Vortex patch dynamics in a coastal current

A two-parametric family of steady-state vortex patches (VP) is constructed for a coastal irrotational background current over a half-plane induced by a balanced source-sink system at its boundary. Barotropic quasi-geostrophic approximation and the constant Coriolis parameter were used. The "moment" model is shown to describe sufficiently well the dependence of steady states on the governing parameters. The structural instability of VPs constructed and their response to the change in the flow rate are revealed with the contour dynamics method. Typical examples of VP propagation across the coastal zone in the vicinity of straits, which are simulated by sources and sinks, are considered.