Quasi-geostrophic vortex solutions over isolated topography

Analytical solutions of barotropic, quasi-geostrophic vortices over an axisymmetric bottom topography are presented. The solutions are based on independent azimuthal modes adapted to the shape of the topography. Modes 0 (circular monopoles) and 1 (asymmetric dipoles) are evaluated for different topographic profiles that represent either submarine mountains or valleys. The interior fields are matched with an exterior flow with streamlines enclosing the vortices, so the structures remain trapped over the topographic feature. The solutions are steady in a reference frame attached to the rotation of the vortices around the topography. The main features of trapped vortices as a function of the topographic parameters, such as the structure, strength and angular speed, are discussed through numerical simulations initialised with theoretical vorticity fields. The model results reproduce reasonably well the analytical solutions when the topographic effects are strong enough to inhibit the dipole self-propagation. In contrast, very intense dipolar modes may escape from the influence of the topography.

Automated summary

Analytical solutions of barotropic, quasi-geostrophic vortices over an axisymmetric bottom topography are presented, discussing how different topographic profiles affect the vortices. The model results reproduce reasonably well the analytical solutions when the topographic effects are strong enough to inhibit the dipole self-propagation.