A Preliminary Study on the Self-Orgnization Process of Multi-Vortex

In this paper, the self-organization process of the initially scattered 12 meso-βand -γscale vortices evolving into a synoptic-scale typhoon-like vortex in the context of advection dynamics is numerically explored with an f-plane 2-D quasi-geostrophic vorticity equation model. The results show that the self-organization process was a step-by-step merging course, namely the two adjacent vortices first merged, then formed a tri-vortex flow pattern, and nally evolved into a resultant vortex of meso-αscale. Thus it can be seen as an interaction of binary vortices self-organization. Each initial vortex or vorticity lump confronted two ways out: it merged with an adjacent vortex, and thus became a source of the inner region vorticity of the new formed vortex; or it was stretched by the circulation of an adjacent vortex, and then became the vorticity source of the spiral band of new vortex. Similarly, each new formed vortex also confronted the two ways out, until the multi-vortex self-organized into a single vortex of lager scale. The representation precision of the initial vortex structure directly a ected the speeds of the mutual rotation and merging of the resultant vortex. Therefore, it is important to provide an accurate description of initial vortex profiles. Finally, a property of the numerical solution of the self-organization for the 2-D quasi-geostrophic flow is that the total kinetic energy decays slowly, the total enstrophy decreases rapidly, and the circulation of the largest scale vortex grows quickly.