近53年江淮流域梅汛期极端降水变化特征

Variation Characteristics of Extreme Precipitation During Meiyu Flood Period over Yangtze-Huaihe Basin in Recent 53 Years

基于1961—2013年江淮流域梅汛期（6—7月）逐日降水资料,利用百分位法确定极端降水阈值,对江淮流域梅汛期极端降水的时空分布及突变特征进行分析,结果表明：95%分位极端降水阈值多在50 mm以上,大值中心主要位于湖北东部到安徽南部一带;平均极端降水强度与阈值大小的空间分布相似。极端降水量和极端降水日数整体呈现由安徽南部向四周递减的空间分布特征,极端降水量约占梅汛期降水总量的1/4~1/3。从季节内分布上看,极端强降水站次在梅汛期呈单峰型分布,各候间差异明显,其中6月第5候到7月第2候最多。极端降水量、极端降水日数以及极端降水量占梅汛期总降水量百分比均具有明显的年际变化,且上升趋势显著;江淮流域梅汛期极端降水量和极端降水站次的这种上升趋势均在1980年发生突变。

Based on the 53 a （1961--2013） daily precipitation data in Meiyu flood period over Yangtze-Hua- ihe Basin, the threshold of extreme precipitation for each station is defined by percentile method, and the spatial and temporal distribution and mutation features are analyzed. The results show that the 95% thresholds of extreme precipitation are more than 50 mm, and their high value centers are mainly located from eastern Hubei to southern Anhui. The average intensity distribution of extreme precipitation is simi- lar to the distribution of thresholds. Both the extreme precipitation and extreme rainfall days present de- creasing features from southern Anhui to its surrounding areas, while the former accounts for about 1/4 to 1/3 of total Meiyu precipitation. In addition, stations of extreme precipitation for each pentad show single peak type with the maximum centered in the 5th pentad of June to the 2nd pentad of July. The extreme precipitation, extreme rainfall days and the extreme precipitation perecntage of the total precipitation in Meiyu period have obvious interannual variability with ascending trends, and the mutations of the extreme precipitation and rainfall stations occur in 1980.