利用双偏振参量估计降水粒子下落末速度及三维风场反演的应用  

Estimating the Final Falling Velocity of Precipitation Particles Using Dual-Polarization Parameters and Application of 3D Wind Field Retrieval in Precipitation System

作　　者：杨华 李瑞义[3] 刘黎平[2] 郑佳锋[1] 王浩宇 YANG Hua;LI Ruiyi;LIU Liping;ZHENG Jiafeng;WANG Haoyu(School of Atmospheric Sciences,Chengdu University of Information Technology,Chengdu 610225;State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,Beijing 100081;CMA Meteorological Observation Centre,Beijing 100081)

机构地区：[1]成都信息工程大学大气科学学院,成都610225 [2]中国气象科学研究院灾害天气国家重点实验室,北京100081 [3]中国气象局气象探测中心,北京100081

出　　处：《气象》2023年第7期855-867,共13页Meteorological Monthly

基　　金：国家自然科学基金项目(U2142210);国家重点研发计划(2018YFC1507400)共同资助。

摘　　要：降水系统三维风场反演的关键问题之一是准确地估算降水粒子下落末速度(W_(t)),为了探究双偏振雷达估计W_(t)的能力,利用广东省龙门地区的雨滴谱数据,建立了W_(t)与S和X波段双偏振雷达观测量的关系,并且将其应用于广州和韶关两部雷达的风场反演。对华南地区2019年4月发生的一次飑线过程进行风场反演试验,分析讨论了此次飑线过程的风场结构配置,并探索了利用不同方法估算的W_(t)在反演出的风场结构上的差异。结果表明:S和X波段雷达通过回波强度(Z H)和差分反射率(Z DR)估算W_(t),其函数形式为幂函数和一次函数,通过Z DR估算的W_(t)均方根误差相较利用Z H估算的W_(t)均方根误差更小、相关系数更大,因此通过Z DR估算的W_(t)的效果更好。此次飑线过程主要从西北向东南方向发展,风场主要是西风和西南风,在飑线前部弓状回波区域内存在明显的辐合区,垂直结构是低层辐合、高层辐散。对比利用不同方法估算W_(t)得到的三维风场,其水平风场变化主要集中在±1 m·s^(-1)的范围,水平经向风速的变化(Δu)主要是正值,水平纬向风速的变化(Δv)主要是负值,垂直方向上风速的变化(Δw)集中在±0.15 m·s^(-1)内,主要是正值,低层Δu、Δv、Δw较高层小。研究结果为降水系统三维风场反演及垂直速度反演提供了参考依据。One of the critical challenges in the retrieval of three-dimensional wind fields in precipitation systems is the accurate estimation of the final falling velocity(W_(t))of precipitation particles.To assess the ability of dual-polarization radar in estimating W_(t),the relationship between W_(t) and dual-polarization radar in the S and X bands is established in this paper based on the raindrop spectrum data collected from the Longmen Area of Guangdong Province.This relationship is then applied to the wind field retrieval of the Guangzhou and Shaoguan radars.In addition,an experiment is conducted to invert a squall line event that occurred in South China in April 2019.The wind field structure of the squall line process is analyzed,and the difference in the wind field structure of W_(t) in retrieval performance is estimated by different methods.The results indicate that the functions of W_(t) estimated by S and X band radars using echo intensity(Z H)and differential reflectivity factor(Z DR)are in the forms of a power function and a primary function,respectively.The root mean square error of W_(t) estimated by Z DR is smaller than by Z H,and the correlation coefficient is larger,which suggests that it is better to estimate W_(t) by Z DR.The squall line process primarily developed from northwest to southeast,with the wind field dominated by westerly and southwesterly winds.There was a distinct convergence zone in the arcuate echo area in the front of the squall line,which had a perpendicular structure with low-level convergence and high-level divergence.Compared to the three-dimensional wind field obtained by estimating W_(t) with different methods,the changes in the horizontal wind field are primarily concentrated in the range of±1 m·s^(-1).Specifically,the change in horizontal meridional wind speed(Δu)is mainly positive,while the variation of horizontal zonal wind speed(Δv)is negative.In the vertical direction,the wind speed(Δw)varies within±0.15 m·s^(-1),but is positive on the whole.Additionally,the values

关 键 词：雨滴谱数据 双多普勒雷达风场反演 降水粒子下落末速度估计 垂直速度 

分 类 号：P412[天文地球—大气科学及气象学]