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Control of Mode and Intermediate Water Mass Properties in Drake Passage by the Amundsen Sea Low

Close, Sally E.; Naveira Garabato, Alberto C.; McDonagh, Elaine L.; King, Brian A.; Biuw, Martin; Boehme, Lars. 2013 Control of Mode and Intermediate Water Mass Properties in Drake Passage by the Amundsen Sea Low. Journal of Climate, 26 (14). 5102-5123. 10.1175/JCLI-D-12-00346.1

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Abstract/Summary

The evolution of the physical properties of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) in the Drake Passage region is examined on time scales down to intraseasonal, within the 1969–2009 period. Both SAMW and AAIW experience substantial interannual to interdecadal variability, significantly linked to the action of the Amundsen Sea low (ASL) in their formation areas. Observations suggest that the interdecadal freshening tendency evident in SAMW over the past three decades has recently abated, while AAIW has warmed significantly since the early 2000s. The two water masses have also experienced a substantial lightening since the start of the record. Examination of the mechanisms underpinning water mass property variability shows that SAMW characteristics are controlled predominantly by a combination of air–sea turbulent heat fluxes, cross-frontal Ekman transport of Antarctic surface waters, and the evaporation–precipitation balance in the Subantarctic zone of the southeast Pacific and Drake Passage, while AAIW properties reflect air–sea turbulent heat fluxes and sea ice formation in the Bellingshausen Sea. The recent interdecadal evolution of the ASL is consistent with both the dominance of the processes described here and the response of SAMW and AAIW on that time scale.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1175/JCLI-D-12-00346.1
ISSN: 0894-8755
Additional Keywords: Atmosphere-ocean interaction, Water masses, Interannual variability
Date made live: 29 Jul 2013 14:58 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/502779

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