中文摘要：

利用台站资料,从气候场的平均态、空间结构、变化趋势以及年内、年际变化方面对IPCC AR4中19个全球气候模式模拟结果及其集合平均在长江源区1961-1999年气温和降水的模拟能力进行了对比,从中优选了CGCM3.1_T47,MRI_CGCM2.3.2,UKMO-HadCM3及MME 18对流域气温和降水模拟较好的模式.然后再利用2000-2009年的台站观测资料分别对四个模式采用差值法和统计降尺度方法进行对比.最后,分别采用Delta和SD方法预估了长江源区21世纪2011-2030年、2031-2060年、2061-2090年A2情景下气温和降水的变化情景.在未来三个时期长江源区将明显增温,多年平均气温将分别升高1.5（1.2～1.9）℃,2.6（2.3～3.2）℃,4.5（3.7～5.3）℃;多年降水呈现微弱的增加趋势,增加幅度分别为9.1%（3.1%～12.7%）,11.2%（4.6%～18.2%）,15.7%（3.0%～26.3%）.

英文摘要：

By using the observations of meteorological stations in the source region of Yangtze river basin（YRB）, modeling capability of 19 IPCC AR4 CGMs were evaluated for spatial distribution of climatic field,trends, intra-and inter-annual variation of air temperature and precipitation from 1961 to 1999.CGCM3.1_T47,MRI _CGCM2.3.2,UKM0-HadCM3 and the ensemble（MME_18） were selected due to their better performance both in temperature and precipitation.The observed monthly precipitation and air temperature from 2000 to 2009 were compared with the simulations downscaled from selected GCMs by Delta and SD,respectively. Finally,Delta and SD methods were used to downscale the output of 4 selected GCMs during 2010—2030, 2031—2060,2061—2090 periods under A2 scenario.The yearly average air temperature was predicted as becoming significantly warmer and was projected to increase 1.5（1.2～1.9）℃,2.6（2.3～3.2）℃,4.5（3.7～5.3）℃for YRB in the three periods respectively.The precipitation was projected to slightly increase by 9.1%（3.1%～12.7%）, 11.2%（4.6%～18.2%）,15.7%（3.0%～26.3%） for YRB in the three periods respectively.