ing. Explicit wind forcing is excluded, although vertical mixing is retained. The character of the resulting
flow is consistent in many ways with the observed ocean circulation with baroclinic western boundary
currents, a strong ACC in the Southern Ocean and an overturning streamfunction which closely resembles
those obtained in full GCMs and in observations.
Our focus is on the complex interplay between the basins, as well as the important sites for up and
downwelling. The inter-basin exchange is reflected in the two dominant overturning cells: the Antarctic
Bottom Water (AABW) cell in the Southern Ocean and the North Atlantic Deep Water (NADW) cell
in the Atlantic. We investigate the relative importance of the two overturning cells for the global ocean
circulation, as well as the sensitivity of the ocean circulation to changes in buoyancy forcing. We find
that reduced Atlantic overturning accelerates the Southern Ocean circulation, while a reduced Southern
Ocean circulation strengthens the Atlantic overturning considerably.
The intimate relation between the NADW cell, ACC and AABW has been explored in previous studies, but the large scale
coupling between the Southern Ocean and the Atlantic in controlling the overturning is still unclear. We
examine the effect of the vertical mixing in setting not only the strength of the overturning, but also
important aspects of the horizontal flow.