Vortex Rossby waves on smooth circular vortices: Part II. Idealized numerical experiments for tropical cyclone and polar vortex interiors

Idealized linear and nonlinear numerical experiments are carried out to test the predictions of the theory developed in Brunet and Montgomery Vortex Rossby Waves on Smooth Circular Vortices Part I: Theory (pages 153–177, this issue)]. For a monopolar tropical cyclone-like vortex whose strength lies between a tropical depression and tropical storm, linear theory remains uniformly valid in time in the vortex core for all azimuthal wavenumbers. Examples elucidate aspects of the vortex Rossby wave/merger spin up mechanism proposed previously. For the case of the polar vortex, however, wavenumber 1 disturbances in the continuous spectrum are predicted to develop a nonlinear evolution for realistic polar-night stratospheric-jet configurations and wave breaking is demonstrated to occur within the dynamics of the continuous spectrum.