The contribution of the Weddell Gyre to the lower limb of the global overturning circulation

Jullion, L. and Naveira Garabato, A. C. and Bacon, S. and Meredith, M. P. and Brown, P. J. and Torres-Vald\?es, S. and Speer, K. G. and Holland, P. R. and Dong, J. and Bakker, D. and Hoppema, M. and Loose, B. and Venables, H.J. and Jenkins, W. J. and Messias, M.-J. and Fahrbach, E.


abstract: The horizontal and vertical circulation of the Weddell Gyre is diagnosed using a box inverse model constructed with recent hydrographic sections and including mobile sea ice and eddy transports. The gyre is found to convey 42\pm8 Sv (1 Sv = 10^6 m^3 s^-1) across the central Weddell Sea and to intensify to 54\pm15 Sv further offshore. This circulation injects 36\pm13 TW of heat from the Antarctic Circumpolar Current to the gyre, and exports 51\pm23 mSv of freshwater, including 13\pm1 mSv as sea ice to the mid-latitude Southern Ocean. The gyre’s overturning circulation has an asymmetric double-cell structure, in which 13\pm4 Sv of Circumpolar Deep Water (CDW) and relatively light Antarctic Bottom Water (AABW) are transformed into upper-ocean water masses by mid-gyre upwelling (at a rate of 2\pm2 Sv) and into denser AABW by downwelling focussed at the western boundary (8\pm2 Sv). The gyre circulation exhibits a substantial throughflow component, by which CDW and AABW enter the gyre from the Indian sector, undergo ventilation and densification within the gyre, and are exported to the South Atlantic across the gyre’s northern rim. The relatively modest net production of AABW in the Weddell Gyre (6\pm2 Sv) suggests that the gyre’s prominence in the closure of the lower limb of global oceanic overturning stems largely from the recycling and equatorward export of Indian-sourced AABW.

@article{Jullion-etal-2014,
  author = {Jullion, L. and Naveira~Garabato, A. C. and Bacon, S. and Meredith, M. P. and Brown, P. J. and Torres-Vald\?{e}s, S. and Speer, K. G. and Holland, P. R. and Dong, J. and Bakker, D. and Hoppema, M. and Loose, B. and Venables, H.J. and Jenkins, W. J. and Messias, M.-J. and Fahrbach, E.},
  title = {The contribution of the Weddell Gyre to the lower limb of the global overturning circulation},
  journal = {J. Geophys. Res.},
  year = {2014},
  pages = {3357--3377},
  volume = {119},
  issue = {6},
  doi = {10.1002/2013JC009725},
  url = {https://eprints.soton.ac.uk/364845/}
}