1951～2013年华北地区极端降水事件的变化

Change in Extreme Precipitation Events over Northern China from 1951 to 2013

利用华北地区90个气象站点1951～2013年逐日降水量资料,计算了8个极端降水指数,采用滑动平均、线性回归、Mann-Kendall非参数检验和Morlet小波分析等方法,分析了华北地区极端降水事件的变化规律。结果表明：华北地区近63a连续干旱日数（CDD）呈明显的增加趋势,连续5d降雨量、连续湿日、年总降雨量趋于减少并通过0.05显著性检验,其他4个极端降水指数都表现为减少趋势且不显著。各极端降水指数与年总降水量（PRCPTOT）有很好的相关性,除连续干旱日数与之呈负的弱相关性以外,其他指数均呈较强的正相关性。在近63a的时间尺度上各项极端降水指数都存在2～4a显著周期,多数指数也存在8a、16a和32a的周期。在时间转折上,连续湿日（CWD）的突变点时间较早,发生于1964年。从空间分布来看,京津冀地区及山西大部是极端降水指数变化最为显著的区域,连续干旱日数增加,其他指数均呈现减小趋势。

Variations and trends in extreme climate events are more sensitive to climate change than the mean values,which have received much attention.In this study,the features for 8in-dices of precipitation extremes over Northern China are examined,broadly based on daily precipitation data from 90 meteorological stations during the period 1951～2013.The methods of 9-year smoothing average,linear regression,Mann-Kendall test and continuous wavelet transform were employed to delineate the rate of change,abrupt change points,statistical significance of the trends,and periodicity of extreme precipitation indices.The results show that Consecutive Dry Days（CDD）exhibited significant increasing trend during the recent 63 years,the maximum 5-day precipitation（RX5day）,Consecutive Wet Days and Annual Total Wet-day Precipitation（PRCPTOT）decreased by 0.05 significance levels.Other 4extreme precipitation indices showed a decreasing trend,and not notable.There is an obvious linear variation trend in all extreme precipitation and Annual Total Wet-day Precipitation.Consecutive Dry Days and Annual Total Wet-day Precipitation have a weak correlation,other indicators showed a strong positive correlation.With regard to the period of variation,almost all extreme precipitation indices vary at three or four years scale,and most indices have such periods as 8a,16 aand 32a.In terms of the change point,Consecutive Dry Days occurs in 1964,which much earlier than other indices.From the spatial distribution characteristics of extreme precipitation indices,the variation trend in central North China is more distinct.Consecutive Dry Days increases,and other indicators show a decreasing trend.