Generation of coastally trapped waves and secondary cyclones by an eddy approaching shelf topography

We consider the evolution of an isolated anticyclonic vortex encountering a continental shelf during its westward β-drift in the framework of an equivalentbarotropic model generalized to allow for the intersection of the layer interface with a sloping bottom. The approaching vortex generates both topographic coastally trapped waves, and secondary cyclonic eddies due to off-shelf advection of water with high potential vorticity. These effects result in a net vortex drift in the direction opposite to that induced by the image-effect, and enhanced vortex decay due to deformations of the vortex core. Given the initial potential vorticity anomaly in the vortex core, the outcome is controlled by eight nondimensional parameters: the amplitude of the anomaly, the vortex size related to the Burger number, the intensity of the vortex relative to the β-drift speed, the initial distance from the shelf, the shelf slope steepness, the shelf width, the Ekman number for bottom friction over the shelf, and the lateral momentum diffusion. We find that the vortex-shelf interaction is more sensitive to the vortex intensity and vortex size, than to the remaining parameters. ∗Corresponding author. E-mail address: [email protected]