that the model representation of erosion threshold velocity, especially the role of vegetation, is a key source of model uncertainty in quantifying anthropogenic dust. The relative importance of agriculture and dried Aral Sea bed (Aralkum) differs greatly among the dust schemes. Despite the increased dust from the expansion of Aralkum, there is a negative trend in the anthropogenic dust proportion, indicating a shift of dust emission toward natural source areas. All dust schemes show a decrease in anthropogenic dust in response to land cover changes over agricultural lands.}, author = {Xi, Xin and Sokolik, Irina N.}, doi = {10.1002/2016JD025556}, issn = {2169897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {oct}, number = {20}, pages = {12270--12281}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Quantifying the anthropogenic dust emission from agricultural land use and desiccation of the Aral Sea in Central Asia}}, url = {http://doi.wiley.com/10.1002/2016JD025556}, volume = {121}, year = {2016} } @article{Xia2009, abstract = {A detailed $\alpha$-pinene oxidation mechanism was reduced systematically through the successive application of five mechanism reduction techniques. The resulting re- duced mechanism preserves the ozone- and organic aerosol- forming properties of the original mechanism, while us- ing less species. The methodologies employed included a directed relation graph method with error propagation (DRGEP, which removed a large number of redundant species and reactions), principal component analysis of the rate sensitivity matrix (PCA, used to remove unnecessary re- actions), the quasi-steady-state approximation (QSSA, used to remove some QSS species), an iterative screening method (ISSA, which removes redundant species and reactions si- multaneously), and a new lumping approach dependent on the hydrocarbon to NOx ratio (which reduced the number of species in mechanism subsets for specific hydrocarbon to NOx ranges). This multistage methodology results in a reduction ratio of 2.5 for the number of both species and reactions com- pared with the full mechanism. The simplified mechanism reproduces the important gas and aerosol phase species (the latter are examined in detail by individual condensing species as well as in classes according to four functional groups: PANs, nitrates, organic peroxides, and organic acids). The total SOA mass is also well represented in the condensed mechanism, to within 16{\%} of the detailed mechanism under a wide range of conditions. The methodology described here is general, and may be used in general mechanism reduction problems.}, author = {Xia, A. G. and Michelangeli, D. V. and Makar, P. A.}, doi = {10.5194/acp-9-4341-2009}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, keywords = {Physical Chemistry (incl. Structural)}, month = {apr}, number = {13}, pages = {4341--4362}, title = {{Mechanism reduction for the formation of secondary organic aerosol for integration into a 3-dimensional regional air quality model: $\alpha$-Pinene oxidation system}}, url = {https://app.dimensions.ai/details/publication/pub.1045473051 https://www.atmos-chem-phys.net/9/4341/2009/acp-9-4341-2009.pdf}, volume = {9}, year = {2009} } @article{XIE2018309, author = {Xie, Yang and Dai, Hancheng and Xu, Xinghan and Fujimori, Shinichiro and Hasegawa, Tomoko and Yi, Kan and Masui, Toshihiko and Kurata, Gakuji}, doi = {https://doi.org/10.1016/j.envint.2018.07.008}, issn = {0160-4120}, journal = {Environment International}, keywords = {Air quality,CGE,Climate mitigation,Economic impact,Health co-benefit}, pages = {309--318}, title = {{Co-benefits of climate mitigation on air quality and human health in Asian countries}}, url = {http://www.sciencedirect.com/science/article/pii/S0160412018305841}, volume = {119}, year = {2018} } @article{https://doi.org/10.1029/2020GL089429, abstract = {Abstract Using observations and model simulations (ESM4.1) during 1988–2018, we show large year-to-year variability in western U.S. PM2.5 pollution caused by regional and distant fires. Widespread wildfires, combined with stagnation, caused summer PM2.5 pollution in 2017 and 2018 to exceed 2 standard deviations over long-term averages. ESM4.1 with a fire emission inventory constrained by satellite-derived fire radiative energy and aerosol optical depth captures the observed surface PM2.5 means and extremes above the 35 $\mu$g/m3 U.S. air quality standard. However, aerosol emissions from the widely used Global Fire Emissions Database (GFED) must be increased by 5 times for ESM4.1 to match observations. On days when observed PM2.5 reached 35–175 $\mu$g/m3, wildfire emissions can explain 90{\%} of total PM2.5, with smoke transported from Canada contributing 25–50{\%} in northern states, according to model sensitivity simulations. Fire emission uncertainties pose challenges to accurately assessing the impacts of fire smoke on air quality, radiation, and climate.}, annote = {e2020GL089429 2020GL089429}, author = {Xie, Yuanyu and Lin, Meiyun and Horowitz, Larry W}, doi = {https://doi.org/10.1029/2020GL089429}, journal = {Geophysical Research Letters}, keywords = {air quality,climate,drought,emission uncertainties,wildfires}, number = {16}, pages = {e2020GL089429}, title = {{Summer PM2.5 Pollution Extremes Caused by Wildfires Over the Western United States During 2017–2018}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL089429}, volume = {47}, year = {2020} } @article{Xu2018428, abstract = {Particulate matter with the diameter smaller than 2.5 {\'{i}} µ{\'{i}}¼‡m (PM2.5) poses health threats to human population. Regardless of efforts to regulate the pollution sources, it is unclear how climate change caused by greenhouse gases (GHGs) would affect PM2.5 levels. Using century-long ensemble sim-ulations with Community Earth System Model 1 (CESM1), we show that, if the anthropogenic emissions would remain at the level in the year 2005, the global surface concentration and atmospheric column burden of sulfate, black carbon, and primary organic carbon would still increase by 5{\%}–10{\%} at the end of 21st century (2090–2100) due to global warming alone. The decrease in the wet removal flux of PM2.5, despite an increase in global precipitation, is the primary cause of the increase in the PM2.5 column burden. Regionally over North America and East Asia, a shift of future precipitation toward more frequent heavy events contributes to weakened wet removal fluxes. Our results suggest climate change impact needs to be accounted for to define the future emission standards necessary to meet air quality standard.}, annote = {cited By 0}, author = {Xu, Yangyang and Lamarque, Jean Fran{\c{c}}ois}, doi = {10.1002/2017EF000684}, issn = {23284277}, journal = {Earth's Future}, keywords = {air pollution,black carbon,global warming,mitigation,organics,sulfate}, number = {3}, pages = {428--440}, title = {{Isolating the Meteorological Impact of 21st Century GHG Warming on the Removal and Atmospheric Loading of Anthropogenic Fine Particulate Matter Pollution at Global Scale}}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043484615{\&}doi=10.1002{\%}2F2017EF000684{\&}partnerID=40{\&}md5=a7199da90e0aa9af5d9c282f91f1ecce}, volume = {6}, year = {2018} } @article{Xu2012, abstract = {We examine the formation of nitrate and ammonium on five types of externally mixed pre-existing aerosols using the hybrid dynamic method in a global chemistry transport model. The model developed here predicts a similar spatial pattern of total aerosol nitrate and ammonium to that of several pioneering studies, but separates the effects of nitrate and ammonium on pure sulfate, biomass burning, fossil fuel, dust and sea salt aerosols. Nitrate and ammonium boost the scattering efficiency of sulfate and organic matter but lower the extinction of sea salt particles since the hygroscopicity of a mixed nitrate-ammonium-sea salt particle is less than that of pure sea salt. The direct anthropogenic forcing of particulate nitrate and ammonium at the top of the atmosphere (TOA) is estimated to be -0.12 W m-2. Nitrate, ammonium and nitric acid gas also affect aerosol activation and the reflectivity of clouds. The first aerosol indirect forcing by anthropogenic nitrate (gas plus aerosol) and ammonium is estimated to be -0.09 W m-2 at the TOA, almost all of which is due to condensation of nitric acid gas onto growing droplets (-0.08 W m-2). {\textcopyright} Author(s) 2012. CC Attribution 3.0 License.}, author = {Xu, L. and Penner, J. E.}, doi = {10.5194/acp-12-9479-2012}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, month = {oct}, number = {20}, pages = {9479--9504}, title = {{Global simulations of nitrate and ammonium aerosols and their radiative effects}}, volume = {12}, year = {2012} } @article{Xu2013, abstract = {There is growing international interest in mitigating climate change during the early part of this century by reducing emissions of short-lived climate pollutants (SLCPs), in addition to reducing emissions of CO2. The SLCPs include methane (CH4), black carbon aerosols (BC), tropospheric ozone (O3) and hydrofluorocarbons (HFCs). Recent studies have estimated that by mitigating emissions of CH4, BC, and O3 using available technologies, about 0.5 to 0.6 C warming can be avoided by mid-21st century. Here we show that avoiding production and use of high-GWP (global warming potential) HFCs by using technologically feasible low-GWP substitutes to meet the increasing global demand can avoid as much as another 0.5 C warming by the end of the century. This combined mitigation of SLCPs would cut the cumulative warming since 2005 by 50{\%} at 2050 and by 60{\%} at 2100 from the CO2-only mitigation scenarios, significantly reducing the rate of warming and lowering the probability of exceeding the 2° C warming threshold during this century. {\textcopyright} 2013 Author(s).}, author = {Xu, Y. and Zaelke, D. and Velders, G. J.M. and Ramanathan, V.}, doi = {10.5194/acp-13-6083-2013}, issn = {16807316}, journal = {Atmospheric Chemistry and Physics}, number = {12}, pages = {6083--6089}, title = {{The role of HFCs in mitigating 21st century climate change}}, url = {https://www.atmos-chem-phys.net/13/6083/2013/}, volume = {13}, year = {2013} } @article{Yang2016, abstract = {Over the past fifty years, considerable efforts have been devoted to measuring the concentration and chemical speciation of volatile organic compounds (VOCs) in ambient air and emissions. Recently, it has become possible to directly determine the overall effect of atmospheric trace gases on the oxidant hydroxyl radicals (OH), by measuring OH reactivity (OH loss frequency). Quantifying total OH reactivity is one way to characterize the roles of VOCs in formation of ground-level ozone and secondary organic aerosols (SOA). Approaches for measuring total OH reactivity in both emissions and ambient air have been progressing and have been applied in a wide range of studies. Here we evaluate the main techniques used to measure OH reactivity, including two methods directly measuring OH decay and one comparative reactivity method (CRM), and summarize the existing experimental and modeling studies. Total OH reactivity varies significantly on spatial, diurnal, seasonal and vertical bates. Comparison with individually detected OH sinks often reveals a significant missing reactivity, ranging from 20{\%} to over 80{\%} in some environments. Missing reactivity has also been determined in most source emission studies. These source measurements, as well as numerical models, have indicated that both undetected primary emissions and unmeasured secondary products could contribute to missing reactivity. A quantitative understanding of total OH reactivity of various sources and ambient environments will enhance our understanding of the suite of compounds found in emissions as well as chemical processes, and will also provide an opportunity for the improvement of atmospheric chemical mechanisms. (C) 2016 Published by Elsevier Ltd.