东亚冬季风环流异常与中国江淮流域夏季旱涝天气的关系

THE RELATIONSHIP BETWEEN THE ANOMALOUS WINTER MONSOON CIRCULATION OVER EAST ASIA AND SUMMER DROUGHT/FLOODING IN THE YANGTZE AND HUAIHE RIVER VALLEY

选取１９５１—１９９１年中的长江淮河流域夏季旱涝各１０年，对它们前期的中高纬大型环流形势，低纬环流特征，垂直环流强弱，热带海洋状况等进行了对比诊断分析，其结果如下：长江淮河流域夏季旱年前冬（１２—１—２月），欧亚中高纬呈经向型环流，东亚大槽较常年强且南伸，乌拉尔山及鄂霍次克海阻塞形势发展，寒潮活动频繁，东亚沿海中低纬冷涌活动强烈，至使该经度带上的跨赤道气流加强，而且使南海至菲律宾地区的对流活动趋于活跃。而涝年前冬则基本上为相反形势。本文的分析清晰地揭示了旱涝年前冬东亚冬季风环流存在着明显的差别，促使我们寻找冬夏季风活动的可能联系及物理机制。

n this paper, 10 cases of the abnormal drought or flooding summers during 1951 1991 in the lower-middle reaches of the Yangtze River and the Huaihe River valley are selected respectively.We analyse comparatively their large scale circulations in the mid-high latitudes and in the tropical convective area. The main conclusions are as follows: In preceding winter (December-January-February ) of the drought year.the flow pattern with a strong major trough and a blocking high in the mid-high latitudes shows a strong meridional circulation over Eurasia, the cold surge in lower latitudes and the convective activity over the southen part of South China Sea and the Philippines are active and so the cross-equatorial current towards the South Hemisphere is greatly strengthened. On the contrary.in preceding winter of the flagging y6ar.those are much weaker. This work reveals obviously the differences of two kinds of winter monsoon circulations with respeCt to summer drought and flooding and facilitates us to search for the possible link and physical mechanism of interaction between the winter monsoon and the summer monsoon over East Asia.