|The Regional Impacts of Climate Change|
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Annex A: Regional Trends and Variations of Temperature and Precipitation
IPCC (1996) provided time-series plots and global maps depicting trends of precipitation and temperature. This Annex extends and updates these records for a broader number of contiguous regions.
Two data sets are used to represent near-surface air temperature change. Over land this includes a near-surface air temperature data set developed by Jones (1994), and over the oceans a sea-surface temperature data set developed by Folland and Parker (1995). Both of these data sets provide the basis for calculating global temperature change as reported in the IPCC Second Assessment Report (1996). Parker et al. (1994) describe the methodology used to aggregate land and ocean temperatures for grid cells that span both regions.
Precipitation changes are also calculated from two data sets. Land-surface precipitation data are derived and updated from Hulme (1991) and from Eischeid et al. (1995); the latter is referred to as the GHCN (version 1) data set in IPCC (1996). Both data sets were available with a resolution of 5°x5°. Since two data sets were used, a procedure was needed to integrate the data. A simple equal weighting scheme was used when both data sets had data available. For some grid cells, data were available from only one data set, and this provided additional coverage relative to the use of a single data set.
In Figures A-1 and A-2, the magnitude of the trends of precipitation and temperature for each 5°x5° grid cell is given by the area of circle centered in each cell; brown and blue circles reflect decreasing trends, and green and red circles increasing trends. Trends are given in %/century for precipitation and °C/century for temperature. Precipitation trends are expressed in percent relative to the 1961-90 average precipitation.
Time-series plots of the annual anomalies of precipitation and temperature (relative to 20th century averages) are depicted for each of the various regions delineated in Figure A-3. For those regions where a 5°x5° grid cell spanned two or more regions, the anomalies for that grid cell were used more than once-once for each region that intersected the grid cell. The time series depicted in Figures A-4 through A-13 show the anomalies from the 1961-90 means. Longer term variation of these annual anomalies are emphasized by a smooth curve using a nine-point binomial filter.
Time-series plots of precipitation are not provided for Antarctica, due to
very poor spatial coverage and large data uncertainties. The trends of temperature
for the small island states include both land and ocean sea-surface temperature
trends for grid cells that include both land and ocean.
Eischeid, J.K., C.B. Baker, T.R. Karl, and H.F. Diaz, 1995:
Folland, C.K. and D.E. Parker, 1995:
Hulme, M., 1991:
Jones, P.D., 1994:
Parker, D.E., P.D. Jones, C.K. Folland, and A. Bevan, 1994:
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