Modeling the ocean's adiabatic pole-to-pole overturning circulation

The adiabatic pole-to-pole cell of the meridional overturning circulation (MOC) is studied using two numerical models: a coarse-resolution numerical model with parametrized eddies and an eddy-resolving general circulation model. Two elements are found to be necessary for the existence of an adiabatic pole-to-pole cell: (1) a thermally-indirect, wind-driven overturning circulation in a zonally-reentrant channel (analogous to the Deacon cell in the Antarctic Circumpolar Current), and (2) a set of outcropping isopycnals shared between the channel and the Northern Hemisphere. Both models give results which are qualitatively very similar, indicating that the two requirements above are general and robust. Contrary to classical theories, these results suggest that the present-day MOC is ocean are primarily controlled by wind and buoyancy forcing in the Southern Ocean rather than diapycnal mixing in the ocean interior.