Details

Autor(en) / Beteiligte

• Orsi, A. H.
• Webb, C. J.

Titel

Impact of Sea Ice Production off Sabrina Coast, East Antarctica

Ist Teil von

• Geophysical research letters, 2022-03, Vol.49 (5), p.n/a

Ort / Verlag

Washington: John Wiley & Sons, Inc

Erscheinungsjahr

2022

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• Sea ice production is critical to ocean overturning. Brine released within Antarctic polynyas transforms surface water into denser Shelf Water (SW). In spite of the persistent Dalton Polynya, SW is absent off Sabrina Coast. To explain its passive role in‐situ and remote datasets for 2003–2015 are analyzed. Combined volume export near the shelf break and inshore volume change render an average sea ice production of 197.41 km3 per year (4.6 m/yr productivity), highly correlated (0.95) to divergent interior sea ice motion. Meltwater input of 157.5 Gt/yr is required to match the salinity of a prominent subsurface Thermostad measured in 2014–2015. SW formed during 2003–2008 but halted in 2009–2011, when summer sea ice divergence and export were at a minimum (<10 km3), significantly freshening the Thermostad (−5.07 ΔS per decade). Large sea ice export (>30 km3) increased its salinity (2.16 ΔS per decade) since 2012. Plain Language Summary Some coastal areas around Antarctica remain free of ice during winter, while still producing sea ice pushed away by strong winds. In determining the stability of upper waters the salt rejected during sea ice formation at some of these coastal polynyas competes with freshwater inputs from melting glaciers and ice shelves. Estimated sea ice productivity at Dalton Polynya off the Sabrina Coast is about 2.5 times higher than at Mertz Polynya off the Adelie Coast, where convection of dense Shelf Water (SW) takes place regularly. In 2014 and 2015 the first measurements in the Sabrina Basin did not reveal SW at the bottom, but a thick subsurface layer with near‐freezing temperature that indicated a large injection of meltwater from Moscow University Ice Shelf. The estimated 2003–2015 history of this Thermostad Water (ThW) salinity suggests interminent convection at the Dalton Polynya. Large summer export of sea ice volume during 2003–2008 rendered salinities higher than the critical salinity to form dense SW. Minimum regional atmospheric forcing diminished sea ice export and suppressed convection during 2008–2011. ThW salinity climbed back starting in 2012 due to large sea ice production, suggesting that convection in the Sabrina Basin could potentially have resumed by 2017. Key Points High sea ice productivity during 2003–2015 resulted from intensified northward winds and sea ice drift, and interior divergence of pack ice Minimum sea ice production and summer sea ice drift divergence suppressed Shelf Water formation during 2009–2011 An input of 157.5 Gt/yr of meltwater from local glaciers and ice shelves resulted in the overall freshening of subsurface Thermostat Water