合肥“4·30”冰雹天气的多源资料分析

Multi-source Data Analysis of Hail Weather on April 30 in Hefei

2021年4月30日夜间,合肥出现大范围冰雹天气,冰雹最大直径约3 cm。为研究这次冰雹天气的形成机制,利用常规观测资料、自动气象站、多普勒天气雷达、风廓线雷达、葵花8卫星和ERA5再分析资料,对此次冰雹天气的环流背景、环境条件和中尺度系统特征进行分析。结果表明:冰雹天气发生在深厚的东北冷涡背景下,地面午后增温,中层东北冷涡携带冷空气南下,温度直减率加大,中低层垂直风切变加大,均为强对流天气的发生提供了有利的热力和动力条件。降雹云团由数个分散的对流云合并,冰雹发生于TBB低于-52℃强对流核附近。垂直累积液态水跃增时间较地面降雹时间提前了22 min。边界层强垂直风切变和1200 m高度的风向不连续线,有利于触发新的对流单体。

On the night of April 30,2021,a large-scale hailstorm occurred in Hefei and the maximum diameter of the hail reached three centimeters.To study the formation mechanism of this hailstorm,this paper analyzes the circulation background,environmental conditions and mesoscale system characteristics using conventional observations,automatic weather stations,doppler weather radar,wind profile radar,Sunflower 8 satellite and ERA5 reanalysis data.The results show that:the severe convective weather occurred under the background of a deep northeast cold vortex.The surface temperature increase in the afternoon,the increase in vertical lapse rate of temperature caused by the northeast cold vortex carrying cold air,and the change of vertical wind shear in the middle and lower layers provide favorable thermal and dynamic conditions for the occurrence of severe convective weather.Satellite cloud images show that the hailfall clouds consist of several scattered convective clouds merging.The hail occurs near the strong convective nucleus with TBB below-52℃.Radar echoes showed that the rapid increase of vertical accumulated liquid water(VIL)was 22 min earlier than the time of ground hail.Strong vertical wind shear in the boundary layer and wind direction discontinuity at the height of 1200 m are conducive to triggering new convective cells.