苏州"7.26"强飑线增强机制分析OA北大核心CSTPCD

This study examined the circulation patterns and factors contributing to the sudden intensification of a squall line near Taihu Lake during a large-scale extreme thunderstorm and gale event in southern Jiangsu Province on July 26,2022.The analysis was based on data from dual-polarization radar,reanalysis data,radiosonde,automatic ground station,wind profile data,and microwave radiometer.The results showed that:(1)The downward propagation of a low-level jet resulted in the formation of an ultra-low-level jet,which enhanced the influx of dry and cold air in the middle layer.This led to the formation of an outflow with sinking airflow reaching the ground,intensifying ground convergence and further developing the squall line.(2)The strong precipitation during the eastward movement of the squall line led to the continuous strengthening of its cold pool,leading to a secondary circulation inside the squall line,strengthening the rear inflow,and further developing the squall line.(3)The reduced friction coefficient of the lake surface significantly increased the speed of the strong squall line passing over the Lake.The cold lake effect and temperature difference between the lake and land maintained and the convective intensity increased as the squall line passed over Taihu Lake.The passage of the squall line over the lake surface replenished water vapor and these effects jointly led to a level 12 strong wind on the ground.