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Pathways of the Agulhas waters poleward of 29°S
Author(s) -
Wang Jinbo,
Mazloff Matthew R.,
Gille Sarah T.
Publication year - 2014
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2014jc010049
Subject(s) - oceanography , water mass , mode water , geology , boundary current , circumpolar deep water , north atlantic deep water , antarctic intermediate water , advection , thermohaline circulation , climatology , plateau (mathematics) , front (military) , ocean current , ocean gyre , subtropics , mathematical analysis , physics , mathematics , fishery , biology , thermodynamics
Passive tracers are advected in a Southern Ocean State Estimate (SOSE) to map the pathways of Agulhas waters, with a focus on determining where the Agulhas waters intrude into the Antarctic Circumpolar Current (ACC). Results show that Agulhas waters spread into all three ocean basins within 3 years of release. After leaving the African continent, the mean Agulhas water pathway tilts northwest toward the South Atlantic and southeast toward the ACC. The majority (from 60% to 100% depending on specific water mass) of the Agulhas waters stay in the South Indian Ocean north of the Sub‐Antarctic Front. From 10 to 28% enters the South Atlantic Ocean through the boundary current along the southern tip of South Africa and via Agulhas rings in the retroflection region. Up to 12% of intermediate depth Agulhas waters enter the ACC. Most of the tracer transport into the ACC occurs just downstream of the Kerguelen Plateau, which clearly demonstrates the importance of topography in elevating cross‐frontal exchange. Agulhas waters also contribute to Sub‐Antarctic Mode Water formation in the Southeast Indian Ocean by lateral advection. The surface Agulhas waters are preconditioned by strong surface buoyancy loss before turning into mode water, while the intermediate Agulhas waters are advected to the mode water formation region along isopycnals before being drawn into the mixed layer.