SUBMESOSCALE SURFACE TIDAL, VORTICAL, AND RESIDUAL CIRCULATIONS IN A SEMI-ENCLOSED BAY

Abstract

We scrutinize three different components of submesoscale surface tidal, vortical, and residual circulations in a semienclosed bay using (1) observations of high-frequency radar-derived surface current maps and (2) numerical model simulations run under realistic vertical stratification and boundary conditions at O(1)-km spatial and 1-hourly temporal resolutions over a 2-year period. Based on the spatial statistics of the identified submesoscale eddies and eddy kinetic energy budget analysis, the submesoscale eddies are primarily generated by the detachment of shoreline-following tidal currents at the coastal boundaries, persist for less than 1.5 days, and are dissipated dominantly via vertical buoyancy fluxes associated with bottom bathymetric interactions of the tidal currents. The residual circulation is clearly shown with the nontidal geostrophic currents associated with the pressure gradients generated by wind-driven Ekman transports against the coast and the ageostrophic low-frequency currents.