中国年和季各等级日降水量的变化趋势分析

通过对中国554个测站1961—2003年的日降水量数据进行线性回归,对我国全年和各个季节的总降水量和各级降水的线性趋势进行分析,并对两种不同的极端降水定义方法所得的变化趋势进行了比较。结果显示,全年总降水量在西北、长江中下游和华南地区具有明显的增加趋势,而在华北和四川盆地地区具有明显的减少趋势。分析各类降水的季节变化趋势可以发现,西北地区各个季节的日降水都是增加的,长江中下游地区的各类降水的增加趋势主要集中在夏季和冬季,而华北地区的各类降水在各个季节基本都呈减少趋势。极端降水趋势方面,西北、长江中下游、西南部分地区和华南沿海地区具有明显的增加趋势,而华北、四川盆地和东北部分地区则有明显的减少趋势。

Analyses on Trends of Annual and Seasonal Four Kinds of Daily Precipitation in China

Basing on a dataset of daily precipitation of 554 stations covering the landmass of China during 1961-2003,the linear trends in the annual precipitation,seasonal precipitation and four kinds of precipitation by the method of linear regression are analyzed,and the trends of extreme precipitation defined by two different definitions are compared.The results reveal that the annual precipitation has significantly increased over the northwest of China,the middle and lower reaches of the Yangtze River valley and the South China but significantly decreased over the northern China and the Sichuan Basin.Through the analyses of the trends of seasonal four kinds of precipitation,it is found that the precipitation of four seasons over northwest of China show increasing trends and the precipitation have increasing trends mostly in summer and winter over the middle and lower reaches of the Yangtze River valley,while the four kinds of precipitation over northern China have decreased in four seasons.It is notable that the extreme precipitation have increased significantly over northern China,the middle and lower reaches of the Yangtze River valley,part of southwest of China and the littoral of southern China,but North China,Sichuan Basin and parts of northeast of China show obvious decreasing trends.