一次西南气流中长生命史多单体风暴过程的演变特征及成因

Analysis on the Evolutionary Characteristics and Formation of a Long-Time Multi-Cell Storm in Southwest Flow

利用常规天气探测资料、自动站资料、FY-2G云顶温度资料、多普勒天气雷达产品和闪电定位资料,对2017年4月8日造成江西省东北部强雷暴大风的长生命史多单体风暴过程进行了分析。结果表明:对流层中层干的西南气流叠加在低层西南暖湿气流之上和发展旺盛的地面倒槽,为江西东北部提供了较强的动力、热力不稳定环境。中低层风速矢端图表现为单一方向的风切变,强的垂直风切变集中在低层,有利于风暴的发生和维持。风暴移动和传播同向,呈前向传播特征。风暴前冷池与移动前方高温区之间的局地温度锋区与地面辐合线是风暴的触发条件和维持机制。雷暴下沉气流及地面辐散、高空动量下传和地面气压梯度风的共同作用,导致了地面大风。地闪活动演变超前地面大风1—2 h。

Based on the conventional weather sounding data,the automatic weather station data,FY-2G TBB and Doppler weather radar products,a long-time multi-cell storm process that resulting in strong thunderstorm winds in the northeast of Jiangxi on April 8,2017 was discussed.The results showed that the dry cold mid-level southwest flow superimposed on the low-level warm wet southwest flow and the enhanced ground trough provided a strong dynamic and thermodynamic unstable environment for the northeastern Jiangxi.The mid-lower wind speed vector diagram presented a single direction wind shear and the strong vertical wind shear concentrated in low-level,which contributed to the occurrence and maintenance of storms.The movement and propagation of storms were in the same forward direction.The local temperature front between the cold pool before storms and the high temperature zone ahead and the ground convergence line were the triggering condition and maintenance mechanism of the storm.The synergies of the downward flow,the ground divergence,the downward transport of momentum and ground pressure gradient wind created the surface gale.The CG lightning flashes evolved 1-2 hours ahead of the gale.