Evolution of supercooling under coastal Antarctic sea ice du

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TitleEvolution of supercooling under coastal Antarctic sea ice during winterAbstractAbstract Here we describe the evolution through winter of a layer of in situ supercooled water beneath the sea ice at a site close to the McMurdo Ice Shelf. From early winter (May), the temperature of the upper water column was below its surface freezing point, implying contact with an ice shelf at depth. By late winter the supercooled layer was c. 40 m deep with a maximum supercooling of c. 25 mK located 1-2 m below the sea ice-water interface. Transitory in situ supercooling events were also observed, one lasting c. 17 hours and reaching a depth of 70 m. In spite of these very low temperatures the isotopic composition of the water was relatively heavy, suggesting little glacial melt. Further, the waterÅ› temperature-salinity signature indicates contributions to water mass properties from High Salinity Shelf Water produced in areas of high sea ice production to the north of McMurdo Sound. Our measurements imply the existence of a heat sink beneath the supercooled layer that extracts heat from the ocean to thicken and cool this layer and contributes to the thickness of the sea ice cover. This sink is linked to the circulation pattern of the McMurdo Sound. ©2011 Antarctic Science Ltd.AcknowledgementsThis study was funded by the Marsden Fund of New Zealand, the Foundation for Research Science and Technology, the University of Otago, the New Zealand National Institute of Water and Atmospheric Research and Industrial Research Ltd. The authors would like to thank Johno Leitch for field support, the Scott Base 2003 winter-over crew, Antarctica New Zealand and the U.S. Antarctic Program for logistical assistance, the technicians of the Department of Physics at the University of Otago for instrument construction, and Nicole Albrecht, Craig Stevens, Natalie Robinson, Inga Smith and Andy Mahoney for valuable discussions, and two anonymous reviewers for their insightful comments and suggestions for improving the manuscript.

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1st AuthorLeonard, G.AuthorLeonard, G.Langhorne, P.Williams, M.Vennell, R.Purdie, C.Dempsey, D.Haskell, T.Frew, R.Year2011JournalAntarctic ScienceVolume23Number4Pages399-409DOI10.1017/S0954102011000265URLhttps://www.scopus.com/inward/recor.....f9ca88e362d1b04199c30594eKeywordscoastal zonefreezingice coverice shelfice thicknessisotopic compositionisotopic ratiooxygen isotopesalinitysea icesupercoolingtemperature profilewater columnwinter, AntarcticaEast AntarcticaMcMurdo Ice Shelf, rank5Author Keywordsfrazil iceice shelfMcMurdo Soundoxygen isotope ratioplatelet iceProgrammeK131 - Sea Ice and Southern Ocean Processes

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TypeArticleCitationLeonard, G., Langhorne, P., Williams, M., Vennell, R., Purdie, C., Dempsey, D., Haskell, T. and Frew, R. (2011). Evolution of supercooling under coastal Antarctic sea ice during winter. Antarctic Science, 23(4): 399-409IdentifierLeonard2011Relevancerank5

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K131 - Sea Ice and Southern Ocean Processes

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