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Comparison of deep-ocean finescale shear at two sites along the Mid-Atlantic Ridge

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dc.contributor.author Duda, Timothy F.
dc.date.accessioned 2006-04-05T12:07:44Z
dc.date.available 2006-04-05T12:07:44Z
dc.date.issued 2005-10-03
dc.identifier.uri http://hdl.handle.net/1912/813
dc.description Author Posting. © The Author, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 53 (2006): 207-225, doi:10.1016/j.dsr2.2005.08.021. en
dc.description.abstract Four drifting floats were used to measure the magnitude of the vertical derivative of horizontal velocity in waters above the rough bathymetry of the Mid Atlantic Ridge. This derivative is typically the dominant component of the velocity gradient (the shear). Two floats were at the site of the Brazil Basin Tracer Release Experiment (BBTRE) in the South Atlantic, and two were near the site of the Guiana Abyssal Gyre Experiment (GAGE) in the North Atlantic. Floats operated for one year except for one BBTRE float which operated for 100 days. Shear was measured over a vertical span of 9.5 m using drag elements that caused the floats to rotate slowly in response to shear. For each float, the first, second and fourth moments of shear were elevated above levels associated with the Garrett-Munk model internal-wave spectrum. Three of the four floats were tracked as they moved over mountainous terrain, allowing shear intensity to be measured as a function of height above the bottom. A deep BBTRE float showed enhancement of rms shear near the bottom. Floats at both areas provided measurements at 2000 m above the bottom, with differing results: The GAGE site had a lower fourth moment of shear (diapycnal diffusivity proxy) than the BBTRE site. However, application of normalization factors accounting for differences between the sites in bottom roughness, latitude-dependent internal-wave dynamics, and tidal current speeds brings the results into agreement. en
dc.description.sponsorship This work was funded by the National Science Foundation under grants OCE9416014 and OCE9906685. en
dc.format.extent 451951 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US en
dc.relation.uri http://dx.doi.org/10.1016/j.dsr2.2005.08.021
dc.subject Internal waves en
dc.subject Internal wave shear en
dc.subject Diapycnal mixing en
dc.title Comparison of deep-ocean finescale shear at two sites along the Mid-Atlantic Ridge en
dc.type Preprint en


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