EVALUATION OF THE SIMULATION PERFORMANCE AND SCENARIO ANALYSIS FOR TEMPERATURE AND PRECIPITATION BY IPCC AR4 GLOBAL CLIMATE MODELS ON YANGTZE RIVER BASIN
IPCC AR4气候模式对长江流域气温和降水的模拟性能评估及未来情景预估

The Fourth Assessment Report of the Intergovernmental Panel on Climate Change(IPCC AR4) presents twentytwo global climate models (GCMs).In this paper,we evaluate the performance of the 22 GCMs in simulating temperature and precipitation over the Yangtze River Basin by comparing with ground observations for 1961～1990.The results suggest that all the GCMs underestimate surface air temperature and some models overestimate precipitation in most regions in the Yangtze River Basin.Only a few models (6 models for precipitation and 5 models for temperature) show roughly consistent with the observations in annual temperature and precipitation variations.Comparatively,UKMO_HadCM3 and NCAR_PCM are able to better reproduce the observed annual temperature and precipitation variability over the Yangtze River Basin.Although the scenarios predicted by the GCMs vary greatly,all the models predict consistent increasing trends in temperature and precipitation in most regions in the Yangtze River Basin in the next 90 years.The paper emphasizes the predictions of UKMO_HadCM3 for temperature and precipitation in 2020s (2010～2039),2050s(2040～2069) and 2080s(2070～2099).The results suggest that the temperature and precipitation will both increase in all three periods under different scenarios,with scenario A1 increasing the most and scenario B1 the smallest.