安徽省近50年汛期极端强降水量特征分析

ANALYSIS OF THE CHARACTERISTICS OF EXTREME HEAVY PRECIPITATION OVER ANHUI PROVINCE IN FLOOD SEASON IN RECENT 50 YEARS

利用安徽省71个台站1961~2008年近50 a的逐日降水资料,根据百分位数法定义了极端强降水的阈值,通过趋势分析、EOF分析、周期分析、Mann-Kendall突变检验等方法对汛期极端强降水量进行特征分析。结果表明:汛期极端强降水阈值平均为55 mm,其空间分布与常年汛期降水量分布基本一致;全省大部分地区汛期极端强降水呈上升趋势;EOF前3个模态累积方差贡献达86%,全省一致型和南北相反型为最主要的两种分布型;汛期极端强降水量存在9~10 a的主周期,此外还有3 a左右的次周期;汛期极端强降水量在1980年左右存在一次突变,1980~2008年年均值比1961~1979年年均值增加了52 mm。因此在全球变暖背景下安徽省汛期极端强降水量存在周期变化,且一直有增多趋势,特别是最近30 a更为明显,需引起高度关注。

With the help of daily precipitation data in 71 stations of Anhui Province during 1961~2008,this paper firstly defines extremely heavy precipitation thresholds by percentile method,and then proceeds to analyze the characteristics of the extremely heavy precipitation in flood season by trend analysis,EOF,period analysis,Mann-Kendall test and so on.The results show that the average of the extremely heavy precipitation threshold is 55 mm and the distribution of it is basically in accordance with the distribution of average precipitation in flood season.In most areas in Anhui Province,the trend of extreme heavy precipitation in flood season ascends.The cumulative percent variance of the EOF first three modes reaches 86%.The patterns of distribution mainly fall into two catalogues:the distribution all over Anhui province is consistent and the distributions between the south and the north are on the contrary.There is a 9~10 years main period and an approximate 3 years subordinate period of extremely heavy precipitation.The extremely heavy precipitation in flood season mutated around the year of 1980,and the average of it from 1980 to 2008 is higher than the average from 1961 to 1979 by 52 mm.Thus,it could be concluded that under the background of global warming,the extremely heavy precipitation in flood season has a periodical change,and it ascends straightly especially during recent 30 years which should be given top priority.