基于VDRAS资料探究河北中南部一次弓状强飑线的演变和机理  

Evolution and Development Mechanisms of an Arc-Shaped Strong Squall Line Occurring in the Center-south Part of Hebei Province Based on VDRAS Data

作　　者：姬雪帅 杜晖 张曦丹 黄若男 郭宏 郭旭晖 JI Xueshuai;DU Hui;ZHANG Xidan;HUANG Ruonan;GUO Hong;GUO Xuhui(Zhangjiakou Meteorological Bureau,Zhangjiakou 075000,China;Guangdong Technical Support Center of Meteorological Public Security,Guangzhou 510641,China)

机构地区：[1]张家口市气象局,河北张家口075000 [2]广东省气象公共安全技术支持中心,广东广州510641

出　　处：《沙漠与绿洲气象》2023年第3期44-51,共8页Desert and Oasis Meteorology

基　　金：灾害天气国家重点实验室开放课题(2019LASW-B04);广东省气象局青年基金(GRMC2021Q09);张家口市气象局创新团队共同资助。

摘　　要：利用常规气象资料、ERA5再分析资料、北京VDRAS资料以及雷达资料,对2021年7月31日发生在河北中南部的一次弓状强飑线过程进行分析。结果表明:(1)此次飑线过程发生在冷涡的背景下,500 hPa涡后的冷空气与850 hPa的暖脊叠加,建立了不稳定层结,在地面辐合线附近触发。(2)雷达回波由分散的对流单体合并加强,强弓形出现时,最大强度值超过55 dBZ,存在径向速度大值区和中层径向辐合等特征,这些都预示地面大风的出现,而回波悬垂预示冰雹出现。(3)雷达反演的风场可以显示飑线的水平和垂直结构,能清楚地指示飑线的出流、入流以及辐合区,对指示飑线不同部位的发展趋势有重要指示意义。(4)地面风场辐合导致雷暴单体触发,雷暴单体在不稳定的大气层结中获得快速发展,发展过程中0~3 km的垂直风切变逐渐增强,低层形成冷池,热力不均匀区域扩大,沿着扰动温度梯度大值区与风场辐合区,新生对流向东向南传播,分散对流单体合并演变为飑线。(5)从飑线发展阶段的热动力结构分析中发现,由倾斜上升气流与下沉气流形成垂直环流,下沉气流增强时,冷池效应增强,低层环境垂直风切变也增强,环境条件的改变是飑线发展的结果,同时新的环境条件驱动飑线向前移动并发展加强。Based on conventional meteorological data,ERA5 reanalysis data,Beijing VDRAS data and radar data,an arc-shaped strong squall line occurred in center-south part of Hebei province on July31,2021 was analyzed.It shows that:(1)The squall line occurred under the background of cold vortex,and the cold air behind the 500 hPa vortex superimposed with the 850 hPa warm ridge,which established unstable stratification and triggered near the ground convergence line.(2)The radar echo is strengthened by the combination of scattered convective cells,the maximum intensity value exceeds 55dBZ when the strong bow appears,there is a region of large radial velocity and the middle layer of radial convergence,etc.These characteristics all indicate the appearance of strong wind on the ground,while the echo overhang indicates the appearance of hail.(3)The wind field retrieved by radar can show the horizontal and vertical structure of the squall line,and can clearly indicate the outflow,inflow and convergence area of the squall line,which is of great significance for indicating the development trend of different parts of the squall line.(4)The local convergence of the surface wind field led to the triggering of thunderstorm cells,and the thunderstorm cells developed rapidly in the unstable atmospheric stratification.During the development process,the vertical wind shear of 0-3 km gradually strengthened,the cold pool formed in the lower layer,and the thermal uneven area expanded.Along the large value area of the disturbance temperature gradient and the convergence area of the wind field,the new convection propagated eastward and southward,and the scattered convection cells merged and evolved into squall lines.(5)The wind field retrieved by radar can display the horizontal and vertical structure of the squall line,clearly indicate the outflow,inflow and convergence area of the squall line,and have important indicative significance to indicate the development trend of different parts of the squall line.

关 键 词：弓状飑线 VDRAS 冷池 雷达回波 风场反演 

分 类 号：P445[天文地球—大气科学及气象学]