江西省一次短历时暖区暴雨中尺度结构及发生维持机制分析

Analysis of Mesoscale Structure and Maintenance Mechanism of a Short Duration Warm Rainstorm in Jiangxi

利用地面和高空、卫星TBB、多普勒雷达和GFS(0.5°×0.5°)逐6 h再分析等资料,对2011年6月10日江西省西北部一次短历时暖区暴雨中尺度结构及发生维持机制进行分析。结果表明:1)此次过程是在有利的高、低空系统配置下发生在梅雨锋南侧的暖区暴雨,边界层急流和低空急流提供了充足的水汽条件,增强低层热力不稳定;高空分流区使大气动力不稳定发展,高低空急流的耦合作用为MCS维持提供了必备的不稳定机制;中低层热力不稳定,中高层对称不稳定,形成此次对流性强降水。2)地面中尺度辐合线、非锋性斜压带、能量锋的抬升作用为MCS生成和发展提够了启动机制。3)低层强盛的水汽输送、层结不稳定和地面持续而强的中尺度抬升使得多个雷暴单体在江西省西北部连续传播,形成"列车效应",降水强而集中。4)在水汽和不稳定条件具备的情况下,暖区对流性强降水发生在强低层辐合与强高层辐散相重迭的区域。

Using surface and high observational data,satellite TBB,Doppler radar data and GFS（0.5°x 0.5°）reanalyzed data,etc.,the m esoscale structure and maintenance mechanism of a short duration warm rainstorm,occurred in the northwest of Jiangxi on June 10,2011,was analyzed. The results showed that：1） this process occurred in the favorable weather system configuration on the south side of the Meiyu front. Boundary layer jet and low-level jet provided sufficient water vapor,and enhanced the low-level thermal instability. Shunt area at high level led to the development of atmospheric dynamical instability. Coupling of high and low-level jets provided the necessary instability mechanism for MCS maintenance. The low-level thermal instability and high-level symmetric instability induced the strong convective precipitation. 2） The uplift of surface mesoscale convergence line,non frontal baroclinic zone and energy front provided enough start-up mechanism for the MCS development. 3） The Low level abundant vapor transport,the stratification instability and the surface sustained and strong mesoscale lifting made the multiple thunderstorm cells continuously spread in the northwestern Jiangxi. This formed ＂train effect＂caused strong and concentrated rainfall. 4） Under moisture and unstable conditions,the short duration warm rainstorm occurred in low-level strong convergence and upper-level strong divergence overlap region.