长生命史冷涡影响下持续对流性天气的环境条件  

Analysis of Environmental Conditions of Continuous Severe Convective Weather Events Caused by Long-Life Cold Vortex

作　　者：易笑园[1,2,3] 李泽椿 李云[4] 朱磊磊[2] 于莉莉[2] 余文韬[2] 

机构地区：[1]南京信息工程大学大气科学学院,南京210044 [2]天津市气象台,天津300074 [3]国家气象中心,北京100081 [4]国家卫星气象中心,北京100081

出　　处：《气象》2010年第1期17-25,共9页Meteorological Monthly

基　　金：公益性行业(气象)科研专项(GYHY200706042);中国气象局新技术推广项目预报员专项(CMATG2009YB04);天津市气象局2008年科研培育项目共同资助

摘　　要：利用云图和NCEP 1°×1°再分析资料,对生命史长达9天的冷涡系统的云图形态、移动轨迹、强度变化及其长久维持的原因进行了分析;并对比分析该冷涡影响下的持续对流性天气与冷涡分裂的冷空气、湿度层结及水汽条件的关系,探讨对流性天气的预报着眼点和不稳定参数阈值。主要结论:(1)连续9天对流性天气分别出现在冷涡涡旋云系头部的南部或东南部。强的对流过程时,云顶TBB温度在-40～-72℃;弱的对流过程时,云顶TBB温度在-40℃以上。(2)东亚阻塞高压两侧高涡度区的正涡度平流交替补充冷涡对正涡度的损耗,是冷涡长久滞留维持的主要原因。(3)冷涡在长生命期中是动态的,冷涡中心距研究代表点的距离与对流性天气的强弱有关;对流层中层V分量能敏感地反映冷涡分裂的冷空气活动情况。(4)随着对流性天气的持续,低空湿度层逐渐增厚,而850～700 hPa相对湿度≤60%的相对于区始终存在;975 hPa水汽通量的大小和方向反映来自渤海的水汽输送状况。(5)强天气威胁指数SWEAT和风暴相对环境螺旋度SREH在判断对流性天气的强度方面比常用的不稳定参数效果好。Using the data of satellite images and NCEP/NCAR 1°×1°reanalysis data,the characteristics on cloud images,track,intensity and the subsisting reason for a 9-day long-life cold vortex are studied,and the cold air activity,humidity vertical structure,water vapor condition and the change of thermodynamic, dynamic convective instability parameters related to continuous severe convective weather events over the western coast of the Bohai Bay are analyzed.In addition,the key of forecast and the threshold of severe convective weather events are approached.The main results show that,firstly,during 9-day period the convective weather events appeared at south or southeast of cold vortex and their TBB values were between -40℃to -72℃in the severe convective process,and above -40℃in the weak convective process.Sec- ondly,the reason for cold vortex subsisting is due to the transport of vorticity advection from two sides of blocking high in eastern Asia.Thirdly,the cold vortex was dynamic during long-life cycle and the distance from the center of cold vortex to the areas studied was related to the intensity of severe convective activity. The V vector at 700-500hPa responded sensitively to the change of shallow trough or cold air activity. Fourthly,humidity layer at low levels becomes thicker as persistence of severe convective events,and the water vapor flux at 975hPa plays an important role in transporting water vapor from the Bohai Bay.Fifthly, indices SWEAT and SREH are better parameters than others used in the current forecast.

关 键 词：冷涡 长生命史 持续对流性天气 环境条件 参数阈值 

分 类 号：P[天文地球]