中文摘要：

利用CAM3.0气候模式模拟研究东亚地区气溶胶浓度增长以及1976/1977年前后发生的海温年代际变化对东亚夏季降水场的影响及其机制。采用四组试验：即对东亚区域（100-150°E,20-50°N）分别进行的单独加倍黑碳气溶胶浓度、单独加倍硫酸盐气溶胶浓度、同时加倍这两种气溶胶浓度的三组关于气溶胶直接气候效应的试验及全球海温在1976/1977前后发生变化的海温年代际变化试验,来比较、探讨海温年代际变化和东亚地区气溶胶浓度增加对东亚夏季降水的影响机制。结果表明,无论是海温年代际变化还是各种气溶胶的浓度加倍,都能导致我国出现长江以北地区降水减少-东南沿海地区降水增加的＂南涝北旱＂的降水异常分布型。但两者在洋面上空降水的迥异表现及东亚低层风场的不同变化,显示其具有不同的异常降水机制。比较三类气溶胶浓度增加的试验结果发现：在单独硫酸盐气溶胶浓度增加试验中,东亚中部出现最显著的中下层大气降温、异常下沉气流以及降水减少;而在黑碳气溶胶试验中,出现在东亚中部的异常下沉气流强度减弱且位置偏南;在同时增加两类气溶胶浓度时,降水异常分布与单独黑碳气溶胶浓度增加所导致的降水异常相近,但强度减小。

英文摘要：

Both the significant increase in aerosol concentration of East Asia in recent years and the global Sea Surface Temperature （SST） decadal change around 1976 have significant effects on East Asian precipitation. So we use CAM3.0 model to investigate the respective effect of these two phenomena on East Asia in boreal summer. By separately doubling the concentration of the sulfate aerosol and that of black carbon aerosol and doubling both of them in East Asia （100-150 θseE, 20-50θseN）, the climate effects of these aerosol species are investigated. And the influence of global change of SST around 1976/1977 on the East Asia Summer Monsoon is also considered in the same model. The results show that all the four experiments could lead to rainfall decreasing in the center of East Asia, north of the Yangtze River but increasing in regions along the Southeastern China coast, similar to a pattern of ＂southern flood and northern drought＂. However, the differences of rainfall in Northwest Pacific and North Indian Ocean and the different patterns of wind field changing between the aerosol experiment and SST experiment indicate the presence of different mechanisms. Three experiments on aerosol show that the scattering effect is the main climate effect of sulphate and black carbon aerosols on the Easter Asian summer. The sulphate aerosol experiment has the most significant temperature decreasing and sinking anomaly, while the black carbon aerosol leads to weakened sinking anomaly. This weakened sinking is south to that induced by sulphate aerosol, and its compensating rising flow results in more rainfall in the south. When both of the aerosols concentration increased synchronously, the anomalous rainfall distribution is somewhat like that in black carbon aerosol experiment but with less intensity.