Editing Polynya (section)

==Formation==
Coastal polynyas are formed through two main processes:
* A '''sensible heat polynya''' is thermodynamically driven, and typically occurs when warm water [[upwelling]] keeps the surface water temperature at or above the [[freezing point]]. This reduces ice production and may stop it altogether.
* A '''latent heat polynya''' is formed through the action of [[katabatic wind]]s, which act to drive ice away from a fixed boundary such as a [[coastline]], [[fast ice]], or an [[ice bridge]]. The polynya forms initially when first-year [[pack ice]] is driven away from the coast, which leaves an area of open water within which new ice is formed. This new ice is then also herded downwind toward the first-year pack ice. When it reaches the pack ice, the new ice is consolidated onto the pack ice. This process continues over time. Latent heat polynyas are therefore a major source of sea ice production in the Antarctic.<ref>{{Cite journal|last1=Skogseth|first1=R.|last2=Haugan|first2=P. M.|last3=Haarpaintner|first3=J.|date=2004-10-01|title=Ice and brine production in Storfjorden from four winters of satellite and in situ observations and modeling|journal=Journal of Geophysical Research: Oceans|language=en|volume=109|issue=C10|pages=C10008|doi=10.1029/2004jc002384|issn=2156-2202|bibcode=2004JGRC..10910008S}}</ref>

Latent heat polynyas are regions of high ice production and therefore are possible sites of dense water production in both [[polar region]]s. The high ice production rates within these polynyas leads to a large amount of [[brine rejection]] into the surface waters; this salty water then sinks. It is an open question as to whether the polynyas of the Arctic can produce enough dense water to form a major portion of the dense water required to drive the [[thermohaline circulation]].

Mid-sea polynyas are formed when specific atmospheric conditions occur over preconditioned oceanographic areas. Such atmospheric conditions should favor ice drift in opposite directions to open the ice pack. [[Polar cyclone]]s are a typical atmospheric trigger for the occurrence of mid-sea polynyas as the cyclonic winds push the ice in opposite directions away from the cyclone center.<ref>{{cite journal|first1=Diana |last1=Francis  |first2=Clare |last2=Eayrs  |first3=Juan |last3=Cuesta  |first4=David |last4=Holland| title=Polar Cyclones at the Origin of the Reoccurrence of the Maud Rise Polynya in Austral Winter 2017|journal= Journal of Geophysical Research: Atmospheres|volume= 124 |issue=10|pages=5251–5267 |date=24 April 2019|doi=10.1029/2019JD030618|bibcode=2019JGRD..124.5251F |s2cid=149497432 |url=https://cnrs.hal.science/hal-04278544/file/Francis_et_al-2019-Polynya_JGR_Atmospheres.pdf }}</ref> Also, cold fronts, where two opposite flows in direction are found, are ideal for creating a mid-sea polynya.
[[File:Narwhal 1 1995-06-10.jpg|thumb|right|The flukes of a [[narwhal]] in a [[Baffin Bay]] polynya]]

===Antarctic bottom water===
[[Antarctic bottom water]] (AABW) is the dense water with high salinity that exists in the abyssal layer of the [[Southern Ocean]]. It plays a major role in the global overturning circulation.<ref>{{Cite journal|last=Johnson|first=Gregory C.|date=2008-05-01|title=Quantifying Antarctic Bottom Water and North Atlantic Deep Water volumes|journal=Journal of Geophysical Research: Oceans|language=en|volume=113|issue=C5|pages=C05027|doi=10.1029/2007jc004477|issn=2156-2202|bibcode=2008JGRC..113.5027J|doi-access=free}}</ref> Coastal polynyas (latent heat polynyas) are a source of AABW as brine rejection during the formation of sea ice at these polynyas increases the salinity of the seawater, which then sinks down to the ocean bottom as AABW.<ref>{{Cite journal|last1=Tamura|first1=Takeshi|last2=Ohshima|first2=Kay I.|last3=Nihashi|first3=Sohey|date=2008-04-01|title=Mapping of sea ice production for Antarctic coastal polynyas|journal=Geophysical Research Letters|language=en|volume=35|issue=7|pages=L07606|doi=10.1029/2007gl032903|issn=1944-8007|bibcode=2008GeoRL..35.7606T|s2cid=128716199 |doi-access=free}}</ref><ref>{{Cite journal|last1=Ohshima|first1=Kay I.|last2=Fukamachi|first2=Yasushi|last3=Williams|first3=Guy D.|last4=Nihashi|first4=Sohey|last5=Roquet|first5=Fabien|last6=Kitade|first6=Yujiro|last7=Tamura|first7=Takeshi|last8=Hirano|first8=Daisuke|last9=Herraiz-Borreguero|first9=Laura|title=Antarctic Bottom Water production by intense sea-ice formation in the Cape Darnley polynya|journal=Nature Geoscience|volume=6|issue=3|pages=235–240|doi=10.1038/ngeo1738|bibcode=2013NatGe...6..235O|year=2013}}</ref> Antarctic polynyas form when ice masses diverge from the coast and move away in the direction of the wind, creating an exposed area of sea water which subsequently freezes over, with brine rejection, to form another mass of ice.<ref>{{Cite journal|last1=Ohshima|first1=Kay I.|last2=Fukamachi|first2=Yasushi|last3=Williams|first3=Guy D.|last4=Nihashi|first4=Sohey|last5=Roquet|first5=Fabien|last6=Kitade|first6=Yujiro|last7=Tamura|first7=Takeshi|last8=Hirano|first8=Daisuke|last9=Herraiz-Borreguero|first9=Laura|title=Antarctic Bottom Water production by intense sea-ice formation in the Cape Darnley polynya|journal=Nature Geoscience|volume=6|issue=3|pages=235–240|doi=10.1038/ngeo1738|bibcode=2013NatGe...6..235O|year=2013}}</ref>