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气象:2021,47(8):932-952
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雷达反射率反演水汽和温度同化技术在一次飑线过程中的应用研究
赖安伟,马鹤翟,崔春光,康兆萍,王志斌,杜牧云,肖艳姣,王珏
(中国气象局武汉暴雨研究所暴雨监测预警湖北省重点实验室,武汉 430205)
A Squall Line Case Study of Assimilating the Radar Data, Retrieval of Water Vapor and In Cloud Potential Temperature from Reflectivity in a 3DVAR Framework
LAI Anwei,MA Hedi,CUI Chunguang,KANG Zhaoping,WANG Zhibin,DU Muyun,XIAO Yanjiao,WANG Jue
(Hubei Key Laboratory for Heavy Monitoring and Warning Research, Institute of Heavy Rain, CMA, Wuhan 430205)
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投稿时间:2020-08-23    修订日期:2021-07-07
中文摘要: 针对2020年5月4日发生在江南的一次飑线过程,在逐15 min快速更新循环同化预报系统中,探讨了利用3DVAR方法同化雷达径向风、反射率和反演观测对短时降水、大风和冰雹等灾害天气的预报影响,同时研究了不同冷启动时刻对降水预报的影响。结果表明:冷启动时刻同化反演水汽和云内温度观测,观测强回波区的水汽和降水回波区内位温增量为正。随着循环次数的增加,背景场中虚假对流区的水汽减弱,对流被抑制;正的温度增量主要集中在观测回波大于背景模拟回波区,其增幅明显减小。相对于只同化雷达资料试验,同化“伪观测”资料能明显改善0~3 h内的雷达组合反射率和降水预报, 2~5 km上升螺旋度路径与大风、冰雹灾害位置更接近;对0~6 h的1 h累计降水量在1、5和10 mm等级的FSS评分改善明显,随着循环同化次数增多,改进效果先明显增加,6~8 h左右改进效果达到顶峰,随后FSS评分相对雷达同化试验有所下降。在12时(世界时)更新背景场后,相对于05时冷启动明显提高降水FSS评分,且同化“伪观测”资料的积极贡献预报时效更长。
Abstract:This paper investigates the influence of assimilating radar radial wind and reflectivity, and pseudo observation on the precipitation, gale and hail and other disastrous weather. At the same time, this paper also discusses the effect of different cold start time on precipitation forecast for a squall line event that occurred in the south of the Yangtze River on 4 May 2020. The results indicate that after assimilating the pseudo- water vapor and pseudo- in-cloud potential temperature at the cold start time, the water vapor and potential temperature are increased in the observed strong echo area. As the number of cycle assimilation increases, the negative water vapor increment mainly appears in the spurious convection of background, and the convection is inhibited. The increase in potential temperature mainly concentrates in the area where the observed echo is larger than the background simulated echo. Compared with only assimilating radar data, the assimilation of pseudo-water vapor and pseudo-in-cloud potential temperature can obviously improve the 0-3 h radar composite reflectivity and precipitation forecast. The simulated 2-5 km updraft helicity path is more consistent with the location of damage wind and hail disaster. The FSS scores at 1, 5, 10 mm threshold of 1 h accumulated precipitation in 0-6 h is significantly improved. With the increase of cycle assimilation times, the FSS score of pseudo observation experiments compared to radar experiments rises significantly at first, reaching the peak after 6-8 h cycle, and then the FSS score declines. In addition, different cold start time experiments show that after the background field is updated at 12:00 UTC, assimilating pseudo observation data has a positive contribution to improving precipitation prediction.
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基金项目:国家自然科学基金项目(41620104009)、国家重点研发计划(2016YFE0109400和2018YFC1507200)、湖北省气象局科技发展基金项目(2021Z03)共同资助
引用文本:
赖安伟,马鹤翟,崔春光,康兆萍,王志斌,杜牧云,肖艳姣,王珏,2021.雷达反射率反演水汽和温度同化技术在一次飑线过程中的应用研究[J].气象,47(8):932-952.
LAI Anwei,MA Hedi,CUI Chunguang,KANG Zhaoping,WANG Zhibin,DU Muyun,XIAO Yanjiao,WANG Jue,2021.A Squall Line Case Study of Assimilating the Radar Data, Retrieval of Water Vapor and In Cloud Potential Temperature from Reflectivity in a 3DVAR Framework[J].Meteor Mon,47(8):932-952.