The Influence of Structure of Upper-tropospheric Cold Vortex on Typhoon Motion

The role of upper-tropospheric cold vortex with different horizontal and vertical structures in the process of typhoon movement is studied. It is found that the structural variation of aloft cold vortex will affect the typhoon motion. The analysis shows that barotropic processes dominate in direction of motion, but under some circumstances, baroclinic processes dominate in its speed. Furthermore, it is also shown that contribution of horizontal vorticity advection to the positive center of TVT (total vorticity tendency) comes from the advection of asymmetric vorticity with steering current, and contribution of divergence field to TVT is mainly from the correlation field between the planetary vorticity and asymmetric divergence. Finally, it is concluded that within the ranging affected by the cold vortex, typhoon will move to the regions of convergence center in the upper-troposphere or divergence center in the mid-and-lower troposphere. This conclusion is useful to forecasters