1960—2018年辽河流域日降水集中程度分析

Characteristics of daily precipitation concentration in Liaohe River Basin from 1960 to 2018

基于1960─2018年的日降水资料,计算辽河流域降水集中指数(CI),分析日降水集中程度的时空特征。结果表明:降水集中指数CI可以有效描述辽河流域降水集中程度,辽河流域年CI指数平均为0.67,降水集中程度总体呈现出东部和西部低、南部和北部高的鞍型空间分布特征;夏季降水集中程度最高,各站点季平均CI指数为0.65,空间分布与年分布较一致,冬季平均CI指数最低,为0.60,由东南向西北递减;研究时段内年CI指数表现为不显著的减小趋势,其中东部区域减小的趋势最大;各子区域年CI指数平均变化周期为3 a左右,其中1985年以前,变化周期较短,在2 a左右,1985年以后,变化周期超过3 a。

Using daily precipitation data from 1960 to 2018 over the Liaohe River Basin,the spatiotemporal characteristics of daily precipitation concentration in this region were analyzed after calculating the precipitation concentration index(CI).The results indicated that CI can reflect the degree of precipitation concentration in the Liaohe River Basin,with an annual mean value of 0.67.The precipitation CI is smaller in the eastern and western regions of Liaohe River Basin and higher in the southern and northern regions,exhibiting a saddle pattern.The precipitation concentration is higher in summer,with the seasonal mean CI value at each station being 0.65.The seasonal mean distribution of CI is similar to the annual mean distribution.The smallest seasonal mean CI value of 0.60 occurs in winter,and the CI values decrease from the southeast to the northwest.During the study period,the annual mean CI values exhibit an insignificant decreasing trend,with the largest decreasing rate occurring in the eastern region.The mean variation cycle of CI in each sub-regions is about 3 years.Before 1985,the variation cycle of CI is relative short,about 2 years,while after 1985,it increases to more than 3 years.