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气象:2015,41(7):842-851
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“2013·7·21”杭州湾北岸短时大暴雨的中尺度分析
(浙江省嘉兴市气象局,嘉兴 314050)
Mesoscale Analysis on a Short Time Severe Rainstorm in the North of Hangzhou Bay on 21 July 2013
(Jiaxing Meteorological Office of Zhejiang, Jiaxing 314050)
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投稿时间:2014-04-28    修订日期:2015-03-11
中文摘要: 利用FY 2E卫星的TBB资料、多普勒雷达资料、中尺度自动站资料以及基于WRF模式的5 km全程同化数据,对2013年7月21日杭州湾北岸短时大暴雨天气进行了中尺度分析,结果表明:此次对流性暴雨发生与近地面西南偏西气流和东南偏东气流的辐合作用密切相关,湖州东部地区由局地热对流引起的偏西气流出流增强了嘉兴西部地区的偏西气流强度,从而触发两股气流间的辐合扰动并产生对流运动,当对流运动发展到一定程度时,在对流层低层出现了下沉气流,其中一部分气流向东契入近地面的偏东气流内,致使此处的辐合抬升运动加强,从而在对流层中层形成了新的垂直上升运动。此外,在对流性暴雨发生前0~3 km的环境风垂直切变较小,导致这次短时大暴雨过程中强对流单体的维持时间较短。暴雨区附近的近地面存在较为浅薄的中性或稳定层结,其上相对位温垂直递减明显,大气层结极不稳定。
Abstract:By using TBB data retrieved from FY 2E satellite, Doppler radar data, mesoscale automatic observation data and fully assimilated model data with 5 km resolution from WRF model, a short time severe rainstorm in the north of Hangzhou Bay on 21 July 2013 is analyzed. The results indicate that the occurrence of the convective storm is related to the convergence of west southwest and east southeast flows near the surface. The westerly outflow caused by local thermal convection in the east of Huzhou enchances the original intensity of the westerly flow in the west of Jiaxing, which is a very important factor to trigger the convection. When the convection develops to some extent, the downward current emerges in the lower troposphere. Part of it flows into east current near the surface and induces enchanced convergence in the lower troposphere and new updraft in the mid troposphere. Because of the weak vertical shear of horizontal wind from surface to 3 km above ground surface prior to the convection, the lifetime of cell thunderstorm in this event is short. In the vicinity of rainstorm the state of atmosphere near surface is neural or stable and the equivalent potential temperature is decreasing significantly above the lower atmosphere.
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基金项目:公益性行业(气象)科研专项(GYHY201406024)资助
引用文本:
何斌,范晓红,盛文斌,潘士雄,范玉芬,2015.“2013·7·21”杭州湾北岸短时大暴雨的中尺度分析[J].气象,41(7):842-851.
HE Bin,FAN Xiaohong,SHENG Wenbin,PAN Shixiong,FAN Yufen,2015.Mesoscale Analysis on a Short Time Severe Rainstorm in the North of Hangzhou Bay on 21 July 2013[J].Meteor Mon,41(7):842-851.