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Platelet ice attachment to instrument strings beneath the Amery Ice Shelf, East Antarctica

Citation

Craven, M and Warner, RC and Galton-Fenzi, B and Herraiz Borreguero, L and Vogel, SW and Allison, I, Platelet ice attachment to instrument strings beneath the Amery Ice Shelf, East Antarctica, Journal of Glaciology, 60, (220) pp. 383-393. ISSN 0022-1430 (2014) [Refereed Article]


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Copyright Statement

Copyright 2014 International Glaciological Society

DOI: doi:10.3189/2014JoG13J082

Abstract

Oceanographic instruments suspended beneath the Amery Ice Shelf, East Antarctica, have recorded sporadic pressure decreases of 1020 dbar over a few days at three sites where basal marine ice growth is expected. We attribute these events to flotation due to platelet ice accretion on the instrument moorings. Some events were transient, rapidly returning to pre-event pressures, probably through dislodgement of loosely attached crystals. Driven by these pressure changes, temperatures recorded by the shallowest instruments (within 20 m of the shelf base) tracked in situ freezing temperatures during the events. These observations provide indirect evidence for the presence of frazil ice in the sub-ice-shelf mixed layer and for active marine ice accretion. At one site we infer that a dense layer of platelet ice ∼1.5 m thick was accreted to the ice shelf over a 50 day period. Following some permanent abrupt pressure decreases (which we interpret as due to the lodgement of the uppermost instrument at the ice-shelf base), altered background trends in pressure suggest compaction rates of 34 m a1 for the accreted basal platelet layer. Attachment of platelet ice and resulting displacement of moorings has ramifications for project design and instrument deployment, and implications for interpretation of oceanographic data from sub-ice-shelf environments.

Item Details

Item Type:Refereed Article
Keywords:glaciological instruments and methods, ice shelves, ice/ocean interactions
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical Oceanography
Objective Division:Environment
Objective Group:Other Environment
Objective Field:Antarctic and Sub-Antarctic Oceanography
Author:Craven, M (Mr Mike Craven)
Author:Warner, RC (Dr Roland Warner)
Author:Galton-Fenzi, B (Dr Ben Galton-Fenzi)
Author:Herraiz Borreguero, L (Dr Laura Herraiz Borreguero)
Author:Vogel, SW (Dr Stefan Vogel)
Author:Allison, I (Dr Ian Allison)
ID Code:93951
Year Published:2014
Web of Science® Times Cited:3
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2014-08-25
Last Modified:2015-02-24
Downloads:0

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