SPATIAL VARIATION OF PRECIPITATION TREND AND INTERDECADAL CHANGE IN JIANGSU

By analyzing the monthly rainfall (R) series of the 60 weather stations for the 1961—2001 period, monthly, seasonal and annual precipitation abnormity percentages (RAP) were calculated. Based on these the spatial patterns of seasonal and annual precipitation trends and interdecadal changes in Jiangsu Province were investigated. Results show that: (1) there are significant positive (negative) trends in January, March and June (April and September); (2) annual rainfall increased in the south, decreased in the north and weakly varied in the middle; (3) seasonal mean precipitation decreased in most parts in spring, increased in southern regions and decreased in northern districts in summer, decreased in most areas in autumn and increased all over the Province in winter; (4) the abnormity percentage sign variation types of the four decadal average are "--+ +" in the south, " + +--" in the north and "+--+" or " +-+-" etc transition types in the middle regions of the Province respectively for annual precipitation. For spring precipitation, they are "-+-+" in north, " +--+" in the middle, " +---" in south and " + +-+" in Xuzhou and yanchen districts. For summer rainfall, they are "+ +--", "+-+-", "+--+", "-+-+" and "--+ +" form north to south. For autumn rainfall, the type "+ +--" appears at almost all stations in the Province. And for winter precipitation the type "--+ +" appears in large area in the south and the east of the Province, the other comparative frequent types such as "-+ + +", "--+ +", "-+-+" and "---+" etc appear mainly in the west.