东北冷涡减弱阶段强对流天气特征及触发机制分析  

Characteristics and Trigger Mechanism of Severe Convection Weather During the Declining Northeast Cold Vortex

作　　者：云天[1] 王宁[1] 刘子琪 姚凯 YUN Tian;WANG Ning;LIU Ziqi;YAO Kai(Jilin Meteorological Observatory,Changchun 130062,China)

机构地区：[1]吉林省气象台,吉林长春130062

出　　处：《沙漠与绿洲气象》2022年第1期24-31,共8页Desert and Oasis Meteorology

基　　金：灾害天气国家重点实验室开放课题“东北冷涡诱发的吉林省对流性暴雨诊断分析”(201109)。

摘　　要：利用常规观测资料、NCEP(0.25°×0.25°)再分析资料及多普勒天气雷达等资料,对2016年6月17—19日吉林省强对流天气过程进行诊断分析。结果表明:(1)此次强对流天气主要发生在冷涡减弱阶段,低空急流的移动和扰动、地面中尺度系统起到关键作用。根据东北冷涡强度的演变将此次过程分为两个阶段。第一阶段(17日11时—18日17时)冷涡缓慢减弱,强降水伴随相对密集的冰雹和雷暴大风出现在中西部地区,热力条件强于第二阶段;第二阶段(18日17时—19日23时)冷涡减弱为高空槽,强降水伴随相对较弱的对流出现在中南部地区,水汽条件优于第一阶段。(2)SI指数、CAPE值、θ;的高、低层差值等在第一阶段均出现了明显高于(或低于)第二阶段的峰值(或谷值),而第二阶段的湿层厚度远高于第一阶段,湿区范围也随之扩大。(3)两个阶段的主要触发条件均为低空急流和地面辐合线,第一阶段辐合线和露点锋双重触发条件产生了直径较大的冰雹,密集降雹引发地面气温骤降和气压骤升,诱发阵风锋再次触发强对流;第二阶段地形抬升为降水的增幅提供了有利条件。Based on the conventional observation data,the NCEP (0.25°×0.25°)reanalysis data and Doppler radar data,the severe convection weather process in Jilin Province from 17 to 19 June 2016 is analyzed.The results are as follows:(1)The movement and perturbation of low-level jet and the surface mesoscale system played a key role in the severe convection weather process which occurred at weakening stage of northeast cold vortex.Based on the strength evolution of northeast cold vortex,the severe convection weather process could be divided into two stages.The strength of northeast cold vortex decreased slowly during the first stage which was from 11:00 BT on 17 to 17:00 BT on 18 June.In the meantime,the intense precipitation with dense hail and thunderstorm were mainly in the central and western regions.The thermal condition in the first stage was obviously better than that in the second stage.In the second stage which was from 17:00 BT on 18 to 23:00 BT on 19 June,the intense precipitation with weaker convection were mainly in the middle south regions when the northeast cold vortex weakened into upper trough.And the condition of water vapour was better than the first stage.(2)They were higher (or lower)in the first stage,compared with the peak (or valley)value of SI index,CAPE,and the difference ofθ;between high and low levels in the second stage.But in the second stage the depth of moisture layer and the range of wet area were higher than that in the first stage.(3)Trigger conditions for the two stages were both low-level jet and the surface convergence line.In the first stage the double trigger conditions of surface convergence line and dew point front were favorable to the hail with larger diameter.Because of the dense hail,the gust front induced by the sudden dropping of temperature and rising of pressure can trigger strong convection again.Terrain elevation provided favorable conditions for increasing precipitation in the second stage.

关 键 词：东北冷涡 强对流天气 触发机制 阵风锋 地形抬升 

分 类 号：P456.1[天文地球—大气科学及气象学]