摘要
采用NCEP再分析资料、自动站加密观测资料、逐时云顶亮温TBB资料、多普勒雷达资料,以及成功模拟基础上的高分辨率模式输出资料,对2004年7月10日北京突发性暴雨过程中茁尺度对流系统的发生发展、结构特征及成因进行了综合分析。结果表明:本次暴雨过程是由具有中茁尺度的对流系统所产生,它发生在大尺度暖脊之中;对流层中层的短波槽,以及低层西风槽前的西南气流与暖切变线北侧的东南气流的汇合,为M茁CS的发生提供了良好的环境条件。该M茁CS由2个中尺度对流云团合并而成,具有椭圆形结构特征,其水平尺度为150km×100km,时间尺度约为5h。该M茁CS在对流层低层表现为中尺度辐合线或强辐合中心,雷达回波和径向速度场所反映的中尺度回波带和辐合线,与M茁CS的演变有密切的关系。在其发展强盛期,中茁尺度对流系统呈现相当正压性;垂直倾斜的上升气流及其两侧,有明显的下沉补偿气流,显示本个例M茁CS具有对流型风暴的结构特征。此次M茁CS发生在强对流不稳定层结条件下,在700hPa以下对流层低层具有明显的假相当位温兹se暖舌;近地面层偏南风与偏东风2支气流的辐合,以及冷空气的侵入,导致行星边界层内能量锋区的加强,从而有利于MCS的发生发展。
analysis of the Meso-β scale Convective System （MβCS） in a heavy rain event on July 10,2004 in Beijing is performed by using the special observational data ,including automatic meteorological stations data, radar images and satellite images, and NCEP re-analysis data on the basis of successful simulation. It is found that： The heavy rainfall process is generated by a meso-β convective system which is produced in a large scale warm aera. The short wave trough in middle level of troposphere and the convergence between the southwest air current from west wind trough and the southeast air current from north part of warm shear line in low troposphere provide a good background condition. The MβCS is consisted by the mergence of two meso-scale convective cluster, which shows a ellips-shape structure of a horizontal scale of 150km×100km and time scale of about 5 hours. The MβCS shows the features of the meso-scale convergence line （or convergence center） in lower levels stream field during its occurrence and development stage, and the strong meso-scale convective clouds echoe band and meso-scale convergence line exhibited in Radar reflectivity image and in radar velocity fields are often related with occurrence and development of the MβCS. During the stage of strong development, the MβCS shows its equivalent-barotropic perpendicular features and has similar structure of slantwise updraft current to convective storm. The occurrence and development of the MβCS is forced by the meso-scale convergence line of lower troposphere in strong convective instability condition and a θse warm tounge in lower of 700hPa; the convergence between the south air current and east air current and invading of the cold air in the boundary layer led to strengthen the energy front, which is helpful to induces the MβCS.
出处
《气象与减灾研究》
2006年第1期7-16,共10页
Meteorology and Disaster Reduction Research
基金
国家重点基础研究发展规划资助项目(2004CB418307)
关键词
中β尺度对流系统
暖切变线
相当正压
对流型风暴
meso-β convective system, warm shear line, equivalent barotropic, convective storm.
