The Weddell Polynya, or Weddell Sea Polynya, is a

polynya A polynya () is an area of open water surrounded by sea ice. It is now used as a geographical term for an area of unfrozen seawater within otherwise contiguous pack ice or fast ice. It is a loanword from the Russian полынья (), which re ...

or irregular area of open water surrounded by sea ice in the

Weddell Sea The Weddell Sea is part of the Southern Ocean and contains the Weddell Gyre. Its land boundaries are defined by the bay formed from the coasts of Coats Land and the Antarctic Peninsula. The easternmost point is Cape Norvegia at Princess Martha ...

of the

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-small ...

off

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...

and near the

Maud Rise Maud Rise () is an oceanic plateau, which rises, at its shallowest, to depths of about a 1,000 meters. It is located in the Weddell Sea in the Southern Ocean. Its name was approved by the Advisory Committee for Undersea Features in June 1987. Ge ...

. The formation of the polynya exposes relatively warmer ocean waters (at surface freezing temperatures of -1.9°C) to a cold atmosphere, leading to a large exchange of heat which drives deep convection in the ocean, often reaching depths of a 1,000 to 2,000 meters!

Occurrences

The size of New Zealand, it re-occurred each winter between 1974 and 1976. These were the first three austral winters observed by the Nimbus-5 Electrically Scanning Microwave Radiometer (ESMR). From 1976 to 2015 this polynya was rarely observed. The polynya reoccurred in 2016, and has since appeared in 2017. The 2010s occurrence has been smaller than the 1970s occurrence, being about the size of Maine in 2017, or roughly . Since the 1970s, the polar Southern Ocean south of the Antarctic Circumpolar Current has freshened and stratified, likely a result of anthropogenic

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

. Such stratification may be responsible for suppressing the return of the Weddell Sea polynya. More recently, it was found that intense cyclones occurring over the ice pack, far south from the ice edge, were at the origin of the reoccurrence of the Weddell or Maud Rise Polynya in austral winter 2017. In certain winter months, the general atmospheric circulation around Antarctica exhibits a strong zonal wave 3 pattern which favor the development of polar cyclones closer to the coast i.e. over preconditioned oceanographic areas for polynya formation such as the Weddell Polynya in the Lazarev Sea and the Cosmonaut polynya in the Cosmonaut Sea around Antarctica.

Other Antarctic polynyas

The presence of polynyas in

McMurdo Sound McMurdo Sound is a sound in Antarctica. It is the southernmost navigable body of water in the world, and is about from the South Pole. Captain James Clark Ross discovered the sound in February 1841, and named it after Lt. Archibald McMurdo ...

provides an ice-free area where penguins can feed, so is important for the survival of the

Cape Royds Cape Royds is a dark rock cape forming the western extremity of Ross Island, facing on McMurdo Sound, Antarctica. It was discovered by the Discovery Expedition (1901–1904) and named for Lieutenant Charles Royds, Royal Navy, who acted as meteor ...

penguin colony.

References

Geography of the Southern Ocean Bodies of water of the Southern Ocean {{Glaciology-stub

Occurrences

Other Antarctic polynyas

See also

References