一次伴有高原低涡和热带气旋活动的持续性暴雨过程分析  

Analysis of a Sustained Rainstorm Accompanied by a Plateau Vortex and a Tropical Cyclone

作　　者：何光碧[1] 肖玉华[2] 师锐[2] HE Guangbi;XIAO Yuhua;SHI Rui(Institute of Plateau Meteorology,Chengdu,China Meteorological Administration/Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province,Chengdu 610072,Sichuan,China;Sichuan Provincial Meteorological Observatory,China Meteorological Administration,Chengdu 610072,Sichuan,China)

机构地区：[1]中国气象局成都高原气象研究所/高原与盆地暴雨旱涝灾害四川省重点实验室,四川成都610072 [2]四川省气象台,四川成都610072

出　　处：《高原气象》2019年第5期1004-1016,共13页Plateau Meteorology

基　　金：国家自然科学基金项目(91337215,40775032);国家重点基础研究发展计划(973)项目(2012CB417202)

摘　　要：为了进一步考察持续性暴雨发生机制,针对2010年7月下旬川、陕、甘地区的一次持续暴雨过程,应用MICAPS资料,FY-2E辐射亮温资料,TRMM卫星降水资料,NCEP每6 h 1°×1°分辨率的分析资料,主要分析了暴雨发生的环流背景,暴雨直接影响系统-高原低涡、热带气旋、中尺度对流系统、冷暖平流等对持续性暴雨的影响。结果表明:(1)本次持续性暴雨过程发生在对流层高层南亚高压由纬向型转为经向型,对流层中层副热带高压东退西进,热带气旋登陆西行,高原低涡东移受阻,中尺度对流系统不断生消的有利条件下。(2)高原低涡与热带气旋相互作用使两者移速减缓,涡区切变流场加强,正涡度平流输送使低涡加强与维持。(3)低涡为暴雨发生提供了有利的抬升条件,使降水期间涡区呈现较强的正涡度和辐合上升运动,降水最大值出现时间对应辐合上升运动最强时,降水过程中对流层中低层为垂直正螺旋度,有利于低涡系统维持和降水持续,垂直正螺旋度大值区及出现时间对强降水发生及落区有一定的指示性。(4)对流层低层暖平流输送使暴雨区能量持续积累,同时也使暴雨区中尺度对流系统生肖不断,降水得以发生和持续。In order to further investigate the mechanism associated with a sustained rainstorm process occurred in Sichuan,Shanxi and Gansu province in late July 2010,analysis were conducted on the circumfluence background and the directly related weather systems,e.g.,the plateau vortex,the tropical cyclone,the mesoscale convective and the warm/cold advection together with their interactions.The data used in this study includes MICAPS data,FY-23 radiation brightness temperature,TRMM satellite rainfall product,and NCEP Reanalysis dataset(1°×1°,6 hours).The results show that:(1)The sustained rainstorm process occurred under favorable conditions when the South Asia High in the upper troposphere changed from a zonal pattern to a meridional pattern,the subtropical high in the middle troposphere shifted from east to west,the landed tropical cyclone moved to the west,the plateau vortex was blocked on the east and the mesoscale convection systems kept reoccurring.(2)The interaction between the plateau vortex and the tropical cyclone decreased the velocity of both systems,enhanced the shear field in the vortex area,therefore a strengthened vortex was maintained by the positive vorticity advection transport.(3)The low vortex provided favorable uplifting conditions for rainstorms to occur and produced strong positive vorticity as well as convergence upward movement during precipitation in the vortex area.The maximum rainfall occurred concurrently with the strongest convergence ascending motion.The positive z-helicity during precipitation process in the lower troposphere helped to maintain low vortex system and sustain precipitation;the position and time of high z-helicity provide certain indicative to the occurring time and location of heavy rainfall.(4)The transport of warm advection in the lower troposphere continuously accumulated energy in the rainstorm area,incurred frequent mesoscale convection system activities and thus resulted in sustained rainfall.

关 键 词：持续性暴雨 高原低涡 热带气旋 中尺度对流系统 影响机制 

分 类 号：P447[天文地球—大气科学及气象学]