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Cold ocean cavity and weak basal melting of the Sorsdal Ice Shelf revealed by surveys using autonomous platforms

Citation

Gwyther, DE and Spain, EA and King, P and Guihen, D and Williams, GD and Evans, E and Cook, S and Richter, O and Galton-Fenzi, BK and Coleman, R, Cold ocean cavity and weak basal melting of the Sorsdal Ice Shelf revealed by surveys using autonomous platforms, JGR Oceans, 125, (6) Article e2019JC015882. ISSN 2169-9275 (2020) [Refereed Article]


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Copyright Statement

Copyright 2020 The Authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

DOI: doi:10.1029/2019JC015882

Abstract

Basal melting of ice shelves is inherently difficult to quantify through direct observations, yet it is a critical factor controlling Antarctic mass balance and global sea‐level rise. While much research attention is paid to larger ice shelves and those experiencing the most rapid change, many smaller, unstudied ice shelves offer valuable insights. Here, we investigate the oceanographic conditions and melting beneath the Sørsdal ice shelf, East Antarctica. We present results from the 2018/2019 Sørsdal deployment of the University of Tasmania's autonomous underwater vehicle nupiri muka . Oceanography adjacent to and beneath the ice shelf front shows a cold and relatively saline environment dominated by Winter Water and Dense Shelf Water, while bathymetry measurements show a deep (∼1,200 m) trough running into the ice shelf cavity. Two multiyear deployments of Autonomous Phase‐sensitive Radar Echo Sounders on the surface of the ice shelf show weak melt rates (average of 1.6 and 2.3 m yr−1) with low temporal variability. These observations are supported by numerical ocean model and satellite estimates of melting. We speculate that the presence of a ∼825 m thick (350 m to at least 1,175 m) homogeneous layer of cold, dense water blocks access from warmer waters that intrude into Prydz Bay from offshore, resulting in weak melt rates. However, the newly identified trough means that the ice shelf is vulnerable to any decrease in polynya activity that allows warm water to enter the cavity. This could lead to increased basal melting and mass loss through this sector of Antarctica.

Item Details

Item Type:Refereed Article
Keywords:Antarctica, ice shelves, AUV, oceanography
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
UTAS Author:Gwyther, DE (Dr David Gwyther)
UTAS Author:Spain, EA (Ms Erica Spain)
UTAS Author:King, P (Mr Peter King)
UTAS Author:Guihen, D (Dr Damien Guihen)
UTAS Author:Williams, GD (Associate Professor Guy Williams)
UTAS Author:Evans, E (Miss Eleri Evans)
UTAS Author:Cook, S (Dr Sue Cook)
UTAS Author:Richter, O (Mr Ole Richter)
UTAS Author:Galton-Fenzi, BK (Dr Ben Galton-Fenzi)
UTAS Author:Coleman, R (Professor Richard Coleman)
ID Code:139536
Year Published:2020
Deposited By:Australian Antarctic Program Partnership
Deposited On:2020-06-19
Last Modified:2020-07-28
Downloads:0

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