一次东北冷涡降水过程的结构特征与影响因子分析  

Analyses on the Structure Characteristic and Formation Mechanism of the Rainstorm Related to a Cold Vortex System over Northeast China

作　　者：钟水新[1,2] 王东海[1] 张人禾[1] 刘英[1] 

机构地区：[1]中国气象科学研究院,北京100081 [2]中国科学院研究生院,北京100049

出　　处：《高原气象》2011年第4期951-960,共10页Plateau Meteorology

基　　金：国家自然科学基金重点项目(40633016);中国气象科学研究院灾害天气国家重点实验室基本科研项目(2008LASWZI01);公益性行业科研专项经费项目(GYHY201006006)共同资助

摘　　要：利用加密观测资料和NCEP再分析资料,对2006年7月20～24日一次东北冷涡降水过程的发生、发展及结构特征进行了分析,并利用MM5模式对此次冷涡过程进行了数值模拟。结果表明,冷涡发展阶段,对流层顶存在两条急流带,一条为南伸的高纬高空急流带,另一条为副热带西风急流带,两条急流带在东北地区汇合,强副热带西风动量的输送增强了低槽的气旋性涡度,使得冷涡切断后东移、发展。冷涡发展阶段,冷涡偏西地区有低空西北强风带,该强风带与冷涡前部东南风急流形成辐合区,降水主要发生在冷涡偏东北的辐合上升区。冷涡发展及成熟阶段,300hPa以下为一深厚的冷性涡旋,以上为一暖中心,强风带位于冷涡外缘,中心为弱风区或无风区。地形试验表明,在去除地形作用后,冷涡在后期(成熟及衰亡阶段)的位置明显偏西,出现了"回撤"现象。对流层顶高位涡(PV)气流的干冷空气下沉,插入高相对湿度区后部,高PV气流叠加在对流层低层的低θse之上,干冷空气侵入具有高PV特征。高空正PV异常中心与低层(θ/p)正异常同位相叠加,使得对应诱生的气旋性环流进一步发展、加强,冷涡加强、东移。Using the encrypt observational data and NCEP/NCAR reanalyses data,the development and structure of a rainstorm event related to a cold vortex system over northeast China during 20～24 July 2006 were investigated.The formation mechanism is numerically simulated using the mesoscale model MM5.Observations show that there are two upper-level jets over the top-troposphere during the evolution of the cold vortex,one stretching southward from high latitude and another from Subtropical Westerly Jet System（SWJS）,which converge over Northeast China.Cyclonic vorticity is reinforced by the SWJS,make cold trough being cut off and develop eastward.During the development stage of the cold vortex system,low level convergence occurs between the southeast jet and northwest wind.The heavy rainfall mainly takes place in the ascending air of the convergence area of the northeast of the cold vortex.At the mature stage of the cold vortex,a deep cold core is located below 300 hPa,above is a warm core.The strong wind area distribute on the edge of the cold vortex,while no apparentwind in the cold core.The topography experiment shows that the cold vortex system retreat at the decrease stage after the remove the terrain of northeast China.The high potential vorticity（PV） stream from the high level tropopause insert the lower level,which characterize by its cold-dry air incursion.High PV stream overlay at the low equivalent potential temperature,which means cold-dry air incursion has high PV characteristic.Positive PV anomaly of high tropopause overlay with positive anomaly of （-θ/p） of low level,which strengthen the new born cyclone and intensify the cold vortex.

关 键 词：东北冷涡 高空急流 高位涡气流 干侵入 

分 类 号：P426.621[天文地球—大气科学及气象学]