一次中尺度急流激发的辽宁大暴雨观测分析

Observation Analysis on a Torrential Rain Event in Liaoning Province Trigged by a Meso-scale Jet

应用地面加密自动气象站、常规探空、卫星及多普勒雷达探测资料对2008年7月31日夜间发生在辽宁省的一次大暴雨过程中的急流特征进行了分析。分析结果显示,在超低空环流场中同时存在着大尺度偏南急流和中尺度西南急流。在中尺度西南急流左侧生成的西南—东北向的中-β尺度云团列直接引发了大暴雨。进一步分析表明,超低空中尺度西南急流与高空急流方向相近且风速相当,形成了二次切变型的空间垂直分布,在其左侧激发了涡旋Rossby重力波的不稳定发展,从而生成中-β尺度云团列。

Based on the data of AWS,radiosonde observations,satellite and Doppler Radar Data,an analysis on the jets in a torrential rain event in Liaoning Province on July 31,2008 was conducted.The results show that,a large scale southerly jet and a meso-scale southwesterly jet preexisted in the boundary layer background and in the left side of latter a southwest-northeast meso-β cloud cluster band caused the heavy precipitation directly.The further analysis indicates that the meso-scale boundary layer southwesterly jet was near to the high level jet in direction and speed.The bi-shear pattern wind field trigged the unstable development of vortex Rossby-gravity wave in the left side of the boundary jet.It gave birth to the meso-β cloud cluster band.