}, annote = {Times Cited: 21 Williams, Jonathan/K-7686-2017 Williams, Jonathan/0000-0001-9421-1703 0 21 1873-2844}, author = {Yang, Yudong and Shao, Min and Wang, Xuemei and Noelscher, Anke C and Kessel, Stephan and Guenther, Alex and Williams, Jonathan}, doi = {10.1016/j.atmosenv.2016.03.010}, isbn = {1352-2310}, journal = {Atmospheric Environment}, pages = {147--161}, title = {{Towards a quantitative understanding of total OH reactivity: A review}}, volume = {134}, year = {2016} } @article{acp-19-2405-2019, author = {Yang, Y and Smith, S J and Wang, H and Mills, C M and Rasch, P J}, doi = {10.5194/acp-19-2405-2019}, journal = {Atmospheric Chemistry and Physics}, number = {4}, pages = {2405--2420}, title = {{Variability, timescales, and nonlinearity in climate responses to black carbon emissions}}, url = {https://www.atmos-chem-phys.net/19/2405/2019/}, volume = {19}, year = {2019} } @article{Yang2019, abstract = {Abstract Anthropogenic sulfur compounds play an important role in acid deposition, aerosol particle formation, and subsequent radiative forcing and human fine particulate exposure. There are substantial uncertainties in processes influencing sulfate and precursor distributions, however, that have not yet been resolved through comparisons with observations. We find here an underappreciated factor that has a large impact on model results: uncertain emission height. Global aerosol-climate model simulations indicate that the assumed effective anthropogenic emission height is very important to SO2 near-surface concentrations and vertical profile. The global range of near-surface SO2 concentration over land (ocean) due to uncertainty in industrial (international shipping) emission injection height is 81{\%} (76{\%}), relative to the average concentration. This sensitivity is much larger than the uncertainty of SO2 emission rates. Black carbon and primary organic matter concentration and profiles are also sensitive to emission heights (53{\%} over land and 28{\%} over oceans). The impact of emission height uncertainty is larger in winter for land-based emissions, but larger in summer over the Northern Hemisphere ocean for shipping emissions. The variation in aerosol optical depth related to shipping emission injection heights is 11{\%} over oceans, revealing the potential importance of injection height on aerosol forcing and climatic effects. The large impact on SO2 concentrations can confound attempts to use surface, aircraft, and satellite observations to constrain the importance of other processes that govern sulfur compound distributions in the atmosphere. The influence of emission height on vertical SO2 column also will impact the accuracy of satellite retrievals.}, author = {Yang, Yang and Smith, Steven J and Wang, Hailong and Lou, Sijia and Rasch, Philip J}, doi = {10.1029/2018JD030001}, issn = {2169-897X}, journal = {Journal of Geophysical Research: Atmospheres}, month = {apr}, number = {8}, pages = {4812--4826}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Impact of Anthropogenic Emission Injection Height Uncertainty on Global Sulfur Dioxide and Aerosol Distribution}}, volume = {124}, year = {2019} } @article{Yang2020, abstract = {The reduced human activities and associated decreases in aerosol emissions during the COVID-19 pandemic are expected to affect climate. Assuming emission changes during lockdown, back-to-work and post-lockdown stages of COVID-19, climate model simulations show a surface warming over continental regions of the Northern Hemisphere. In January–March, there was an anomalous warming of 0.05–0.15 K in eastern China, and the surface temperature increase was 0.04–0.07 K in Europe, eastern United States, and South Asia in March–May. The longer the emission reductions undergo, the warmer the climate would become. The emission reductions explain the observed temperature increases of 10–40{\%} over eastern China relative to 2019. A southward shift of the ITCZ is also seen in the simulations. This study provides an insight into the impact of COVID-19 pandemic on global and regional climate and implications for immediate actions to mitigate fast global warming.}, author = {Yang, Yang and Ren, Lili and Li, Huimin and Wang, Hailong and Wang, Pinya and Chen, Lei and Yue, Xu and Liao, Hong}, doi = {10.1029/2020GL089788}, issn = {0094-8276}, journal = {Geophysical Research Letters}, keywords = {COVID-19,aerosol,climate response,emission reduction,global warming}, month = {oct}, number = {19}, pages = {e2020GL089788}, publisher = {Blackwell Publishing Ltd}, title = {{Fast Climate Responses to Aerosol Emission Reductions During the COVID‐19 Pandemic}}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2020GL089788}, volume = {47}, year = {2020} } @article{Yao2019, author = {Yao, Xiaohong and Zhang, Leiming}, doi = {10.1021/acsomega.9b03284}, issn = {2470-1343}, journal = {ACS Omega}, month = {dec}, number = {26}, pages = {22133--22142}, publisher = {American Chemical Society}, title = {{Causes of Large Increases in Atmospheric Ammonia in the Last Decade across North America}}, volume = {4}, year = {2019} } @article{Yarragunta2017, abstract = {In the present study, MOZART-4 (Model for Ozone and Related chemical Tracers-Version-4) simulation has been made from 2003 to 2007 and compared with satellite and in-situ observations with a specific focus on Indian subcontinent to illustrate the capabilities of MOZART-4 model. The model simulated CO have been compared with latest version (version-6) of MOPITT (Measurement Of Pollution In The Troposphere) carbon monoxide (CO) retrievals at 900, 800 and 700{\"{i}}¿½hPa. Model reproduces major features present in satellite observations. However model significantly overestimates CO over the entire Indian region at 900{\"{i}}¿½hPa and moderately overestimates at 800{\"{i}}¿½hPa and 700{\"{i}}¿½hPa. The frequency distribution of all simulated data points with respect to MOZART error shows maximum in the error range of 10–20{\%} at all pressure levels. Over total Indian landmass, the percentage of gridded CO data that are being overestimated in the range of 0–30{\%} at 900{\"{i}}¿½hPa, 800{\"{i}}¿½hPa and 700{\"{i}}¿½hPa are 58{\%}, 62{\%} and 66{\%} respectively. The study reflects very good correlation between two datasets over Central India (CI) and Southern India (SI). The coefficient of determination (r2) is found to be 0.68–0.78 and 0.70–0.78 over the CI and SI respectively. The weak correlation is evident over Northern India (NI) with r2values of 0.1–0.3. Over Eastern India (EI), Good correlation at 800{\"{i}}¿½hPa (r2{\"{i}}¿½={\"{i}}¿½0.72) and 700{\"{i}}¿½hPa (r2{\"{i}}¿½={\"{i}}¿½0.66) whereas moderately weak correlation at 900{\"{i}}¿½hPa (r2{\"{i}}¿½={\"{i}}¿½0.48) has been observed. In contrast, Over Western India (WI), strong correlation is evident at 900{\"{i}}¿½hPa (r2{\"{i}}¿½={\"{i}}¿½0.64) and moderately weak association is found to be present at 800{\"{i}}¿½hPa and 700{\"{i}}¿½hPa. Model fairly reproduces seasonal cycle of CO in the lower troposphere over most of the Indian regions. However, during June to December, model shows overestimation over NI. The magnitude of overestimation is increasing linearly from 900{\"{i}}¿½hPa to 700{\"{i}}¿½hPa level. During April–June months, model results are coinciding with observed CO concentrations over SI region at 900{\"{i}}¿½hPa. Model simulation has been compared with surface in-situ observations over ten Indian locations. Model performance is found to be moderate to good over various observational locations. However, over highly polluted megacities, model underestimates observed CO concentration by up to 3500{\"{i}}¿½ppbv. A case study over the forest fire prone area reveals the clear increase of modeled and retrieved CO in February–March and a decrease in May which is coinciding with biomass burning emissions and fire counts. Model performance is found to be relatively poor over this region with r2of 0.29 and slope of 0.56.}, author = {Yarragunta, Y. and Srivastava, S. and Mitra, D.}, doi = {10.1016/j.atmosres.2016.09.010}, issn = {01698095}, journal = {Atmospheric Research}, keywords = {Carbon monoxide,Chemistry transport modeling,MOPITT,MOZART}, month = {feb}, pages = {35--47}, title = {{Validation of lower tropospheric carbon monoxide inferred from MOZART model simulation over India}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0169809516303477}, volume = {184}, year = {2017} } @article{Yienger1995, author = {Yienger, J. J. and Levy, H.}, doi = {10.1029/95JD00370}, issn = {0148-0227}, journal = {Journal of Geophysical Research: Atmospheres}, number = {D6}, pages = {11447}, title = {{Empirical model of global soil-biogenic NOx emissions}}, url = {http://doi.wiley.com/10.1029/95JD00370}, volume = {100}, year = {1995} } @article{Young2013a, abstract = {We have analysed time-slice simulations from 17 global models, participating in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), to explore changes in present-day (2000) hydroxyl radical (OH) concentration and methane (CH4) lifetime relative to preindustrial times (1850) and to 1980. A comparison of modeled and observation-derived methane and methyl chloroform lifetimes suggests that the present-day global multi-model mean OH concentration is overestimated by 5 to 10{\%} but is within the range of uncertainties. The models consistently simulate higher OH concentrations in the Northern Hemisphere (NH) compared with the Southern Hemisphere (SH) for the present-day (2000; inter-hemispheric ratios of 1.13 to 1.42), in contrast to observation-based approaches which generally indicate higher OH in the SH although uncertainties are large. Evaluation of simulated carbon monoxide (CO) concentrations, the primary sink for OH, against ground-based and satellite observations suggests low biases in the NH that may contribute to the high north-south OH asymmetry in the models. The models vary widely in their regional distribution of present-day OH concentrations (up to 34 {\%}). Despite large regional changes, the multi-model global mean (mass-weighted) OH concentration changes little over the past 150 yr, due to concurrent increases in factors that enhance OH (humidity, tropospheric ozone, nitrogen oxide (NOx) emissions, and UV radiation due to decreases in stratospheric ozone), compensated by increases in OH sinks (methane abundance, carbon monoxide and non-methane volatile organic carbon (NMVOC) emissions). The large inter-model diversity in the sign and magnitude of preindustrial to present-day OH changes (ranging from a decrease of 12.7{\%} to an increase of 14.6 {\%}) indicate that uncertainty remains in our understanding of the long-term trends in OH and methane lifetime. We show that this diversity is largely explained by the different ratio of the change in global mean tropospheric CO and NOx burdens (Delta CO/Delta NOx, approximately represents changes in OH sinks versus changes in OH sources) in the models, pointing to a need for better constraints on natural precursor emissions and on the chemical mechanisms in the current generation of chemistry-climate models. For the 1980 to 2000 period, we find that climate warming and a slight increase in mean OH (3.5 +/- 2.2 {\%}) leads to a 4.3 +/- 1.9{\%} decrease in the methane lifetime. Analysing sensitivity simulations performed by 10 models, we find that preindustrial to present-day climate change decreased the methane lifetime by about four months, representing a negative feedback on the climate system. Further, we analysed attribution experiments performed by a subset of models relative to 2000 conditions with only one precursor at a time set to 1860 levels. We find that global mean OH increased by 46.4 +/- 12.2{\%} in response to preindustrial to present-day anthropogenic NOx emission increases, and decreased by 17.3 +/- 2.3 {\%}, 7.6 +/- 1.5 {\%}, and 3.1 +/- 3.0{\%} due to methane burden, and anthropogenic CO, and NMVOC emissions increases, respectively.