2014年淮河流域一次飑线过程的结构及环境分析

Analysis of the structure and environment of a squall line in Huaihe river basin in 2014

基于多普勒天气雷达、LAPS模式(Local Analysis and Prediction System)和地面加密观测等资料,细致分析了2014年6月1日发生在安徽阜阳的一次飑线过程的结构以及环境特征。结果表明:降水过程发生在对流层中层槽前的偏南暖湿气流中,初期呈现"人"字形结构,之后其西段增强为飑线。综合分析显示:冷锋的强迫抬升是该飑线的主要触发原因。这次飑线以强降水为主,其在强盛期呈现明显的弓状回波,此时在其南北两端呈现为反气旋与气旋涡旋对,同时从对流层高层下沉卷入飑线后部的较弱干冷空气使飑线的后侧入流更加明显,与此特征相伴,地面出现7级大风。当低层出流截断了暖湿入流时,降水区内转为以偏西下沉气流为主,地面出现弱冷池,之后飑线快速减弱。此次飑线生命史约5 h。

A squall line moved through Huaihe river basin on June lth. 2014. Using Doppler radar data, the Local Analysis and Prediction System （LAPS） and surface observation data etc., the structure and the environment characteristics of the squall line were analyzed. A cold front provided the primary lifting responsible for the formation of the squall line, which located south of the tough in the middle level of troposphere. Initially, the precipitation took a ＂人＂ shape, being stronger in west part. A squall line occurred in the west part. The squall line brought mainly heavy rain. When the squall line was at the strongest stage, the classical bow echo appeared. There was a pair of anticyclone and cyclone on the two ends of the squall line, respectively. At the same time, a cold-dry air sank from the high level of troposphere and rolled into the rear of the squall line, and then the rear inflow became faster. Near surface, there was 16.6 m·s^-1 gale. After the outflow cut off the inflow in low level, the downdraft was dominant in the rain area, and the squall line quickly declined. The squall line brought a weak cold pool. The lifetime of the squall line was about 5 h.