河南“7·19”豫北罕见特大暴雨降水特征及极端性分析

Analysis on Extremity and Characteristics of the 19 July 2016 Severe Torrential Rain in the North of Henan Province

2016年7月18-20日受低涡气旋影响,河南省出现了一次全省大范围的强降水过程("7·19"),其中豫北部分地区出现特大暴雨,最大过程雨量达732 mm。本文基于自动气象站降水、地面风场观测资料、雷达组合反射率资料、常规气象探空资料和1°×1°ECMWF再分析资料,对"7·19"过程的降水特征、大尺度环流特征和中尺度系统进行了分析,同时也对比分析了"7·19"过程和1980-2016年以来发生在豫北太行山东麓的71个强降水过程(所选区域至少有一个站点的日降水量大于100 mm)的物理量场特征。结果表明:太行山地形和低涡气旋背景下有利的大尺度环流为"7·19"特大暴雨提供了充沛的水汽和辐合抬升条件;中尺度地形辐合线的生成、发展和维持、多个地面中尺度气旋移动造成的列车效应是导致局地特大暴雨的主要原因,对比不同强降水过程的物理量场显示"7·19"的动力因子具有明显的极端性特征。

An extremely severe rainfall event occurred in Henan in 18-20 July 2016（the ＂7 · 19＂ rainstorm） under the influence of vortex and cyclone. The precipitation was mainly concentrated in northern Henan, and the maximum accumulated rainfall was 732 mm observed at Dongmaan Station in Anyang.This paper analyzes the fundamental features of precipitation, large-scale circulation and mesoscale system of the ＂7 · 19＂ rainstorm based on the hourly rainfall and surface wind data of automatic weather stations,the composite reflectivity data of SA radar, the conventional sounding data and ECMWF（European Centre of Medium-Range Weather Forecasts） reanalysis data. At the same time, this paper also analyzes the physical quantity properties of 71 extreme rain events, which are defined as precipitation ≥100 mm ·（24 h）^（-1） at any representative weather station within selected areas. These severe rainfall events took place in the east of Taihang Mountain in northern Henan. The results show that the topography of Taihang Mountain and favorable large-scale circulation under the background of vortex and cyclone provided abundant water vapor and better convergent lifting conditions for the ＂7 · 19＂ rainstorm. The train effect produced by the generation, development and maintenance of mesoscale terrain convergence lines and the movement of multiple surface cyclones are the main cause for the ＂7 · 19＂ severe torrential rain in northern Henan. Compared to the physical characteristics of various extreme rain events, the dynamic factors of ＂7 · 19＂ have obvious features of extremity.