1960~2010年西北干旱区极端降水特征研究

基于中国西北干旱区1960~2010 年70个台站逐日降水资料,采用欧盟组织(STARDEX)定义的降水极值指数,分析结果表明: ① 研究区近51 a来强降水发生频次、湿期平均长度表现出增多和增长趋势,干日数和干期平均长度表现出减少和变短趋势; ② 单次强水的强度在增加,表现为：湿日数减少,而降水的总量却显著增加。③ 湿日数减少主要是0~6 mm强度的降水日数减少,12~24 mm强度的降水日数显著增加,后者对降水总量的增加贡献较大。④ 绝大部分站点强降水（>12 mm）的雨日（量）都以上升趋势为主,表现为下降趋势的站点极少。

Extreme Precipitation Features of Arid Regions in Northwest of China

This article mainly analyzes the mean precipitation, the maximum consecutive wet (dry) days, the yearly extreme precipitation frequency, the mean wet (dry) spell lengths, as well as the typical value of precipitation of wet days in the past fifty years, and the long-term trends. It is based on the daily precipitation datasets of seventy meteorological stations in arid areas in the northwest of China in 1960-2010. It uses the definitions of nine extreme precipitation indices by STARDEX. The results indicate that: 1) Both strong rainfall frequency and mean wet spell lengths in the past fifty years have increased significantly, however the dry days and the dry spell lengths have decreased; 2) Both the individual strong rainfall intensity and the total precipitation increased, the latter becoming more apparent; 3) The precipitation days of 0.1-6 mm density decreased, but that of 12-24 mm intensity rose and greatly contributed to the increase of the total precipitation; 4) Most stations show the rising tendency of rain days with more than 12 mm strong rainfall, among which the typical stations, are located in mountain areas. The areas with significantly increasing precipitation are consistent with the spatial distribution of strong rainfall, and that there exists evident relevance between the yearly extreme precipitation events and the annual precipitation. All of the above demonstrates that the rising total precipitation in arid areas result from the strong rainfall increase in the northwest of China since the late 1980s.