THE FORMATION MECHANISM OF CONCENTRIC DOUBLE EYE WALL TYPHOON—PART Ⅰ: DYNAMICAL ANALYSIS^*

The strong vortex will mutually adjust the thermodynamic field and dynamic field to a state of gradient balance whilst forced by an external cold source,namely,the gradient adjustment process,in which a linearized two-layer model is dealt with in this paper.The analyses show that on account of the heterogeneous radial distribution of the cold source,the adjustment of the thermodynamic and dynamic fields results in the two-peak tangential wind feature,which is analogous to the character of concentric double eyewalls in the strong typhoon.Consequently,the gradient adjustment may be one possible mechanism for the formation of a concentric double-eye typhoon.