一次强寒潮过程的多相态降水分析  

Analysis of Multiphase Precipitation During a Strong Cold Wave at End of March 2020

作　　者：温静 雷正翠 温龙[3] 姚丽娜 黄文彦 WEN Jing;LEI Zhengcui;WEN Long;YAO Lina;HUANG Wenyan(Changzhou Meteorological Bureau,Jiangsu,Changzhou 213022;China Meteorological Administration Traffic Meteorological Municipal Key Laboratory,Nanjing 210008;Xichang Satellite Launch Center,Sichuan,Xichang 615099)

机构地区：[1]江苏省常州市气象台,常州213022 [2]中国气象局交通气象重点实验室,南京210041 [3]西昌卫星发射中心,西昌615099

出　　处：《气象科技》2023年第5期704-714,共11页Meteorological Science and Technology

基　　金：中国气象局预报员专项(CMAYBY2019-043);江苏省气象局科研基金项目(KM202208、KQ202319)共同资助。

摘　　要：综合利用常规观测资料、双偏振雷达和雨滴谱仪探测资料,对2020年3月28日发生在常州地区的一次罕见强寒潮引起的降雨、雨夹雪和雪不同相态降水天气进行了分析。结果表明:(1)此次3月末罕见强寒潮和降水主要是在高空槽、中低层切变线和西南急流与地面冷高压配合下,强冷平流入侵以及850 hPa明显干层的蒸发(或升华)吸热的共同作用引起的,中低层温度的急剧下降,导致降水相态发生变化。(2)双偏振雷达监测到3种降水相态呈现出不同的偏振变量特征:降雨相态向雨夹雪转变时,反射率因子Z增大,差分反射率因子Z_(DR)增大,相关系数C_(C)有明显的低值带状分布,呈现出Z>30 dBz,Z_(DR)>1 dB,C_(C)<0.95组成的雨雪相态混合区域;而纯雪则为Z>22 dBz,Z_(DR)<1 dB,C_(C)>0.98。(3)雨滴谱仪显示降雨阶段主要由高浓度小粒子构成,雨滴速度-尺度谱呈现为倾斜的带状;雨夹雪阶段数浓度减小,粒径范围较宽,质量加权平均直径明显增大,雨滴速度-粒径范围介于降雨和纯雪之间;纯雪阶段速度-尺度谱下压右伸,粒子直径分布较宽。Based on conventional observation data,dual-polarisation radar data,and raindrop spectrometer data,different phases of rain,sleet,and pure snow caused by a rare cold wave that occurred in Changzhou on 28 March 2020 are analyzed.The results show that:(1)The impact of this intense cold wave weather happened in the winter and spring alternating season at the end of March.There was a severe drop in cooling weather in Changzhou(the temperate drop in early spring ranked second in history),and light rain,light sleet,or light snow occurred successively.During the cold wave,the temperature fell sharply twice.The first drop(8.7℃in 6 h)was caused by the weak cold air at the surface.The second cooling period(2 h drop of 5.0℃during this time)occurred primarily due to a combination of high altitude trough,mid to low-level shear,and surface cold high pressure,as well as strong cold advection intrusion and the absorption of evaporative(or sublimative)heat by an apparent dry layer at 850 hPa.This triggered a sharp decrease in temperature at the mid and low levels during precipitation,causing the entire layer to become a cold layer and remained low.This provided favourable conditions for the rain to turn into snow,resulting in rapid changes in the precipitation phase.(2)The dual-polarisation radar determined that the three precipitation phases displayed different polarisation variable characteristics.When the precipitation phase changed to sleet,Z increased,Z_(DR)increased significantly,C_(C)showed an evident low-value zonal distribution,and K_(DP)increased slightly.During the transition from sleet to pure snow,the mixed region of rain and snow phase composed of Z>30 dBz,Z_(DR)1 dB,C_(C)<0.95 was gradually pressured south,and then became Z>22 dBz,Z_(DR)1 dB,C_(C)>0.98 pure snow,and K_(DP)decreased slightly.It was also observed that dual-polarisation radar had more reference significance for monitoring precipitation in different phase states than single polarisation radar.(3)The rain phase consisted of high-concentration small

关 键 词：强寒潮 降水相态 双偏振雷达 雨滴谱 

分 类 号：P415.2[天文地球—大气科学及气象学] P426