浙江中部地区一次超单体降雹过程的数值分析

Numerical Analysis of A Supercell Hail Process in the Middle Zhejiang

本文利用WRF(weather research and forecasting,天气预报)中尺度模式模拟2020年3月22日在浙江中部地区发生的一次超单体降雹过程,并结合多普勒雷达资料、常规天气资料分析了超单体的雷达回波特征、内部风场结构和云物理特征,研究冰雹形成、生长的机制。结果表明:本次超单体过程是在高空急流入口区右侧并配合低层冷切、配合较大的风切变、充足的不稳定能量等动力热力条件共同作用下发生发展,雷达图上有典型的钩状回波、高悬垂回波、有界弱回波区、三体散射长钉以及强烈发展的中气旋等特征。数值试验成功地再现了超单体的时空演变特征和垂直结构,降雹过程的雹粒子的增长和过冷却水密切相关,发展阶段的过冷却水、上升气流、雹三者处在统一位置,有利于冰雹的粒子增长;成熟阶段和减弱阶段则缺少这一配置,导致雹粒子缺少增长和补充,降雹趋于结束。

The WRF mesoscale model is used to simulate the hail process of a supercell in the middle Zhejiang on March 22,2020.Combined with Doppler radar data and conventional weather data,the radar echo characteristics,internal wind field structure and cloud physical characteristics of the supercell are analyzed,and the mechanism of ice hail formation and growth is studied.The results show that the supercell process occurred and developed on the right side of the upper jet inlet area with low-level cold shear,large wind shear,sufficient unstable energy and other dynamic and thermal conditions.The radar map has typical hook echo,high overhang echo,bounded weak echo area,three body scattering spike and strong developed mesocyclone and so on.The numerical test successfully reproduced the space-time evolution characteristics and vertical structure of the supercell.The growth of hail particles in this hail fall process is closely related to the supercooled water.The supercooled water,updraft and hail in the development stage are in a unified position,which is conducive to the growth of hail particles.The mature stage and weakening stage are lack of this configuration,leading to the lack of growth and supplement of hail particles,and the hail tends to end.