Evolution of double-eye wall hurricanes and emergence of complex tripolar end states in moist-convective rotating shallow water model

Abstract

A detailed investigation of linear instabilities of double-eyewall hurricane-like vortices with double maxima (“walls”) of azimuthal velocity and vorticity around the central minimum (“eye”) and of their nonlinear saturation is carried out in the framework of the moist-convective rotating shallow water model. It is shown that developing barotropic instability leads to inward displacement and gradual disappearance of the inner wall and to the formation of a nontrivial tripolar quasi-stationary structure, provided the second, outer, wall of the initial vortex is high enough. The effects of moist convection lead to the enhancement of the outer wall. In comparison, under the influence of the same instability, vortices with an inner wall stronger than the outer one evolve toward monopolar single-eyewall structures.