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一次极端降水的中尺度雨团分析
引用本文:武威,顾佳佳.一次极端降水的中尺度雨团分析[J].气象科学,2021,41(1):108-118.
作者姓名:武威  顾佳佳
作者单位:漯河市气象局, 河南 漯河 462300;沙颍河流域气象中心, 河南 漯河 462300;漯河市雾霾监测预警工程技术研究中心, 河南 漯河 462300
基金项目:河南省气象局预报员专项资助(KQ201741)
摘    要:利用常规观测资料、ECMWF ERA-Interim 0.125°×0.125°分析资料、FY-2G卫星云图和多普勒天气雷达资料等,对2017年8月18-19日漯河极端降水的中尺度特征及降水成因进行分析。结果表明:(1)本次过程在200 hPa高空分流区、500 hPa高空槽以及副热带高压、低层急流切变、地面低压倒槽等天气尺度系统合理配置及其相互作用下发生。(2)探空显示漯河上空具有较高的对流潜势,有利于中尺度雨团初生和发展。低层饱和、厚暖云层、弱风切变有利于暴雨云团产生,高CAPE值、高比湿和高降水效率是极端雨团的重要原因。(3)中尺度对流云团一个随槽前西南气流东移北上,一个随低层切变线南压,相向合并发展为MβCS,有利于暴雨云团增强。不同于以往本地区的云团"同向合并",持续的列车效应以及低质心高效率的中尺度对流单体后向传播导致强回波长时间维持,极端降水发展。(4)地面中尺度辐合线和强辐合中心对强降水起到动力触发作用,有利于对流发展。冷池出流与交汇北上的东南风和偏东风相互作用,导致水平温度梯度增大形成和冷池前侧锋生加强,一方面致使雨团组织化发展和单体后向传播,另一方面也在降水区下游触发新生雨团,冷池持续增强。(5)本次过程整层风场较弱,且低层气流传播速度大于引导气流速度,平移与传播方向的反向夹角大,导致两者矢量和大幅度偏离了引导气流方向,同时产生的减速效应导致暴雨中尺度系统移动缓慢,导致极端降水形成。

关 键 词:极端降水  雨团  相向合并  地面辐合  冷池  准静止
收稿时间:2019/9/28 0:00:00

Analysis of the mesoscale rain clusters in the extremely heavy precipitation
WU Wei,GU Jiajia.Analysis of the mesoscale rain clusters in the extremely heavy precipitation[J].Scientia Meteorologica Sinica,2021,41(1):108-118.
Authors:WU Wei  GU Jiajia
Institution:Luohe Meteorological Bureau, Henan Luohe 462300, China;Shaying River Basin Meteorology Center, Henan Luohe 462300, China;Luohe Monitoring and Early Warning Engineering for Fog-Haze Technology Research Center, Henan Luohe 462300, China
Abstract:Based on conventional meteorological data,ECMWF ERA-Interim 0.125°×0.125°analysis data,FY-2G satellite images and doppler radar data,the mesoscale characteristics and precipitation causes in the extremely rainfall process occurred in Luohe on 18-19 August was analyzed.Results show that:(1)The process occurred in the favorable configuration of 200 hPa jet diversion area,500 hPa trough and the subtropical high,jet shear in the middle and lower layers and surface low-pressure trough.(2)The sounding showed that there was a high convective potential over Luohe,which helped the convective rain clusters newborn and development.Saturated humidity,thick warm cloud heights and weak wind shear were beneficial to storm clouds.High CAPE values,high specific humidity and high precipitation efficiency all were important reasons for the extremely rain clusters.(3)While the convective cloud moved eastward with the southwest airflow in front of the trough,the other one in the lower shear line moved southward,opposite merging into MβCS,which was different from the previous merging cloud clusters in the region and was conducive to the enhancement of storm clouds.The continuous train effect and backward propagation of low-mass and high-efficiency mesoscale convective monomers lead to long-term maintenance of strong echo and the development of extreme precipitation.(4)The surface convergence line with the strong convergence center acted the triggering force,which superimposed on the weather-scale shear line,lead to the maintenance of mesoscale rain clusters.The cold pool outflow interacts with the southeast and the eastward wind on the north of the junction,making the horizontal temperature gradient to increase to form front of the cold pool front.On one hand,it helped organizational development of mesoscale rain clusters and backward propagation of convective monomers.On the other hand,the new convection was triggered downstream of the precipitation area and the cold pool continued to increase.(5)The wind field in the whole layer was weak and the low-level airflow propagation speed was more than the guiding airflow.The reverse angle was large between them,resulting in the large deviation from the direction of the guiding airflow.At the same time,the deceleration effect caused the mesoscale system moving slowly,which was conducive to extreme precipitation.
Keywords:extremely precipitation  rain clusters  opposite merger  suface convergence  cold pool  quasi-stationary
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