衡阳近五十年暴雨气候特征和变化规律分析

The Climatic Characteristics and Variation of Rainstorm in Hengyang during Recent Five Years

利用统计分析、Morlet小波分析和墨西哥帽小波诊断方法,对近50n衡阳暴雨的时空变化进行分析,得到其变化规律和周期震荡的突变点,结果表明:衡阳暴雨分布不均,其中南、北部偏多,中部偏少,平均暴雨数为3.0次/n;≥100 mm暴雨占暴雨总数的11.0%,特大暴雨较少出现;衡阳局地性暴雨占23.6%,主要以区域性和全市性暴雨为主;暴雨主要出现在5-8月,所占比例为72.1%;历年暴雨变化存在3n、6-9n和21n周期,2009年衡阳处于暴雨低发时期。

By using the statistical analysis,Morlet wavelet and Mexico-hat wavelet analysis,the catastrophe point of periodical vibration and the space-time change law of rainstorms in Hengyang during recent five years are obtained.The results show that an average of rainstorm days is 3 times every year.But there is an uneven distribution： the number of rainstorm days in the central Hengyang is less than that in the south and north of Hengyang;The percentage of heavy rainstorm and regional rainstorm were 11.0% and 23.6% respectively,while the heavy torrential rain was rare;By the seasonal distribution,the time of rainstorm occurred is mainly from the May to August,and the percentage occupied by all year was 72.1%.There are quasi-periodic variations of the Hengyyang rainstorm： the dominant quasi-periods of 3,6-9 and 21 years.The year of 2009 was low period by using Morlet wavelet and Mexico-hat wavelet analysis.