1987～2016年武汉市极端降水事件特征分析

Characteristic Analysis of Extreme Precipitation Events in Wuhan from 1987 to 2016

基于1987~2016年武汉市及附近共5个格点的日降水量资料,选取5个极端降水指数Rx1day(单日最大降水量)、Rx5day(5日最大降水量)、R95p(极端降水量)、R20(大雨日数)、SDII(降水强度),采用百分位阈值法、气候倾向率法、滑动平均法和Mann-Kendall突变检验等方法,对武汉极端降水事件的时空变化进行了分析.结果表明:1987~2016年武汉市极端降水事件的阈值整体上呈中部小、周边大的空间分布特征.极端降水事件发生频次的高值中心位于南部,低值区为北部.频次年际波动大,呈微弱减少趋势,年代际频次则呈明显的逐年代递减的规律.极端降水指数的空间分布中,Rx1day和R95p的空间变化差异较大,而Rx5day,R20和SDII的空间变化差异较小.Rx1day与R95p变化趋势均为北部下降、南部上升;Rx5day则为南部下降、北部上升;所有地区的R20均呈下降趋势;只有位于西南部的SDII呈上升趋势,其他地区均下降.1987~2016年,极端降水指数年际波动剧烈,Rx1day,Rx5day和R95p波动幅度相似,且均呈微弱的上升趋势,R20和SDII波动幅度类似,均呈微弱的下降趋势,总体表明这30a年间极端降水量随时间变化而增加,但是降水强度在减弱.

Based on the data of the daily precipitation of 5 grid points in Wuhan and nearby,from 1987 to 2016,5 extreme precipitation indexes,including Rx1day(maximal 1-day rainfall),Rx5day(maximal 5-day total rainfall),R95p(extreme precipitation),R20(days of precipitation more than 20 mm),SDII(precipitation intensity),were selected.The spatial and temporal changes of extreme precipitation events in Wuhan were analyzed by using the percentile threshold method,the climate inclination rate method,the sliding average method,the Mann-Kendall mutation test.The results showed that the spatial distribution in threshold of extreme precipitation events is characterized by small in central part and large in surrounding part in Wuhan from 1987 to 2016;the maximum value of frequency of extreme precipitation events is in the south,and the minimum value is in the north.The inter-annual fluctuation of frequency is fierce,and it shows a slight trend of reduction,and the inter-decadal value decreases gradually.Among the spatial distribution of these extreme precipitation indexes,Rx1day and R95p varies greatly while the spatial variation differences of Rx5day,R20 and SDII is very small.Both Rx1day and R95p decrease in the north and increase in the south,while Rx5day decreases in the south and increases in the north;R20 declines in all regions;SDII increases in the south-west and decreases in other regions.The inter-annual fluctuation of these extreme precipitation indexes is fierce,from 1987 to 2016.Rx1day,Rx5day,R95p shows a trend of increase,while R20 and SDII displayes a trend of decrease,which indicates that the extreme precipitation increases while the precipitation intensity decreases over the course of 30 years.