Weddell Polynya
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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 language, Russian (), whic ...
, 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 C ...
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 60th parallel south, 60° S latitude and encircling Antarctica. With a size of , it is the seco ...
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 (also known as the Antarctic Ocean), it contains the geographic South Pole. ...
and near the Maud Rise. 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 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 Nimbus 5 (also called Nimbus E or Nimbus V) was a meteorological satellite for the research and development of sensing technology. It was the fifth successful launch in a series of the Nimbus program. The objective of Nimbus 5 was to test and ev ...
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 Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
. 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 favors the development of polar cyclones closer to the coast, that is, over preconditioned oceanographic areas for polynya formation, such as the Weddell Polynya in the
Lazarev Sea The Lazarev Sea (, ''More Lazareva'') is a proposed name for a marginal sea of the Southern Ocean. It would be bordered by two proposals from a 2002 International Hydrographic Organization (IHO) draft, a King Haakon VII Sea to the west and a ...
and the Cosmonaut polynya in the Cosmonaut Sea around Antarctica.


Other Antarctic polynyas

The presence of polynyas in
McMurdo Sound The McMurdo Sound is a sound in Antarctica, known as the southernmost passable body of water in the world, located approximately from the South Pole. Captain James Clark Ross discovered the sound in February 1841 and named it after Lieutenant ...
provides an ice-free area where penguins can feed, and is therefore 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 British National Antarctic Expedition (BrNAE) (1901–1904) and named for Lieutenant Charles Royds, ...
penguin colony.


See also

* Polar Cyclones *
Coriolis force In physics, the Coriolis force is a pseudo force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the motio ...
*
Ekman layer Ekman transport is part of Ekman motion theory, first investigated in 1902 by Vagn Walfrid Ekman. Winds are the main source of energy for ocean circulation, and Ekman transport is a component of wind-driven ocean current. Ekman transport occurs ...
*
Ekman number The Ekman number (Ek) is a dimensionless number used in fluid dynamics to describe the ratio of viscous forces to Coriolis forces. It is frequently used in describing geophysical phenomena in the oceans and atmosphere in order to characterise the r ...
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Ekman spiral Ekman transport is part of Ekman motion theory, first investigated in 1902 by Vagn Walfrid Ekman. Winds are the main source of energy for ocean circulation, and Ekman transport is a component of wind-driven ocean current. Ekman transport occurs ...
*
Ekman transport Ekman transport is part of Ekman motion theory, first investigated in 1902 by Vagn Walfrid Ekman. Winds are the main source of energy for ocean circulation, and Ekman transport is a component of wind-driven ocean current. Ekman transport occurs w ...
* Ekman velocity *
Fridtjof Nansen Fridtjof Wedel-Jarlsberg Nansen (; 10 October 1861 – 13 May 1930) was a Norwegian polymath and Nobel Peace Prize laureate. He gained prominence at various points in his life as an explorer, scientist, diplomat, humanitarian and co-founded the ...
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Nansen's Fram expedition Nansen's ''Fram'' expedition of 1893–1896 was an attempt by the Norway, Norwegian explorer Fridtjof Nansen to reach the geographical North Pole by harnessing the natural east–west current of the Arctic Ocean. In the face of much discouragem ...
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Upwelling Upwelling is an physical oceanography, oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water from deep water towards the ocean surface. It replaces the warmer and usually nutrient-depleted sur ...
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Vagn Walfrid Ekman Vagn Walfrid Ekman (3 May 1874 – 9 March 1954) was a Swedish oceanographer. Born in Stockholm to Fredrik Laurentz Ekman, himself an oceanographer, he became committed to oceanography while studying physics at the University of Uppsala an ...


References

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