2017年4—8月江西9次飑线天气诊断分析

Diagnosis and Analysis of the Ninth Squall Line Weatherin Jiangxi from April to August 2017

基于常规天气资料、江西WebGIS雷达拼图、欧洲中心格点物理量等资料,对2017年4—8月江西9次飑线天气过程,采用对比统计与形态分类方法进行诊断分析。结果表明:高层冷槽叠加在低层暖中心之上,上冷下暖造成大气层结不稳定;同时低层切变线配合地面低压或倒槽中的辐合上升运动,触发对流不稳定能量释放而产生中尺度飑线系统。在热力不稳定和垂直风切变的环境条件下,飑线至西向东移动发展加强,沿途产生雷暴大风、冰雹、短时强降水等强对流天气。在预报雷暴大风时,比湿场、假相当位温、K指数、沙氏指数、风暴强度指数的指示性比水汽通量、相对湿度、抬升指数要更有参考意义。在雷达拼图上,飑线表现为带状回波结构特征,有飑线带状回波、弓状回波带和回波短带等多种形式变化。对于江西飑线的预警预报有明显参考价值。

Based on conventional weather data,Jiangxi WebGIS radar puzzle,European central grid physical quantities and other data,the 9 squall line weather processes in Jiangxi from April to August 2017 were diagnosed and analyzed using comparative statistics and morphological classification methods.The results show that:the high-level cold trough is superimposed on the low-level warm center,and the upper cooling and lower warming cause the atmosphere stratification instability;at the same time,the low-level shear line cooperates with the ground low pressure or the convergent upward movement in the inverted trough,triggering the release of convective instability energy.Mesoscale squall line system.Under the environmental conditions of thermal instability and vertical wind shear,the movement of the squall line from west to east has strengthened,resulting in strong convective weather such as thunderstorms,hail,and short-term heavy rainfall along the way.When forecasting thunderstorms and high winds,the indicators of specific wet field,false equivalent potential temperature,K index,Sabouraud index,and storm intensity index have more reference significance than water vapor flux,relative humidity,and uplift index.In the radar puzzle,the squall line is characterized by a band echo structure,and there are various changes in the form of squall line band echo,bow echo band and echo short band.It has obvious reference value for the early warning and forecast of Jiangxi squall line.