Deep boundary current disintegration in Drake Passage

• Main Authors: J. Alex, Er Brearley, Katy L. Sheen, Alberto C. Naveira Garabato, David A. Smeed, Kevin G. Speer, Andreas M. Thurnherr, Michael P. Meredith, Stephanie Waterman
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Drake Passage; Pacific; Separation Point; Southern Ocean; The Antarctic; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.655.2478; http://eprints.soton.ac.uk/354488/1/grl51239_Brearley.pdf

Abstract 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 breakdownmay constitute an important process in the Southern Ocean overturning circulation. 1.