中国降水极值变化趋势检测

DETECTION OF TRENDS IN CHINA'S PRECIPITATION EXTREMES

利用中国２９６个分布均匀的测站的逐日降水资料，研究了中国过去４５ａ中降水量、降水频率、降水强度等方面的极值变化趋势。结果表明，总体上讲，中国年降水量、１日和３日最大降水量以及不同级别的强降水总量没有发现明显的极端化倾向，但伴随着降水日数极端偏多的区域范围越来越小的变化趋势，平均降水强度极端偏高的区域范围表现为扩大的趋势。中国降水极值变化还反映出明显的区域性特点。在中国东部，平均降水强度极值出现的范围趋于扩大。如华北地区在年降水量明显趋于减少的同时，年降水量极端偏多的范围减少，１日和３日最大降水量、日降水≥５０ｍｍ和１００ｍｍ的暴雨日数极端偏多的情况也趋于减少，而平均降水强度极值显著增加。在年降水明显趋于增多的西北西部地区，降水日数的极值变化趋势不明显，但年降水量、１日和３日最大降水量以及日降水≥１０ｍｍ的降水总量极端偏多的区域范围均反映出趋于增加的变化趋势。

On the basis of 296 stations with complete daily precipitation records during 1951-1995, this paper mainly studied extreme changes of precipitation amount, precipitation frequency, and precipitation intensity in China. The results revealed that there are no obvious trends in annual precipitation, 1 day and 3 day maximum precipitation , and precipitation amount for daily precipitation above different intensities. However, a significant increasing trend in extremely above normal mean intensity of precipitation in China is accompanied with reduction of rain days. Regional difference is very evident in the trends of China's precipitation extremes. In eastern China, much above normal mean intensity of precipitation tends to increase. In North China, under the background of decrease in annual precipitation totals, decreasing trends are very obvious for 1-day and 3-day maximum precipitation, and for rain days with daily precipitation above 50 mm and 100 mm. However, annual mean intensity of precipitation still tends to increase in North China. Exception is in western Northwest China, where the annual precipitation amount displayed an increasing trend and the area coverage of extreme amount of high intensity precipitation displayed an increasing trend but it showed no significant trend for wet days.