登陆孟湾风暴结构演变特征数值模拟研究

利用MM5V3中尺度数值模式对2004年5月19日登陆的孟湾风暴进行了数值模拟分析,讨论了风暴中心移动路径,分析了风暴登陆前后的流场、动力场和热力场结构,并与西太平洋登陆台风的结构变化做了比较。结果表明,风暴中心的模拟路径与实况路径虽有一定误差,但总趋势均向东北方向移动,表明模式对本个例的模拟预报可以参考;孟湾风暴登陆前后,其结构与登陆台风变性阶段一样,经历了从热带气旋的基本对称的垂直分布结构演变到斜压非对称结构;风暴登陆后,由于地形和冷空气的作用,动力场和热力场表现为对流层中低层锋区增强、倾斜涡度发展,导致对流不稳定和斜压不稳定。

Numerical Simulation of Structural Evolution of a Landfalling over the Bay of Bengal Storm

The Bay of Bengal storm of Landfalling on 19 May 2004 is simulated by the mesoscale numerical(model) MM5V3,the moving track of the storm centre is discussed,the circulation,dynamical and therodynamic structures before and after landfalling are analyzed as well,meanwhile the comparing with the structure variation of west Pacific ocean landfall typhoon.The results show that the there are certain errors between the simulated track of storm center and the observed one,but both the total tend is moving northeastward and the simulated results can be referenced.Before and after the storm landfalling,its structure is the same as the typhoon transformation stage,which go through the course from a symmetric tropical cyclone to a baroclinic asymmetric cyclone.The dynamical and trermodynamic characteristics appear as the frontal zone in mid-lower troposphere strengthen and slantwise voiticity develop which result in the convective instability and baroclinic instability due to the effects of topography and cold air after the storm landfalling.