Ross Gyre

Ross Gyre
Name	Ross Gyre
Location	Southern Ocean, Ross Sea
Type	oceanic gyre
Coordinates	74°S 176°W (approx.)
Basin countries	Antarctica

Ross Gyre The Ross Gyre is a major anticyclonic ocean circulation feature in the Ross Sea sector of the Southern Ocean off Antarctica. It organizes regional water masses, sea-ice distribution, and biological production, and interacts with atmospheric systems such as the Southern Annular Mode, El Niño–Southern Oscillation, and the Antarctic Circumpolar Current. Scientists from institutions like the British Antarctic Survey, National Oceanic and Atmospheric Administration, Scripps Institution of Oceanography, University of Washington, and Lamont–Doherty Earth Observatory study its role in global climate change, oceanography, and marine biology.

Overview

The Ross Gyre sits within the Ross Sea basin between the Ross Ice Shelf and the Transantarctic Mountains, bounded by the eastern limb near the Amundsen Sea and the western edge approaching the Balleny Islands. As an anticyclonic feature it resembles other large-scale gyres such as the North Atlantic Gyre, South Pacific Gyre, and the Beaufort Gyre in behavior, but occupies a polar environment influenced by the Antarctic Circumpolar Current, Weddell Sea exchanges, and the Southern Ocean frontal systems like the Subantarctic Front and Polar Front. Its dynamics couple to ice shelves studied by programs such as International Thwaites Glacier Collaboration, SCAR, and national programs from United States Antarctic Program and Australian Antarctic Division.

Physical Characteristics

The gyre spans several hundred kilometers, characterized by a doming of the thermocline, a core of cold, saline water, and seasonal to interannual variability in stratification measured by platforms like Argo floats, CTD casts from RV Laurence M. Gould, and moorings deployed by NIWA and Plymouth Marine Laboratory. Its circulation interacts with water masses including Circumpolar Deep Water, Antarctic Bottom Water, and Modified Circumpolar Deep Water. Sea ice regimes around the gyre are influenced by features such as the Ross Ice Shelf front, pack ice formation, and polynyas including the Ross Sea Polynya; satellite remote sensing from NASA missions like ICESat and MODIS and agencies like ESA provide synoptic mapping. Bathymetric constraints from surveys by GEBCO and USGS influence topographic steering near features such as the Drygalski Basin and Victoria Land Basin.

Circulation and Dynamics

Anticyclonic circulation arises from wind forcing associated with the Southern Annular Mode and eddy fluxes resolved by high-resolution models from MITgcm, ROMS, and coupled climate models used in IPCC assessments. Eddy-driven transport, western boundary currents near the Victoria Land Coast, and cross-shelf exchanges modulate heat and salt budgets measured during cruises by NOAA Ship Ronald H. Brown and RV Polarstern. Processes such as upwelling of Circumpolar Deep Water, brine rejection during sea-ice formation, and freshwater input from melting of the Ross Ice Shelf and glaciers like Pine Island Glacier affect stratification and the formation of dense waters that can ventilate the Southern Ocean and influence global thermohaline circulation patterns tied to research by WOA, CLIVAR, and WOCE.

Climate and Ecological Significance

The Ross Gyre shapes primary productivity hotspots supporting ecosystems including krill populations studied by CCAMLR, penguin colonies at Ross Island and Cape Adare, and benthic communities on the continental shelf documented in expeditions by NOAA and NIWA. Variability in sea ice and nutrient upwelling alters phytoplankton blooms detected by instruments from BAS and satellites operated by JAXA and EUMETSAT. The gyre influences carbon sequestration processes evaluated by projects like Biogeochemical-Argo and programs under the Global Carbon Project. Its interactions with atmospheric patterns such as ENSO, SAM, and the Amundsen Sea Low can modulate regional climate, affecting research priorities for IPCC and national polar research agencies including NSF, NSIDC, and AARI.

Human Impacts and Research

Human activities affecting the Ross Gyre region are primarily scientific operations by organizations such as United States Antarctic Program, Australian Antarctic Division, Japanese Antarctic Research Expedition, British Antarctic Survey, and logistical support from vessels like RV Polarstern and RV Investigator. Conservation and management are guided by CCAMLR and the Antarctic Treaty System, including the Protocol on Environmental Protection to the Antarctic Treaty. Research addresses impacts from climate-driven ice loss documented by NASA Jet Propulsion Laboratory and ESA and biological responses monitored by programs like SCAR-MarBIN. International collaborations including SOOS, SCAR, and Southern Ocean Observing System coordinate long-term observing strategies using autonomous vehicles such as gliders, Argo, and Ice-Tethered Profilers.

History of Exploration and Study

The Ross Gyre region was first circumnavigated and mapped during exploration eras including voyages by James Clark Ross and 19th-century expeditions that charted the Ross Sea and Ross Ice Shelf. Twentieth-century Antarctic programs led by nations including United Kingdom, United States, Australia, and New Zealand expanded systematic oceanographic work through efforts like Operation Deep Freeze, Discovery Investigations, and scientific stations including McMurdo Station, Scott Base, and Mawson Station. Modern study accelerated with programs such as WOCE, CLIVAR, and the deployment of satellite remote sensing by NASA and ESA, and continues with multidisciplinary initiatives involving IPCC-affiliated researchers and polar consortia tracking changes in circulation, ice, and ecosystems.

Category:Ocean currents of the Southern Ocean