涡旋自组织过程影响0604号热带气旋Bilis降水的数值研究

利用PSU/NCAR中尺度天气预报模式MM5,成功模拟了0604号热带气旋Bilis登陆后的移动路径和降水分布。在此基础上,讨论了不同尺度涡旋自组织过程对热带气旋Bilis产生局地暴雨的影响。结果表明:(1)引发强降水的对流系统不是来源于热带气旋螺旋云带内的对流云团,而是受热带气旋外围环流与局地地形影响下形成的多个中小尺度系统之间自组织的结果;(2)与0604号热带气旋Bilis登陆前后24小时的强降水相关的自组织过程是分阶段进行的,即第一阶段的双涡自组织过程和第二阶段的多涡自组织过程;(3)局地多尺度涡旋之间的自组织过程,是0604号热带气旋Bilis陆上强降水发生的主要动力机制。

NUMERICAL STUDY ON THE INFLUENCES OF VORTEX SELF-ORGANIZATION PROCESS ON THE RAINSTORM OF BILIS (2006)

The track and precipitation of Tropical cyclone(TC) Bilis(2006) are simulated successfully with PSU/NCAR MM5 model.Then the influences of self-organization processes among different scale vortices on the heavy rain resulting from Bilis are discussed.The main results show that the convective system resulting in rainstorms is not the convective cloudy cluster produced in the TC’s spiral bands but results from the self-organization process of multiple meso-and fine-scale vortices,which is a combined effect of the outer circulation of the TC and local terrain.The self-organization process of vortices during TC’s landfalling can be classed into two phases,i.e.,the double vortices self-organization process in the first phase and the multiple vortices self-organization process in the second phase.The principal dynamic mechanism causing rainstorms during TC’s landfalling is the self-organization process of local multi-scale vortices.