摘要
利用Micaps软件系统、多普勒雷达和NCEP 1°×1°再分析等资料,对2011年6月14日江西北部地区一次超历史极值的短时强降水过程的天气尺度系统和中小尺度系统及其两者关系进行了分析。结果表明,南支槽移动缓慢、中层干冷空气入侵、强盛的西南急流、高低空急流耦合及地面辐合线维持是造成此次极端降水的主要影响系统。反射率因子表现为低质心、垂直发展旺盛、高效率的强回波连续经过同一地区;同时,回波具有明显的后向传播特征和热带降水回波特点;径向速度表现出锋面过境特征,"牛眼"结构表明了低空西南气流较强。当暖湿急流输送方向与地面辐合线平行时,孟加拉湾的水汽被低槽前西南气流源源不断地输送到辐合线上空,使辐合线稳定、维持或发展。干冷气流入侵有利于对流单体的产生;大风速区和辐合区的发展有利于中小尺度对流单体及其次级垂直环流的维持、发展,且这些次级环流规则排列,从而"列车效应"得以维持。有组织的多单体风暴活动、地面静止锋及其附近多条中尺度地面辐合线长时间维持,是形成"列车效应"的主要原因;降水回波处于东北—西南向的高能舌北侧移动,江西东北部特殊的地形作用促使"列车效应"形成和维持。
Using Micaps,Doppler radar data and NCEP reanalysis data,the rainstorm occurred in the north of Jiangxi with the rainfall exceeding the history extreme value on 14 June 2011 w as analyzed. Synoptic scale systems、mesoscale systems、microscale systems and their relationship of the rainstorm w ere also analyzed. It is show n that: The main impact system of this extreme precipitation are the south trough,Mid-level dry air intrusion,the strong low level jet( LLJ),the coupling of high and low level jet stream and the maintenance of the surface convergence line. Due to the low mass center structure、strong vertical development and high efficiency of precipitation strong echo through the same area continuously,the ‘train effect'w as occurred in the short-duration rainstorm. M eanw hile,the radar echo w hich w as similar to tropical heavy synoptic scale systems had the characteristic of the backw ard propagation. There w as the characteristic of frontal passage in the speed image,and the speed image with a ‘bull eye'structure show s that there w as a low level southw est jet. When the direction of the w arm and humid Jet w as paralleling to the trend of the ground convergence lines,the ever fount vapor from the Bengal reached the convergence lines along the southw est airflow of the trough,and the convergence lines w ere stable,maintained and developed. Dry cold air invasion prompted the occurrence of the microscale and mesoscale system in the heavy precipitation. The development of the large wind velocity zone and the convergent region w ere favorable to the maintenance and development of the microscale and mesoscale convective cells and their sub-vertical circulation,thus the‘train effect'can be maintained. The activity of organized multicell storm,the ground quasi-stationary front and the mesoscale lines w hich maintained for a long time are the main causes for the formation of ‘train effect'. The precipitation echoes move along with the CAPE center,and the special terrain is also one reason of the ‘train
出处
《高原气象》
CSCD
北大核心
2015年第1期190-201,共12页
Plateau Meteorology
基金
中国气象局预报员专项(CMAYBY2012030)
国家科技部"十二五"科技支撑计划项目(2012BAK09B04)
关键词
强降水
列车效应
辐合区
地面辐合线
Heavy precipitation
Train effect
Convergence area
Ground convergence line
