Observations of amplified roughness from crystal accretion i

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TitleObservations of amplified roughness from crystal accretion in the sub-ice ocean boundary layerAbstractIce crystal accretion on the underside of sea ice and ice shelves, a signature of pressure-induced supercooling, has the potential to alter the energy balance in the ocean boundary layer through enhanced hydrodynamic roughness. Here we present estimates of crystal-driven ocean boundary layer roughness in supercooled water beneath sea ice adjacent to the McMurdo/Ross Ice Shelf. Data were collected from four sites in McMurdo Sound, Antarctica, between 2007 and 2015, and represent a range of ice shelf-affected conditions. The results show that drag of the rough ice underside in the presence of platelets is 6-30 times larger than typical levels homogeneously applied in ice-ocean interaction models. The crystal-enhanced drag promotes increased entrainment into the boundary layer from the upper ocean, which has the potential to affect ice shelf evolution and sea ice growth through enhanced turbulent exchange of heat and momentum. Copyright2017. American Geophysical Union.AcknowledgementsTim Haskell, Brett Grant, Cecilia Bitz, Gabby O'Connor, Andy Mahoney, Alex Gough, Brian Staite, and Antarctica New Zealand are thanked for their assistancein the field. Inga Smith, Pat Langhorne, Mike Williams, Ken Hughes, Greg Leonard, Ben Galto n-Fenzi, and David Gwyther are thanked for valuable discussion. David Plew is thanked for the loan of equipment. We thank two anonymous reviewers for their insightful comments which have helped to improve the clarity and applicabilityof the manuscript. Funding was provided by the Royal Society of NewZealand Marsden Fund, NIWA Core Funding, Antarctica New Zealand, a University of Otago Research Grant, the Deep South National Science Challenge project `Targeted observations and process-informed modeling of Antarctic sea ice, Ìand the New Zealand Antarctic Research Institute. Metadata are lodged with Antarctica New Zealand. Data are archived with NIWA, New Zealand, and are available from the authors upon request (natalie.robinson@niwa.co.nz).

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1st AuthorRobinson, N.AuthorRobinson, N.Stevens, C.Mcphee, M.Year2017JournalGeophysical Research LettersVolume44Number4Pages1814-1822DOI10.1002/2016GL071491URLhttps://www.scopus.com/inward/recor.....8caea4f0d44a1b999d6e630bcKeywordsrank5

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TypeArticleCitationRobinson, N., Stevens, C. and Mcphee, M. (2017). Observations of amplified roughness from crystal accretion in the sub-ice ocean boundary layer. Geophysical Research Letters, 44(4): 1814-1822 IdentifierRobinson2017Relevancerank5Antarctica NZ supported?YesNZARI?Yes

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Robinson, N.

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