摘要
本文利用常规、自动气象站观测资料,卫星、雷达、风廓线探测资料和NCEP再分析资料(1°×1°逐6小时),对2012年7月21日北京地区特大暴雨的中尺度对流条件和对流系统特征进行了初步探讨,结果表明:本次极端强降雨成因主要包括非常充沛的水汽,一定的对流不稳定性,对流系统持续的"列车效应",以及低质心高效率的降雨对流系统。低层的切变线和地面辐合线相交的地区,是对流单体初生和强烈发展的区域;根据中层风的风向风速及地面辐合线的位置和走向,可以大致判断对流单体的移动方向及是否存在列车效应。基于静止卫星红外云图和雷达反射率因子资料的中尺度对流系统分析表明该次降水过程存在三个阶段:第一阶段为对流系统强烈发展的前期阶段;第二阶段对流系统发展最为强烈,北京大部分地区出现极端强降雨;第三阶段为北京地区对流和降雨显著减弱阶段。
Using the data of conventional and automatic weather stations （AWS）, Doppler radar, satellite and wind-profiler radar （WPR） as well as the associated NCEP reanalysis data （1°×1°）, this paper analyzed the convection conditions and mesoscale characteristics of an extreme rainstorm in Beijing and its surrounding areas on 21 July 2012. The results suggested that sufficient moisture, convective instability, continuous ＂train effect＂ of the convection systems and a low-mass center precipitation echo structure with high precipitation efficiency were the main causes for the generation and development of the extreme heavy rainfalls. It also showed that the newborn and severely developing convective ceils were located at the intersection part of low-level shear line and surface convergence line. The movement direction of convective cells and the presence of ＂train effect＂ can approximately be judged according to the direction and speed of the mid-level winds as well as the position and direction of surface convergence line. Mesoscale analysis on the severe precipitation was made based on satellite infrared cloud images and radar reflectivity data, and the results showed that there were three stages in the process of the rainstorm： （1） The first stage is the generation period of the convective systems before their strongly developing; （2） The second stage is the most severely developing period in which extreme rainstorm can be observed by most meteorological stations in Beijing; （3） The third stage is significantly diminishing period of the severe convection and precipitation.
出处
《气象》
CSCD
北大核心
2012年第10期1278-1287,共10页
Meteorological Monthly
基金
中国气象局预报员专项(CMAYBY2012-073)
国家自然科学基金面上项目(41175048)
公益性行业(气象)科研专项(GYHY201206004和GYHY201006005)
气象关键技术集成与应用项目(GMAGJ2012M59)共同资助
关键词
短时强降雨
列车效应
低质心
垂直风切变
基本反射率
风廓线
short-term heavy rainfall
＂train effect＂
low-mass center precipitation
vertical wind shear
base reflectivity
wind-profiler radar （WPR）
