Eddy-induced diapycnal fluxes and their role in the maintenance of the thermocline

High-resolution numerical experiments are diagnosed to study the integral effects of geostrophic eddy fluxes on the large-scale ocean circulation. Three characteristic large-scale flows are considered: 1) an anticyclonic single gyre, 2) a double gyre, and 3) an unblocked zonal flow, a simple analog of the Antarctic Circumpolar Current. It is found that buoyancy and potential vorticity budgets in the presence of eddies are dominated by a balance between vertical advection into the control volume by Ekman pumping and eddy transfer across the density surfaces achieved by diapycnal eddy fluxes, with small-scale mixing making only a minor contribution. Possible oceanographic implications of the results are discussed.