Antarctic high

Antarctic high
Name	Antarctic high
Type	Semipermanent subtropical anticyclone
Location	Antarctic region
Latitude	~60°–90°S
Typical pressure	High sea-level pressure
Seasonality	Strong austral winter maximum

Antarctic high

The Antarctic high is a semipermanent polar anticyclone located over the Antarctic region that influences Southern Hemisphere climate of Antarctica, Southern Ocean circulation, and extratropical weather patterns. It interacts with systems such as the Southern Annular Mode, El Niño–Southern Oscillation, Indian Ocean Dipole, and polar stratospheric dynamics including the Antarctic ozone hole and Stratospheric sudden warming events. Research into the Antarctic high spans institutions like the National Aeronautics and Space Administration, European Centre for Medium-Range Weather Forecasts, and the British Antarctic Survey.

Overview

The Antarctic high is a persistent high-pressure system centered near the Antarctic coast and over the Weddell Sea, Ross Sea, and interior Antarctic plateau that modulates the circumpolar wind field and the polar vortex. Its strength and position are documented by agencies such as the World Meteorological Organization and the National Oceanic and Atmospheric Administration, and influence ice-related features monitored by the Scientific Committee on Antarctic Research and the International Arctic Research Center. The anticyclonic circulation contributes to cold-air outbreaks affecting regions like Patagonia, New Zealand, and southern Australia, interacting with frontal zones tracked by the Australian Bureau of Meteorology.

Formation and Dynamics

The Antarctic high forms through radiative cooling over the Antarctic plateau, diabatic processes tied to Antarctic elevation, and wave–mean flow interactions with planetary waves emanating from the South American Andes, Antarctic Peninsula, and Southern Ocean storm tracks. Baroclinic instability linked to the Drake Passage and Falkland Current alters its position, while stratosphere–troposphere coupling involving the Antarctic polar vortex and ozone chemical processes in the Antarctic ozone hole modulate intensity. Dynamics are investigated with tools developed at the Max Planck Institute for Meteorology, Scripps Institution of Oceanography, and Monash University.

Seasonal Variability

Seasonal shifts peak in austral winter when radiative cooling, longwave loss, and polar night enhance the anticyclonic center, often correlated with variations in the Southern Annular Mode and interannual phenomena such as El Niño and La Niña. Summer months see a weakened and displaced high influenced by melting sea ice around the Ross Ice Shelf and the seasonal retreat of the Antarctic sea ice edge monitored by NSIDC. Decadal trends link to forcings studied by the Intergovernmental Panel on Climate Change and reanalysis products from ECMWF Reanalysis and the NCEP/NCAR reanalysis.

Climatic and Weather Impacts

The Antarctic high shapes katabatic flows from the Antarctic ice sheet, influencing coastal polynyas near Davis Station, Mawson Station, and McMurdo Station, and modulates precipitation patterns over the Transantarctic Mountains and East Antarctica. It steers atmospheric rivers that affect southern continents such as Chile, Argentina, South Africa, and Tasmania, and contributes to blocking patterns implicated in extreme events recorded by the Australian Bureau of Meteorology and MetService (New Zealand). Long-term shifts in the high affect sea-ice extent observed by satellite missions from NASA and ESA and influence ocean heat transport along the Antarctic Circumpolar Current.

Interactions with Atmospheric Circulation

The Antarctic high interacts with the Southern Ocean storm track, the Antarctic Circumpolar Current, and teleconnections including the Pacific Decadal Oscillation, Indian Ocean Dipole, and modes like the Madden–Julian Oscillation that modulate convective activity. Coupling between the anticyclone and the polar vortex affects the frequency of sudden stratospheric warming analogues in the Southern Hemisphere and ties to ozone recovery under the Montreal Protocol. These interactions are central to seasonal forecasting by centers such as the Bureau of Meteorology and global climate modeling efforts by the Coupled Model Intercomparison Project.

Observational Methods and Modeling

Observation of the Antarctic high uses satellite missions like Aqua (satellite), Terra (satellite), Sentinel-6, and scatterometer data, airborne campaigns endorsed by NASA and ESA, in situ observations from research stations including Palmer Station, and drifting buoys from the Global Drifter Program. Numerical modeling employs global circulation models from institutions such as the Hadley Centre, NOAA Geophysical Fluid Dynamics Laboratory, and ensembles within the CMIP6 framework, using reanalyses like ERA5 to resolve anticyclonic structure and teleconnections. Data assimilation efforts are coordinated through centers like ECMWF and the WMO.

Environmental and Ecological Effects

By controlling wind patterns, sea-ice formation, and ocean mixing, the Antarctic high influences habitats for species including Emperor penguin, Weddell seal, Antarctic krill, and foraging ranges of seabirds such as the albatross species tracked by conservation groups like the BirdLife International and the IUCN. Impacts on polynya dynamics affect primary productivity that supports ecosystems studied by the Scientific Committee on Antarctic Research and fisheries regulated through the Commission for the Conservation of Antarctic Marine Living Resources. Changes in the high have implications for coastal erosion near research bases like Rothera Research Station and for shipping routes regulated under the Antarctic Treaty System.

Category:Antarctic climatology