冷涡背景下河北雷暴大风环境条件与对流风暴演变个例分析  

Analysis of environmental condition and convective storm evolution of a thunderstorm gale event under cold vortex in Hebei

作　　者：杨晓亮 杨敏[3] 隆璘雪 艾敬宜 YANG Xiaoliang;YANG Min;LONG Linxue;AI Jingyi(Hebei Meteorological Observatory,Shijiazhuang 050021;Hebei Key Laboratory for Meteorological and Eco-environment,Shijiazhuang 050021;Heibei Meteorological Administrative&Technical Service Center,Shijiazhuang 050021)

机构地区：[1]河北省气象台,石家庄050021 [2]河北省气象与生态环境重点实验室,石家庄050021 [3]河北省气象行政技术服务中心,石家庄050021

出　　处：《暴雨灾害》2020年第1期52-62,共11页Torrential Rain and Disasters

基　　金：环渤海区域科技协同创新基金项目(QYXM201804);河北省气象局“强对流创新团队”;河北省科技厅科技研发平台建设专项(18964201H)。

摘　　要：2017年7月9日河北中南部出现一次区域性雷暴大风天气过程,该过程属于典型的高空冷平流强迫型强对流天气,对流云团先后影响河北中南部的南(Ⅰ)、北(Ⅱ)两个区域。利用常规地面高空观测资料以及卫星云图、多普勒天气雷达、区域自动站与NCEP 1°×1°再分析资料,分析了此过程发生的环境条件以及对流风暴的演变特征。结果表明:(1)本次过程发生在蒙古冷涡天气背景下,冷涡后部冷空气与低层暖湿空气在河北南部形成“上干冷下暖湿”的不稳定层结以及较强垂直风切变,区域Ⅰ对流由地形抬升触发,并在高空西北气流作用下向东南方向移动,而区域Ⅱ对流由冷锋直接触发,在平流和传播的共同作用下向东偏北方向移动。(2)造成区域Ⅰ大风的对流系统有飑线、与中气旋伴随的超级单体,飑线成熟阶段后侧入流急流在1 km以下超过31 m·s^-1,地面大风出现在大风速核前沿、雷暴高压移向的前方和小时正变压中心附近;造成区域Ⅱ大风的对流系统有多种形态,如超级单体、块状回波和飑线,飑线大风出现在阵风锋后侧到小时正变压中心之间。飑线回波强度减弱后冷池密度流、动量下传和变压风共同作用仍可造成地面大风。(3)雷达低仰角径向速度图超过30m·s^-1的大风速核配合地面5 hPa以上的小时正变压,风廓线雷达5 km以下的7~10 m·s^-1下沉速度伴随1 km以下强的西北风,可作为地面8级以上雷暴大风0~2 h临近预警的参考指标。A regional thunderstorm gale weather event occurred in central and southern Hebei on 9 July 2017. It is a typical severe convective weather with the cold advection forcing in upper air. The convective cloud clusters successively affected the south area(Ⅰ) and north area(Ⅱ)of central and southern Hebei during this event. Based on the routine upper-air and surface observations, satellite cloud images, Doppler weather radar data, observations from regional automatic weather stations and NCEP reanalysis data with 1°×1° resolution, we have conducted an analysis of the environmental conditions and the evolution characteristics of the convective storm when this event occurred. The main results are as follow.(1) This event occurs under the background of the Mongolian cold vortex weather. The cold air at the rear of the cold vortex and the warm and wet air in the low-level jointly form an unstable stratification with the dry and cold air in high level and the warm and humid air in low level, in which vertical wind shear is strong in southern Hebei Province. The convection in area Ⅰ is triggered by topographic uplift, and moves southeastwards under the action of northwest airflow in the high level. Nevertheless, the convection in area Ⅱ is directly triggered by the cold front, and moves eastwards and northwards under the combined action of advection and propagation.(2) The convective systems causing the gale in area I include the squall line and the supercell associated with mesocyclone. The rear inflow jet below 1 km exceeds 31 m·s-1 in mature stage of the squall line. The surface gale appears at the front of the center of high wind speed, the front of the thunderstorm high and the vicinity of hourly positive pressure center. There are various types of convective systems causing the gale in area Ⅱ, including supercell, block-shaped echo and squall line. The gale squall line appears between the rear side of gust front and the hourly positive pressure center. After the echo intensity of the squall line is decr

关 键 词：雷暴大风 对流风暴 飑线 雷暴高压 临近预警 

分 类 号：P458.123[天文地球—大气科学及气象学]