Numerical Simulations of Climate Change under IPCC A1B Scenario in Southwestern China

Climate change over southwestern China is simulated by a regional climate model(RegCM3),using the output from a global coupled atmosphere-ocean model(ECHAM5/MPI-OM) as lateral and surface boundary conditions.Two sets of 15 years of simulations at 20-km gird resolution for present days(1986-2000) and future(2011-2025,under IPCC_A1B scenario) are conducted to analyze the effects of surface air temperature and precipitation on the drought as a focal area.Results show that RegCM3 can reproduce well the spatial distribution of surface air temperature and precipitation in southwestern China compared with the observed data of 32 meteorological stations and grid data of CRU,and simulated annual and summer precipitation is much higher than winter precipitation.The simulated precipitation in winter is higher than observed values.During 2011-2025,there might be a remarkably warming either annually or in other seasons.The temperature change in the northern region is bigger than that in the southern region.The maximum and minimum temperature changes in winter are bigger than those in summer.Annually,precipitation increase is consistent with that in autumn and winter,while precipitation increase is significant in winter.Precipitation decrease in spring and summer is not significant.Temperature increase and precipitation decrease in spring and summer might induce high temperature and droughts to parts of the region,while precipitation increase in winter might increase the risk of local flood disasters.