中文摘要：

利用NCEP再分析资料和NOAA海表温度等资料,分析了东亚冬季风在不同纬度上的表现。根据我们定义的东亚中纬度冬季风（The mid latitudinal East Asian winter monsoon,简称EAWM-M）和低纬度冬季风（The low latitudinal East Asianwinter monsoon,简称EAWM-L）指数,探讨了它们对应的影响系统,并重点分析了它们与海温异常之间联系的异同。研究主要发现：（1）EAWM-L和EAWM-M指数所反映的东亚冬季大气环流形势不尽相同。在对流层低层,EAWM-L与中国南海、菲律宾附近环流异常的关系密切,EAWM-M与贝加尔湖阻塞高压的关系更为密切;在对流层中层,EAWM-M同样与贝加尔湖阻塞高压异常的联系相对更为紧密,而EAWM-L指数则与东亚大槽的关系更为紧密。在对流层高层,副热带西风急流强度变化通过调制次级环流进而与EAWM-L联系起来,而EAWM-M强弱变化主要与副热带西风急流北界的位置有关。（2）EAWM-L与冬季赤道中东太平洋和热带印度洋海温异常的联系都很紧密,而EAWM-M变化与冬季热带印度洋海温异常的联系更为密切,与赤道中东太平洋海温异常的关系相对偏弱。EAWM-L与冬季赤道中东太平洋和热带印度洋海温异常的紧密联系在年际和年代际尺度上都是存在的,而EAWM-M与冬季热带印度洋海温异常的紧密联系主要体现在年代际尺度上。

英文摘要：

The National Cemers for Environmental Prediction （NCEP） reanalysis data and the National Oceanic and Atmospheric Administration （NOAA） Extended Reconstructed Sea Surface Temperatures （SSTs）are used in this study to investigate characteristics of the East Asian winter monsoon （EAWM） at various latitude zones. On the basis of two indices describing the strengths of the low-latitudinal EAWM （EAWM-L） and mid latitudinal EAWM （EAWM-M）, theirvariation characteristics, associated atmospheric circulation, and related SST patterns are examined. The results indicate that although both the EAWM-M and EWAM-L indices can reflect the intensity of the EAWM, the atmospheric circulation associated with the two indices is clearly distinct. In the lower troposphere, the EAWM-L is closely related to anomalous circulation around the South China Sea and the Philippines, while the EAWM-M presents a closer relationship with the circulation adjacent to Lake Baikal, known as the Baikal blocking high. In the middle troposphere, the close relationship of EAWM-M and the Baikal blocking high remains persistent, while the EAWM-L has a relatively closer linkage with a major Asian trough. In the upper troposphere, variation in the intensity of a subtropical westerly jet may modulate secondary circulation and is eventually linked with the EAWM-L index, while the variation of EAWM-M is mainly related to a shift of the north boundary of the westerly jet. In addition, the EAWM-L is significantly correlated with SSTs in the central and eastern equatorial Pacific and that in the tropical Indian Ocean, while the EAWM-M has a closer relationship with the latter than with the former. The close relationships of the EAWM-L with the central and eastern equatorial Pacific and with the tropical Indian Ocean are clearly revealed on interannual and interdecadal scales; however, the significant linkage of the EAWM-M with the tropical Indian Ocean exists mainly on the interdecadal scale.