热带环流强度变化与我国夏季降水异常的关系

RELATIONSHIP BETWEEN TROPICAL CIRCULATION INTENSITY AND SUMMER PRECIPITATION ANOMALY IN CHINA

该文用８５０ｈＰａ和２００ｈＰａ纬向风距平差定义南海热带季风、沃克环流及热带环流强度指数，并讨论它们的天气气候学意义．指出由南海热带季风指数和沃克环流指数之差表征的热带环流强度指数与我国夏季降水，尤其是与长江流域降水有密切的关系；通过热带环流强度指数与冬、春、夏季５００ｈＰａ高度场、ＳＬＰ、ＳＳＴ、ＯＬＲ的相关分析，揭示用热带环流强度指数表征的热带环流异常影响我国夏季降水的可能途径．热带环流强度指数的季节变化规律及其与前期环境场的相关关系，对夏季雨带位置的预报有一定的参考价值．

The differences between mean monthly zonal wind anomalies at 850 hPa and 200 hPa are defined as the South China Sea Tropical Monsoon Index(STMI), the Walker Circulation Index(WKCI) and the Tropical Circulation Intensity Index(TCIX), and the significance of these indexes for synoptic climatology is discussed. TCIX, which is the difference between STMI and WKCI, has a close relation with the summer precipitation in China, especially in the Yangtze River basin. Based on the correlation analysis between TCIX and 500 hPa height fields, SLP, SST and OLR for winter, spring and summer, the possible influence of TCIX on the summer precipitation in China is revealed. The interseasonal variation of TCIX and the correlation with the ambient field of earlier stage are usefull for the forecast of summer rain belts.