呼和浩特近59年降水极端事件分析

Analysis on the Extreme Precipitation Events in Recent 59 Years in Hohhot

利用呼和浩特气象站1951—2009年逐日降水量资料,以年序列的第90个百分位,建立了日降水量极端气候事件的阈值,检测了近59年来呼和浩特逐日降水量极端事件的出现频率,分析了极端事件阈值和日数及降水量的年际、年代际和季节变化,结果显示:①呼和浩特日降水极端事件的阈值小,为10.6mm;全年极端事件出现的频次11d。②降水极端事件主要出现在4-10月,且8月最多。③近59年来呼和浩特全年降水极端事件及其降水量没有显著的增减变化趋势,但而进入21世纪后,极端降水事件及其降水量的变率加大,降水强度明显减小。

The threshold value of extreme precipitation event was established according to the 90th percentile value of annual series by using the daily precipitation data at Hohhot meteorological stations during the period of 1951-2009 years.The frequencies of episodes of extreme rainfall were tested in recent 59 years.And the thresh-old and day number of the extreme precipitation,the inter-annual,inter-decadal and seasonal variation of pre-cipitation were analyzed.The results showed that： 1.The threshold value of the daily episodes of extreme rainfall is 10.6mm which is small in Hohhot;the occurrence frequency of annual episodes of extreme rainfall is 11d.2.The episodes of extreme rainfall occurred mainly from April to October,and the most in August.3.There weren＇t obvious variation of episodes of extreme rainfall and annual precipitation in recent 59 years,but in 21th century,the variability of episodes of extreme rainfall and precipitation is enhancive,rainfall intensity decreased signifi-cantly.