1960-2009年湖南省暴雨极端事件的气候特征

Climatic Characteristics of Extreme Rainstorm Events in Hunan Province during 1960-2009

本文采用湖南省88个地面气象站点1960-2009年的逐日降水资料,运用一元线性回归、M-K突变分析及小波分析等方法分析了湖南省50年来区域暴雨极端事件的时空分布特征及变化趋势。研究表明:过去50年暴雨极端事件增多、强度增大。暴雨极端事件有波动上升的趋势,20世纪60年代和80年代偏少,70年代和90年代偏多;在80年代末到90年代初暴雨极端事件由小变大是一突变现象,且存在2年、5年、7年和21年左右的周期振荡。降水量明显高于平均值的月份集中在4-8月,而暴雨降水量和暴雨总次数明显高于平均值的月份集中在5-8月。降水量湘西地区可能更加少雨,湘北洞庭湖区和湘中部分地区有可能向多雨转变的趋势;湘东和湘南有可能向干旱转变。暴雨降水量、最大日降水量、暴雨次数、暴雨强度和降水集中率在湘中、湘西南和湘西北个别地区可能比原来更少,其余地区均可能增多。

Using 1960-2009 daily precipitation data of 89 stations, the spatio-temporal distribution of extreme rainstorm events in Hunan Province in recent 50 years is analysed by linear regression, abrupt change analysis and wavelet analysis. The results showed that the intensity and frequency of rainstorm events increased in the last 60 years. Extreme rainstorm events showed a wave-increase： low in the 1960s and 1980s whereas high in the 1970s and 1990s. A abrupt change （from dry to wet） can be observed from the late 1980s to early 1990s. In addition, the extreme rainstorms also occurred in cycles of 2-year, 5-year, 7-year, and 21-years. Generally, the numbers of rainstorms and the associated precipitation of May to August are significantly higher than the average. Precipitation of the western Hunan shows a decreasing trend, while that of the northern and central Hunan is increasing. The eastern and southern Hunan may become much drier. Extreme rainstorm shows a increasing trend, while that of the southwestern, northwestern and central Hunan shows a decreasing trend.