江西“6·19”特大暴雨天气过程诊断分析

DIAGNOSTIC ANALYSIS OF A CATASTROPHIC RAINSTORM IN JIANGXI

利用NCEP逐6 h 1°×1°的grib再分析资料和常规气象观测等资料,对2010年6月19—20日江西地区特大暴雨天气过程的物理量演变及高低空急流配置进行了分析。结果表明,此次特大暴雨过程发生在副高与高空槽稳定维持的有利背景场环境下。暴雨落区上空强烈的垂直上升运动,持续的西南水汽输送和高低空急流配置,共同造成了此次大范围暴雨的发生和维持。在高空急流入口区右后侧、低空急流的前方造成正涡度辐合上升运动,暴雨出现在低空急流的左前方。气流的高层辐散与低层辐合的叠加,形成强烈的上升运动,为这次暴雨天气的产生提供了有利的环境条件,也是对流维持、持续的重要机制。湿位涡低层为负、高层为正,高、低值中心和密集带的演变显示了强对流系统暖湿气流与外界干冷空气的相互作用。

Using conventional meteorological observation data,NCEP 1°×1° reanalysis data and FY2E TBB data,the persistent heavy rain process occurred in Jiangxi on 19 June 2010 was analyzed.The results showed that the maintenance of stable subtropical high-level trough was the main synoptic system of this heavy rainfall.The strong vertical ascending movement,persistent water vapor transportation and upper and low level jets configuration were the main mesoscale systems.There was positive vorticity in the front of low level jet which caused ascending movement.The strong rainstorm appeared at the right side of the entry of the upper level jet and the left side of the low level jet.Positive vorticity at low level,minus vorticity at upper level and vertical ascent motion probably provided the suitable dynamic environment for the generation and development of the mesoscale convective system.In this process,MPV1 of low level was positive while MPV1 of upper level was minus.The center of extreme value and the concentrated MPV1 lines can indicate interaction between warm-wet air and cold-dry air.