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| Southern Ocean Gyre | |
|---|---|
| Name | Southern Ocean Gyre |
| Location | Southern Ocean |
| Type | Oceanic gyre |
| Basin countries | Antarctica |
Southern Ocean Gyre The Southern Ocean Gyre is a large-scale, wind- and thermohaline-driven circulation feature encircling the high-latitude waters around Antarctica, interacting with the Antarctic Circumpolar Current, Southern Ocean water masses, and polar fronts. It plays a central role in Southern Hemisphere climate regulation, biogeochemical cycling, and the distribution of marine ecosystems that include Antarctic krill, Adelie penguin, and Antarctic toothfish habitats.
The gyre occupies subpolar to polar sectors adjacent to Antarctic Peninsula, Ross Sea, Weddell Sea, and the broader Southern Ocean basin, linking with water masses such as Antarctic Bottom Water, Circumpolar Deep Water, Weddell Sea Bottom Water, and Antarctic Surface Water. It is shaped by forcing from atmospheric systems including the Southern Annular Mode, El Niño–Southern Oscillation, South Pacific Convergence Zone, and storm tracks tied to Roaring Forties and Furious Fifties latitudes. Studies by institutions like the British Antarctic Survey, National Oceanic and Atmospheric Administration, CSIRO, Scripps Institution of Oceanography, and NIWA have mapped its extent and variability.
The gyre is characterized by a cold, saline surface layer under seasonal sea ice influenced by Antarctic sea ice formation and melt, a stratified thermocline interacting with Circumpolar Deep Water, and abyssal flows linked to Antarctic Bottom Water formation in polynyas such as Pine Island and McMurdo regions. Key physical features include frontal systems like the Antarctic Polar Front, the Subantarctic Front, and the Southern ACC Front, which delineate biogeographic zones containing species like Minke whale, Blue whale, and Southern elephant seal. Physical monitoring uses platforms from Argo program floats, SOOP lines, research vessels such as RV Investigator, and technologies developed at Lamont–Doherty Earth Observatory.
Circulation arises from wind stress associated with the Southern Annular Mode and the west-to-east momentum of the Antarctic Circumpolar Current, modified by mesoscale eddies, topographic steering around features like the Kerguelen Plateau, South Georgia, and Maud Rise, and by buoyancy fluxes from ice-ocean interaction near Ross Sea Polynya. Eddy kinetical energy links to processes documented by Satellite Altimetry missions including TOPEX/Poseidon, Jason-1, and Sentinel-3, while heat and salt transport are quantified in studies by IPCC assessment reports and projects involving the World Meteorological Organization and Intergovernmental Oceanographic Commission. The gyre contains sub-gyres and recirculation zones influenced by boundary currents near Patagonia, Cape Horn, Kerguelen Islands, and Prince Edward Islands.
Through ventilating the deep ocean and modulating carbon uptake via the solubility pump and biological pump, the gyre influences global carbon cycles addressed in IPCC Assessment Report chapters and in work by International Geosphere-Biosphere Programme researchers. Nutrient upwelling sustains phytoplankton blooms that support food webs including Antarctic krill, Antarctic silverfish, and seabirds such as Wandering albatross and Snow petrel, with implications for fisheries managed under the Convention on the Conservation of Antarctic Marine Living Resources and by the Commission for the Conservation of Antarctic Marine Living Resources. Climate-driven changes in gyre strength affect ice shelf stability at sites like Pine Island Glacier and Thwaites Glacier, with downstream effects noted by United Nations Framework Convention on Climate Change deliberations and reports from the Scientific Committee on Antarctic Research.
The gyre is dynamically coupled to the Antarctic Circumpolar Current where shear and frontogenesis produce eddies and mixing that redistribute heat, salt, and biogeochemical tracers between Subantarctic Mode Water and polar water masses. Bathymetric features including Drake Passage, Macquarie Ridge, and South Sandwich Trench modulate ACC pathways and lead to localized intensification or separation of gyre circulation. Observational campaigns by WOCE, GLOBEC, and Census of Marine Life programs have traced exchanges of circumpolar deep water onto continental shelves, influencing melt beneath ice shelves monitored by investigators from National Snow and Ice Data Center.
Human activities affecting the gyre include climate change driven by emissions tracked by the Intergovernmental Panel on Climate Change, long-range pollution such as persistent organic pollutants documented by United Nations Environment Programme, and fishing pressure regulated through Commission for the Conservation of Antarctic Marine Living Resources protocols and national fleets from countries like Argentina, Chile, South Africa, Japan, and Norway. Research priorities involve multidisciplinary efforts by universities such as University of Cambridge, University of Tasmania, University of California, Santa Cruz, and consortia including SCAR and IOCCG to integrate oceanography, glaciology, and ecology using platforms like Icebreaker Aurora Australis, autonomous gliders from Bluefin Robotics, and long-term datasets maintained by Global Ocean Observing System. Emerging topics include ocean acidification documented by Global Carbon Project, shifts in krill distribution relevant to Convention on Biological Diversity targets, and potential feedbacks to global sea level assessed in IPCC Special Reports.