Vortex Rossby wave propagation in baroclinic tropical cyclone‐like vortices

Abstract

AbstractThis study extends the vortex Rossby wave (VRW) propagation theory into baroclinic tropical cyclone‐like vortices. Dispersion relation, group velocities, and stagnation radius/height of propagating wave packets in baroclinic conditions are derived using the Wenzel‐Kramers‐Brillouin approximation. It is found that the VRW dispersion relation in baroclinic vortices in isentropic coordinates has the same mathematical form as that in barotropic vortices in pseudoheight coordinates. However, baroclinicity causes the vertical wave number to increase as wave packets propagate upward, resulting in different wave propagation features from those in barotropic vortices. The stagnation radius and level are constrained by a “critical” surface where the initial central angular phase velocity equals the angular velocity of the vortex. Depending on the specific structure of vortex basic‐state baroclinicity and positions where asymmetries are located, the excited waves can either be trapped vertically and behave like those in barotropic conditions or effectively propagate upward but with their radial propagation largely suppressed.