华北冷涡背景下山东两次强对流天气过程对比分析

Comparative Analysis of Two Severe Convective Weather Processes in Shandong Under Background of North China Cold Vortex

基于地面和高空观测资料、NCEP 1°×1°再分析资料及多普勒雷达等资料,对发生在山东两次相似环流形势的华北冷涡背景下,造成不同类型的强对流天气进行对比分析。结果表明:(1)2016年6月14日发生的强对流天气(“6·14”过程)以雷暴大风和短时强降水为主,发生在低层弱的垂直风切变环境中,对流层中下层(400~900 hPa)存在较为深厚的暖湿平流,水汽输送充沛,同时造成0℃、-20℃层高度抬升,有利于短时强降水而不利于冰雹产生;2018年6月13日发生的强对流天气(“6·13”过程)以雷暴大风和冰雹为主,发生在较强的条件不稳定层结和强的低层垂直风切变环境中,400~500 hPa冷平流以及低层暖平流的同时增强,有利于对流层中层的温度垂直递减率进一步增大,造成-30~-20℃层进一步下降,促成了大冰雹的发生环境。(2)“6·14”过程是由地面辐合线触发,“6·13”过程是由锋面触发。(3)“6·14”过程强反射率因子高度低,无明显高悬强回波结构,利于出现短时强降水;“6·13”过程具有单体结构密实和明显高悬强回波结构特征,因此,“6·13”过程对流强度更强,更容易出现冰雹。

This paper compares and analyzes different types of strong convective weather under the background of the North China cold vortex that occurred in two similar circulation situations in Shandong based on ground and highaltitude observations,NCEP 1°×1°Reanalysis data and Doppler radar data.The results show that the strong convection weather process on 14 June 2016(6·14)was dominated by thunderstorm gale and shortterm heavy precipitation,which occurred in the lowlevel vertical wind shear,and there was relatively deep warm and moist advection in the middle and lower troposphere(400 to 900 hPa)with abundant water vapour transport.At the same time,the height of the 0℃and-20℃layers would rise,which was conducive to shortterm heavy precipitation but not hail generation.The strong convective weather process on 13 June 2018(6·13)was dominated by thunderstorm gale and hail,which occurred in strong conditional instability layers and strong lowlevel vertical wind shear,and the simultaneous enhancement of 400 to 500 hPa cold advection and lowlevel warm advection was conducive to the further increase of the vertical decline rate of temperature in the middle troposphere,resulting in the further decline of-20℃to-30℃layer,and contributing to the occurrence environment of the large hail.The“6·14”strong convective weather process was triggered by the surface convergence line,and the“6·13”strong convective weather process was triggered by the front.The strong reflectivity factor of the“6·14”strong convective weather process was low in height,and there was no obvious highhanging strong echo structure,which was conducive to the occurrence of shortterm heavy precipitation,and the“6·13”strong convective weather process had the characteristics of the dense single structure and obvious high hanging strong echo structure.Therefore,the convective intensity of the“6·13”strong convective weather process was stronger and more prone to hail.