Antarctic Bottom Water production by intense sea-ice formation in the Cape Darnley polynya

The formation of Antarctic Bottom Water-the cold, dense water that occupies the abyssal layer of the global ocean-is a key process in global ocean circulation. This water mass is formed as dense shelf water sinks to depth. Three regions around Antarctica where this process takes place have been prev...

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Bibliographic Details
Published in:Nature Geoscience
Main Authors: Ohshima, KI, Fukamachi, Y, Williams, GD, Nihashi, S, Roquet, F, Kitade, Y, Tamura, T, Hirano, D, Herraiz Borreguero, L, Field, I, Hindell, MA, Aoki, S, Wakatsuchi, M
Format: Article in Journal/Newspaper
Language:English
Published: Nature Publishing Group 2013
Subjects:
Earth Sciences
Oceanography
Physical Oceanography
Antarctic
Cape Darnley
Darnley
Antarc*
Antarctica
Elephant Seals
Ice Shelf
Mirounga leonina
Sea ice
Online Access:https://doi.org/10.1038/ngeo1738
http://ecite.utas.edu.au/84349
Description
Summary:The formation of Antarctic Bottom Water-the cold, dense water that occupies the abyssal layer of the global ocean-is a key process in global ocean circulation. This water mass is formed as dense shelf water sinks to depth. Three regions around Antarctica where this process takes place have been previously documented. The presence of another source has been identified in hydrographic and tracer data, although the site of formation is not well constrained. Here we document the formation of dense shelf water in the Cape Darnley polynya (65-69E) and its subsequent transformation into bottom water using data from moorings and instrumented elephant seals (Mirounga leonina). Unlike the previously identified sources of Antarctic Bottom Water, which require the presence of an ice shelf or a large storage volume, bottom water production at the Cape Darnley polynya is driven primarily by the flux of salt released by sea-ice formation. We estimate that about 0.3-0.7 106 m3 s-1 of dense shelf water produced by the Cape Darnley polynya is transformed into Antarctic Bottom Water. The transformation of this water mass, which we term Cape Darnley Bottom Water, accounts for 6-13% of the circumpolar total. Copyright 2013 Macmillan Publishers Limited.

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