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Modeling interannual dense shelf water export in the region of the Mertz Glacier Tongue (1992-2007)


Cougnon, EA and Galton-Fenzi, B and Meijers, AJS and Legresy, B, Modeling interannual dense shelf water export in the region of the Mertz Glacier Tongue (1992-2007), Journal of Geophysical Research: Oceans, 118, (10) pp. 5858-5872. ISSN 2169-9275 (2013) [Refereed Article]


Copyright Statement

Copyright 2013 American Geophysical Union

DOI: doi:10.1002/2013JC008790


Ocean observations around the Australian-Antarctic basin show the importance of coastal latent heat polynyas near the Mertz Glacier Tongue (MGT) to the formation of Dense Shelf Water (DSW) and associated Antarctic Bottom Water (AABW). Here, we use a regional ocean/ice shelf model to investigate the interannual variability of the export of DSW from the Adélie (west of the MGT) and the Mertz (east of the MGT) depressions from 1992 to 2007. The variability in the model is driven by changes in observed surface heat and salt fluxes. The model simulates an annual mean export of DSW through the Adélie sill of about 0.07 ± 0.06 Sv. From 1992 to 1998, the export of DSW through the Adélie (Mertz) sills peaked at 0.14 Sv (0.29 Sv) during July to November. During periods of mean to strong polynya activity (defined by the surface ocean heat loss), DSW formed in the Adélie depression can spread into the Mertz depression via the cavity under the MGT. An additional simulation, where ocean/ice shelf thermodynamics have been disabled, highlights the fact that models without ocean/ice shelf interaction processes will significantly overestimate rates of DSW export. The melt rates of the MGT are 1.2 ± 0.4 m yr−1 during periods of average to strong polynya activity and can increase to 3.8 ± 1.5 m/yr during periods of sustained weak polynya activity, due to the increased presence of relatively warmer water interacting with the base of the ice shelf. The increased melting of the MGT during a weak polynya state can cause further freshening of the DSW and ultimately limits the production of AABW.

Item Details

Item Type:Refereed Article
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical oceanography
Objective Division:Environmental Management
Objective Group:Fresh, ground and surface water systems and management
Objective Field:Measurement and assessment of freshwater quality (incl. physical and chemical conditions of water)
UTAS Author:Cougnon, EA (Dr Eva Cougnon)
UTAS Author:Galton-Fenzi, B (Dr Ben Galton-Fenzi)
UTAS Author:Legresy, B (Dr Benoit Legresy)
ID Code:89430
Year Published:2013
Web of Science® Times Cited:32
Deposited By:IMAS Research and Education Centre
Deposited On:2014-03-04
Last Modified:2017-11-30
Downloads:123 View Download Statistics

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