}, author = {Young, P. J. and Archibald, A. T. and Bowman, K. W. and Lamarque, J.-F. and Naik, V. and Stevenson, D. S. and Tilmes, S. and Voulgarakis, A. and Wild, O. and Bergmann, D. and Cameron-Smith, P. and Cionni, I. and Collins, W. J. and Dals{\o}ren, S. B. and Doherty, R. M. and Eyring, V. and Faluvegi, G. and Horowitz, L. W. and Josse, B. and Lee, Y. H. and MacKenzie, I. A. and Nagashima, T. and Plummer, D. A. and Righi, M. and Rumbold, S. T. and Skeie, R. B. and Shindell, D. T. and Strode, S. A. and Sudo, K. and Szopa, S. and Zeng, G.}, doi = {10.5194/acp-13-2063-2013}, isbn = {1680-7316}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {feb}, number = {4}, pages = {2063--2090}, title = {{Pre-industrial to end 21st century projections of tropospheric ozone from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)}}, url = {http://www.atmos-chem-phys.net/13/2063/2013/}, volume = {13}, year = {2013} } @article{Young2018, abstract = {The goal of the Tropospheric Ozone Assessment Report (TOAR) is to provide the research community with an up-to-date scientific assessment of tropospheric ozone, from the surface to the tropopause. While a suite of observations provides significant information on the spatial and temporal distribution of tropospheric ozone, observational gaps make it necessary to use global atmospheric chemistry models to synthesize our understanding of the processes and variables that control tropospheric ozone abundance and its variability. Models facilitate the interpretation of the observations and allow us to make projections of future tropospheric ozone and trace gas distributions for different anthropogenic or natural perturbations. This paper assesses the skill of current-generation global atmospheric chemistry models in simulating the observed present-day tropospheric ozone distribution, variability, and trends. Drawing upon the results of recent international multi-model intercomparisons and using a range of model evaluation techniques, we demonstrate that global chemistry models are broadly skillful in capturing the spatio-temporal variations of tropospheric ozone over the seasonal cycle, for extreme pollution episodes, and changes over interannual to decadal periods. However, models are consistently biased high in the northern hemisphere and biased low in the southern hemisphere, throughout the depth of the troposphere, and are unable to replicate particular metrics that define the longer term trends in tropospheric ozone as derived from some background sites. When the models compare unfavorably against observations, we discuss the potential causes of model biases and propose directions for future developments, including improved evaluations that may be able to better diagnose the root cause of the model-observation disparity. Overall, model results should be approached critically, including determining whether the model performance is acceptable for the problem being addressed, whether biases can be tolerated or corrected, whether the model is appropriately constituted, and whether there is a way to satisfactorily quantify the uncertainty.}, author = {Young, P. J. and Naik, V. and Fiore, A. M. and Gaudel, A. and Guo, J. and Lin, M. Y. and Neu, J. L. and Parrish, D. D. and Rieder, H. E. and Schnell, J. L. and Tilmes, S. and Wild, O. and Zhang, L. and Ziemke, J. R. and Brandt, J. and Delcloo, A. and Doherty, R. M. and Geels, C. and Hegglin, M. I. and Hu, L. and Im, U. and Kumar, R. and Luhar, A. and Murray, L. and Plummer, D. and Rodriguez, J. and Saiz-Lopez, A. and Schultz, M. G. and Woodhouse, M. T. and Zeng, G.}, doi = {10.1525/elementa.265}, issn = {2325-1026}, journal = {Elementa: Science of the Anthropocene}, keywords = {air quality,extremes,global models,greenhouse gas,observations,pollution,trends,tropospheric ozone,variability}, number = {1}, pages = {10}, title = {{Tropospheric Ozone Assessment Report: Assessment of global-scale model performance for global and regional ozone distributions, variability, and trends}}, url = {https://www.elementascience.org/article/10.1525/elementa.265/}, volume = {6}, year = {2018} } @article{Yu2018, abstract = {The concentrations of atmospheric ammonia ([NH3]) have been observed to be increasing over the United States in the last decade, especially in Eastern United States. It is important to understand this temporal trend and variation due to the role of NH3 in particle formation and its ecological effects. Here the long-term trend of [NH3] over the United States is investigated using GEOS-Chem, a global 3-D tropospheric chemistry model, and is corroborated with empirical evidence from the Ammonia Monitoring Network. Model simulations, consistent with observations, show increase in [NH3] over the United States from 2001 to 2016, with magnitude largest in the East ({\~{}}5{\%} to 12{\%}/year) and smallest in the West ({\~{}}0{\%} to 5{\%}/year). Reasons for this are examined, and evidence for the role of decreasing SO2 and NOx emissions in increasing [NH3] is provided. The contributions of meteorology and NH3 emission changes to the [NH3] increase appear to be small during the period. Our sensitivity study suggests that decreasing SO2 and NOx emissions over the United States owing to stringent regulations explain about 2/3 and 1/3 of the increase in [NH3], respectively. This effect is different for various NH3 and SO2 and NOx regimes. Given the continued reduction of SO2 and NOx emissions due to U.S. regulations mainly aimed at PM2.5 reduction, the present results are important towards better assessing the environmental impact of emission controlling policies.}, author = {Yu, Fangqun and Nair, Arshad Arjunan and Luo, Gan}, doi = {10.1029/2018JD028412}, issn = {21698996}, journal = {Journal of Geophysical Research: Atmospheres}, keywords = {Ammonia Monitoring Network,ecosystem,emission reduction,gaseous ammonia,long-term trend,particle formation}, month = {aug}, number = {15}, pages = {8315--8325}, publisher = {American Geophysical Union ({\{}AGU{\}})}, title = {{Long-Term Trend of Gaseous Ammonia Over the United States: Modeling and Comparison With Observations}}, volume = {123}, year = {2018} } @article{Yu2019, abstract = {The ambient air quality of Guangzhou in 2016 has significantly improved since Guangzhou and its surrounding cities implemented a series of air pollution control measures from 2014 to 2016. This study not only estimated the effects of meteorology and emission control measures on air quality improvement in Guangzhou but also assessed the contributions of emissions reduction from various sources through the combination of observation data and simulation results from Weather Research and Forecasting - Community Multiscale Air Quality (WRF-CMAQ) modeling system. Results showed that the favorable meteorological conditions in 2016 alleviated the air pollution. Compared to change in meteorology, implementing emission control measures in Guangzhou and surrounding cities was more beneficial for air quality improvement, and it could reduce the concentrations of SO2, NO2, PM2.5, PM10, and O3 by 9.7 $\mu$g m−3 (48.4{\%}), 9.2 $\mu$g m−3 (17.7{\%}), 7.7 $\mu$g m−3 (14.6{\%}), 9.7 $\mu$g m−3 (13.4{\%}), and 12.0 $\mu$g m−3 (7.7{\%}), respectively. Furthermore, emission control measures that implemented in Guangzhou contributed most to the concentration reduction of SO2, NO2, PM2.5, and PM10 (46.0{\%} for SO2, 15.2{\%} for NO2, 9.4{\%} for PM2.5, and 9.1{\%} for PM10), and it increased O3 concentration by 2.4{\%}. With respect to the individual contributions of source emissions reduction, power sector emissions reduction showed the greatest contribution in reducing the concentrations of SO2, NO2, PM2.5, and PM10 due to the implementation of Ultra-Clean control technology. As for O3 mitigation, VOCs product-related source emissions reduction was most effective, and followed by transportation source emissions reduction, while the reductions of power sector, industrial boiler, and industrial process source might not be as effective. Our findings provide scientific advice for the Guangzhou government to formulate air pollution prevention and control policies in the future.}, author = {Yu, Meifang and Zhu, Yun and Lin, Che-Jen and Wang, Shuxiao and Xing, Jia and Jang, Carey and Huang, Jizhang and Huang, Jinying and Jin, Jiangbo and Yu, Lian}, doi = {10.1016/j.jenvman.2019.05.046}, issn = {03014797}, journal = {Journal of Environmental Management}, keywords = {Air quality,Emission control measures,Guangzhou,Meteorology,WRF-CMAQ model}, month = {aug}, pages = {127--137}, title = {{Effects of air pollution control measures on air quality improvement in Guangzhou, China}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0301479719306565}, volume = {244}, year = {2019} } @article{Yu2016, abstract = {Abstract Stratospheric aerosols cool the Earth by scattering sunlight. Although sulfuric acid dominates the stratospheric aerosol, this study finds that organic material in the lowermost stratosphere contributes 30?40{\%} of the nonvolcanic stratospheric aerosol optical depth (sAOD). Simulations indicate that nonvolcanic sAOD has increased 77{\%} since 1850. Stratospheric aerosol accounts for 21{\%} of the total direct aerosol radiative forcing (which is negative) and 12{\%} of the total aerosol optical depth (AOD) increase from organics and sulfate. There is a larger stratospheric influence on radiative forcing (i.e., 21{\%}) relative to AOD (i.e., 12{\%}) because an increase of tropospheric black carbon warms the planet while stratospheric aerosols (including black carbon) cool the planet. Radiative forcing from nonvolcanic stratospheric aerosol mass of anthropogenic origin, including organics, has not been widely considered as a significant influence on the climate system.}, annote = {doi: 10.1002/2016GL070153}, author = {Yu, Pengfei and Murphy, Daniel M and Portmann, Robert W and Toon, Owen B and Froyd, Karl D and Rollins, Andrew W and Gao, Ru-Shan and Rosenlof, Karen H}, doi = {10.1002/2016GL070153}, issn = {0094-8276}, journal = {Geophysical Research Letters}, keywords = {aerosols,organics,radiative forcing,stratosphere,sulfate}, month = {sep}, number = {17}, pages = {9361--9367}, publisher = {John Wiley {\&} Sons, Ltd}, title = {{Radiative forcing from anthropogenic sulfur and organic emissions reaching the stratosphere}}, url = {https://doi.org/10.1002/2016GL070153}, volume = {43}, year = {2016} } @article{Yu2020, author = {Yu, Pei and Xu, Rongbin and Abramson, Michael J and Li, Shanshan and Guo, Yuming}, doi = {https://doi.org/10.1016/S2542-5196(19)30267-0}, issn = {2542-5196}, journal = {The Lancet Planetary Health}, number = {1}, pages = {e7--e8}, title = {{Bushfires in Australia: a serious health emergency under climate change}}, url = {http://www.sciencedirect.com/science/article/pii/S2542519619302670}, volume = {4}, year = {2020} } @article{acp-17-6073-2017, author = {Yue, X and Unger, N and Harper, K and Xia, X and Liao, H and Zhu, T and Xiao, J and Feng, Z and Li, J}, doi = {10.5194/acp-17-6073-2017}, journal = {Atmospheric Chemistry and Physics}, number = {9}, pages = {6073--6089}, title = {{Ozone and haze pollution weakens net primary productivity in China}}, url = {https://www.atmos-chem-phys.net/17/6073/2017/}, volume = {17}, year = {2017} } @article{Yue2014, abstract = {We apply an off-line process-based vegetation model (the Yale Interactive Terrestrial Biosphere model) to assess the impacts of ozone (O3) vegetation damage on gross primary productivity (GPP) in the United States during the past decade (1998–2007). The model's GPP simulation is evaluated at 40 sites of the North American Carbon Program (NACP) synthesis. The ecosystem-scale model version reproduces interannual variability and seasonality of GPP at most sites, especially in croplands. Inclusion of the O3 damage impact decreases biases of simulated GPP at most of the NACP sites. The simulation with the O3 damage effect reproduces 64{\%} of the observed variance in summer GPP and 42{\%} on the annual average. Based on a regional gridded simulation over the US, summertime average O3-free GPP is 6.1 g C m−2 day−1 (9.5 g C m−2 day−1 in the east of 95° W and 3.9 g C m−2 day−1 in the west). O3 damage decreases GPP by 4–8{\%} on average in the eastern US and leads to significant decreases of 11–17{\%} in east coast hot spots. Sensitivity simulations show that a 25{\%} decrease in surface O3 concentration halves the average GPP damage to only 2–4{\%}, suggesting the substantial co-benefits to ecosystem health that may be achieved via O3 air pollution control.