中文摘要：

利用多成员集合试验结果，比较分析了热带印度洋和太平洋增暖各自对东亚夏季风趋势变化的影响。试验所用模式是GFDLAM2大气环流模式，增暖是通过在气候平均海洋表面温度（SST）基础上，叠加随时间线性增加的、相当于实际50a左右达到的SST异常来实现的。结果表明：热带印度洋和太平洋共同增暖有使东亚夏季风减弱的趋势。相比较而言，单独印度洋增暖有使东亚夏季风增强、华北降水增多的趋势，而单独太平洋增暖有使东亚夏季风减弱的趋势，即印度洋增暖与太平洋增暖对东亚夏季风存在相反的、竞争性影响。进一步分析指出，热带太平洋特别是热带中东太平洋的增温可能对20世纪70年代末期开始的夏季风年代际减弱有更重要的贡献；在未来热带印度洋和太平洋持续增暖、但增暖强度纬向差异减小的新情况下，东亚夏季风减弱的趋势可能还将持续。

英文摘要：

Results of ensemble experiments are used to investigate the influence of separated tropical In- dian Ocean and Pacific Ocean warming on East Asian summer monsoon （EASM）. The model used is an atmospheric general circulation model（ AGCM）, the GFDL AM2, and the warming is realized by pre- scribing an idealized and temporally ramping warm anomaly over climatological sea surface temperature （SST） in the tropical Indian Ocean and the combined Indo-Pacific Ocean, respectively. The results sug- gest that the combined Indo-Pacific Ocean warming makes EASM have a weakened trend. Singled Pa- cific Ocean warming favors the weakening of EASM,in contrast with Indian Ocean warming which fa- vors the enhancing of EASM and more rainfall in North China. A further analysis reveals that warming in the tropical Pacific Ocean, especially in the central-eastern Pacific Ocean, may play an important role in shaping the decadal shift of EASM beginning since late 1970s. Under the future case that the tropical Indian Ocean and Pacific Ocean warming persists and their zonal contrast decreases, the weakened trend of EASM may continue in the future.