采用加密探空资料、Himawari-8气象卫星云图、雷达资料及地面加密观测资料,对2016年6月四川北部一次造成大风灾害的飑线过程进行综合观测分析,着重分析该飑线成熟阶段地面灾害性大风的落区特征;结合中尺度数值模式模拟的高分辨率产品数据,分析此次飑线大风落区与飑线系统后部入流急流的关系,并深入探讨了飑线系统后部入流急流的形成、维持机制.结果表明:该飑线成熟阶段,地面大风中心位于后部入流急流的中心轴顶端的强对流云团附近区域;成熟飑线前侧存在一地面中尺度辐合线,该辐合线对飑线演变具有一定的指示意义,指示时间约提前1h;由于成熟飑线系统自身的扰动温度分布不均衡,在对流单体后边界产生的水平涡度对飑线中层后部入流的加速作用下,形成了后部入流急流;在飑线的中层,后部入流急流与水平扰动温度梯度之间存在正反馈效应,它是成熟飑线产生地面大风的一种重要物理机制,也是弓形回波形成的物理机制;飑线地面大风极值的主要预报着眼点为环境对流有效位能(CAPE)和中高层干冷平流强度;中低层水汽条件对飑线维持发展起重要作用.%Based on intensive radiosonde data,visible cloud images from Himawari-8 satellite,radar data and observations from regional automatic weather stations,we have made the comprehensive analysis of a squall line event in northern Sichuan on 4 June 2016,with focus on the falling area characteristics of ground-disastrous gale induced by squall line in the mature stage.Then combining with high resolution data simulated by WRF,we have analyzed the relationship between the gale area and rear inflow jet with the squall line system,and explored the formation and maintenance mechanism of rear inflow jet.The results show that the gale center in the ground is located in the vicinity of the strong convective cloud clusters at the top end of the central axis of the rear inflow jet at the mature stage of the squall line.A surface meso-scale convergence line is observed at the front side of matured squall line,and has a high indicative significance for the development of squall line,with indicative time being ahead about one hour.The rear inflow jet is formed under the accelerated effect of the horizontal vorticity pro-duced in the rear boundary of convective cell on the rear inflow of squall line in the middle level due to the unbalanced temperature distribu-tion of the squall system.A positive feedback effect between the rear inflow jet and the horizontal perturbation temperature gradient is an im-portant physical mechanism for the formation of the gale at the mature stage and bow-shaped echo.Convective Available Potential Energy and dry and cold advection intensity in the mid-and upper-level are main factors for forecasting surface maximum gale induced by squall line. Water vapor conditions in the mid-and low-level play major roles for the maintenance and development of squall line.
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