}, author = {Yue, X. and Unger, N.}, doi = {10.5194/acp-14-9137-2014}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, keywords = {pzanis}, month = {sep}, number = {17}, pages = {9137--9153}, title = {{Ozone vegetation damage effects on gross primary productivity in the United States}}, url = {http://www.atmos-chem-phys.net/14/9137/2014/}, volume = {14}, year = {2014} } @article{Zakoura2018, abstract = {This study examines the role of grid resolution on particulate nitrate predictions over the Eastern US during the summer using the three-dimensional chemical transport model (CTM) PMCAMx. The Base Case simulation with coarse resolution (36 × 36 km) often predicts high nighttime nitrate production rates thus leading to overprediction of aerosol nitrate levels. This overprediction is due to the artificial mixing of NOx-rich plumes from major point and area sources with the background atmosphere. Three different horizontal grid resolutions were tested (12 × 12 km, 4 × 4 km and telescoping 12x12/4 × 4 km) for parts of the northeastern US. The bias for PM2.5 nitrate decreased by 65{\%} when the grid resolution was increased to 4 × 4 km. However, the remaining discrepancies between nitrate predictions and measurements indicate the need for additional improvements including better simulation of the total emissions of ammonia and their temporal evolution, improved description of nighttime chemistry and mixing etc.}, author = {Zakoura, M. and Pandis, S. N.}, doi = {10.1016/j.atmosenv.2018.05.066}, issn = {18732844}, journal = {Atmospheric Environment}, keywords = {Aerosol nitrate,Grid resolution,PMCAMx}, pages = {390--400}, title = {{Overprediction of aerosol nitrate by chemical transport models: The role of grid resolution}}, url = {http://www.sciencedirect.com/science/article/pii/S1352231018303765}, volume = {187}, year = {2018} } @article{Zanatta2017, abstract = {{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Black carbon (BC) contributes to Arctic warming, yet sources of Arctic BC and their geographic contributions remain uncertain. We interpret a series of recent airborne (NETCARE 2015; PAMARCMiP 2009 and 2011 campaigns) and ground-based measurements (at Alert, Barrow and Ny-{\AA}lesund) from multiple methods (thermal, laser incandescence and light absorption) with the GEOS-Chem global chemical transport model and its adjoint to attribute the sources of Arctic BC. This is the first comparison with a chemical transport model of refractory BC (rBC) measurements at Alert. The springtime airborne measurements performed by the NETCARE campaign in 2015 and the PAMARCMiP campaigns in 2009 and 2011 offer BC vertical profiles extending to above 6{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}km across the Arctic and include profiles above Arctic ground monitoring stations. Our simulations with the addition of seasonally varying domestic heating and of gas flaring emissions are consistent with ground-based measurements of BC concentrations at Alert and Barrow in winter and spring (rRMSE{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater} {\&}lt; 13{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}) and with airborne measurements of the BC vertical profile across the Arctic (rRMSE{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater} = 17{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}) except for an underestimation in the middle troposphere (500–700{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}hPa).{\textless}br{\textgreater}{\textless}br{\textgreater}Sensitivity simulations suggest that anthropogenic emissions in eastern and southern Asia have the largest effect on the Arctic BC column burden both in spring (56{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}) and annually (37{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}), with the largest contribution in the middle troposphere (400–700{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}hPa). Anthropogenic emissions from northern Asia contribute considerable BC (27{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%} in spring and 43{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%} annually) to the lower troposphere (below 900{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}hPa). Biomass burning contributes 20{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%} to the Arctic BC column annually.{\textless}br{\textgreater}{\textless}br{\textgreater}At the Arctic surface, anthropogenic emissions from northern Asia (40–45{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}) and eastern and southern Asia (20–40{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}) are the largest BC contributors in winter and spring, followed by Europe (16–36{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}). Biomass burning from North America is the most important contributor to all stations in summer, especially at Barrow.{\textless}br{\textgreater}{\textless}br{\textgreater}Our adjoint simulations indicate pronounced spatial heterogeneity in the contribution of emissions to the Arctic BC column concentrations, with noteworthy contributions from emissions in eastern China (15{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}) and western Siberia (6.5{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}). Although uncertain, gas flaring emissions from oilfields in western Siberia could have a striking impact (13{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}) on Arctic BC loadings in January, comparable to the total influence of continental Europe and North America (6.5{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%} each in January). Emissions from as far as the Indo-Gangetic Plain could have a substantial influence (6.3{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%} annually) on Arctic BC as well.{\textless}/p{\textgreater}}, author = {Zanatta, Marco and Huang, Lin and Herber, Andreas B. and Abbatt, Jonathan P. D. and Henze, Daven K. and Leaitch, W. Richard and Lee, Colin J. and Schulz, Hannes and Willis, Megan D. and Morrow, Andrew and Sharma, Sangeeta and Burkart, Julia and Xu, Jun-Wei and Martin, Randall V.}, doi = {10.5194/acp-17-11971-2017}, journal = {Atmospheric Chemistry and Physics}, number = {19}, pages = {11971--11989}, publisher = {Copernicus GmbH}, title = {{Source attribution of Arctic black carbon constrained by aircraft and surface measurements}}, volume = {17}, year = {2017} } @article{Zanis2020, abstract = {In this work, we use Coupled Model Intercomparison Project Phase 6 (CMIP6) simulations from 10 Earth system models (ESMs) and general circulation models (GCMs) to study the fast climate responses on pre-industrial climate, due to present-day aerosols. All models carried out two sets of simulations: a control experiment with all forcings set to the year 1850 and a perturbation experiment with all forcings identical to the control, except for aerosols with precursor emissions set to the year 2014. In response to the pattern of all aerosols effective radiative forcing (ERF), the fast temperature responses are characterized by cooling over the continental areas, especially in the Northern Hemisphere, with the largest cooling over East Asia and India, sulfate being the dominant aerosol surface temperature driver for present-day emissions. In the Arctic there is a warming signal for winter in the ensemble mean of fast temperature responses, but the model-to-model variability is large, and it is presumably linked to aerosol-induced circulation changes. The largest fast precipitation responses are seen in the tropical belt regions, generally characterized by a reduction over continental regions and presumably a southward shift of the tropical rain belt. This is a characteristic and robust feature among most models in this study, associated with weakening of the monsoon systems around the globe (Asia, Africa and America) in response to hemispherically asymmetric cooling from a Northern Hemisphere aerosol perturbation, forcing possibly the Intertropical Convergence Zone (ITCZ) and tropical precipitation to shift away from the cooled hemisphere despite that aerosols' effects on temperature and precipitation are only partly realized in these simulations as the sea surface temperatures are kept fixed. An interesting feature in aerosol-induced circulation changes is a characteristic dipole pattern with intensification of the Icelandic Low and an anticyclonic anomaly over southeastern Europe, inducing warm air advection towards the northern polar latitudes in winter.}, author = {Zanis, Prodromos and Akritidis, Dimitris and Georgoulias, Aristeidis K. and Allen, Robert J. and Bauer, Susanne E. and Boucher, Olivier and Cole, Jason and Johnson, Ben and Deushi, Makoto and Michou, Martine and Mulcahy, Jane and Nabat, Pierre and Olivi{\'{e}}, Dirk and Oshima, Naga and Sima, Adriana and Schulz, Michael and Takemura, Toshihiko and Tsigaridis, Konstantinos}, doi = {10.5194/acp-20-8381-2020}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {jul}, number = {14}, pages = {8381--8404}, title = {{Fast responses on pre-industrial climate from present-day aerosols in a CMIP6 multi-model study}}, url = {https://acp.copernicus.org/articles/20/8381/2020/}, volume = {20}, year = {2020} } @article{Zare2014, abstract = {Abstract. Accurate estimates of emissions from natural sources are needed for reliable predictions of ozone and fine particulate matter (PM2.5) using air quality models. In this study, the large-scale atmospheric chemistry transport model, DEHM (the Danish Eulerian Hemispheric Model) is further developed, evaluated and applied to study and quantify the contributions of natural emissions of VOCs, NOx, NH3, SO2, CH4, PM, CO and sea salt to the concentration of ozone and formation of PM2.5 for the year 2006. Natural source categories adopted in the recent model are vegetation, lightning, soils, wild animals and oceans. In this study, the model has been further developed to include more Biogenic Volatile Organic Compounds (BVOCs) and to implement a scheme for secondary organic aerosols as well as an updated description of sea-salt emissions. Our simulations indicate that in the Northern Hemisphere the contribution from natural emissions to the average annual ozone mixing ratios over land is between 4–30 ppbV. Among the natural emissions, BVOCs are found to be the most significant contributors to ozone formation in 2006, enhancing the average ozone mixing ratio by about 11{\%} over the land areas of the Northern Hemisphere. The relative contribution of all the natural emissions to ozone is found to be highest in the northern part of South America by about 42{\%}. Similarly, the highest contribution of all the natural sources to total fine particles over land is found to be in South America by about 74{\%} and sea-salt aerosols demonstrated to play the most important role. However, over the rest of the regions in the model domain the largest contribution from the natural sources to PM2.5 in the specific year 2006 is due to wildfires. The contribution from natural emissions to the mean PM2.5 concentration over the land areas in the model domain is about 34{\%}.