Deep boundary current disintegration in Drake Passage

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,...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Brearley, J. Alexander, Sheen, Katy L., Naviera Garabato, Alberto C., Smeed, David A., Speer, Kevin G., Thurnherr, Andreas M., Meredith, Michael P., Waterman, Stephanie
Format: Article in Journal/Newspaper
Language:English
Published: 2014
Subjects:
Southern Ocean
Drake Passage
Pacific
Separation Point
Online Access:http://nora.nerc.ac.uk/id/eprint/502161/
https://nora.nerc.ac.uk/id/eprint/502161/3/grl51239_Brearley.pdf
https://doi.org/10.1002/2013GL058617
Description
Summary: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 ACC, 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.

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