2007年济南“7.18”大暴雨的持续拉长状对流系统研究  

A study of the permanently elongated convective system during the heavy torrential rain event over Jinan on 18 July 2007

作　　者：卓鸿[1,2,3] 赵平[1,4] 任健[3] 刘爱梅[3] 杨芙蓉[3] 

机构地区：[1]中国气象科学研究院灾害天气国家重点实验室,北京100081 [2]南京信息工程大学,南京210044 [3]济南市气象局,济南250002 [4]国家气象信息中心,北京100081

出　　处：《气象学报》2011年第2期263-276,共14页Acta Meteorologica Sinica

基　　金：中国气象科学研究院灾害天气国家重点实验室项目(2009LASW B08和2008LASWZI01);山东省气象局项目(2005sdqxz17和2008sdqxjj01);山东科技发展计划项目(2009GG10008001)

摘　　要：利用常规观测、中尺度自动站、卫星和雷达等资料,分析了2007年7月18—19日造成华北南部强降水的持续拉长状对流系统(Permanent elongated convective system,简称PECS)的发生和发展过程。结果表明:持续拉长状对流系统的发生发展与低层来自东北方向冷空气和正在减弱的中尺度对流复合体尾部的向外气流有关。云图分析表明:这次持续拉长状对流系统先后由10个对流单体复合而成,其中2个α中尺度的对流单体复合时造成了济南市北部的商河县强降水,并且强降水发生在持续拉长状对流系统发展阶段,位于持续拉长状对流系统的后部,与低于201K的冷云盖相对应;当对流单体复合时,在可见光云图上出现云线(即飑锋),并且在窄小的云线中又包含4个γ中尺度的对流单体,其中一个产生高达13 km的降水回波;当云线出现时,地面冷锋后部出现γ中尺度雷暴高压,随后逐渐发展成为α中尺度的雷暴群,降水产生在雷暴高压前和冷锋后。济南市强降水过程则是由合并后的对流单体内部的2个强度不同的上冲云顶合并成一个更强的上冲云顶时造成的。雷达回波分析进一步显示,这次持续拉长状对流系统降水回波表现出后部扩建类和回波交叉类的特征,其中商河县的降水由主冷空气涌产生,而济南市强降水可能与主冷空气涌与次冷空气涌合并所形成的2个β中尺度和1个γ中尺度的多单体雷暴有关。Using the conventional observations,the satellite infrared and visible cloud images,the Doppler weather radar data, and the meso-scale automatic weather station data in the Jinan city,we investigate the formation and development processes of a permanently elongated convective system（PECS）that leads to severe rainfall over the southern part of north China on 18-19 July 2007.The results indicate that the formation and development of the PECS was associated with the intrusion of the lowlevel cold air mass from northeast China and the outward flows from the rear of the weakening meso-scale convective complex. The invaded cold air mass behind a cold front and the southwesterly warm/wet flow in front of the cold front strengthened the convergence of low-level wind over the southern part and triggered the local frontogenesis.The interactions of the frontogenesis with the outward flow from a weakened MCC produced the PECS.The analysis of cloud images shows that the PECS was a meso-α-scale convective system with a long life,persisting for 18 h from its formation to extinction.This PECS was successively composed of 10 convection cells,in which a combination of twoα-scale convective systems resulted in the severe rainfall at the Shanghe county in the north of the Jinan city.The severe rainfall occurred at the developing stage of the PECS and in the rear of PECS,corresponding to a cold cloud lid with a temperature of lower than 201 K.At the same time,a narrow cloud line （also called the squall front）that contained 4γ-scale convective cells was seen on visible cloud images.Of them,one cell produced the radar echo up to the height of 13 km above the ground surface.The PECS is accompanied by the formation and development of the meso-scale systems associated with the squall that contain a thunderstorm high,a wake low,and a squall front. A meso-γ-scale thunderstorm high occurred behind the cold front with the emergence of the cloud line and then developed into the meso-α-scale thunderstorm complex,with rainfall appea

关 键 词：对流系统 云线 雷暴高压 尾流低压 上冲云顶 

分 类 号：P404[天文地球—大气科学及气象学]