华北回流天气多普勒雷达径向速度分布特征  

Distribution of Doppler Radar Radial Velocity of the Return-flow Events over North China

作　　者：张守保 张迎新[1] 王福侠 裴玉杰 

机构地区：[1]河北省气象台,石家庄050021

出　　处：《气象》2008年第2期33-37,130,131,共7页Meteorological Monthly

基　　金：中国气象局气象灾害天气国家重点实验室开放课题CMATG2005Y06资助

摘　　要：使用多普勒雷达资料对四次华北回流天气过程进行了分析,结果表明:(1)回波具有较大水平范围的、连绵成片的均匀幕状特征。回波顶较平整,回流降雨过程中还存在零度层亮带。属层状云降水回波。(2)速度图上,在零速度线两侧常分布范围较大数值不等的正负径向速度中心,低空零速度线呈"S"型,风随高度顺时针旋转,有暖平流存在。在强降水时段出现前常伴有区域性的冷平流层。(3)风廓线图上,从低层到高层由东北风转为西南风,风向发生了近180度的顺时针旋转,存在强垂直切变。降水开始与结束时分别表现为低层偏东风与中高层西南气流叠加、低层偏东风与中高层西南气流任何一者消失。边界层顶部出现浅薄的冷平流层是降水强度加强的信号。Using Doppler radar data, the four return flow events were analyzed. The results are as follows： （1） PPI showed a large range symmetrical flaky reflectivity with flat top. And 0℃ bright belt occurred in higher beams. （2） On VPPI, ＂0＂ line crossed through the radar station and showed a structure like ＂S＂. The wind veered with height from NE to W, until SW with warm advection in lower layer. Acompanying with the cold advection around the top of boundary, efficiency of precipitation became strong. （3） The wind direction were discontinuous in the vertical direction, NE in the low layer and SW in the middle. The vertical shear was observed on VAD. The start and end time of precipitation was closely related to the wind direction, including boundary layer NE wind and middle layer SW wind.

关 键 词：多普勒雷达 华北回流 径向速度 反射率因子 

分 类 号：P457.2[天文地球—大气科学及气象学] V321.2[航空宇航科学与技术—人机与环境工程]