Signatures of supercooling: McMurdo Sound platelet ice

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TitleSignatures of supercooling: McMurdo Sound platelet iceAbstractNear ice shelves around Antarctica the ocean becomes supercooled and has been observed to carry small suspended ice crystals. Our measurements demonstrate that these small crystals are persistently present in the water column beneath the winter fast ice, and when incorporated in sea ice they reduce the mean grain size of the sea-ice cover. By midwinter, larger ice crystals below the ice/water interface are observed to form a porous sub-ice platelet layer with an ice volume fraction of 0.25 ± 0.06. The magnitude and direction of the oceanic heat flux varied between (5 ± 6)Wm-2 (upwards) and (-15 ± 10)Wm -2 (downwards) in May, but by September it settled between (-6 ± 2) and (-11 ± 2)Wm -2. The negative values imply that the ocean acts as a heat sink which is responsible for the growth of 12% of the ice thickness between June and September. This oceanic contribution should not be ignored in models of Antarctic sea-ice thickness close to an ice shelf.AcknowledgementsThis work, a part of New Zealand's contribution to the International Polar Year, was funded by the Foundation for Research Science and Technology, the University of Otago, Industrial Research Ltd and the National Institute of Water and Atmospheric Research Ltd. A.J.G. was supported by a University of Otago Postgraduate Scholarship. We are grateful to Antarctica New Zealand for logistical support and Myles Thayer, Richard Sparrow and Peter Stroud for help constructing instruments. We thank Brian Staite and the Scott Base 2009 winter team for field support, Wolfgang Rack for supplying RADARSAT imagery for Figure 2, Joe Trodahl for some temperature data, and Craig Stevens and Craig Stewart for help with the mooring. The comments of two anonymous reviewers significantly improved the paper.

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1st AuthorGough, A.AuthorGough, A.Mahoney, A.Langhorne, P.Williams, M.Robinson, N.Haskell, T.Year2012JournalJournal of GlaciologyVolume58Number207Pages38-50DOI10.3189/2012JoG10J218URLhttps://www.scopus.com/inward/recor.....a84fccce51725d2a30167acefKeywordsgrain sizeheat fluxice coverice crystalice mechanicsice shelfice thicknesslow temperaturesea icetemperature anomaly, AntarcticaEast AntarcticaMcMurdo SoundSouthern Ocean, rank5ProgrammeK131 - Sea Ice and Southern Ocean Processes

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TypeArticleCitationGough, A., Mahoney, A., Langhorne, P., Williams, M., Robinson, N. and Haskell, T. (2012). Signatures of supercooling: McMurdo Sound platelet ice. Journal of Glaciology, 58(207): 38-50 IdentifierGough2012bRelevancerank5

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Author

Robinson, N.

Programme

K131 - Sea Ice and Southern Ocean Processes