}, author = {Zare, A. and Christensen, J. H. and Gross, A. and Irannejad, P. and Glasius, M. and Brandt, J.}, doi = {10.5194/acp-14-2735-2014}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {mar}, number = {6}, pages = {2735--2756}, title = {{Quantifying the contributions of natural emissions to ozone and total fine PM concentrations in the Northern Hemisphere}}, url = {https://www.atmos-chem-phys.net/14/2735/2014/}, volume = {14}, year = {2014} } @article{Zeng2015, abstract = {{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} We investigate the impact of biogenic emissions on carbon monoxide (CO) and formaldehyde (HCHO) in the Southern Hemisphere (SH), with simulations using two different biogenic emission inventories for isoprene and monoterpenes. Results from four atmospheric chemistry models are compared to continuous long-term ground-based CO and HCHO column measurements at the SH Network for the Detection of Atmospheric Composition Change (NDACC) sites, the satellite measurement of tropospheric CO columns from the Measurement of Pollution in the Troposphere (MOPITT), and in situ surface CO measurements from across the SH, representing a subset of the National Oceanic and Atmospheric Administration's Global Monitoring Division (NOAA GMD) network. Simulated mean model CO using the Model of Emissions of Gases and Aerosols from Nature (v2.1) computed in the frame work of the Land Community Model (CLM-MEGANv2.1) inventory is in better agreement with both column and surface observations than simulations adopting the emission inventory generated from the LPJ-GUESS dynamical vegetation model framework, which markedly underestimate measured column and surface CO at most sites. Differences in biogenic emissions cause large differences in CO in the source regions which propagate to the remote SH. Significant inter-model differences exist in modelled column and surface CO, and secondary production of CO dominates these inter-model differences, due mainly to differences in the models' oxidation schemes for volatile organic compounds, predominantly isoprene oxidation. While biogenic emissions are a significant factor in modelling SH CO, inter-model differences pose an additional challenge to constrain these emissions. Corresponding comparisons of HCHO columns at two SH mid-latitude sites reveal that all models significantly underestimate the observed values by approximately a factor of 2. There is a much smaller impact on HCHO of the significantly different biogenic emissions in remote regions, compared to the source regions. Decreased biogenic emissions cause decreased CO export to remote regions, which leads to increased OH; this in turn results in increased HCHO production through methane oxidation. In agreement with earlier studies, we corroborate that significant HCHO sources are likely missing in the models in the remote SH.{\textless}/p{\textgreater}}, author = {Zeng, G. and Williams, J. E. and Fisher, J. A. and Emmons, L. K. and Jones, N. B. and Morgenstern, O. and Robinson, J. and Smale, D. and Paton-Walsh, C. and Griffith, D. W.T.}, doi = {10.5194/acp-15-7217-2015}, isbn = {1680-7316}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, number = {13}, pages = {7217--7245}, title = {{Multi-model simulation of CO and HCHO in the Southern Hemisphere: comparison with observations and impact of biogenic emissions}}, volume = {15}, year = {2015} } @article{Zeng2012, abstract = {Abstract. We analyse the carbon monoxide (CO), ethane (C2H6) and hydrogen cyanide (HCN) partial columns (from the ground to 12 km) derived from measurements by ground-based solar Fourier Transform Spectroscopy at Lauder, New Zealand (45° S, 170° E), and at Arrival Heights, Antarctica (78° S, 167° E), from 1997 to 2009. Significant negative trends are calculated for all species at both locations, based on the daily-mean observed time series, namely CO (−0.94 ± 0.47{\%} yr−1), C2H6 (−2.37 ± 1.18{\%} yr−1) and HCN (−0.93 ± 0.47{\%} yr−1) at Lauder and CO (−0.92 ± 0.46{\%} yr−1), C2H6 (−2.82 ± 1.37{\%} yr−1) and HCN (−1.41 ± 0.71{\%} yr−1) at Arrival Heights. The uncertainties reflect the 95{\%} confidence limits. However, the magnitudes of the trends are influenced by the anomaly associated with the 1997–1998 El Ni{\~{n}}o Southern Oscillation event at the beginning of the time series reported. We calculate trends for each month from 1997 to 2009 and find negative trends for all months. The largest monthly trends of CO and C2H6 at Lauder, and to a lesser degree at Arrival Heights, occur during austral spring during the Southern Hemisphere tropical and subtropical biomass burning period. For HCN, the largest monthly trends occur in July and August at Lauder and around November at Arrival Heights. The correlations between CO and C2H6 and between CO and HCN at Lauder in September to November, when the biomass burning maximizes, are significantly larger that those in other seasons. A tropospheric chemistry-climate model is used to simulate CO, C2H6, and HCN partial columns for the period of 1997–2009, using interannually varying biomass burning emissions from GFED3 and annually periodic but seasonally varying emissions from both biogenic and anthropogenic sources. The model-simulated partial columns of these species compare well with the measured partial columns and the model accurately reproduces seasonal cycles of all three species at both locations. However, while the model satisfactorily captures both the seasonality and trends in HCN, it is not able to reproduce the negative trends in either C2H6 or CO. A further simulation assuming a 35{\%} decline of C2H6 and a 26{\%} decline of CO emissions from the industrial sources from 1997 to 2009 largely captures the observed trends of C2H6 and CO partial columns at both locations. Here we attribute trends in HCN exclusively to changes in biomass burning and thereby isolate the influence of anthropogenic emissions as responsible for the long-term decline in CO and C2H6. This analysis shows that biomass burning emissions are the main factors in controlling the interannual and seasonal variations of these species. We also demonstrate contributions of biomass burning emission from different southern tropical and sub-tropical regions to seasonal and interannual variations of CO at Lauder; it shows that long-range transport of biomass burning emissions from southern Africa and South America have consistently larger year-to-year contributions to the background seasonality of CO at Lauder than those from other regions (e.g. Australia and South-East Asia). However, large interannual anomalies are triggered by variations in biomass burning emissions associated with large-scale El Ni{\~{n}}o Southern Oscillation and prolonged biomass burning events, e.g. the Australian bush fires.}, author = {Zeng, G. and Wood, S. W. and Morgenstern, O. and Jones, N. B. and Robinson, J. and Smale, D.}, doi = {10.5194/acp-12-7543-2012}, isbn = {1680-7316}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {aug}, number = {16}, pages = {7543--7555}, title = {{Trends and variations in CO, C2H6, and HCN in the Southern Hemisphere point to the declining anthropogenic emissions of CO and C2H6}}, url = {https://acp.copernicus.org/articles/12/7543/2012/}, volume = {12}, year = {2012} } @article{Zhang201764, annote = {cited By 7}, author = {Zhang, H and Wang, Y and Park, T.-W. and Deng, Y}, doi = {10.1016/j.atmosres.2016.11.010}, journal = {Atmospheric Research}, pages = {64--79}, title = {{Quantifying the relationship between extreme air pollution events and extreme weather events}}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010369554{\&}doi=10.1016{\%}2Fj.atmosres.2016.11.010{\&}partnerID=40{\&}md5=c17c70746a00ae4fda6ae3e279ebf016}, volume = {188}, year = {2017} } @article{acp-16-9533-2016, author = {Zhang, Y and Bowden, J H and Adelman, Z and Naik, V and Horowitz, L W and Smith, S J and West, J J}, doi = {10.5194/acp-16-9533-2016}, journal = {Atmospheric Chemistry and Physics}, number = {15}, pages = {9533--9548}, title = {{Co-benefits of global and regional greenhouse gas mitigation for US air quality in 2050}}, url = {https://www.atmos-chem-phys.net/16/9533/2016/}, volume = {16}, year = {2016} } @article{Zhang2007, abstract = {Organic aerosol (OA) data acquired by the Aerosol Mass Spectrometer (AMS) in 37 field campaigns were deconvolved into hydrocarbon-like OA (HOA) and several types of oxygenated OA (OOA) components. HOA has been linked to primary combustion emissions (mainly from fossil fuel) and other primary sources such as meat cooking. OOA is ubiquitous in various atmospheric environments, on average accounting for 64{\%}, 83{\%} and 95{\%} of the total OA in urban, urban downwind, and rural/remote sites, respectively. A case study analysis of a rural site shows that the OOA concentration is much greater than the advected HOA, indicating that HOA oxidation is not an important source of OOA, and that OOA increases are mainly due to SOA. Most global models lack an explicit representation of SOA which may lead to significant biases in the magnitude, spatial and temporal distributions of OA, and in aerosol hygroscopic properties. Copyright 2007 by the American Geophysical Union.}, author = {Zhang, Q. and Jimenez, Jose L. and Canagaratna, M. R. and Allan, J. D. and Coe, H. and Ulbrich, I. and Alfarra, M. R. and Takami, A. and Middlebrook, A. M. and Sun, Y. L. and Dzepina, K. and Dunlea, E. and Docherty, K. and DeCarlo, P. F. and Salcedo, D. and Onasch, T. and Jayne, J. T. and Miyoshi, T. and Shimono, A. and Hatakeyama, S. and Takegawa, N. and Kondo, Y. and Schneider, J. and Drewnick, F. and Borrmann, S. and Weimer, S. and Demerjian, K. and Williams, P. and Bower, K. and Bahreini, R. and Cottrell, L. and Griffin, R. J. and Rautiainen, J. and Sun, J. Y. and Zhang, Y. M. and Worsnop, D. R.}, doi = {10.1029/2007GL029979}, issn = {00948276}, journal = {Geophysical Research Letters}, month = {jul}, number = {13}, pages = {L13801}, title = {{Ubiquity and dominance of oxygenated species in organic aerosols in anthropogenically-influenced Northern Hemisphere midlatitudes}}, url = {http://doi.wiley.com/10.1029/2007GL029979}, volume = {34}, year = {2007} } @article{Zhang2017e, abstract = {Abstract. In the present study, a ground-based counterflow virtual impactor (GCVI) was used to sample cloud droplet residual (cloud RES) particles, while a parallel PM2.5 inlet was used to sample cloud-free or cloud interstitial (cloud INT) particles. The mixing state of black carbon (BC)-containing particles and the mass concentrations of BC in the cloud-free, RES and INT particles were investigated using a single-particle aerosol mass spectrometer (SPAMS) and two aethalometers, respectively, at a mountain site (1690 m a. s. l. ) in southern China. The measured BC-containing particles were extensively internally mixed with sulfate and were scavenged into cloud droplets (with number fractions of 0.05–0.45) to a similar (or slightly lower) extent as all the measured particles (0.07–0.6) over the measured size range of 0.1–1.6 µm. The results indicate the preferential activation of larger particles and/or that the production of secondary compositions shifts the BC-containing particles towards larger sizes. BC-containing particles with an abundance of both sulfate and organics were scavenged less than those with sulfate but limited organics, implying the importance of the mixing state on the incorporation of BC-containing particles into cloud droplets. The mass scavenging efficiency of BC with an average of 33 {\%} was similar for different cloud events independent of the air mass. This is the first time that both the mixing state and cloud scavenging of BC in China have been reported. Our results would improve the knowledge on the concentration, mixing state, and cloud scavenging of BC in the free troposphere.