Topographic Effects on Barotropic Vortex Motion: No Mean Flow

Abstract

Abstract The impact of the island topographic β effect on hurricane-like vortex tracks is studied. Both f plane and spherical geometry without a mean flow are considered. The simulations used in this study indicate the existence of a track mode in which vortices are trapped by the topography and follow a clockwise island-circulating path. The trapping of a hurricane-like vortex can be interpreted in terms of the influence of the island topographic β effect on the vortex track. Experiments on the f plane indicate that the drift speed along the clockwise path is proportional to the square root of βevmax. The applicability of the square root law on the f plane is dependent on the degree to which the local βe effect is felt by the vortex. The experiments on the sphere also demonstrate that the speed along the clockwise path is larger for a vortex with a larger maximum wind vmax. The occurrence of hurricane-like vortex trapping, however, is not sensitive to the value of vmax. When there is no background flow, ...