Axisymmetrically Tropical Cyclone-like Vortices with Secondary Circulations

TL;DR

This paper presents analytical solutions for axisymmetric tropical cyclone-like vortices, revealing intrinsic radii and secondary circulation structures crucial for understanding cyclone formation and intensification.

Contribution

It introduces new analytical solutions with three intrinsic radii, detailing secondary circulation structures and their relation to primary vortex features.

Findings

Identified three intrinsic radii: $r_m$, $r_k$, and $r_d$.

Established relations: $r_k= ext{sqrt}(2)r_m$, $r_d=2r_m$.

Solutions applicable to tornados, TCs, and mesoscale eddies.

Abstract

The secondary circulation of the tropical cyclone (TC) is related to its formation and intensification, thus becomes very important in the studies. The analytical solutions have both the primary and secondary circulation in a three-dimensionally nonhydrostatic and adiabatic model. We prove that there are three intrinsic radiuses for the axisymmetrically ideal incompressible flow. The first one is the radius of maximum primary circular velocity $r_m$. The second one is radius of the primary kernel $r_k>r_m$, across which the vorticity of the primary circulation changes sign and the vertical velocity changes direction. The last one is the radius of the maximum primary vorticity $r_d$, at which the vertical flow of the secondary circulation approaches its maximum, and across which the radius velocity changes sign. The first TC-like vortex solution has universal inflow or outflow. The relations between the intrinsic length scales are $r_k=\sqrt{2}r_m$ and $r_d=2r_m$. The second one is a multi-planar solution, periodically in $z$-coordinate. Within each layer, the solution is a convection vortex. The number of the secondary circulation might be one, two, three, and even more. There are also three intrinsic radiuses $r_m$, $r_k$ and $r_d$, but they have different values. It seems that the relative stronger radius velocity could be easily found near boundaries. The above solutions can be applied to study the radial structure of the tornados, TCs and mesoscale eddies.