东风急流影响下海南非热带气旋暴雨个例分析  

The Diagnostic Analysis of Heavy Rainstorm Associated with Low-level Easterly Jet in Hainan Province

作　　者：刘丽君[1] 冯文[1] 陈德明[2] 

机构地区：[1]海南省气象台,海口570203 [2]海南省气象局,海口570203

出　　处：《暴雨灾害》2010年第4期328-333,共6页Torrential Rain and Disasters

基　　金：海南重点科技项目(20080222)

摘　　要：利用常规天气资料、NCEP 0.5°×0.5°再分析资料、卫星云图和海南省自动站资料,对2007年10月12—14日海南岛秋季暴雨天气过程的主要影响系统、物理过程及形成机制进行了分析。结果表明:多股冷空气从中低层东移南下并在华南沿海堆积、变性,副高稳定加强西伸,850 hPa上在华南沿海地区与变性的大陆高压合并加强,热带地区赤道辐合带活跃,其共同作用促使低空东风急流形成、发展和加强;低空东风急流、弱冷空气南侵、西太平洋副热带高压南侧的东风波等为暴雨的发生提供了有利的条件;东风急流是此次暴雨所需水汽最大的提供者;θse面陡立造成对流系统斜压发展,激发位势不稳定能量释放,正差动假相当位温平流加强了层结对流不稳定发展,对流层中层正差动涡度平流破坏了海南岛的准地转平衡;动力强迫和热力强迫共同作用激发了次级环流,导致暴雨区上空垂直运动的发展,促使降水增强。Using conventional meteorological data,NCEP 0.5°×0.5° reanalysis data,satellite images and automatic meteorological station data,the major weather system,atmospheric circulation background,physical condition and formation mechanism of the Hainan Fall rainstorm from 12th to 14th October 2007 are analyzed.The results show that cold air from low-middle level moved southeast,accumulated and transformed over the South China coast.The Western Pacific Subtropical High（WPSH） steadily strengthened moving westerly and merged with the transformed continental high at 850 hPa over the South China coast and strengthened further,then worked together with the Intertropical Convengence Zone（ITCZ） which was active to make low-level easterly jet formed,developed and strengthened.The low-level easterly jet,weak cold air invading south and easterly wave in south of WPSH provided favorable condition for the rainstorm.The low-level easterly jet supplied enough water vapor during the rainstorm process.The vertical structure of pseudo-equivalent potential temperature was changed by the convergence of cold and warm air resulting in the development of baroclinic convective system and release of instability energy.The positive differential advection of pseudo-equivalent potential temperature made convection developed unsteadily.The positive differential vorticity advection in middle-level of convection damaged the quasi-geostrophic balance.The secondary circulations were motivated by the interaction of dynamical and thermal forcing resulting in vertical motion and heavy rain.

关 键 词：大暴雨 低空急流 东风波 差动假相当位温平流 差动涡度平流 

分 类 号：P458.121.1[天文地球—大气科学及气象学]