Weddell Gyre

Weddell Gyre
Hannes Grobe, Alfred Wegener Institute · CC BY-SA 2.5 · source
Name	Weddell Gyre
Location	Southern Ocean
Type	Antarctic gyre
Area	~3,000,000 km²
Max depth	~5,000 m
Countries	Antarctica

Weddell Gyre The Weddell Gyre is a major clockwise oceanic circulation feature in the Southern Ocean adjacent to Antarctic Peninsula, Coats Land, and Queen Maud Land, bounded by the Weddell Sea and influencing Antarctic and global climates. It interacts with nearby features such as the Antarctic Circumpolar Current, Drake Passage, Ronne Ice Shelf, and Filchner-Ronne Ice Shelf, and it mediates exchanges among water masses connected to Atlantic Ocean and Southern Ocean convection sites.

Overview

The gyre occupies much of the Weddell Sea basin between Brunt Ice Shelf and the continental margin near Maud Rise and Larsen Ice Shelf, comprising a clockwise circulation influenced by winds over the Southern Ocean, the regional bathymetry of the Antarctic continental shelf, and the interaction with the Antarctic Circumpolar Current. Important adjacent regions and features include South Orkney Islands, South Georgia and the South Sandwich Islands, Prince Harald Coast, and the Maudheim operational area historically used by United States Antarctic Program and British Antarctic Survey expeditions. The gyre's extents have been mapped by surveys conducted by institutions such as Scripps Institution of Oceanography, Woods Hole Oceanographic Institution, Alfred Wegener Institute, British Antarctic Survey, and National Oceanic and Atmospheric Administration.

Physical Oceanography

The gyre's dynamics arise from wind stress associated with the Southern Annular Mode, mesoscale eddy activity linked to Maud Rise and Easter Slope Water topography, and interactions with the Antarctic Slope Current and Antarctic Bottom Water formation regions near Weddell Sea polynya sites such as those observed by Jason-1 and Envisat altimetry missions. Drifting platforms like Argo floats and instrumented seals from programs by Scripps Institution of Oceanography and British Antarctic Survey have documented variability in temperature, salinity, and stratification related to processes studied by researchers at Columbia University Lamont-Doherty Earth Observatory and University of Cambridge polar groups.

Circulation and Water Masses

The circulation supports transformation among Weddell Sea Deep Water, Weddell Sea Bottom Water, and modified Circumpolar Deep Water as it exchanges with the Antarctic Circumpolar Current and contributes to the global Meridional Overturning Circulation as described in studies from National Aeronautics and Space Administration and International Council for the Exploration of the Sea. Water mass formation involves brine rejection near Filchner Ice Shelf and dense water export across bathymetric gateways like the South Scotia Ridge and Larsen Ice Shelf front, processes monitored by research vessels including RV Polarstern and RRS James Clark Ross and analyzed in modeling efforts at Geophysical Fluid Dynamics Laboratory and Max Planck Institute for Meteorology.

Sea Ice Interactions

Seasonal and interannual sea ice dynamics in the gyre are linked to pack ice variability around Weddell Polynya events, impacts on sea ice concentration observed by ERS-1, MODIS, and Sentinel-1 satellites, and feedbacks involving albedo changes recorded by National Snow and Ice Data Center. Interaction with ice shelves such as Ronne Ice Shelf and Filchner Ice Shelf affects basal melting and brine production, with processes investigated by teams from Lamont-Doherty Earth Observatory, British Antarctic Survey, and Alfred Wegener Institute using autonomous underwater vehicles like Autosub and SeaBED platforms.

Ecosystem and Biological Impacts

The gyre influences productivity and biogeography of krill around South Georgia and the South Sandwich Islands, populations of seals including Weddell seal and Crabeater seal, and penguin colonies on South Orkney Islands and South Shetland Islands, with trophic studies conducted by Commission for the Conservation of Antarctic Marine Living Resources, Scientific Committee on Antarctic Research, and university groups at University of Cape Town and University of Otago. Phytoplankton blooms linked to upwelling of nutrient-rich Circumpolar Deep Water and iron inputs from icebergs have been sampled by expeditions aboard RV Polarstern and monitored by sensors from United Kingdom Met Office and European Space Agency missions, informing assessments by the Intergovernmental Panel on Climate Change and conservation planning by Convention on the Conservation of Antarctic Marine Living Resources.

Climate Role and Variability

The gyre contributes to deep and intermediate water export that feeds the Atlantic Meridional Overturning Circulation and modulates regional carbon uptake via the biological pump studied by Scripps Institution of Oceanography, Woods Hole Oceanographic Institution, and Plymouth Marine Laboratory. Variability tied to modes like the Southern Annular Mode and teleconnections with El Niño–Southern Oscillation have been linked to shifts in sea ice extent and polynya frequency, with paleoclimate reconstructions using ice cores from Dome C and Byrd Station and sediment cores analyzed at British Antarctic Survey laboratories.

Human Observations and Research History

Exploration and scientific study date from early voyages by James Clark Ross and later 20th-century campaigns led by RRS Discovery expeditions, through the establishment of research stations such as Rothera Research Station, Mawson Station, Halley Research Station, and research programs by United States Antarctic Program and Australian Antarctic Division. Modern observations use platforms and programs including Argo, SOCCOM, Southern Ocean Observing System, Polarstern cruises, and satellite missions by European Space Agency, NASA, and National Oceanic and Atmospheric Administration, with data synthesized in assessments by Intergovernmental Panel on Climate Change and operational forecasting centers like Met Office and National Centers for Environmental Prediction.

Category:Southern Ocean