Boundary layer-mediated vorticity generation in currents over sloping bathymetry

Abstract Current-topography interactions in the ocean give rise to eddies spanning a wide range of spatial and temporal scales. Latest modeling efforts indicate that coastal underwater topography are important generation sites for submesoscale coherent vortices (SCVs), characterized by horizontal scales (0.1 – 10) km. Using idealized, BBL-resolving simulations adopting an integrated vorticity balance formulation, we quantify precisely role bottom boundary layers (BBLs) process. In particular, show on topographic slopes is attributable primarily torque exerted vertical divergence stress at bottom. We refer this as Bottom Stress Divergence Torque (BSDT). BSDT fundamentally nonconservative appears source term budget be distinguished from more familiar Curl (BSC). It closely connected pressure (BPT) via momentum fact shown dominant component BPT solutions with well-resolved BBL. This suggests interpretation sum viscous, generating (BSDT) inviscid, ‘flow-turning ’ component. Companion without drag illustrate although can still occur through inviscid mechanisms vortex stretching tilting, wake tend have weaker circulation, substantially less energetic, smaller