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TitleEvolution of supercooling under coastal Antarctic sea ice during winter
Publication TypeJournal Article
Year of Publication2011
AuthorsLeonard, G.H., Langhorne P.J., Williams M.J.M., Vennell R., Purdie C.R., Dempsey D.E., Haskell T.G., and Frew R.D.
JournalAntarctic Science
Pagination399 - 409
Date Published2011
ISSN09541020 (ISSN)
KeywordsAntarctica, coastal zone, East Antarctica, Freezing, ice cover, ice shelf, ice thickness, Isotopic composition, isotopic ratio, McMurdo Ice Shelf, oxygen isotope, salinity, Sea ice, supercooling, temperature profile, Water column, winter
AbstractAbstract 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 water's 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.

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