云南西部一次中β尺度对流系统特征分析

Characteristic analysis of a β-mesoscale convective system in West of Yunnan

利用雷电定位资料、加密观测资料、FY-2E卫星红外资料和NCEP-GFS 0.5°×0.5°再分析资料,对云南西部一次中β尺度对流系统的结构和成因进行了分析,结果表明:地面风场辐合以及中高层冷空气侵入是此次过程发生发展的主要原因,地面风场辐合区的位置和移动可以作为对流系统短临预报的重要参考依据,中高层下沉的冷空气与低层辐合抬升的暖空气相互作用,有利于对流不稳定能量的积累及释放,从而触发强对流天气的发生和发展;地闪活动与垂直上升运动区和不稳定能量释放区存在密切关系,地闪频数的变化,可作为对流云团发生发展的判据之一.

Based on lighting data,Dopplar radar data and FY-2E satellite infrared data and NCEP-GFS reanalysis data with 0. 5° × 0. 5° resolution,the structures and the causes of β-mesoscale convective systems( MβCS) event in west of Yunnan are analyzed.The results show that the main cause of the event is the convergence of surface winds and the intrusion of cold air in the middle and upper troposphere.The location and movement of the convergence of wind on ground surface could be used as important reference for the imminent forecast of short-time severe precipitation.The interaction between the cold air in the mid-and upper-level and the warm air of the low-level uplifting,which is conducive to the accumulation and release of conventive unstable energy and triggering the occurrence and development of severe convective weather.The cloud-to-ground lightning activity is closely related to vertical ascending motion and the unstable energy release area.And the frequency change of cloud-to-ground lightning could be one of the signals indicating the occurrence and development of convective cloud cluster.