Relationship Between Summer Precipitation In Jiangsu And Pacific SSTA Together With Atmospheric Circulations In East Asia

With summer rainfall data from 13 stations in Jiangsu from 1960 to 2004, NCEP/NCARreanalysis monthly data and Reynolds & Smith reconstructed SST data, characters of summerprecipitation in Jiangsu and also its relations with pacific SSTA and East Asian circulation areinvestigated. And also a conceptual diagram explaining the physical process of Jiangsu summerprecipitation is achieved.Conclusions are as follows: (1) Seen from the long term trend, the annual rainfall of June hasincreased quickly, while the annual rainfall of July has decreased slowly. The annual rainfall ofsummer has increased very slowly. (2) During flood years, there was '+-+' anomaly pattern fromlow latitude to high over East Asia at 500hPa height fields. There were blocking highs in highlatitude area. Abnormal anticyclone was south and cyclone was north in 850hPa streamdifference fields. At 100hPa height fields, there were positive anomaly in equator and its nearbyarea and negative anomaly in the mid-latitude Asia During draught years, there was '-+-'anomaly pattern from low latitude to high over East Asia at 500hPa height fields. There was noblocking high in high latitude area. Abnormal anticyclone was more north than flood years in850hPa stream difference fields. At 100hPa height fields, there were negative anomaly in equatorand its nearby area and positive anomaly in the mid-latitude Asia. Correlation between summerprecipitation and the South Asian High was negative. (3)It is proved that the correlation betweeneast equator pacific SSTA and summer precipitation was positive, and the correlation betweennorthwest pacific SSTA and summer precipitation was negative. (4) Based on the analysismentioned above, a conceptual diagram explaining the physical process is put forward: when seasurface temperature in east tropical pacific was warmer (colder), Hadley circulation wasstronger (weaker) and Walker circulation was weaker (stronger),which caused EAP (negativeEAP) pattern in 500hPa. In this case, there was (no) blocking high in middle and high latitudeand Subtropical High was too south (north), which finally caused more (less) rainfall in Jiangsusummer.