近55年的日照市极端降水事件分析

Analysis of Extreme Precipitation Events in Rizhao City for Nearly 55 Years

为了揭示华北局部地区极端降水事件变化的区域细节,研究该区极端降水事件的变化规律,依据1955—2009年日照市的降水日值资料,对日照市的极端降水事件变化进行统计分析。结果表明:(1)近55年来,日照市平均年最大日降水量呈不显著的下降趋势,整个分析时期的最大值出现在2008年;(2)极端强降水量及其贡献率和日数呈减少趋势,突变年份在1975年。极端强降水年平均强度呈弱增加,突变不明显,但2006年以后处于上升趋势。极端强降水量的变化主要受到极端强降水日数变化的影响;(3)随年代变化暴雨日数有减少的趋势,平均一般干燥事件和严重干燥事件的总频次均呈增加趋势。分析表明,近55年来,日照市极端降水事件趋于减少,干燥事件趋于增加。但进入21世纪后,降水有向极端化发展的趋势。

In order to explore the changes of area details of the local area in the north China in extreme precipitation events and study the changing rules of the extreme precipitation events,according to the data of daily precipitation in Rizhao City from 1955 to 2009,the extreme precipitation events were analyzed.The results showed that：（1） the average annual maximum one day precipitation of Rizhao City had not significantly deceased in the recent 55years.The maximum of the analysis period appeared in 2008;（2） the amount and its ＇ contribution and days of extreme precipitation showed a declining trend and 1975 was the mutational site.The intensity of extreme precipitation had increased weakly and no significant mutation,but there was an upward trend after 2006.The changes of extreme precipitation amount were mainly affected by extreme precipitation days change;（3） the total frequency of general average dry events and severe dry events were in the trend of increasing along with the decreasing of the heavy rains days.These results indicated that the extreme precipitation events tended to reduce and the dry events tended to increase in Rizhao City in the recent 55 years.But in the 21st century,the precipitation trended to the extreme events.