I repost the following information from Reply #9 of the "Risks & Challenges of RCMs for the Southern Ocean", which cites the following references that indicate that increases in the Antarctic Westerlies (related both to the ozone hole and to increasing GHGs) interact with eddies in the Southern Ocean to increasing local upwelling, and associated ventilation of CO2 from deep waters in the Southern Ocean:
"Meredith, Michael P., Alberto C. Naveira Garabato, Andrew McC. Hogg, Riccardo Farneti, 2012: Sensitivity of the Overturning Circulation in the Southern Ocean to Decadal Changes in Wind Forcing. J. Climate, 25, 99–110.
doi:
http://dx.doi.org/10.1175/2011JCLI4204.1 Abstract
The sensitivity of the overturning circulation in the Southern Ocean to the recent decadal strengthening of the overlying winds is being discussed intensely, with some works attributing an inferred saturation of the Southern Ocean CO2 sink to an intensification of the overturning circulation, while others have argued that this circulation is insensitive to changes in winds. Fundamental to reconciling these diverse views is to understand properly the role of eddies in counteracting the directly wind-forced changes in overturning. Here, the authors use novel theoretical considerations and fine-resolution ocean models to develop a new scaling for the sensitivity of eddy-induced mixing to changes in winds, and they demonstrate that changes in Southern Ocean overturning in response to recent and future changes in wind stress forcing are likely to be substantial, even in the presence of a decadally varying eddy field. This result has significant implications for the ocean’s role in the carbon cycle, and hence global climate.
Munday, David R., Helen L. Johnson, David P. Marshall, 2013: Eddy Saturation of Equilibrated Circumpolar Currents. J. Phys. Oceanogr., 43, 507–532.
doi:
http://dx.doi.org/10.1175/JPO-D-12-095.1 Abstract
This study uses a sector configuration of an ocean general circulation model to examine the sensitivity of circumpolar transport and meridional overturning to changes in Southern Ocean wind stress and global diapycnal mixing. At eddy-permitting, and finer, resolution, the sensitivity of circumpolar transport to forcing magnitude is drastically reduced. At sufficiently high resolution, there is little or no sensitivity of circumpolar transport to wind stress, even in the limit of no wind. In contrast, the meridional overturning circulation continues to vary with Southern Ocean wind stress, but with reduced sensitivity in the limit of high wind stress. Both the circumpolar transport and meridional overturning continue to vary with diapycnal diffusivity at all model resolutions. The circumpolar transport becomes less sensitive to changes in diapycnal diffusivity at higher resolution, although sensitivity always remains. In contrast, the overturning circulation is more sensitive to change in diapycnal diffusivity when the resolution is high enough to permit mesoscale eddies.
Morrison, Adele K., Andrew McC. Hogg, 2013: On the Relationship between Southern Ocean Overturning and ACC Transport. J. Phys. Oceanogr., 43, 140–148.
doi:
http://dx.doi.org/10.1175/JPO-D-12-057.1 Abstract
The eddy field in the Southern Ocean offsets the impact of strengthening winds on the meridional overturning circulation and Antarctic Circumpolar Current (ACC) transport. There is widespread belief that the sensitivities of the overturning and ACC transport are dynamically linked, with limitation of the ACC transport response implying limitation of the overturning response. Here, an idealized numerical model is employed to investigate the response of the large-scale circulation in the Southern Ocean to wind stress perturbations at eddy-permitting to eddy-resolving scales. Significant differences are observed between the sensitivities and the resolution dependence of the overturning and ACC transport, indicating that they are controlled by distinct dynamical mechanisms. The modeled overturning is significantly more sensitive to change than the ACC transport, with the possible implication that the Southern Ocean overturning may increase in response to future wind stress changes without measurable changes in the ACC transport. It is hypothesized that the dynamical distinction between the zonal and meridional transport sensitivities is derived from the depth dependence of the extent of cancellation between the Ekman and eddy-induced transports."