我国极端降水阈值确定方法的对比研究

A Comparison of Methods for Benchmarking the Threshold of Daily Precipitation Extremes in China

在全球变暖趋势下，极端降水频发，引起了国内外学者的广泛关注，而极端降水阈值的确定是研究极端降水事件的起点。基于中国499个气象站点1960-2009年的逐日降水数据，采用 DFA 法、百分位法和 Pearson-III 概率分析法，对中国各站点及区域的极端降水阈值进行对比分析。结果表明：DFA 法确定的极端降水阈值远大于百分位法确定的极端降水阈值，约为 Pearson-III 两年一遇情景下的极端降水；中国极端降水阈值从东南沿海向西北内陆递减，其中四川盆地边缘地区、长江中下游流域地区和华南地区南部极端降水阈值最大；南方地区、北方地区、青藏地区和西北地区的建议极端降水阈值分别为80 mm、50 mm、25 mm 和20～25 mm。

Precipitation extremes have become more frequent under global warming,which attract widely at-tention of scholars at home and abroad,and the appropriate threshold is the first step of studying precipitation ex-tremes.In this paper,we use data sets of daily precipitation recorded in 499 meteorological stations,through the comparison of DFA method,percentile method and Pearson-III distribution to define the proper threshold for each station and each region.Results show that：Thresholds calculated by DFA are much higher than the percentile method and the values are around the return period of two years.Thresholds decreasing from southeastern coastal areas to northwestern inlands and thresholds are the highest in Sichuan Basin,middle and lower Yangtze River and southern part of South China.Our suggest thresholds in four major regions-South China,North China,Qinghai-Ti-bet Region and Northwest China are 80mm,50mm,25mm and 15 ~25mm.