Flow‐Topography Interaction Along the Spanish Slope in the Alboran Sea: Vorticity Generation and Connection to Interior Fronts

Abstract

AbstractFlow‐topography interaction is examined using a realistic simulation at submesoscale resolution. The study focuses on a strong, eastward fresh current flowing along the Spanish margin in the Alboran Sea. The current develops large cyclonic vertical vorticity over the irregular slope and separates downstream at a headland; vertical vorticity is advected offshore and an interior density front is sustained by the presence of denser waters to the east. Using a depth‐integrated vorticity balance formulation, we evince the major role of bottom stress as a vorticity generation mechanism, in the form of a bottom stress divergence torque. Our proposed formulation provides an alternative to the classic transport curl balance for quantifying vorticity budgets around the oceans, using high resolution models with well resolved bottom boundary layers. Also as a result of topographic interaction, we show that the fronts observed in the basin interior could be originated along the margins prior to current separation. This is manifested by large values of the Lagrangian frontogenetic tendency for buoyancy gradients, spanning the vertical extent of the boundary current and extending toward the interior.