近54a湖南区域暴雨的时空分布特征

Climatic characteristics of regional heavy rain over Hunan during the last 54 years

基于1960—2013年湖南88个台站逐日降水数据,采取线性趋势分析等方法分析了近54 a湖南区域暴雨的时空分布特征。从时间变化上看,近54 a湖南区域暴雨日以6月208 d为最多,1月0 d为最少;夏季、春季、秋季及冬季区域暴雨日数占总日数的百分比依次为60%、29%、10%及1%。暴雨日数、暴雨强度均值突变点分别为1994年、1995年,暴雨初日的均值突变点为1983、1994年,暴雨终日无均值突变;暴雨日数与暴雨强度（暴雨发生终日）总体上呈上升（后延）趋势。基于突变点分段线性趋势分析表明,仅暴雨日数在1994—2013年及暴雨强度在1960—1994年期间呈显著下降趋势。从空间分布上看,区域暴雨强度及其与非区域暴雨强度的差值、区域暴雨持续2日或以上的暴雨强度及其与单日暴雨强度的差值的大值区主要位于湘西北及湘东南,小值区主要位于湘西南-湘东北的带状区域;全部站点的区域暴雨强度均大于非区域暴雨强度,89%的台站持续2日或以上的区域暴雨强度大于单日区域暴雨强度。区域暴雨、总体暴雨的台站暴雨最长持续日数分别为1~4 d、2~4 d,均集中在2~3 d且其站数占总站数的百分比分别为97.7%、96.6%。

Basted on the daily precipitation data collected from 88 stations over Hunan during 1960-2013, the temporal and spatial distribu- tion characteristics of heavy rain in Hunan were analyzed using statistical methods. For temporal characteristics, the most heavy rain days are observed in June and the least in January with 208 days and 0 day in June and January, respectively. The percentage of summer, spring, autumn, or winter heavy rain days to annular heavy rain days is 60, 29, 10, or 1, respectively. Mean value jump point of heavy rain days, heavy rain intensity, the beginning dates of heavy rain are in 1994, in 1995, in 1983 and in 1994, respectively, and there is no catastrophe point for heavy rain ending dates. Heavy rain days and heavy rain intensity （the ending dates of rainstorm） show a rising （later） trend. Only heavy rain days during 1994-2013 and heavy rain intensity during 1960-1994 show decreasing trends according to the piecewise linear trend analysis based on mean value jump point. For spatial distribution, the large value region of the difference of heavy rain intensity be- tween the regional heavy rain and the non-regional heavy rain, the difference of regional heavy rain intensity between lasted 2 days or more and lasted 1 day are located in northwestern Hunan and southeast Hnnan. At the same time, the small value regions of the above differences are located in belt area from southwestern to northeastern Hunan. Regional heavy rain intensity is greater than non-regional heavy rain in- tensity at all stations. The percentage of the stations whose regional heavy rain lasted 2 days or more greater than that lasted 1 day to total stations is about 89. The stations＂ maximum duration of regional heavy rain and total heavy rain are 1-4 day and 2-4 day, and the percent- age of maximum duration of them between 2 day to 3 day are 97.7, and 96.6, respectively.