苏北一次强降水超级单体风暴过程的诊断分析
投稿时间:2016-03-11  修订日期:2016-06-02  点此下载全文
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闵锦忠 南京信息工程大学 气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044 minjz@nuist.edu.cn 
贾瑞怡 南京信息工程大学 气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044  
王晨珏 南京信息工程大学 气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044  
基金项目:国家重点基础研究发展计划项目(OPPAC-2013CB430102)
中文摘要:利用常规观测资料、NCEP再分析资料、FY2C卫星和多普勒雷达资料,对2008年7月22日发生在苏北的一次强降水超级单体风暴过程进行诊断分析。天气分析显示,风暴发生于高湿、较低的抬升凝结高度、强对流不稳定(3 445 J/kg)和中到强的垂直风切变(0~6 km,18 m/s)环境,这种大气环境非常有利于强降水超级单体风暴的发生发展。雷达回波分析揭示,该超级单体的演化可归结为"孤立单体-经典强降水超级单体-减弱东移"三个阶段,持续时间超过2 h。强降水超级单体风暴成熟期,呈现出典型的倒"V "型缺口、中低层有界弱回波区和反射率因子大值区由低层向高层往低层入流一侧倾斜的特征,相应的雷达径向速度场显示在倒" V"型缺口附近的强降水区中存在一个成熟的中气旋。湿位涡的诊断结果表明:高层干冷空气侵入触发潜在对流不稳定能量释放,有利于对流运动的发展;中低层大气对流不稳定与条件对称不稳定共存,既有垂直对流,又有倾斜对流发生,同时边界层的偏东风入流向暴雨区提供充沛的水汽,对暴雨的发生发展起增幅作用。
中文关键词:强降水超级单体  中气旋  中尺度对流系统  暴雨  湿位涡
 
Diagnostic analysis on a heavy precipitation supercell storm process in northern Jiangsu
Abstract:The diagnostic analysis on a heavy precipitation supercell storm process in northern Jiangsu province on 22 July 2008 is implemented by using the conventional observation data,NCEP reanalysis data,FY2C satellite products and CINRAD-SA Doppler radar data.Weather analysis shows that the synoptic environment is characterized by the high humidity,strong convective instability(convective available potential energy,3 445 J/kg),medium to strong vertical wind shear (0-6 km,18 m/s) and low LCL (lifting condensation level),which directly result in the generation and development of the heavy precipitation supercell storm.The radar echo analysis shows that the evolution of the heavy precipitation supercell can be generalized into three stages:the isolated cell develops increasingly,evolves into a classic heavy precipitation supercell and then weakens eastward gradually,lasting more than 2 h.Doppler radar base reflectivity and storm-relative radial velocity observations on various elevation angles are used to investigate the radar echo features of the heavy precipitation supercell storm.The results show that at its mature stage,the heavy precipitation supercell storm displays a low-middle-level bounded weak echo,the larger radar reflectivity factor sloping toward the low-level inflow from low level to high level,and associated typical front inverted "V" notch echo with the inflow in middle and lower levels.Corresponding radar radial velocity images show that a well-developed mesoscale cyclone is in company with the inverted "V" notch echo in front of the supercell storm,and coincident with the heavy precipitation area at the surrounding of the inverted "V" notch echo.Through diagnosing the moist potential vorticity on isentropic surface and the moist potential vorticity during the process,results suggest that the intrusion of the durative dry cold air in upper levels touches off the release of potential convective instability energy,which is in favor of the development of convective motion.The atmospheric convective instability and conditional symmetric instability coexist in middle and low levels,so there are vertical convection and slantwise convection during the heavy rainfall,meanwhile the easterly inflow adjacent to the boundary layer transports ample water vapor to the heavy rain area,which plays an important role on the generation and development of the heavy rainstorm.
keywords:heavy precipitation supercell  mesocyclone  mesoscale convective system  rainstorm  moist potential vorticity
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