热带气旋在陆地上重新加强的非轴对称性

以2006年1月澳大利亚北领地热带气旋"NT2006"为例,以非轴对称的观点对其登陆后的重新加强过程进行了数值模拟研究.首先以平均项和涡动项的形式分解了切向动量方程,其次对涡动动量通量和亚网格动量通量进行了对比研究.结果表明,平均切向动量的竖向对流是造成平均切向风速增大最主要的因素;而在对流层中上部,涡动通量项也局部促进了平均切向风速的增大.通过对比动量通量发现,涡动动量通量的数值比亚网格动量通量大得多,而且各动量通量之间的分布形式相差很大.

Asymmetric Dynamics of the Reintensification of a Tropical Cyclone over Land

This paper presents numerical simulations to investigate the reintensification of a tropical cyclone that formed to the north coast of the Northern Territory of Australia in January 2006 (NT2006) with an asymmetric view. The azimuthally averaged tangential momentum equation is partitioned into mean and eddy terms, and then the magnitudes of the eddy momentum fluxes and subgrid momentum fluxes are compared. The results show that the mean vertical advection of tangential momentum contributes most to the spin up of the azimuthal mean tangential wind, and in the middle upper troposphere the eddy momentum fluxes partly contribute to the spin up of the vortex as well. The comparison of momentum fluxes indicates that the resolved eddy momentum fluxes are much larger than the subgrid momentum fluxes and they are quite different from each other in pattern.