中文摘要：

利用1981—2016年的中国160站降水资料、OISST海温资料和NCEP/NCAR大气环流资料,对比分析了中等强度El Nino和2015/2016超强El Nino对中国东南部、江淮流域和西南地区冬春季降水影响的异同。结果表明：在中等强度El Nino的冬季,偏暖的赤道中东太平洋海表面温度（Sea Surface Temperature,SST）所激发的西北太平洋和日本附近的异常反气旋环流,其异常的西南风会加强南海—西北太平洋的水汽向中国东部输送,造成中国东南部和江淮流域的降水一致偏多。2015/2016超强El Nino的冬季,赤道中东太平洋SST的强度异常偏强,中国东部异常偏冷的表面气温和对流层低层温度加强大陆冷高压,长江流域及其以北地区受异常强的北风控制,从而造成中国东南部降水增多、江淮流域降水减少。在2015/2016超强El Nino事件衰减位相的春季,中国东南部和西南部降水的增加主要归因于异常偏暖的西北印度洋和东南印度洋SST的作用。经CAM5模式试验证明,西北印度洋异常偏暖的SST引起了北印度洋的异常西南风,激发了孟加拉湾—西北太平洋的异常反气旋,加强了印度洋和南海—西北太平洋的水汽向中国西南和东南部输送。此外,东南印度洋异常偏暖的SST还会激发局地异常上升运动,通过经向垂直环流加强南海—西北太平洋异常下沉运动,诱使中国东南部的上升运动加强,导致降水增多。

英文摘要：

The different influences of moderate El Nino and 2015/2016 extreme El Nino on winter and spring precipitation over southeast China,Yangtze-Huaihe Rivers Basins and southwest China are invested,based on monthly precipitation of 160 stations in China,OISST and NCEP/ NCAR circulation datasets. The results are as follows： in the winter of moderate El Nino,anomalous warmer sea surface temperature（ SST） over equatorial central-eastern Pacific triggers a pair of anomalous anticyclone over northwest Pacific and around Japan. The anomalous southwesterly enhances water vapor from South China Sea-northwest Pacific（ SCS-WNP） to eastern China and causes positive anomalies of precipitation over southeast China and Yangtze-Huaihe Rivers Basins. On contrast,the equatorial central-eastern Pacific SST gets much warmer in the winter of 2015/2016 extreme El Nino. Meanwhile,anomalous cooler surface and lower troposphere temperature over eastern China intensify continental cold high,which results in northerly anomalies over north of Yangtze River. It is responsible for the increase of precipitation over southeast China and the decrease of precipitation over Yangtze-Huaihe Rivers Basins. Compare to the decaying phase of moderate El Nino in the spring,the increase of precipitations over southeast China and southwest China is attributed to anomalous warmer SST over northwest Indian Ocean and southeast Indian Ocean. The numerical experiments of CAM5 model demonstrate that the anomalous warmer SST over northwest Indian Ocean leads to southwesterly anomaly and triggers anomalous anticyclonic circulations over the Bay of Bengal and northwest Pacific,which is responsible for an increase in water vapor from the Indian Ocean and SCS-WNP to southwest China and southeast China. The anomalous warmer SST over southeast Indian Ocean arouses local ascending motion,and then it strengthens anomalies of descent over SCS-WNP and ascent over southeast China,resulting in positive anomalies of southeast China rainfall.