2020年6月25日京津冀风雹灾害成因分析

Cause Analysis of Wind and Hail Disasters in Beijing,Tianjin and Hebei on June 25,2020

利用常规气象观测资料、加密自动气象站观测资料,详细分析了2020年6月25日京津冀地区大范围风雹灾害。结果表明:此次风雹灾害是在深厚的蒙古气旋环境背景下产生的;高层一致的西北干冷气流叠加在低层较强的东南—西南暖湿气流形成深厚的垂直环流,增大了对流性不稳定能量;动量下传后中层产生较强的垂直风切变;“速冻”是冰雹产生的必要条件,这就要求-20℃高度层以上具有大的垂直温度递减率,远比0℃~-20℃层垂直温度递减率大;地形的抬升作用和地面辐合线是此次过程的抬升机制。

By using the conventional meteorological observation data and the observation data of the densified automatic meteorological station,the large-scale wind and hail disaster in Beijing Tianjin Hebei region on June 25,2020 was analyzed in detail.The results show that the hailstorm disaster occurred in the deep Mongolian cyclone environment;The high level consistent northwest dry and cold air flow superimposed on the low level strong southeast southwest warm and wet air flow to form a deep vertical circulation,increasing the convective instability energy;Strong vertical wind shear occurs in the middle layer after momentum is transmitted downward;“Quick freezing”is a necessary condition for hail generation,which requires a large vertical temperature decline rate above the -20℃ level,which is far greater than the vertical temperature decline rate from 0 to -20℃;The uplift of the terrain and the convergence line of the ground are the uplift mechanisms of this process.