中文摘要：

将IPCC第5次评估报告国际耦合模式比较计划中的18个气候模式模拟结果与美国气候预报中心的观测资料进行对比,系统评估了18个气候模式对东亚干旱、半干旱区过去58 a（1948-2005年）夏季降水变化的模拟能力,并根据分数值的大小选取模式G1和G2进行对比分析.结果表明,G1对东亚干旱、半干旱区夏季降水变化趋势的模拟与观测资料较为一致,其中中国西北地区的降水增加,而中国东北及蒙古地区的降水表现为减少的趋势,模拟的蒙古西部地区的降水变率偏小;G2的模拟结果与观测值相差较大,尤其中国东北、西北局地及蒙古地区夏季降水的变化趋势与观测值相反.合成分析结果表明,在季风偏强年,G1模拟的夏季降水变化与观测值具有较好的一致性,即中国东北和蒙古地区降水明显偏多,但在季风偏弱年,G1模拟的夏季降水变化与观测值相比偏差较大,尤其在中国东北及蒙古地区,模拟的降水变化比观测值明显偏弱.在RCP4.5和RCP8.5排放情景下,G1的模拟结果表明到2100年大部分东亚干旱、半干旱区夏季降水呈增多趋势,其中以中国西北南部及东北地区最为显著.

英文摘要：

The simulated capability of summer precipitation was systematically evaluated using 18 mod- els from the fifth coupled model intercomparison project during the past 58 years （1948-2005）, and was compared with the observations from the Climate Prediction Center over arid and semiarid regions in East Asia. According to a comparison of 7 precise and poor models as G1 and G2 multi-model ensembles, there was a good agreement of the linear trend of summer precipitation between G1 historical simulation and the observations. The results indicated that summer precipitation decreased significantly in northeast China and Mongolian regions but increased in Northwest China and that precipitation change of G1 was a little underestimated in west Mongolia but with large differences between G2 simulation and observa- tions. For example, the observed linear trend of summer precipitation was conversed with the simulation over Inner Mongolia and some other regions in Northern China. There was a good relationship between the anomaly precipitation of G1 simulation and the observations in strong East Asian summer monsoon years, indicating that there was obviously more precipitation in Northeast China and East Mongolia.There was a large bias between the simulations and observations in weaker East Asian summer monsoon years. The simulation with RCP4.5 and RCP8.5 emission scenarios indicated that the linear trend of summer precipitation would increase until 2100.