一次台风倒槽暴雨过程中的锋生与湿对称不稳定分析

摘 要：本文利用气象常观测资料、卫星云图以及NCEP/NCAR （1°×1°）再分析资料对1822号台风“山竹”给贵州带来的暴雨天气过程中的锋生与湿对称不稳定进行分析。结果发现：（1）台风“山竹”登陆减弱后，其北部倒槽影响贵州，同时受贵州东低西高的地形影响，倒槽系统出现斜压性，在倒槽附近出现锋生现象，其东侧出现湿对称不稳定的发展，造成贵州暴雨天气。（2）通过分析发现锋生区的东侧即湿对称不稳定区与中尺度雨带有较好的对应关系。（3）锋生与湿对称不稳定的发展与增强过程中，伴随着降雨的长时间维持，雨强变化不大，降水率大多为5~10mm/h。当锋生与湿对称不稳定减弱西移后，降雨天气减弱停止。（4）锋生现象与对称不稳定的形成具有一定的关系，两者均主要是由假相当位温的经向密集区（）发展起来的，对称不稳定区位于锋生区的东侧，即东南暖湿气流中，垂直结构上对称不稳定区位于锋生区的上部，与倾斜的上升运动区相对应。

Analysis on Moist Symmetric Instability and Frontogenesis of one rainstorm caused by the Inverted Trough of Typhoon

Abstract: Based on conventional observation data, satellite images and NCEP/NCAR reanalysis data (1°×1°),the characteristics of a rainstorm caused by the Inverted Trough of Typhoon Mangkhut were analyzed. The major conclusions were as follow.After Landfalled Typhoon Mangkhut was decreased and moving to north-westward,the rainstorm occurred under the condition of the inverted trough.When the inverted trough was monving ,it affected by the terrain,the temperature-pressure field changed into baroclinic structure.The strong convergence in low layer led to the frontogenesis ,strengthened the frontal secondary circulation and the oblique upward flow along the frontal surface.The diagnosis of MPV showed that there existed the conditional symmetric instability (CSI) in the frontogenetical area,caused the mesoscale rainbands. There was a relationship between the frontogenesis and the moist symmetric instability ,they both happened in the same time and caused by the ,the area of CSI located in the east of the area of frontogenetical.In the vertical, the area of CSI located in the upper of the area of frontogenetical and the oblique upward flow.