2017年6月24日与7月1日两次典型暴雨对比分析

Contrast Analysis of Two Typical Torrential Rain Events on June 24^th and July 1^st 2017

摘要: 利用常规观测资料、FY-2G卫星TBB资料，自动站降水量以及NCEP/NCEP逐6小时再分析资料，对2017年6月底至7月初持续性暴雨中影响长沙的最强暴雨时段(2017年6月24~25日以及6月30日~7月1日)进行对比分析，结果表明：1) “6.24”暴雨属于梅雨型暴雨，表现为高能高湿型降水；“7.1”暴雨则为高空槽稳定少动的持续性暴雨；2) “6.24”暴雨副热带高压表现为南北移动，“7.1”暴雨主要表现为东西移动；3) “6.24”暴雨急流位于暴雨区南部，“7.1”暴雨在暴雨区有明显的高低空急流配合，并且中尺度系统的存在对暴雨的增强有直接作用。4) 与“6.24”暴雨相比，“7.1”暴雨的水汽净流量更大，这是西南低空急流将充足的水汽输送到暴雨区的结果。

Abstract: Based on data of conventional observation, FY-2G, automatic weather station precipitation, and NCEP/NCAR reanalysis, comparisons are made between two periods of maximum rainfall in Changsha during the persistent heavy precipitation event from the end of June to the beginning of July in 2017. Results indicate that 1) “6.24” heavy rain is caused by MeiYu front and has the characteristics of high energy and high humidity while “7.1” heavy rain is a persistent rainstorm caused by a stable upper trough; 2) during “6.24” heavy rain, subtropical high is represented by north-south move-ment while during “7.1” heavy rain, subtropical high is characterized by east-west advance and re-treat; 3) there is no obvious low-level jet during “6.24” heavy rain, while “7.1” heavy rain has obvious coordination with high and low level jet, and the existence of mesoscale system has a direct effect on rainstorm enhancement; 4) compared with “6.24” event, the net flow of water vapor during “7.1” heavy rain is greater, which is the result of sufficient water vapor transported by southwest low-level jet to rainstorm area.