摘要
利用常规观测资料、卫星、雷达资料以及NCEP再分析资料、LAPS局地分析资料,对2011年6月湖南两次暴雨过程的中尺度特征进直行比分析。结果表明:两次过程均属于湖南盛夏低涡冷槽型暴雨过程,但中尺度特征、降水性质和环境条件有差异。"6.09暴雨"由一个及地的β中尺度低涡产生,过程期间低涡稳定少动,卫星云图上表现为一个发展强烈的中尺度对流云图,度对流云团,雷达回波前期为窄型带状积云降水回波,后期逐渐转变为秘层混合云降水回波;而"6.13暴雨"影响系统为中尺度切变线,切变线维持时间长,移动缓慢,卫星云图上是一条长时间维持的对流云带,雷达回波为积层混合云降水回波。水汽输送通道的建立和中低层水汽的大量集中为中尺度对流系统的发展提供发有利的环境条件,暴雨发生在锋前高温高湿的不稳定阹结和强上升运动区域中,锋区的动力强迫上升运动加强了低层能量和水汽的往上输送。两次过程中尺度对流系统均具有深契的垂直环流结构,"6.09暴雨"湘东北特大暴雨区是一支近乎垂直的深厚上升气流,南北两侧有明显的补偿下沉气流,而"6.13暴雨"湘中暴雨区垂直上升运动是倾斜向上的,只有南侧存在补偿下沉气流。
Abstract： Based on the routine observational data, FY2C TBB data, radar data, NCEP reanalysis data and LAPS analysis data, a comparative analysis on mesoscale characteristics of two torrential rain processes in Hunan Province in June 2011 was analyzed. The results show that： The two processes belong to the type of low vortex and cold-trough rainstorm, but their mesoscale characteristics, precipitation nature and environmental conditions are different. The rainstorm on 9 June 2011 is generated by a meso-β scale low vortex, which is stable and immobile during the process. The satellite image manifests a mesoscale convective cloud cluster which develops severely, and the radar echoes are convective precipitation echoes in the earli- er stage and transform to convective-stratiform mixed clouds echoes in the later stage. In comparison, the rainstorm on 13 June 2011 is mainly produced by mesoscale convective shear lines which maintain for a long time and move slowly. The satellite images show it a convective cloud band that exits for a long time, and the radar echoes are convective-stratiform mixed clouds echoes. The establishment of vapour transferchannels and strong convergence of water vapor in the middle-and-low troposphere provide favorable condi- tions for the mesoscale convective system. The two severe rainstorms both occur in the unstable stratifications with high temperature and humidity and strong ascending motions. The ascending movements caused by the dynamic forcing in the frontal zone enhance upward transfer of energy and water vapor from low levels. The obvious compensation descending airflows appear on the north and south sides of the deep vertical motion in the first process, but in the second process, the ascending motion is inclined, and the com- pensation descending airflows only appear on the south side.
出处
《气象》
CSCD
北大核心
2013年第12期1580-1590,共11页
Meteorological Monthly
基金
国家自然科学基金项目(41075034)
公益性行业(气象)科研专项(GYHY201306016)
中国气象局预报员专项(CMAYBY2013-046)
湖南省气象局重点科研课题(No.201203)共同资助
关键词
暴雨
中尺度特征
垂直环流结构
对比分析
rainstorm, mesoscale characteristics, vertical circulation structure, comparative analysis