}, author = {Zhang, Guohua and Lin, Qinhao and Peng, Long and Bi, Xinhui and Chen, Duohong and Li, Mei and Li, Lei and Brechtel, Fred J. and Chen, Jianxin and Yan, Weijun and Wang, Xinming and Peng, Pingan and Sheng, Guoying and Zhou, Zhen}, doi = {10.5194/acp-17-14975-2017}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {dec}, number = {24}, pages = {14975--14985}, title = {{The single-particle mixing state and cloud scavenging of black carbon: a case study at a high-altitude mountain site in southern China}}, url = {https://acp.copernicus.org/articles/17/14975/2017/}, volume = {17}, year = {2017} } @article{acp-19-14755-2019, abstract = {Organic aerosol (OA) particles are recognized as key factors influencing air quality and climate change. However, highly time-resolved long-term characterizations of their composition and sources in ambient air are still very limited due to challenging continuous observations. Here, we present an analysis of long-term variability of submicron OA using the combination of an aerosol chemical speciation monitor (ACSM) and a multiwavelength Aethalometer from November 2011 to March 2018 at a peri-urban background site of the Paris region (France). Source apportionment of OA was achieved via partially constrained positive matrix factorization (PMF) using the multilinear engine (ME-2). Two primary OA (POA) and two oxygenated OA (OOA) factors were identified and quantified over the entire studied period. POA factors were designated as hydrocarbon-like OA (HOA) and biomass burning OA (BBOA). The latter factor presented a significant seasonality with higher concentrations in winter with significant monthly contributions to OA (18 {\%}–33 {\%}) due to enhanced residential wood burning emissions. HOA mainly originated from traffic emissions but was also influenced by biomass burning in cold periods. OOA factors were distinguished between their less- and more-oxidized fractions (LO-OOA and MO-OOA, respectively). These factors presented distinct seasonal patterns, associated with different atmospheric formation pathways. A pronounced increase in LO-OOA concentrations and contributions (50 {\%}–66 {\%}) was observed in summer, which may be mainly explained by secondary OA (SOA) formation processes involving biogenic gaseous precursors. Conversely, high concentrations and OA contributions (32 {\%}–62 {\%}) of MO-OOA during winter and spring seasons were partly associated with anthropogenic emissions and/or long-range transport from northeastern Europe. The contribution of the different OA factors as a function of OA mass loading highlighted the dominant roles of POA during pollution episodes in fall and winter and of SOA for highest springtime and summertime OA concentrations. Finally, long-term trend analyses indicated a decreasing feature (of about −175 ng m−3 yr−1) for MO-OOA, very limited or insignificant decreasing trends for primary anthropogenic carbonaceous aerosols (BBOA and HOA, along with the fossil-fuel and biomass-burning black carbon components) and no statistically significant trend for LO-OOA over the 6-year investigated period.}, author = {Zhang, Y and Favez, O and Petit, J.-E. and Canonaco, F and Truong, F and Bonnaire, N and Crenn, V and Amodeo, T and Pr{\'{e}}v{\^{o}}t, A S H and Sciare, J and Gros, V and Albinet, A}, doi = {10.5194/acp-19-14755-2019}, journal = {Atmospheric Chemistry and Physics}, number = {23}, pages = {14755--14776}, title = {{Six-year source apportionment of submicron organic aerosols from near-continuous highly time-resolved measurements at SIRTA (Paris area, France)}}, url = {https://acp.copernicus.org/articles/19/14755/2019/}, volume = {19}, year = {2019} } @article{Zhang2012a, abstract = {Nitrate and sulfate account for a significant fraction of PM2.5 mass and are generally secondary in nature. Contributions to these two inorganic aerosol components from major sources need to be identified for policy makers to develop cost effective regional emission control strategies. In this work, a source-oriented version of the Community Multiscale Air Quality (CMAQ) model that directly tracks the contributions from multiple emission sources to secondary PM2.5 is developed to determine the regional contributions of power, industry, transportation and residential sectors as well as biogenic sources to nitrate and sulfate concentrations in China in January and August 2009. The source-oriented CMAQ model is capable of reproducing most of the available PM10 and PM2.5 mass, and PM2.5 nitrate and sulfate observations. Model prediction suggests that monthly average PM2.5 inorganic components (nitrate + sulfate + ammonium ion) can be as high as 60 $\mu$g m−3 in January and 45 $\mu$g m−3 in August, accounting for 20–40{\%} and 50–60{\%} of total PM2.5 mass. The model simulations also indicate significant spatial and temporal variation of the nitrate and sulfate concentrations as well as source contributions in the country. In January, nitrate is high over Central and East China with a maximum of 30 $\mu$g m−3 in the Sichuan Basin. In August, nitrate is lower and the maximum concentration of 16 $\mu$g m−3 occurs in North China. In January, highest sulfate occurs in the Sichuan Basin with a maximum concentration of 18 $\mu$g m−3 while in August high sulfate concentration occurs in North and East China with a similar maximum concentration. Power sector is the dominating source of nitrate and sulfate in both January and August. Transportation sector is an important source of nitrate (20–30{\%}) in both months. Industry sector contributes to both nitrate and sulfate concentrations by approximately 20–30{\%}. Residential sector contributes to approximately 10–20{\%} of nitrate and sulfate in January but its contribution is low in August.}, author = {Zhang, Hongliang and Li, Jingyi and Ying, Qi and Yu, Jian Zhen and Wu, Dui and Cheng, Yuan and He, Kebin and Jiang, Jingkun}, doi = {https://doi.org/10.1016/j.atmosenv.2012.08.014}, issn = {1352-2310}, journal = {Atmospheric Environment}, pages = {228--242}, title = {{Source apportionment of PM2.5 nitrate and sulfate in China using a source-oriented chemical transport model}}, volume = {62}, year = {2012} } @article{Zhang2020c, abstract = {Carbonaceous aerosols significantly affect global radiative forcing and climate through absorption and the scattering of sunlight. Black carbon (BC) and brown carbon (BrC) are light-absorbing carbonaceous aerosols. The direct radiative effect (DRE) of BrC is uncertain. A recent study suggests that BrC absorption is comparable to BC in the upper troposphere over biomass burning regions and that the resulting radiative heating tends to stabilize the atmosphere. Yet current climate models do not include proper physical and chemical treatments of BrC. In this study, we derived a BrC global biomass burning emission inventory on the basis of the Global Fire Emissions Database version 4 (GFED4), developed a module to simulate the light absorption of BrC in the Community Atmosphere Model version 5 (CAM5) of the Community Earth System Model (CESM), and investigated the photobleaching effect and convective transport of BrC on the basis of Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) and Deep Convective Clouds and Chemistry Project (DC3) measurements. The model simulations of BC were also evaluated using HIAPER (High- Performance Instrumented Airborne Platform for Environmental Research) Pole-to-Pole Observations (HIPPO) measurements. We found that globally BrC is a significant absorber, the DRE of which is 0.10Wm-2, more than 25{\%} of BC DRE (+39Wm-2). Most significantly, model results indicated that BrC atmospheric heating in the tropical mid and upper troposphere is larger than that of BC. The source of tropical BrC is mainly from wildfires, which are more prevalent in the tropical regions than higher latitudes and release much more BrC relative to BC than industrial sources. While BC atmospheric heating is skewed towards the northern midlatitude lower atmosphere, BrC heating is more centered in the tropical free troposphere. A possible mechanism for the enhanced convective transport of BrC is that hydrophobic high molecular weight BrC becomes a larger fraction of the BrC and less easily activated in a cloud as the aerosol ages. The contribution of BrC heating to the Hadley circulation and latitudinal expansion of the tropics is likely comparable to BC heating.}, author = {Zhang, Aoxing and Wang, Yuhang and Zhang, Yuzhong and Weber, Rodney J. and Song, Yongjia and Ke, Ziming and Zou, Yufei}, doi = {10.5194/acp-20-1901-2020}, issn = {16807324}, journal = {Atmospheric Chemistry and Physics}, pages = {1901--1920}, title = {{Modeling the global radiative effect of brown carbon: A potentially larger heating source in the tropical free troposphere than black carbon}}, volume = {20}, year = {2020} } @article{ZHANG2012150, abstract = {The object of this study was to investigate the chemical compositions of PM2.5 and its correlations with visibility and meteorological parameters in peri-urban of Xiamen, a southeast coastal city, China. PM2.5 samples were collected monthly from June 2009 to May 2010. The major compositions of PM2.5 such as water soluble inorganic ions (WSIIs) (F−, Cl−, NO2−, NO3−, SO42−, Na+, K+, NH4+, Mg2+, and Ca2+) and carbonaceous fractions (organic carbon (OC) and elemental carbon (EC)) were determined to estimate their contribution to light extinction coefficients. The results showed that the annual average concentration of PM2.5 was 86.16$\mu$g/m3, with monthly individual values ranging from 58.61$\mu$g/m3 to 109.39$\mu$g/m3. The correlation analysis showed that PM2.5 had higher correlations with visibility (r=−0.89) and relative humidity (r=−0.75), while there was no apparent correlation between PM2.5 and wind speed. Water soluble inorganic ions and carbonaceous fractions were the major compositions of PM2.5 accounting for 28.7{\%} and 20.7{\%} of the total PM2.5 mass, respectively. NO3−, SO42−, and NH4+ were the major water soluble inorganic ions, accounting for 22.7{\%}, 44.4{\%}, and 17.7{\%} of the total water soluble inorganic ions (TWSIIs), respectively. The average concentrations of secondary organic carbon (SOC) in summer, autumn, winter, and spring in Xiamen were 4.16, 6.48, 13.00 and 8.01$\mu$g/m3, which accounted for 43.4{\%}, 45.5{\%}, 54.6{\%} and 58.8{\%} of OC, respectively. The annual average light extinction coefficient of PM2.5 ((bext)fine particle) was 214.3Mm−1, which was estimated by the IMPROVE algorithm. The average percentage contributions to (bext)fine particle were 39.5{\%} for organic mass, 31.4{\%} for ammonium sulfate, 15.3{\%} ammonium nitrate, and 13.9{\%} for elemental carbon.}, author = {Zhang, Fuwang and Xu, Lingling and Chen, Jinsheng and Yu, Yanke and Niu, Zhenchuan and Yin, Liqian}, doi = {https://doi.org/10.1016/j.atmosres.2011.12.005}, issn = {0169-8095}, journal = {Atmospheric Research}, keywords = {Elemental carbon,Fine particles,Light extinction coefficients,Organic carbon,Water soluble inorganic ions,Xiamen}, pages = {150--158}, title = {{Chemical compositions and extinction coefficients of PM2.5 in peri-urban of Xiamen, China, during June 2009–May 2010}}, url = {http://www.sciencedirect.com/science/article/pii/S0169809511004157}, volume = {106}, year = {2012} } @article{Zhao2019a, author = {Zhao, Zijian and Wang, Yuxuan and Qin, Momei and Hu, Yongtao and Xie, Yuanyu and Russell, Armistead G}, doi = {10.1021/acs.est.8b04842}, journal = {Environmental Science {\&} Technology}, number = {1}, pages = {242--250}, title = {{Drought Impacts on Secondary Organic Aerosol: A Case Study in the Southeast United States}}, url = {https://doi.org/10.1021/acs.est.8b04842}, volume = {53}, year = {2019} } @article{Zhao2019, abstract = {±30 ppbv. Over the full 2000–2016 time period, using a common state-of-the-art but nonoptimized emission scenario, the impact of [OH] changes tested here can explain up to 54 {\%} of the gap between model simulations and observations. This result emphasizes the importance of better representing OH abundance and variations in CH4 forward simulations and emission optimizations performed by atmospheric inversions.]]