湖南一次罕见低温雨雪冰冻天气过程分析  

Analysis of a Rare Consecutive Cryogenic Freezing Rain in Hunan Province

作　　者：刘红武 李振 陈龙 尹忠海 徐靖宇 蔡瑾婕 LIU Hongwu;LI Zheng;CHEN Long;YIN Zhonghai;XU Jingyu;CAI Jinjie(Meteorological Observatory of Hunan Province,Changsha 410118,China;Meteorological Bureau of Hunan Province,Changsha 410118,China)

机构地区：[1]湖南省气象台,湖南长沙410118 [2]湖南省气象局,湖南长沙410118

出　　处：《沙漠与绿洲气象》2020年第2期18-26,共9页Desert and Oasis Meteorology

基　　金：中国气象局预报员专项(CMAYBY2017-050);2016-2017年湖南省气象局能力建设项目(YBNL16-12-1);湖南省预报员专项(XQKJ19C010);湖南省气象局预报员专项(XQKJ18C013)。

摘　　要：利用常规观测资料、地面自动站资料、NCEP 1°×1°再分析资料及雷达资料等多源资料对2016年1月20-24日发生在湖南的一次低温、雨雪(暴雪)、冻雨灾害性天气过程进行了综合分析。结果表明:(1)整个降雪过程分为3个阶段,雨雪区域自北向南逐步推进,最低气温长沙站低至-6.6℃,破2008年记录,创21世纪以来最低值。(2)500 hPa中高纬度为倒"Ω"型,横槽深入巴尔喀什湖地区,在转竖的过程当中不断引导冷空气南下,是产生低温、雨雪、冻雨的大尺度环流背景;地面冷高压中心最强达1090 hPa,锋区温度差超过25℃是造成最低气温破记录的主要原因。(3)高空南支有低槽分裂东移,中低层西南大风核上强烈的水汽辐合与横槽转竖带来的冷空气共同作用时,为此次过程提供了动力、水汽和凝结条件。(4)分析探空站的大气层结、地面气象要素与冰冻的关系表明,大气层结的逆温层、融化层,地面温度在0℃附近及以下是形成冰冻的关键因子。(5)多普勒雷达产品资料显示,不管是雨雪强的时段还是弱的时段,均表现为基本反射率因子回波边缘模糊不清,丝缕状纹理结构明显,径向速度图上的"牛眼"等特征。但回波强度、回波顶高及径向速度图"牛眼"和零速度线位置、风场大小差别很大。Based on the data from conventional observation,surface automatic meteorological station,the NCEP reanalysis data(1°×1°)and radar data,this study analyzed the cryogenic freezing rain processes happened in Hunan from 20 January to 24 January,2016.The results illustrated that:(1)The whole snowfall process was divided into three stages.Rain/snow areas were gradually advancing from north to south.The minimum temperature at Changsha station was-6.6℃,which break the record in 2008 and set the lowest level since the 21 st century.(2)The middle and high latitudes of 500 hPa were inverted shape.The transverse trough penetrates into the Balkhash lake area and continuously guides the cold air southward in the process of vertical rotation,which was the background of large-scale circulation that produces cryogenic freezing rain.Surface cold high pressure center of 1090 hPa,strongest temperature differences of frontal strength more than 25℃was the main cause of lowest temperature record.(3)The south branch of the upper air has a low trough splitting to the east,and the strong water vapor convergence on the southwest wind core in the middle and lower layers and the cold air brought by the vertical turn of the transverse trough act together to provide the power,water vapor and condensation conditions for this process.(4)Analysis of the relationship between atmospheric stratification,surface meteorological factors and phase transformation of rain and snow at sounding station shows that the inversion layer,melting layer of atmospheric stratification and the ground temperature near and below 0℃were the key factors for ice formation.(5)Doppler radar product data shows that the basic reflectivity factor echo edge was blurred,the filament texture structure was obvious,and the bull’s eye on the radial velocity map was the characteristics of both strong rain/snow period and weak period.However,echo intensity,echo top height and radial velocity map,position of bull’s eye and zero velocity line,wind field size are very differ

关 键 词：低温雨雪冰冻 横槽转竖 最低气温 锋区 多普勒雷达特征 

分 类 号：P458.121.1[天文地球—大气科学及气象学]