Study On The Temporal And Spatial Distribution Of The Summer Precipitation In East China And Its Anomaly In Recent Fifty Years

East China play an important role in China and its climate and precipitation had always been studied all over the world.In this study,we will study the correlation with500 hPa potential height field,the temporal and spatial distribution of the summer precipitation in East China based on the 74 circulation parameters which comes from China National Climate Center,the precipitation data in June,July and August comes from159 stations in East China from 1960 to 2012.We also pay attention to the circulation of the summer precipitation anomaly in order to find out it's climatic reasons.The major methods used in this study are trend analysis method,Wavelet,Empirical Orthogonal Function(EOF),Rotated Empirical Orthogonal Function(REOF)and Singular Value Decomposition(SVD).The result shows:(1)The Mutation of annual precipitation in East China occurred in the early 1990 s,the precipitation is fewer in the early and more later.The temporal distribution of the summer precipitation in Zhejiang,Fujian and Jiangxi province is consistent with that in East China.The temporal distribution of summer precipitation in Anhui province is consistent with that in Jangsu province,great difference with that in East China,and the obvious periodicity exist in both region.Shandong province is the unparalleled region that the precipitation shows a decreasing trend in East China.(2)The characteristics of the summer precipitation's spatial distribution in East China is significant.In addition to the mountain with high altitude,the proportion of the summer precipitation is litter in the south than that in the north.The climatic trend rate of the summer precipitation,beside that in Shandong province,is positive,it's said that the major trend of the summer precipitation is increasing.The principal eigenvector's load of summer precipitation in East China is that the southward is negative and the northward is positive.The separatrix between positive and negative located in the middle of Anhui and Jiangsu province.The trend of the summer precipitation in the north and south of East China is opposite.(3)In order to study on the climate division in East China,we analysis the relative data by REOF.The result of REOF shows that can be divided into 5 region.The region?includes the middle-north of Shandong province.The region ? includes the south of Shandong province,the middle-north of Anhui and Jiangsu province.The region ?includes the middle-south of Anhui and Jiangsu province,the north of Jiangxi province,thenorth-west of Zhejiang province and Shanghai.The region ? includes the middle of Jiangxi province,Zhejiang province apart from the north-west of it and the middle-north of Fujian province.The region ? includes the south of Jiangxi province and the middle-south of Fujian province.(4)This study concentrates on the correlation between 500 hPa potential height field and the summer precipitation in East China.The result shows that the deference of the correlation is obvious from month to month.The negative correlation located in East China Sea is the major correlation in June.The positive correlation located in Korea or Yellow Sea is the major correlation in July,August,and the most significant correlation occurs in July.As far as the precipitation in whole summer,the result of SVD is consistent with that in July,August.It's said that the correction above in July and August is more important than that in June.(5)In the year with larger precipitation,West Pacific subtropical high(WPSH)is more westward and larger,and it can be seen a trough of low pressure located over East China.On the geopotential height of 850 hPa,the east wind comes from the east of Eastern Pacific with a large of water vapor and the warm air comes from Indian Ocean converge on the northeast of Philippines,and transport the water vapor into East China.The circulation above is beneficial for the summer precipitation.In the year with litter precipitation,WPSH weakened eastward and the region for the two pair of airflow above to converge near 150°E.The circulation above can not transport much water vapor into East China.