“7·20”郑州极端特大暴雨降水细节特征和成灾过程研究

Study on the Precipitation Details and Disaster Formation Process of“7·20”Extreme Rainstorm in Zhengzhou

基于常规探测资料、区域气象站资料、郑州双偏振多普勒雷达产品和ERA-5逐小时再分析数据等对“7·20”郑州特大暴雨降水细节演变、成灾过程和中尺度特征进行探究。结果表明:特大暴雨环流背景罕见,海上远距离台风起到了“水汽转运站”的作用;降水时空分布的复杂性致使西部山区和郑州主城区成灾原因不同;关键环境参数对比分析表明,极端强降水对CAPE值要求不高,高的暖云层厚度和近地面大的露点等指标利于高降水效率的产生,中等强度以上的深层垂直风切变有利于中尺度对流系统的高度组织化;西部山区强降水主要由中尺度孤立对流单体频繁影响所致,列车效应显著;郑州主城区强降水是由高降水效率的对流系统长时间维持造成的,降水粒子尺度大,数密度高,KDP值增大与雨强的突增对应关系较好。

Based on the conventional detection data,regional meteorological station data,Zhengzhou dual polarization doppler radar products and ERA-5 hourly reanalysis data,the detailed evolution,disaster process and mesoscale characteristics of the“7·20”heavy rain in Zhengzhou are explored.Results show that the circulation background of the heavy rain is rare,and the long-distance typhoon on the sea acts as a water vapor transfer station;The complexity of the spatial and temporal distribution of precipitation leads to different causes of disasters in the western mountainous area and the main urban area of Zhengzhou;The comparative analysis of key environmental parameters shows that extreme heavy precipitation does not require high CAPE,high warm cloud thickness and high dew point near the ground are conducive to the generation of high precipitation efficiency,and deep vertical wind shear above medium intensity is conducive to the high organization of mesoscale convective system;The heavy rainfall in western mountainous area is mainly caused by the frequent influence of mesoscale isolated monomer,and the train effect is significant;The heavy rainfall in the main urban area of Zhengzhou is caused by the long-term maintenance of the convective system with high precipitation efficiency.The precipitation particle size is large and the number density is high.The increase of KDP value corresponds to the sudden increase of rainfall intensity.