Daily precipitation data from climate change simulations using the latest generation of coupled climate system models are analyzed for potential future changes in precipitation characteristics. For the emission scenarios SRES B1 (a low projection), A1B (a medium projection), and A2 (a high projection) during the 21st century, all the models consistently show a shift towards more intense and extreme precipitation for the globe as a whole and over various regions. For both SRES B1 and A2, most models show decreased daily precipitation frequency and all the models show increased daily precipitation intensity. The multi-model averaged percentage increase in the precipitation intensity (2.0% K-1) is larger than the magnitude of the precipitation frequency decrease (-0.7% K-1). However, the shift in precipitation frequency distribution towards extremes results in large increases in very heavy precipitation events (>50 mm day-1), so that for very heavy precipitation, the percentage increase in frequency is much larger than the increase in intensity (31.2% vs. 2.4%). The climate model-projected increases in daily precipitation intensity are, however, smaller than that based on simple thermodynamics (~7% K-1). Multi-model ensemble means show that precipitation amount increases during the 21st century over high latitudes, as well as over currently wet regions in low- and mid-latitudes more than other regions. This increase mostly results from a combination of increased frequency and intensity. Over the dry regions in the subtropics, precipitation amount generally declines because of decreases in both frequency and intensity. This indicates that wet regions may get wetter and dry regions may become drier mostly because of simultaneous increase (decrease) of precipitation frequency and intensity.

Full Article: http://www.cgd.ucar.edu/cas/adai/papers/Sun_etal_JC_2007Jan15.pdf

Last Updated: 2007-02-27