广西“4·20”暖区飑线的形成及结构

Formation and Structure of '4·20' Warm Sector Squall Line in Guangxi Province

为深入了解暖区飑线的形成机理,利用多种观测资料对2016年4月20日暖区飑线过程的环境条件、形成及飑线的结构进行深入分析。结果表明:(1)高空槽前滞留的冷温槽利于产生强的对流不稳定,飑线发生前期低层强烈暖湿平流对建立静力不稳定起主导作用;(2)探空显示广西南部的环境条件更有利于对流的强盛发展和组织化加强;(3)近地面冷池出流与低层环境风场相互作用是飑线发展和维持的主要机制,飑线朝着其前方1 h负变压中心发展。此次飑线是具有前导对流线和尾随层状云区的飑线系统,以离散性传播为主。

A warm area squall Iine occurred in Guangxi province on 20 April 2016, bringing strong wind and heavy rainfall. For insight into the formation mechanism of the warm sector squall line, the environmental condi tions, formation and structure of the squall line were further analyzed by using varieties of observation data. The results showed that the stranded cold temperature trough ahead of upper trough was beneficial to strongly convective instability. Meanwhile, the lower strong warm and moist air advection played a leading role in establishing static instability. The diagram of T-lnP indicated that the environmental conditions of the southern part of Guangxi were more conducive to the development and organizational reinforcement of convection than that of the northern part. In addition, the cold pool outflow interacting with lower environmental wind field was the main mechanism for the squall line to develop and maintain. The squall line moved and developed toward the one hour katallobaric center ahead. Moreover, the squall line was given priority to dispersive transmission, along with a guiding streamline and the trailing stratiform cloud area.