鄂东一次下击暴流天气的中尺度分析  

Analyses of a downburst event in the eastern part of Hubei province

作　　者：张家国[1] 王平[1] 吴涛[1] 

机构地区：[1]武汉中心气象台,武汉430074

出　　处：《气象科学》2010年第2期239-244,共6页Journal of the Meteorological Sciences

基　　金：武汉区域基金项目(QY-Z-200904);中国气象局中尺度分析示范项目(CMATG2008Y04)

摘　　要：利用自动气象站观测网资料,计算了逐分钟地面散度场,并将散度场等与多普勒天气雷达资料叠加形成综合分析场,对2007年7月27日鄂东地区雷雨大风天气过程进行了中尺度分析。结果表明:地形辐合线对中尺度对流系统(MCS)触发和加强起到重要作用。MCS发生发展期间,多普勒天气雷达上相继有两个弓状回波形成。第一个弓状回波在速度图上因弓状回波移动方向与雷达波束有较大夹角后部入流急流特征不明显,但强度图上有弱回波通道特征;第二个弓状回波沿雷达径向移动,后部入流急流特征明显。武汉地区灾害性雷雨大风是一个强盛的多单体风暴所产生的系列下击暴流造成的,它位于第二弓状回波向前突出的位置。系列下击暴流发生期间,地面附近强辐散峰值与多单体风暴强回波高度显著下降的时间和位置基本一致。除弓状回波特征、后部入流急流、中层速度辐合及回波重心高度下降等特征外,弱回波通道、风暴相对速度图上沿雷达波束方向的正负速度对等也是下击暴流发生的典型特征。A severe convective weather event is analyzed using Doppler radar, conventional and automatic weather station data, etc. The result shows that the topographic convergence plays an important role in developing and strengthening mesoscale convection system. During the development of MCS, there are two bow echoes in MCS. The first one has no characteristics of the rear inflow jet at velocity image but characteristics of weak echo channel at reflectivity image The second one moves along the radial direction is characterized by its clear inflow jet. The disaster gale in Wuhan area is caused by series of downbursts produced by strong multi-cell storm. During downbursts, the location and time of the surface divergence peak are in agreement with the significant height decrease of strong echo of the muhicell storm. Except the characteristics of bow echo, middle level convergence, rear inflow jet echo, weak echo channel and a pair of positive and negative speed are also typical characteristics.

关 键 词：中尺度对流系统 多单体风暴 下击暴流 弓状回波 

分 类 号：P458.2[天文地球—大气科学及气象学]