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An introduction to the physical oceanography of six seamounts in the southwest Indian Ocean

Read, Jane; Pollard, Raymond. 2017 An introduction to the physical oceanography of six seamounts in the southwest Indian Ocean. Deep Sea Research Part II: Topical Studies in Oceanography, 136. 44-58. 10.1016/j.dsr2.2015.06.022

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© 2015 Elsevier B.V. This is the author’s version of a work that was accepted for publication in Deep Sea Research Part II: Topical Studies in Oceanography. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was/will be published in Deep Sea Research Part II: Topical Studies in Oceanography (doi:10.1016/j.dsr2.2015.06.022).
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Abstract/Summary

Exploratory surveys of six seamounts in the Southwest Indian Ocean provide a description of physical processes induced by seamounts along the Southwest Indian Ridge. Mean currents (15–25 cm s−1) in the vicinity of each seamount were dominated by mesoscale eddies. The dominant seamount-driven process was the generation of internal tides by the barotropic tide interacting with the seamount crests. This led to enhanced shear in the vicinity of the crests resulting in mixing where stratification was weak, for example in the core of an anticyclonic mesoscale eddy or where there had been a winter mixed layer. Tidally driven up- and downwelling was observed at the seabed with associated variability in bottom temperature of up to 3 °C over a tidal cycle. Vertical displacement of isopycnals by internal tidal waves reached 200 m peak to trough. Fluorescence in the surface (eutrophic) layer could thus extend down to the seamount crest on each tidal cycle. Apparently spatial variations in short conductivity/temperature/depth sections across each seamount were probably aliased temporal variations from the strong tidal signal. Evidence for Taylor caps or other potential trapped circulations at the seamount crest was weak, most likely because currents associated with mesoscale eddies were too strong to allow their formation.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/j.dsr2.2015.06.022
ISSN: 09670645
Additional Keywords: Southwest Indian Ridge; Seamounts; Ocean circulation; Internal tides
NORA Subject Terms: Marine Sciences
Date made live: 09 Jul 2015 12:41 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/511286

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