1960-2019年成都地区极端降水时空演变特征分析

基于成都市域及周边21个国家级地面气象观测站逐日降水观测资料，通过构建极端降水指标体系，采用去趋势预置白处理(TFPW-MK)方法、经验正交函数分解法(EOF)等，从时程变化和空间变化角度解析1960—2019年成都地区极端降水时空演变特征。结果表明：成都地区极端降水呈下降趋势，尤以湿日降水量、强降水量两个指标下降趋势最为显著，这一特征与我国西南、南方城镇化地区极端降水变化特征有显著区别；成都地区不同极端降水指标具有相似的分布模态，呈“南北型”“东西型”“辐射型”3种分布形式，“南北型”模态是主要分布态势，极端降水由20世纪60年代以北部为中心逐渐在2000年后转移至南部和东南部，“东西型”和“辐射型”模态则反映了地形和城镇化对该地区极端降水的影响；城镇化进程对成都地区极端降水具有一定的增雨效应，2005年为增雨效应突变点，2005年后城区发生极端降水的概率和等级均超过郊区，增加了城区洪涝风险概率。

Analysis of spatial and temporal evolution characteristics of extreme precipitation in Chengdu area from 1960 to 2019

Based on daily precipitation data from 21 national ground meteorological observation stations in and around Chengdu City from 1960 to 2019, through constructing an extreme precipitation index system, the trend free pre-whitening Mann-Kendall (TFPW-MK) method and empirical orthogonal function (EOF) method were used to analyze spatial and temporal evolution characteristics of extreme precipitation in Chengdu area in the past 60 years from the perspective of time-history and spatial changes. Results indicate that extreme precipitation in Chengdu area showed a decreasing trend, especially demonstrated by indexes of wet-day precipitation and heavy precipitation. This feature is significantly different from extreme precipitation variation in urbanization areas in southwestern and southern China. Different extreme precipitation indexes have similar distribution modes in Chengdu area, including the modes of north-south type, west-east type, and radiation type. The north-south type is the main distribution mode, and the center of extreme precipitation gradually shifted from northern parts of Chengdu area in the 1960s to the south and southeast after 2000. The distribution modes of west-east type and radiation type reflect the impact of topography and urbanization on extreme precipitation in this area. The urbanization process has a certain precipitation enhancement effect in Chengdu area, the year 2005 was the abrupt change point of the precipitation enhancement effect, and after 2005, the probability and level of extreme precipitation in urban areas were higher than those in suburban areas, increasing the risk of urban flooding.