江苏降水长期趋势及年代际变化空间差异分析

SPATIAL VARIATION OF PRECIPITATION TREND AND INTERDECADAL CHANGE IN JIANGSU

根据江苏省 60个气象站 1 961～ 2 0 0 1年的逐月降水量资料 ,计算了逐月、季和年降水量距平百分率 (RAP) ,以此研究了江苏降水的长期趋势和年代际变化特征及其空间差异。结果表明 :全省平均降水量 1、3、6月有显著的增多趋势 ,而 4、9两月有显著的减少趋势 ;年降水量 ,南部增多 ,而北部减少 ;春季降水量大部分地区减少 ,夏季降水量主要是南部增多 ,北部减少 ,秋季大部分地区降水量减少 ,冬季全省降水量增多。 4个年代年RAP符号变化 ,在江苏南部呈“ - - + +”型 ,北部为“ + + - -”型 ,中部则呈“ + - - +”、“ + - + -”等过渡型。春季则在北方呈“ - + - +”型 ,中部呈“ + - - +”型 ,南部呈“ + - - -”型 ,徐州和盐城地区主要为“ + + - +”型。夏季RAP符号 ,主要分布型由北到南依次为“ + + - -”、“ +- + -”、“ + - - +”、“ - + - +”和“ - - + +”。秋季RAP符号全省绝大多数台站为“ +- + -”型。冬季RAP符号在东部和南部大片地区为“ - + - +”型 ,而西部则主要为“ - ++ +”、“ - - + +”、“ - + - +”和“ - - - +”

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“--++”from 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.