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Deep boundary current disintegration in Drake Passage
Author(s) -
Brearley J. Alexander,
Sheen Katy L.,
Naveira Garabato Alberto C.,
Smeed David A.,
Speer Kevin G.,
Thurnherr Andreas M.,
Meredith Michael P.,
Waterman Stephanie
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2013gl058617
Subject(s) - boundary current , oceanography , geology , current (fluid) , eddy , ocean current , circumpolar star , anticyclone , circumpolar deep water , water mass , climatology , mooring , deep water , meteorology , north atlantic deep water , geography , turbulence
The fate of a deep boundary current that originates in the Southeast Pacific and flows southward along the continental slope of South America is elucidated. The current transports poorly ventilated water of low salinity (a type of Pacific Deep Water, PDW), into Drake Passage. East of Drake Passage, the boundary current breaks into fresh anticyclonic eddies, nine examples of which were observed in mooring data from December 2009 to March 2012. The observed eddies appear to originate mainly from a topographic separation point close to 60°W, have typical diameters of 20–60 km and accompanying Rossby numbers of 0.1–0.3. These features are likely to be responsible for transporting PDW meridionally across the Antarctic Circumpolar Current, explaining the near homogenization of Circumpolar Deep Water properties downstream of Drake Passage. This mechanism of boundary current breakdown may constitute an important process in the Southern Ocean overturning circulation.