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Seasonal transformation and spatial variability of water masses within MacKenzie Polynya, Prydz Bay

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journal contribution
posted on 2023-05-21, 05:12 authored by Portela, E, Stephen Rintoul, Sophie BestleySophie Bestley, Herraiz-Borreguero, L, van Wijk, E, Clive McMahonClive McMahon, Roquet, F, Mark HindellMark Hindell
We provide a detailed description of the spatial distribution, seasonality and transformation of the main water masses within MacKenzie Polynya (MP) in Prydz Bay, East Antarctica, using data from instrumented southern elephant seals. Dense Shelf Water (DSW) formation in MP shows large spatial variability that is related to the (a) local bathymetry, (b) water column preconditioning from the presence/absence of different water masses, and (c) proximity to the Amery Ice Shelf meltwater outflow. MP exhibits sustained sea ice production and brine rejection (thus, salinity increase) from April to October. However, new DSW is only formed from June onward, when the mixed layer deepens and convection is strong enough to break the stratification set by Antarctic Surface Water above and Ice Shelf Water below. We found no evidence of DSW export from MP to Darnley polynya, as previously suggested. Rather, our observations suggest some DSW formed in Darnley Polynya may drain toward the western Prydz Bay. Then, DSW is exported offshore from Prydz Bay through the Prydz Channel. The interplay between sea ice formation, meltwater input, and sea floor topography is likely to explain why some coastal polynyas form more DSW than others, as well as the temporal variability in DSW formation within a particular polynya.

Funding

Australian Research Council

History

Publication title

Journal of Geophysical Research: Oceans

Volume

126

Issue

12

Article number

e2021JC017748

Number

e2021JC017748

Pagination

1-21

ISSN

2169-9275

Department/School

Institute for Marine and Antarctic Studies

Publisher

Wiley-Blackwell Publishing Inc.

Place of publication

United States

Rights statement

© 2021. American Geophysical Union. All Rights Reserved

Repository Status

  • Open

Socio-economic Objectives

Antarctic and Southern Ocean ice dynamics; Antarctic and Southern Ocean oceanic processes

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