长江三角洲地区的极端降水变化及其原因分析

ccording to the daily precipitation data in Yangtze River Delta from 1961 to 2010, using the method as M-K test, EOF and SVD, we discussed temporal and spatial variation and abnormal distribution of the intensity, frequency and amount in the area, also we find some conclusion about the relation between summer extreme precipitation and sea surface temperature of North Pacific. The results show that the yearly extreme precipitation intensity maximum value occurs in the early 1960s, minimum value occurs in the late 1970s. Extreme precipitation intensity shows the maximum value in summer, followed by autumn, winter minimum. The yearly extreme precipitation frequency maximum value occurs in the early 1970s, minimum value occurs in the late 1970s. Extreme precipitation frequency in summer and winter shows a upward trend but in winter it shows a downward trend, it's stable in spring. The turning point of annual precipitation occurs in early 1980s from less to more, total precipitation in both summer and winter turns abrupt change from less to more. Annual extreme precipitation intensity decreases from south to north. In spring, the maximum value occurs in Hangzhou region, the maximum value occurs in north Gaoyou. In summer and autumn, the maximum value occurs in Dongtai and Nanjing and in winter it occurs between Shengsi and Hangzhou. The trend of the extreme precipitation amount in the area of Yangtze River Delta is consistent. Extreme precipitation amount in summer, winter and all around the year shows a upward trend, while it shows a downward trend in spring and autumn. The abnormal distribution of extreme precipitation in Yangtze River Delta contains 3 main models. Teleconnec between extreme precipitation amount in summer and the SST in North Pacific mainly manifested in the Pacific Ocean of 150。E~150。W、30~50。N and 140~100。W、10。S~10。N. Teleconnec exists between extreme precipitation days in summer and the SST in the Pacific Ocean of 155。E~170。W、35~45。N and 140~100。W、10。S~10。N.