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

In 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 (Dember-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-uatorial current towards the South Hemisphere is greatly strengthened.On the contrary,in preceding winter of the flooding year,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.