长沙一次大暴雨的双偏振及风场反演特征分析  

Analysis of Dual Polarization and Wind Field Inversion Characteristics of a Heavy Rainstorm in Changsha

作　　者：唐明晖 付炜 罗源 周慧 蔡荣辉 TANG Minghui;FU Wei;LUO Yuan;ZHOU Hui;CAI Ronghui(Hunan Meteorological Observatory,Changsha 410118,China;Key Laboratory of Preventing and Reducing Meteorological Disaster of Hunan Province,Changsha 410118,China;Zhuzhou Meteorological Bureau,Zhuzhou,Hunan 412000,China)

机构地区：[1]湖南省气象台,湖南长沙410118 [2]气象防灾减灾湖南省重点实验室,湖南长沙410118 [3]株洲市气象局,湖南株洲412000

出　　处：《热带气象学报》2024年第4期623-632,共10页Journal of Tropical Meteorology

基　　金：湖南省科技厅重点研发项目(2019SK2161);国家重点研发计划(2023YFC3007804)共同资助。

摘　　要：利用S波段双偏振雷达和X波段相控阵雷达对2022年4月25日长沙大暴雨过程进行分析。(1)回波带由东北-西南向带状演变成东-西向带状,差分反射率因子(Z_(DR))大值区(≥1.0 dB)呈带状分布,列车效应造成长沙大暴雨天气过程。(2)过程对流单体东-西向排列且强回波(≥45 dBZ)扩展至6 km,Z_(DR)、差分相移率(K_(DP))柱扩展至融化层高度以上;对流单体融化层高度以下Z_(DR)大部分为正值,且底层Z_(DR)、K_(DP)大值区说明雨滴不仅水平直径大且数浓度高,对应雨强大。(3)分钟雨量超过1 mm对应1.7~2.4°·km^(-1)K_(DP)值,且出现K_(DP)空洞;分钟雨量超过2 mm对应2.4~3.1°·km^(-1)K_(DP)值。(4)三维风场显示强降水期间,带状对流回波前侧、南侧强西南风为大暴雨源源不断输送水汽;较深厚的辐合有利于带状回波维持;弓型回波伴有气旋式风场;高层风场有强辐散。(5)三维风场和强度垂直剖面显示最强降水时段有明显云砧回波,有利的动力抬升和水汽输送使得强回波中心M得以维持;随着中低层逐渐转为西北风或西风,回波减弱、分钟雨量陡降。以上分析结果表明双偏振产品对对流性降雨有明显的指示意义,X波段相控阵雷达反演的三维风场较好地刻画了对流强度及辐合、辐散特征。This study aims to help forecasters to apply dual polarization and phased array radar products in the analysis of rainstorm process.The heavy rainstorm in Changsha on April 25,2022,is analyzed by using S-band dual-polarization radar and X-band phased-array radar.The findings are as follows:(1)The precipitation echo belt changed from a northeast-southwest orientation to an east-west orientation.The high value region(≥1.0 dB)of difference reflectance factor(Z_(DR))showed zonal distribution,and the train effect caused the heavy rain in Changsha.(2)Multiple convective cells were arranged in an east-west direction and extended to a height of 6km.The expansion of Z_(DR) and K_(DP) columns above the height of the melting layer indicated that strong upward airflow provided favorable conditions for water droplets to break through the melting layer and form supercooled water droplets.Below the height of the melting layer of convective cells,most Z_(DR) values were positive,with noticeable high values of Z_(DR) and K_(DP) in the bottom layer.This indicated large horizontal raindrop diameters and high number concentrations,corresponding to strong rainfall.(3)When minute rainfall exceeded 1 m,K_(DP) ranged from 1.7°to 2.4°·km^(-1),and K_(DP) cavities appeared.When minute rainfall exceeded 2 mm,K_(DP) ranged from 2.4°to 3.1°·km^(-1).(4)The three-dimensional wind field of phased-array radar inversion showed that during the heavy precipitation,strong southwest wind in front and south of the zonal precipitation echo carried water vapor,contributing to the heavy rain process.The deep shear line facilitated the maintenance of banded echo,with a strong bow echo accompanied by cyclonic wind fields and strong divergence in the upper wind field.Guided by the airflow,the banded echo continuously passed through Changsha,forming the train effect.(5)The vertical section of three-dimensional wind field and intensity showed distinct anvil-shaped echoes during the heaviest precipitation period.The strong echo center was influenced by

关 键 词：大暴雨 双偏振雷达 相控阵雷达 列车效应 ZDR KDP 

分 类 号：P426.6[天文地球—大气科学及气象学]