广东一次强飑线过程的地闪变化特征分析

Analysis on Lightning Activity Characteristic of a Strong Squall Line System in Guangdong

利用广东的地闪定位资料、天气雷达资料、卫星资料以及探空资料,对2014年3月31日广东的一次飑线过程的地闪活动进行分析。重点分析飑线过程地闪活动变化特征以及地闪活动与同期气象观测资料的关系。分析表明:飑线发展初期,地闪活动快速增加;在旺盛阶段,地闪频数维持较高水平;减弱阶段,地闪活动明显减少,在整个飑线发展过程中,负地闪活动占主导地位,正地闪比峰值落后于地闪频数峰值约在1 h出现;飑线过程单位面积内92.8%的地闪活动发生在组合反射率>40 dBz的回波区,其中组合反射率>60 dBz的回波区地闪活动最为活跃;飑线旺盛阶段,在雷达图上表现出明显“弓形回波”、速度模糊以及明显的速度辐合等强对流天气特征;TBB亮温≤220 K区域与闪电活动的密集区域有很好的对应关系;地闪活动活跃期:温度露点差垂直分布呈现明显的不稳定层结特性,在湿度垂直分布主要表现出“上干下湿”型和“湿层深厚”型两个阶段,飑线的旺盛发展阶段中低空有强的垂直风切变。

Based on the cloud-to-ground(CG)lightning location data,weather radar data,satellite data and radiosonde data of Guangdong Province,this paper analyzes the lightning activity of a squall line process in Guangdong Province on 31 March 2014.This paper focuses on the analysis of the variation characteristics of the CG activity in the squall line process and the relationship between the CG activity and the meteorological observation data in the same period.The results show that:in the early stage of squall line development,the CG activity increases rapidly;in the vigorous stage,the CG frequency maintains a high level;in the weakened stage,the CG activity decreases obviously.In the whole squall line development process,the negative CG activity takes the dominant position,and the peak value of positive lightning ratio is about 1h behind the peak value of CG frequency;92.8%of the CG activity per unit area of squall line process occurred in the echo area with combined reflectivity greater than 40 dBz,and the echo area with combined reflectivity greater than 60 dBz was the most active;In the strong stage of squall line,there are obvious“bow echo”,fuzzy velocity and obvious velocity convergence on radar image;TBB bright temperature lower than 220 K area has a good corresponding relationship with the dense area of lightning activity;the active period of ground lightning activity is usually accompanied by obvious unstable stratification characteristics,mainly including the“upper dry and lower wet”type and the“wet layer deep”type,and there is strong vertical wind shear in the middle and low altitude during the vigorous development stage of squall line.