不同控制变量方案对广州暴雨过程雷达资料同化和预报的影响  

Effects of different control variable schemes on radar data assimilation and forecast of a rainfall event in Guangzhou

作　　者：庞盈 陈生 胡俊俊 陈海琴 黄朝盈 PANG Ying;CHEN Sheng;HU Junjun;CHEN Haiqin;HUANG Chaoying(School of Atmospheric Sciences/Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies,Sun Yat-sen University,Zhuhai 519082,China;Southern Laboratory of Ocean Science and Engineering(Zhuhai),Zhuhai 519082,China;Key Laboratory of Remote Sensing of Gansu Province,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;Key laboratory of Land Surface Process and Climate Change in Cold and Arid Regions,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;Nagqu Station of Plateau Climate and Environment,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Nagqu 852000,China;AVIC Leihua Electronic Technology Institute,Wuxi 214063,China)

机构地区：[1]中山大学大气科学学院/广东省气候变化与自然灾害研究重点实验室,广东珠海519082 [2]南方海洋科学与工程广东省实验室(珠海),广东珠海519082 [3]中国科学院西北生态环境资源研究院甘肃省遥感重点实验室,甘肃兰州730000 [4]中国科学院西北生态环境资源研究院寒旱区陆面过程与气候变化重点实验室,甘肃兰州730000 [5]中国科学院西北生态环境资源研究院那曲高寒气候环境观测研究站,西藏那曲852000 [6]中国航空工业集团雷华电子技术研究所,江苏无锡214063

出　　处：《中山大学学报（自然科学版）（中英文）》2023年第3期35-46,共12页Acta Scientiarum Naturalium Universitatis Sunyatseni

基　　金：国家自然科学基金(41875182);广州科技局计划项目(201904010162);广西重点研发项目(2021AB40108,2021AB40137)

摘　　要：为了探讨WRFDA同化系统中不同控制变量方案(CV5,CV6和CV7)所构建的背景误差协方差对雷达资料同化的影响,本文以2017年5月7日发生在广州的一次暖区暴雨为研究个例,开展了不同控制变量方案的单点观测同化试验和雷达同化试验(Exp-CV5,Exp-CV6和Exp-CV7),并对同化试验结果进行诊断分析。单点试验和单次雷达资料同化试验的分析结果表明,Exp-CV6对湿度场的影响最大且在大气中层的比湿均方根误差最小,而Exp-CV7分析增量的影响更集中且梯度更大,更有利于保留中小尺度信息,对风场的模拟效果最好。经过3 h雷达资料循环同化后,Exp-CV7可以更准确地模拟出对流系统的结构,并对本次暖区暴雨雨带与强降水中心位置的预报效果最佳,其次是Exp-CV6。这主要是因为CV7方案对动力场的调整更有利于局地对流的发展,而CV6方案对湿度场的调整较CV5方案更有优势。To explore the influence of background error covariance constructed by different control variable schemes(CV5,CV6,and CV7)on radar data assimilation in the WRFDA assimilation system,a warm-sector torrential rainfall in Guangzhou on May 7,2017 was taken as a case study in this paper.The single and radar observation data assimilation(DA)tests(Exp-CV5,Exp-CV6,and Exp-CV7)of three control variable schemes were carried out,and the results of the assimilation tests were diagnosed and analyzed.After the single and one-cycle(or one-time)radar observation DA experiments,it is found that Exp-CV6 has the greatest influence on the humidity field and the least root mean square error of specific humidity in the middle atmosphere.In addition,the influence of Exp-CV7 analysis increments is more concentrated and the gradient of analysis increments is larger,which is more conducive to retaining medium and small-scale information and has the best simulation effect on wind fields.After cyclic radar DA,Exp-CV7 is able to simulate the structure of the convective system more accurately,and the rainfall coverage and heavy precipitation center forecasted by Exp-CV7 align well with the observations.In conclusion,Exp-CV7 produces the best simulation and forecast for this study case,followed by Exp-CV6.This is mainly because the adjustment of a dynamic field by the CV7 scheme is more beneficial to the development of local convection,while the adjustment of the humidity field by the CV6 scheme is more advantageous than that by the CV5 scheme.

关 键 词：控制变量 背景误差协方差 雷达资料同化 

分 类 号：P456.7[天文地球—大气科学及气象学]