RELATIONSHIP OF SUMMER EAP TO THE RAINFALL IN THE MIDDLE LOWER REACHES OF THE YANGTZE RIVER

Based on the Northern Hemispheric 500hPa height and rainfall in China,study is performed of relations of the East Asia general circulation and rainfall anomalies in the middle lower reaches of the Yangtze river in terms of EOF,composites and SVD analyses.Results suggest that the EAP index has a close relartion with the system configuration of 500 hPa height field and the summer rainfall in the middle lower reaches of the Yangtze river.That is to say,in the flood (higher EAP index) years the general circulation at 500 hPa displays a typical EAP pattern with a strong West Pacific subtropic high south of 30 °N,while in the drought (lower EAP index) year,the West Pacific subtropic high is weak and lies north of 30 °N.The EAP index shows biennial,quasi 3 and quasi 6 year,and interdecadal variations,which also reflect well the interannual and interdecadal trends of flood/drought and 500 hPa height pattern over the middle lower reachds of the Yangtze river.