利用我国西南地区96个测站近40a的月降水量资料,采用主成分分析、旋转主成分分析、小波分析等方法对西南地区年降水资源变化的时空特征进行了分析。结果表明:近40a西南地区的西部高原地区降水资源呈增加趋势,而东部除重庆地区外,大部分地区降水资源减少。西南地区年降水资源空间特征复杂,存在南北和东西相反变化的差异,空间异常可分为8个异常区,即滇南区、川西高原区、滇黔交界区、四川盆地东部、四川盆地西部、滇西区、黔渝交界区和凉山区。西部高原地区年降水量都经历了多雨-少雨-多雨的过程,20世纪90年代降水量呈增加的趋势,四川盆地东部经历了少雨-多雨-少雨的过程,四川盆地西部和整个西南地区东南部的降水量整体都呈下降趋势。川西高原区、滇南区和滇黔交界区在整个时段存在显著的准14a周期,其他异常区的显著周期及其年代变化有较大差异。

On the basis of the monthly precipitation data for the period 1961-2000 collected from 96 observational stations in Southwest China (SWC),the methods of principal component analysis, rotated principal component analysis,and wavelet analysis are used to analyze the spatial and temporal characteristics of annual precipitation resource.The main results show that the yearly precipitation resource in the western part of SWC increased in these 40 years,and the yearly precipitation resource decreased in most eastern areas except Chongqing.The spatial characteristics of precipitation resource in Southwest China are complex with anomaly differencebetween the south and the west,and in the east and the west of SWC.The precipitation resource abnormal area can be divided into eight subregions:southern Yunnan,western Sichuan Plateau, eastern Yunnan and western Guizhou,eastern part of Sichuan Basin,western part of Sichuan Basin,western Yunnan,northeastern Guizhou and southeastern Chongqing,and Liangshan mountain. The precipitation in the plateau of western part of SWC had a dry-wet-dry process and an increasing trend in 1990s.The precipitation in eastern part of Sichuan Basin had a wet-dry-wet process.The precipitation appeared a decreasing trend in western part of Sichuan Basin and entire southeastern part of SWC.Except the remarkable period of 14 years in the regions of western Sichuan Plateau,southern Yunnan,eastern Yunnan and western Guizhou,the main periodic and annual change laws of other regions are different from each other.