长江中下游梅雨期中小尺度涡旋族发生演变分析

FORMATION AND EVOLUTION ANALYSIS OF THE MESOSCALE VORTEX GROUP IN THE MIDDLE AND LOWER REACHES DURING MEIYU OF THE YANGTZE RIVER

中文关键词:  γ中尺度涡旋族  中尺度数值模拟  梅雨暴雨  诊断分析

英文关键词:Meso-γ-scale vortex group  Mesoscale numerical simulation  Meiyu frontheavy rainfall  Diagnosis and analysis

中文摘要:

      利用密集的地面观测资料和高分辨率的中尺度数值模拟结果,分析了1999年6月22日长江中下游地区的梅雨过程。分析发现:暴雨过程是由排列于边界层中尺度辐合线上近乎同时产生的小扰动所致;涡旋扰动的初始动力条件和触发系统与边界层内的中尺度辐合和低压倒槽有关;随着涡旋中心降水量的增大,近地面γ中尺度涡旋扰动出现气旋式的辐散环流,导致涡旋在低层减弱,同时又促使相邻γ中尺度涡旋发展的涡旋族相互作用过程。

英文摘要:

      The Meiyu process in the middle and lower reaches of the Yangtze river on 22 June 1999 was analyzed in this paper using the dense observational data and the high-resolution out put of numerical simulation.The results show the heavy rainf all process was due to some meso-γ-scale disturbances formed in the mesoscale convergence line almost simult aneously in the boundary layer.Such meso-γ-scale vortex was located in the boundary layer initially,and the duration is a fewhours.The clarity of the cyclonic circulation is also different in the boundary layer,the cyclonic circulation of the disturbance in this paper is mostclear at 0.91 sigma level.