与海南岛秋季暴雨有关的一类热带中尺度涡旋的动力学分析

DYNAMIC ANALYSIS OF A KIND OF TROPICAL MESOSCALE VORTEX RELATED TO THE AUTUMN RAINSTORM IN HAINAN ISLAND

对惯性重力内波方程组分别通过线性和非线性求解探讨造成2010年10月海南岛一次特大暴雨中一类热带中尺度涡旋生成发展的动力、热力机制,研究发现:(1)在副热带高压和大陆冷高压南侧反气旋性纬向水平风切变大值区、静力不稳定大气层结、积云对流潜热释放、低空急流、适当强度的冷空气有利于热带中尺度涡旋的形成和发展;(2)非线性惯性重力内波的孤立波解与这类热带中尺度涡旋有很好的联系,在静力不稳定的大气层结下,热带中尺度涡旋的形态主要由对流凝结潜热加热所决定,即潜热加热下的孤立波解要求热带中尺度涡旋在垂直方向是一个浅薄的涡旋系统;另外强盛的对流凝结潜热对热带中尺度涡旋垂直运动振幅的增强起主要作用,更有利于涡旋的发展和维持。基于天气事实分析的理论研究为深化影响海南的热带中尺度涡旋乃至南海中尺度对流系统的机理认识进行了探索。

This paper discusses the dynamic and thermal mechanisms of the generation and development of a type of tropical mesoscale vortex during a heavy rainstorm on Hainan Island in October 2010 by solving the inertial gravity internal wave equations through linear and nonlinear solutions. The results are as follows:(1) In the large value area of anticyclonic zonal horizontal wind shear in the south of subtropical high and continental cold high pressure, static unstable atmospheric junction, cumulus convective latent heat release, low-level jet and cold air with moderate intensity are conducive to the formation and development of tropical mesoscale vortex.(2) The solitary wave solution to nonlinear inertial gravity internal wave is well connected with tropical mesoscale vortex. Under the static unstable atmosphere, the shape of tropical mesoscale vortex is mainly determined by convective condensation latent heat heating. The solitary wave solution under the background of latent heat heating requires that the tropical mesoscale vortex is a shallow vortex system in the vertical direction. In addition, the strong latent heat of convective condensation plays a major role in enhancing the vertical motion amplitude of tropical mesoscale vortex, further strengthening the development and maintenance of vortex. The theoretical research in this paper based on the analysis of weather conditions provides a useful exploration for deepening the understanding of the mechanism of tropical mesoscale vortices that affect Hainan and even the mesoscale convective systems in the South China Sea.