{\textgreater}}, author = {Zhao, Yuanhong and Saunois, Marielle and Bousquet, Philippe and Lin, Xin and Berchet, Antoine and Hegglin, Michaela I. and Canadell, Josep G. and Jackson, Robert B. and Hauglustaine, Didier A. and Szopa, Sophie and Stavert, Ann R. and Abraham, Nathan Luke and Archibald, Alex T. and Bekki, Slimane and Deushi, Makoto and J{\"{o}}ckel, Patrick and Josse, B{\'{e}}atrice and Kinnison, Douglas and Kirner, Ole and Mar{\'{e}}cal, Virginie and O'Connor, Fiona M. and Plummer, David A. and Revell, Laura E. and Rozanov, Eugene and Stenke, Andrea and Strode, Sarah and Tilmes, Simone and Dlugokencky, Edward J. and Zheng, Bo}, doi = {10.5194/acp-19-13701-2019}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {nov}, number = {21}, pages = {13701--13723}, publisher = {Copernicus Publications}, title = {{Inter-model comparison of global hydroxyl radical (OH) distributions and their impact on atmospheric methane over the 2000–2016 period}}, url = {https://acp.copernicus.org/articles/19/13701/2019/}, volume = {19}, year = {2019} } @article{Zhao2019b, abstract = {The physical properties of black carbon (BC) including the mass loading, size distribution and mixing state were in-situ characterized by aircraft measurements using a single particle soot photometer (SP2) in the lower troposphere over Beijing area. The flights were conducted in both late spring and winter during the daytime with well-developed planetary boundary layer (PBL). The BC mass in the PBL (BCPBL) in late spring showed no apparent vertical gradient nor correlation with the PBL height (PBLH) due to strong convective mixing; in winter the BCPBL was more concentrated near ground and anti-correlated with the PBLH due to dilution effect of the dominant cleaner northerly air masses at higher altitude. The BC mass loading at height h, C(h) within the PBL can be extended from the surface level (C0) in late spring; for levels above the PBL, C(h) can be parameterized by applying an exponential decline function C(h) = C0*exp(h/hs), with the scale height (hs) of 0.31 ± 0.16 km and 0.66 ± 0.24 km for late spring and winter respectively. This parameterization excluded the profiles for: turbulent conditions when the BC mass was efficiently vented upwards and diluted, expressed as C(h) = C0 up to the top of the PBL; or in periods of strong southerly advection, when the entire column was significantly influenced by regional transport from the polluted south regions. The BC core mass median diameters (MMD) were commonly populated at 205–220 nm in both seasons, with additional mode of MMD ∼195 nm also frequently observed in late spring. The bulk relative coating thickness of BC (coated diameter divided by uncoated core diameter Dp/Dc) in the PBL mostly populated at 2.0–2.2 but at ∼1.2–1.6 in the lower free troposphere (FT). The mass absorption cross section of BC at 550 nm (MAC550), constrained by the SP2 measurements, was largely influenced by the coating thickness, was relatively consistent in the PBL at ∼8.6 m2 g−1, but reduced to 7–7.5 m2 g−1 in the FT or turbulent condition due to decreased coatings. The BC was found to exhibit smaller particle size in the FT but larger in the PBL, which may imply larger BC have been scavenged by low-level clouds. The BC particles trapped in the PBL or regionally transported from polluted region represent the most absorbing element in the particulate matter population and should be particularly considered in evaluating the radiative forcing impact of aerosols over this region.}, author = {Zhao, Delong and Huang, Mengyu and Tian, Ping and He, Hui and Lowe, Douglas and Zhou, Wei and Sheng, Jiujiang and Wang, Fei and Bi, Kai and Kong, Shaofei and Yang, Yan and Liu, Quan and Liu, Dantong and Ding, Deping}, doi = {10.1016/j.atmosenv.2019.06.007}, issn = {13522310}, journal = {Atmospheric Environment}, keywords = {Absorption,Aircraft measurement,Black carbon,Mixing state}, month = {sep}, pages = {296--310}, title = {{Vertical characteristics of black carbon physical properties over Beijing region in warm and cold seasons}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1352231019303929}, volume = {213}, year = {2019} } @article{Zhao2020, abstract = {The COVID-19 outbreak in China led to dramatic changes in human activities resulting from the sudden infection prevention and control measures. Here, we use ground-level observations and model simulations to examine the nationwide spatial-temporal variations of six air pollutants before and after the initiation of First-Level Public Health Emergency Response. The level of ambient NO2 declined significantly, and in most cities, the decline was dominated by reduced emissions. Meanwhile, the level of O3 increased significantly during this period, and the nonmeteorological factors explained the increase. For the other air pollutants (PM2.5, SO2, and CO), the observed declines on the national scale were obviously affected by the meteorological conditions. In Wuhan, significant declines were found for air pollutants except O3 and emissions dominated the changes, while in Beijing during the same period, only the level of NO2 significantly declined. This study clearly shows that the meteorological changes contributed substantially to the observed changes in most air pollutants, and this must be considered in evaluating the impacts of pollutant source changes on air quality during the specific event and in assessing source-oriented risks.}, author = {Zhao, Yanbin and Zhang, Kun and Xu, Xiaotian and Shen, Huizhong and Zhu, Xi and Zhang, Yanxu and Hu, Yongtao and Shen, Guofeng}, doi = {10.1021/acs.estlett.0c00304}, issn = {2328-8930}, journal = {Environmental Science {\&} Technology Letters}, month = {jun}, number = {6}, pages = {402--408}, publisher = {American Chemical Society}, title = {{Substantial Changes in Nitrogen Dioxide and Ozone after Excluding Meteorological Impacts during the COVID-19 Outbreak in Mainland China}}, url = {https://pubs.acs.org/doi/10.1021/acs.estlett.0c00304}, volume = {7}, year = {2020} } @article{Zhao2020b, author = {Zhao, Yuanhong and Saunois, Marielle and Bousquet, Philippe and Lin, Xin and Berchet, Antoine and Hegglin, Michaela I and Canadell, Josep G and Jackson, Robert B and Dlugokencky, Edward J and Langenfelds, Ray L and Ramonet, Michel and Worthy, Doug and Zheng, Bo}, doi = {10.5194/acp-20-9525-2020}, issn = {1680-7324}, journal = {Atmospheric Chemistry and Physics}, month = {aug}, number = {15}, pages = {9525--9546}, publisher = {Copernicus Publications}, title = {{Influences of hydroxyl radicals (OH) on top-down estimates of the global and regional methane budgets}}, url = {https://acp.copernicus.org/articles/20/9525/2020/ https://acp.copernicus.org/articles/20/9525/2020/acp-20-9525-2020.pdf}, volume = {20}, year = {2020} } @article{acp-13-4631-2013, author = {Zhao, P S and Dong, F and He, D and Zhao, X J and Zhang, X L and Zhang, W Z and Yao, Q and Liu, H Y}, doi = {10.5194/acp-13-4631-2013}, journal = {Atmospheric Chemistry and Physics}, number = {9}, pages = {4631--4644}, title = {{Characteristics of concentrations and chemical compositions for PM2.5 in the region of Beijing, Tianjin, and Hebei, China}}, url = {https://acp.copernicus.org/articles/13/4631/2013/}, volume = {13}, year = {2013} } @article{acp-2018-374, abstract = {Abstract. To tackle the problem of severe air pollution, China has implemented active clean air policies in recent years. As a consequence, the emissions of major air pollutants have decreased and the air quality has substantially improved. Here, we quantified China's anthropogenic emission trends from 2010{\&}ndash;2017 and identified the major driving forces of these trends by using a combination of bottom-up emission inventory and Index Decomposition Analysis (IDA) approaches. The relative change rates of China's anthropogenic emissions during 2010{\&}ndash;2017 are estimated as follows: {\&}minus;62{\%} for SO2, {\&}minus;17{\%} for NOx, {\&}plus;11{\%} for NMVOC, {\&}plus;1{\%} for NH3, {\&}minus;27{\%} for CO, {\&}minus;38{\%} for PM10, {\&}minus;35{\%} for PM2.5, {\&}minus;27{\%} for BC, {\&}minus;35{\%} for OC, and {\&}plus;18{\%} for CO2. The IDA results suggest that emission control measures are the main drivers of this reduction, in which the pollution controls on power plants and industries are the most effective mitigation measures. The emission reduction rates markedly accelerated after the year 2013, confirming the effectiveness of China's Clean Air Action that was implemented in 2013. We estimated that during 2013{\&}ndash;2017, China's anthropogenic emissions decreased by 59{\%} for SO2, 21{\%} for NOx, 23{\%} for CO, 36{\%} for PM10, 33{\%} for PM2.5, 28{\%} for BC, and 32{\%} for OC. NMVOC emissions increased by 11{\%} and NH3 emissions remained stable from 2010{\&}ndash;2017, representing the absence of effective mitigation measures for NMVOC and NH3 in current policies. The relative contributions of different sectors to emissions have significantly changed after several years' implementation of clean air policies, indicating that it is paramount to introduce new policies to enable further emission reductions in the future.}, author = {Zheng, Bo and Tong, Dan and Li, Meng and Liu, Fei and Hong, Chaopeng and Geng, Guannan and Li, Haiyan and Li, Xin and Peng, Liqun and Qi, Ji and Yan, Liu and Zhang, Yuxuan and Zhao, Hongyan and Zheng, Yixuan and He, Kebin and Zhang, Qiang}, doi = {10.5194/acp-2018-374}, issn = {1680-7375}, journal = {Atmospheric Chemistry and Physics}, pages = {14095--14111}, title = {{Trends in China's anthropogenic emissions since 2010 as the consequence of clean air actions}}, url = {https://doi.org/10.5194/acp-18-14095-2018}, volume = {18}, year = {2018} } @article{Zheng2018, abstract = {Measurements of Pollution in the Troposphere (MOPITT) satellite and ground-based carbon monoxide (CO) measurements both suggest a widespread downward trend in CO concentrations over East Asia during the period 2005–2016. This negative trend is inconsistent with global bottom-up inventories of CO emissions, which show a small increase or stable emissions in this region. We try to reconcile the observed CO trend with emission inventories using an atmospheric inversion of the MOPITT CO data that estimates emissions from primary sources, secondary production, and chemical sinks of CO. The atmospheric inversion indicates a {\~{}} −2{\%} yr−1 decrease in emissions from primary sources in East Asia from 2005–2016. The decreasing emissions are mainly caused by source reductions in China. The regional MEIC inventory for China is the only bottom up estimate consistent with the inversion-diagnosed decrease of CO emissions. According to the MEIC data, decreasing CO emissions from four main sectors (iron and steel industries, residential sources, gasoline-powered vehicles, and construction materials industries) in China explain 76{\%} of the inversion-based trend of East Asian CO emissions. This result suggests that global inventories underestimate the recent decrease of CO emission factors in China which occurred despite increasing consumption of carbon-based fuels, and is driven by rapid technological changes with improved combustion efficiency and emission control measures.