Energetics of a model ocean basin with surface buoyancy and wind forcing

We present a new test case for rotating horizontal convection, where the flow is driven by differential buoyancy forcing along a horizontal surface. This simple model is used to understand and quantify the combined influence of surface heating and cooling and surface wind stress on the Meridional Overturning Circulation. The domain is a rectangular basin with cooling at both ends (to represent the poles) and warming in the middle (equatorial) region. To model the effect of the Antarctic Circumpolar Current (ACC), a zonally reentrant channel is placed near the Southern pole, where periodic boundary conditions are imposed. The model is forced by wind stress and buoyancy along the surface. The problem is solved numerically using a finite-volume Adaptive Mesh Refinement solver for the Boussinesq Navier-Stokes equations with rotation. Simulations are run at a Rayleigh number of 10⁸ with different strengths and combinations of surface buoyancy and wind forcing in a domain with a relatively high aspect ratio of [5, 10, 1] in zonal, meridional and vertical directions, respectively. For each simulation, terms in the energy budget are calculated using the local Available Potential Energy framework introduce in Scotti and White (2014, J. Fluid Mech.) to investigate the effects of surface forcing on the large-scale overturning, baroclinic eddy generation in the ACC, deep convective plumes, and diapycnal mixing.