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

作　　者：翟国庆[1] 王智[1] 何斌[1] 

机构地区：[1]浙江大学地球科学系,杭州310028

出　　处：《测绘科技动态》2003年第6期661-672,共12页

基　　金：973国家重点基础研究发展规划项目 (G19980 40 90 7);国家自然科学基金资助项目 (4 0 0 75 0 0 9);浙江省自然科学基金(N2 9984)

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 2 2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。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 output of numerical simulation.The results show the heavy rainfall process was due to some meso-γ-scale disturbances formed in the mesoscale convergence line almost simultaneously in the boundary layer.Such meso-γ-scale vortex was located in the boundary layer initially,and the duration is a few hours.The clarity of the cyclonic circulation is also different in the boundary layer,the cyclonic circulation of the disturbance in this paper is most clear at 0.91 sigma level. The initial dynamical condition and trigger system of the vortex disturbances were closely linked to the mesoscale convergence and reversed trough in the boundary layer.Affected by the intensification of the north airflow in its back,a weak mesoscale convergence line turned to be a strong convergence line from south to north when it moved east.The qualitative convergence caused by the convergence line is prior to the vorticity.So,the intensification of convergence line in the boundary layer is one of important dynamical conditions,and under favorable environmental conditions,such as reversed trough near surface,several weak mesoscale disturbance can form along the reversed trough and convergence line.Some weak disturbances could be intensified through reciprocity with the other and turned to be meso-β-scale vortexes,and developed to be meso-α-scale vortexes.Two airflows from boundary layer were related to the formation of the meso-γ-scale vortexes,one is the north wind in the boundary layer,the other is the south wind near the top of the boundary layer.The mesoscale shear between the intensified south wind in the left of the southwest low-level jet and the intensified north wind in the north is very important to the formation of the meso-γ-scale vortexes.Mesoscale vortexes,convergence and upward movement developed in the mesoscale shear line. The mesoscale heavy rainfall

关 键 词：长江中下游地区 梅雨期 中尺度数值模拟 暴雨分析 涡旋族 低涡扰动 演变分析 中尺度扰动 

分 类 号：P458.121[天文地球—大气科学及气象学]