A scale-dependent analysis of barotropic vorticity budget in an eddy-permitting global ocean simulation

Abstract: We analyse the barotropic vorticity budget using an output from an eddy-permitting global ocean simulation to understand how bathymetry and mesoscale eddies affect the large-scale flows in the oceans. We examine the vorticity budget terms as a function of length scale and our analysis shows that bottom pressure torque, surface wind stress and the depth-integrated meridional flow are in balance at very large scales. On the other hand, contributions from nonlinear advection and bottom drag are generally prominent in mesoscales. Even within gyre circulations, bottom pressure torque is a dominant term. Thus, the traditional Sverdrup balance may not be sufficient in explaining all aspects of the gyre circulation.