摘要
利用常规观测资料、NCEP、卫星、雷达和地面加密观测等资料,对2010年6月1 7 20日江西北部一次罕见大暴雨过程进行天气动力学诊断分析、中尺度分析和WRF模式模拟分析。结果表明:(1)这次罕见大暴雨是一次典型梅雨锋暴雨,是在极为有利的天气形势下导致的强β中尺度系统强烈发展所致。500hPa东亚大槽槽后冷平流与强盛稳定的副高西北侧西南气流汇合,导致冷暖交汇带在江南北部维持。(2)冷暖交汇带的稳定和西南暖湿气流的异常强盛,使暴雨的水汽、动力、热力条件十分充足,非常有利于触发中小尺度对流系统强烈发展。(3)强盛水汽及辐合上升运动、低层西南急流加强、中层弱冷空气活动、对流不稳定层结加剧、地面辐合线维持少动、β中尺度强低涡形成并维持、高层强辐散等多种因素的共同组合叠加作用导致了特大暴雨发生。(4)数值模拟分析显示,19日08时β中尺度低涡形成与暖湿气流和弱冷空气共同作用有关;该低涡垂直厚度在550～950hPa之间,850和900hPa最强;并在该低涡南侧出现一串近东西向排列的30～60km更小尺度的强对流系统,它们与特大暴雨区相吻合。
By using conventional meteorological observation data,NCEP reanalysis data,satellite and radar data,densified surface observational data,etc.,a rare rainstorm process which happened during June 17—20,2010 in northern Jiangxi was analyzed.In this paper,the heavy rain process was analyzed from three aspects：dynamics and diagnosis analysis,mesoscale analysis,and simulation analysis by WRF model.The analysis results show that：（1） This rare rainstorm is a typical heavy rain over Meiyu front,it is caused by the vigorous development of strong meso-βsystem generated in the extremely favorable weather situations. The cold air flow behind the 500 hPa East Asia trough joined up the SW flow located in the northwest part of the strong and stable subtropical high,thus the cold air and warm air converged and maintained over the northern part of Jiangnan.（2） Since the area that cold air and warm air joined up is stable and the SW warm and wet flow is abnormal strong,the vapor,dynamical,and thermodynamic conditions leading to heavy rain are quite adequate,the physical quantities are significantly higher,these are very helpful to trigger the strongly development of meso and microscale convection systems.（3） The extraordinary rainstorm is caused by the interaction of many factors such as strong vapor and convergence ascending motion, weak cold air activities in middle-levels,the strengthening of SW low-level jet,the weakening of stablility of convection layer,stability of surface convergence lines,the formation and maintenance of meso-βvortexes and strong divergence in higher-levels,etc.（1） Numerical simulation analysis of WRF model shows that at 08：00 BT 19 June 2010,the formation of meso-βvortex is related to the strengthening of weak cold air and warm and wet flow,the vertical thickness of this vortex is between 950 and 550 hPa.and it is the strongest between 800 and 950 hPa.In addition,a string of intense convective systems appear in the southern part of this meso-βvortex,these systems are nearly in east-west direction and the scales are about 30 to 60 km,and their positions are well corresponding to the severe rain area.
出处
《气象》
CSCD
北大核心
2011年第7期827-837,共11页
Meteorological Monthly
基金
中国气象局预报员专项(CMAYBY2011-025)资助
关键词
特大暴雨
水汽
动力热力条件
中小尺度系统
WRF数值模拟
中尺度低压
heavy rain
vapor
dynamic and thermodynamic conditions
meso- and micro-scale systems
WRF model simulation
meso-scale low-pressure
