冬季亚洲大陆的热力差异对亚洲季风活动的影响  

The Influence of Wintertime Thermal Contrast over the Asian Continent on Asian Monsoon

作　　者：晏红明[1] 杞明辉[1] 肖子牛[2] 陈艳[1] 

机构地区：[1]云南省气象科学研究所 [2]云南省气象局,昆明650034

出　　处：《大气科学》2005年第4期549-564,共16页Chinese Journal of Atmospheric Sciences

基　　金：云南省科学基金2002D0082M;云南省气象局青年基金YQ200106

摘　　要：亚洲冬季地面的热力状况与冬季风活动有关,对后期的天气气候变化也有重要的作用。作者用EOF方法分析了亚洲冬季地面气温的时空特征,发现第二模态表明东北亚和南亚地区的地面气温有反相变化的特征并具有明显的年代际变化。进一步研究发现,这种南亚东北亚的热力差特征与亚洲夏季风强弱有非常好的对应关系,籍此定义了一个大陆冬季南亚—东北亚热力差指数。分析表明热力差指数有非常明显的年代际变化,根据这一特征,进一步研究了夏季北半球大尺度环流和中国气候的年代际变化,发现其年代际变化对前冬亚洲大陆热力差指数的年代际特征敏感,相应大陆正、负热力差指数年代,东亚季风的变化特征几乎完全相反:南亚东北亚热力差正(负)指数年代,东亚夏季风较强(弱)。热力差指数对中国夏季降水的年代际变化也有重要影响,正(负)指数年代,中国夏季降水主要以第1(2)类雨型为主。同时,作者还分析了低纬度热带地区海温和对流活动对大陆冬季南亚东北亚热力差异响应的滞后性特征。Anomalous variations of wintertime surface air temperature (WSAT) over the Asian continent and the relationship between WSAT and Asian winter monsoon are first examined by using empirical orthogonal function (EOF) and correlation analysis. Both the second EOF pattern and correlation distribution exhibit that WSAT anomaly over Northeast Asia is opposite to that over South Asia, and this variation is closely associated with Asian summer monsoon activities. Thus, two regionally averaged WSATs over South Asia(15°N30°N, 75°E100°E) and Northeast Asia (30°N50°N, 100°E130°E) are chosen respectively and thermal contrast index is defined as the difference of WSAT between two regions. The opposite interdecadal variation is found in this index anomaly. It is positive during the 1950s and 1960s, but negative since the mid1970s. Based on above two different interdecadal timescale stages, the anomalous variations of general circulation and climate in summer over the Northern hemisphere are further investigated. The results show that their variations also have distinct interdecadal features. During positive index times, a strong summer monsoon tends to occur, the 500 hPa height over mid- and high-latitude regions is higher than that over low-latitude regions and East Asian trough weakens, the summer rainfall regions are located northward in the Yellow River valley, which result in less precipitation in the Huaihe River valley. On the contrary, during negative index times, a weak summer monsoon tends to occur, the 500 hPa height over mid- and high-latitude regions is lower than that over low-latitude regions and East Asian trough deepens, the summer rainfall regions are located southward in the Huaihe River valley. As for air temperature anomaly of 100010 hPa over East Asia and Northeast Asia areas, the variations are more complex. It includes not only interdecadal feature, but also distinct seasonal feature, especially in the troposphere. In the meantime, the studies also show that the previous WSAT has a strong impact o

关 键 词：亚洲大陆热力差异 地面气温 亚洲夏季风 中国夏季降水 

分 类 号：P425[天文地球—大气科学及气象学]