Fig. 3: Schematic showing four different scenarios.
From: Controls of the global overturning circulation of the ocean
a Buoyancy forcing applied at the surface. This configuration corresponds to the horizontal convection regime, where mixing is solely generated by flow instabilities. b Buoyancy forcing and mechanical mixing, producing a deeper stratification and a stronger overturning circulation. c Buoyancy forcing and surface winds, in a configuration that resembles tropical cells. In this configuration, wind-driven Ekman pumping maintains a deeper thermocline and the interior flow is largely adiabatic. d Combined buoyancy forcing, wind and mixing, in the presence of a circumpolar gateway (black dashed line). The green dotted line represents the Ekman circulation cell and the orange dotted line represents the circulation induced by eddies across the open channel. This configuration bears much resemblance with the present-day deep and bottom overturning circulation.