}, author = {Zheng, Bo and Chevallier, Frederic and Ciais, Philippe and Yin, Yi and Deeter, Merritt N and Worden, Helen M and Wang, Yilong and Zhang, Qiang and He, Kebin}, doi = {10.1088/1748-9326/aab2b3}, issn = {1748-9326}, journal = {Environmental Research Letters}, number = {4}, pages = {44007}, publisher = {IOP Publishing}, title = {{Rapid decline in carbon monoxide emissions and export from East Asia between years 2005 and 2016}}, url = {http://dx.doi.org/10.1088/1748-9326/aab2b3}, volume = {13}, year = {2018} } @article{Zheng2019, abstract = {Atmospheric carbon monoxide (CO) concentrations have been decreasing since 2000, as observed by both satellite-and ground-based instruments, but global bottom-up emission inventories estimate increasing anthropogenic CO emissions concurrently. In this study, we use a multi-species atmospheric Bayesian inversion approach to attribute satellite-observed atmospheric CO variations to its sources and sinks in order to achieve a full closure of the global CO budget during 2000-2017. Our observation constraints include satellite retrievals of the total column mole fraction of CO, formaldehyde (HCHO), and methane (CH4) that are all major components of the atmospheric CO cycle. Three inversions (i.e., 2000-2017, 2005-2017, and 2010-2017) are performed to use the observation data to the maximum extent possible as they become available and assess the consistency of inversion results to the assimilation of more trace gas species. We identify a declining trend in the global CO budget since 2000 (three inversions are broadly consistent during overlapping periods), driven by reduced anthropogenic emissions in the US and Europe (both likely from the transport sector), and in China (likely from industry and residential sectors), as well as by reduced biomass burning emissions globally, especially in equatorial Africa (associated with reduced burned areas). We show that the trends and drivers of the inversionbased CO budget are not affected by the inter-annual variation assumed for prior CO fluxes. All three inversions contradict the global bottom-up inventories in the world's top two emitters: for the sign of anthropogenic emission trends in China (e.g., here-0:8 ± 0:5 {\%} yr-1 since 2000, while the prior gives 1:3 ± 0:4 {\%} yr-1) and for the rate of anthropogenic emission increase in South Asia (e.g., here 1:0 ± 0:6 {\%} yr-1 since 2000, smaller than 3:5 ± 0:4 {\%} yr-1 in the prior inventory). The posterior model CO concentrations and trends agree well with independent ground-based observations and correct the prior model bias. The comparison of the three inversions with different observation constraints further suggests that the most complete constrained inversion that assimilates CO, HCHO, and CH4 has a good representation of the global CO budget, and therefore matches best with independent observations, while the inversion only assimilating CO tends to underestimate both the decrease in anthropogenic CO emissions and the increase in the CO chemical production. The global CO budget data from all three inversions in this study can be accessed from https://doi.org/10.6084/m9.figshare.c.4454453.v1 (Zheng et al., 2019).}, author = {Zheng, Bo and Chevallier, Frederic and Yin, Yi and Ciais, Philippe and Fortems-Cheiney, Audrey and Deeter, Merritt N. and Parker, Robert J. and Wang, Yilong and Worden, Helen M. and Zhao, Yuanhong}, doi = {10.5194/essd-11-1411-2019}, issn = {18663516}, journal = {Earth System Science Data}, number = {3}, pages = {1411--1436}, title = {{Global atmospheric carbon monoxide budget 2000-2017 inferred from multi-species atmospheric inversions}}, volume = {11}, year = {2019} } @article{Zhou2017, abstract = {Interannual variability in baseline carbon monoxide (CO) and ozone (O3), defined as mixing ratios under minimal influence of recent and local emissions, was studied for seven rural sites in the Northeast US over 2001–2010. Annual baseline CO exhibited statistically significant decreasing trends (−4.3 to −2.3 ppbv yr−1), while baseline O3did not display trends at any site. In examining the data by season, wintertime and springtime baseline CO at the two highest sites (1.5 km and 2 km asl) did not experience significant trends. Decadal increasing trends (∼2.55 ppbv yr−1) were found in springtime and wintertime baseline O3in southern New Hampshire, which was associated with anthropogenic NOxemission reductions from the urban corridor. Biomass burning emissions impacted summertime baseline CO with ∼38{\%} variability from wildfire emissions in Russia and ∼22{\%} from Canada at five sites and impacted baseline O3at the two high elevation sites only with ∼27{\%} variability from wildfires in both Russia and Canada. The Arctic Oscillation was negatively correlated with summertime baseline O3, while the North Atlantic Oscillation was positively correlated with springtime baseline O3. This study suggested that anthropogenic and biomass burning emissions, and meteorological conditions were important factors working together to determine baseline O3and CO in the Northeast U.S. during the 2000s.}, author = {Zhou, Y. and Mao, H. and Demerjian, K. and Hogrefe, C. and Liu, J.}, doi = {10.1016/j.atmosenv.2017.06.017}, isbn = {1527253201}, issn = {13522310}, journal = {Atmospheric Environment}, keywords = {Baseline CO,Baseline O3,Emission,Meteorology,Northeast U.S.,Temporal variability}, month = {sep}, pages = {309--324}, title = {{Regional and hemispheric influences on temporal variability in baseline carbon monoxide and ozone over the Northeast US}}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1352231017303989}, volume = {164}, year = {2017} } @article{doi:10.1002/2017GL073859, abstract = {Abstract Satellite observations of formaldehyde (HCHO) columns provide top-down information on emissions of highly reactive volatile organic compounds (VOCs). We examine the long-term trends in HCHO columns observed by the Ozone Monitoring Instrument from 2005 to 2014 across North America. Biogenic isoprene is the dominant source of HCHO, and its emission has a large temperature dependence. After correcting for this dependence, we find a general pattern of increases in much of North America but decreases in the southeastern U.S. Over the Houston-Galveston-Brazoria industrial area, HCHO columns decreased by 2.2{\%} a−1 from 2005 to 2014, consistent with trends in emissions of anthropogenic VOCs. Over the Cold Lake Oil Sands in the southern Alberta in Canada, HCHO columns increased by 3.8{\%} a−1, consistent with the increase in crude oil production there. HCHO variability in the northwestern U.S. and Midwest could be related to afforestation and corn silage production. Although NOx levels can affect the HCHO yield from isoprene oxidation, we find that decreases in anthropogenic NOx emissions made only a small contribution to the observed HCHO trends.}, author = {Zhu, Lei and Mickley, Loretta J and Jacob, Daniel J and Marais, Elo{\"{i}}se A and Sheng, Jianxiong and Hu, Lu and Abad, Gonzalo Gonz{\'{a}}lez and Chance, Kelly}, doi = {10.1002/2017GL073859}, journal = {Geophysical Research Letters}, keywords = {HCHO,Ozone Monitoring Instrument,trend}, number = {13}, pages = {7079--7086}, title = {{Long-term (2005–2014) trends in formaldehyde (HCHO) columns across North America as seen by the OMI satellite instrument: Evidence of changing emissions of volatile organic compounds}}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017GL073859}, volume = {44}, year = {2017} } @article{acp-15-12823-2015, abstract = {Bidirectional air–surface exchange of ammonia (NH3) has been neglected in many air quality models. In this study, we implement the bidirectional exchange of NH3 in the GEOS-Chem global chemical transport model. We also introduce an updated diurnal variability scheme for NH3 livestock emissions and evaluate the recently developed MASAGE{\_}NH3 bottom-up inventory. While updated diurnal variability improves comparison of modeled-to-hourly in situ measurements in the southeastern USA, NH3 concentrations decrease throughout the globe, up to 17 ppb in India and southeastern China, with corresponding decreases in aerosol nitrate by up to 7 $\mu$g m−3. The ammonium (NH4+) soil pool in the bidirectional exchange model largely extends the NH3 lifetime in the atmosphere. Including bidirectional exchange generally increases NH3 gross emissions (7.1 {\%}) and surface concentrations (up to 3.9 ppb) throughout the globe in July, except in India and southeastern China. In April and October, it decreases NH3 gross emissions in the Northern Hemisphere (e.g., 43.6 {\%} in April in China) and increases NH3 gross emissions in the Southern Hemisphere. Bidirectional exchange does not largely impact NH4+ wet deposition overall. While bidirectional exchange is fundamentally a better representation of NH3 emissions from fertilizers, emissions from primary sources are still underestimated and thus significant model biases remain when compared to in situ measurements in the USA. The adjoint of bidirectional exchange has also been developed for the GEOS-Chem model and is used to investigate the sensitivity of NH3 concentrations with respect to soil pH and fertilizer application rate. This study thus lays the groundwork for future inverse modeling studies to more directly constrain these physical processes rather than tuning bulk unidirectional NH3 emissions.}, author = {Zhu, L and Henze, D and Bash, J and Jeong, G.-R. and Cady-Pereira, K and Shephard, M and Luo, M and Paulot, F and Capps, S}, doi = {10.5194/acp-15-12823-2015}, journal = {Atmospheric Chemistry and Physics}, number = {22}, pages = {12823--12843}, title = {{Global evaluation of ammonia bidirectional exchange and livestock diurnal variation schemes}}, url = {https://www.atmos-chem-phys.net/15/12823/2015/}, volume = {15}, year = {2015} } @article{Zou2017, abstract = {The East China Plains (ECP) region experienced the worst haze pollution on record for January in 2013. We show that the unprecedented haze event is due to the extremely poor ventilation conditions, which had not been seen in the preceding three decades. Statistical analysis suggests that the extremely poor ventilation conditions are linked to Arctic sea ice loss in the preceding autumn and extensive boreal snowfall in the earlier winter. We identify the regional circulation mode that leads to extremely poor ventilation over the ECP region. Climate model simulations indicate that boreal cryospheric forcing enhances the regional circulation mode of poor ventilation in the ECP region and provides conducive conditions for extreme haze such as that of 2013. Consequently, extreme haze events in winter will likely occur at a higher frequency in China as a result of the changing boreal cryosphere, posing difficult challenges for winter haze mitigation but providing a strong incentive for greenhouse gas emission reduction.}, author = {Zou, Yufei and Wang, Yuhang and Zhang, Yuzhong and Koo, Ja Ho}, doi = {10.1126/sciadv.1602751}, issn = {23752548}, journal = {Science Advances}, month = {mar}, number = {3}, pages = {e1602751}, title = {{Arctic sea ice, Eurasia snow, and extreme winter haze in China}}, volume = {3}, year = {2017} } @article{Zusman2013, author = {Zusman, E. and Miyatsuka, A. and Evarts, D. and Oanh, N.K. and Klimont, Z. and Amann, M. and Suzuki, K. and Mohammad, A. and Akimoto, H. and Romero, J. and {Hannan Khan}, S.M. and Kuylenstierna, J. and Hicks, K. and Ajero, M. and Patdu, K.}, doi = {10.4155/cmt.13.12}, issn = {17583004}, journal = {Carbon Management}, keywords = {co-benefits,research-policy divides,short-lived climate pollutants}, number = {2}, pages = {135--137}, title = {{Co-benefits: Taking a multidisciplinary approach}}, url = {http://www.future-science.com/doi/full/10.4155/cmt.13.12}, volume = {4}, year = {2013} }