Climate Change 2001:
Working Group I: The Scientific Basis
Other reports in this collection

Figure 4.9: (left panel) Observed versus modelled (1) HO2 abundance (ppt), (2) OH abundance (ppt), and (3) HO2/OH ratio in the upper troposphere (8 to 12 km altitude) during SONEX. Observations are for cloud-free, daytime conditions. Model calculations are constrained with local observations of the photochemical background (H2O2, CH3OOH, NO, O3, H2O, CO, CH4, ethane, propane, acetone, temperature, pressure, aerosol surface area and actinic flux). The 1:1 line (solid) and instrumental accuracy range (dashed) are shown. Adapted from Brune et al. (1999). (right panel) Observed (4) HO2 abundance (ppt), (5) OH abundance (ppt), and (6) derived O3 production rate (ppb/day) as a function of the NOx (NO+NO2) abundance (ppt). Data taken from SONEX (8 to 12 km altitude, 40° to 60°N latitude) and adapted from Jaeglé et al. (1999). All values are 24-hour averages. The lines correspond to model-calculated values as a function of NOx using the median photochemical background during SONEX rather than the instantaneous values (points).

Back to text

Table of contents
Other reports in this collection