The contribution of the Weddell Gyre to the lower limb of the Global Overturning Circulation

• Main Authors: Alberto C. Naveira Garabato, Sheldon Bacon, Michael P. Meredith, Pete J. Brown, Kevin G. Speer, Paul R. Holl, Jun Dong, Brice Loose, Hugh J. Venables, William J. Jenkins, Eberhard Fahrbach
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Indian; Southern Ocean; The Antarctic; Weddell; Weddell Sea; Antarc*; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.667.419; http://eprints.soton.ac.uk/364845/1/jgrc20685.pdf

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 426 8 Sv (1 Sv5 106 m3 s–1) across the central Weddell Sea and to intensify to 546 15 Sv further offshore. This circulation injects 366 13 TW of heat from the Antarctic Circumpolar Current to the gyre, and exports 516 23 mSv of freshwater, including 136 1 mSv as sea ice to the midlati-tude Southern Ocean. The gyre’s overturning circulation has an asymmetric double-cell structure, in which 136 4 Sv of Circumpolar Deep Water (CDW) and relatively light Antarctic Bottom Water (AABW) are trans-formed into upper-ocean water masses by midgyre upwelling (at a rate of 26 2 Sv) and into denser AABW by downwelling focussed at the western boundary (86 2 Sv). The gyre circulation exhibits a substantial throughflow component, by which CDW and AABW enter the gyre from the Indian sector, undergo ventila-tion 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 (66 2 Sv) suggests that the gyre’s prominence in the closure of the lower limb of global oceanic overturning stems largely from the recycling