Callaghan Innovation Research Papers

Back to Research Papers

TitleEvolution of a supercooled Ice Shelf Water plume with an actively growing subice platelet matrix
Publication TypeJournal Article
Year of Publication2014
AuthorsRobinson, N.J., Williams M.J.M., Stevens C.L., Langhorne P.J., and Haskell T.G.
JournalJournal of Geophysical Research: Oceans
Pagination3425 - 3446
Date Published2014
ISSN21699291 (ISSN)
KeywordsAntarctica, ice, ISW plume, McMurdo sounds, Platelet ices, Platelets, Ross ice shelves, Supercooled water, supercooling, Surface topography
AbstractWe use new observations in Western McMurdo Sound, combined with longitudinal hydrographic transects of the sound, to identify a northward-flowing Ice Shelf Water (ISW) plume exiting the cavity of the McMurdo-Ross Ice Shelf. We estimate the plume's net northward transport at 0.4±0.1 Sv, carving out a corridor approximately 35 km wide aligned with the Victoria Land Coast. Basal topography of the McMurdo Ice Shelf is such that the plume is delivered to the surface without mixing with overlying warmer water, and is therefore able to remain below the surface freezing temperature at the point of observation beneath first-year ice. Thus, the upper ocean was supercooled, by up to 50 mK at the surface, due to pressure relief from recent rapid ascent of the steep basal slope. The 70 m thick supercooled layer supports the growth and maintenance of a thick, semirigid, and porous matrix of platelet ice, which is trapped by buoyancy at the ice-ocean interface. Continued growth of individual platelets in supercooled water creates significant brine rejection at the top of the water column which resulted in convection over the upper 200 m thick, homogeneous layer. By examining the diffusive nature of the intermediate water between layers of ISW and High Salinity Shelf Water, we conclude that the ISW plume must have originated beneath the Ross Ice Shelf and demonstrate that it is likely to expand eastward across McMurdo Sound with the progression of winter. Key Points An ISW plume is identified exiting the RIS cavity via Western McMurdo Sound Recent pressure relief gives rise to significant supercooling of the ISW plume A growing platelet matrix causes density instability at the ice-ocean interface © 2014. American Geophysical Union. All Rights Reserved.

Back to top