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Measurements of Sea Surface Height Variability in the Eastern South Atlantic from Pressure Sensor-Equipped Inverted Echo Sounders: Baroclinic and Barotropic

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dc.contributor.author Baker-Yeboah, Sheekela
dc.contributor.author Watts, D. Randolph
dc.contributor.author Byrne, Deirdre A.
dc.date.accessioned 2011-06-10T17:25:52Z
dc.date.available 2011-06-10T17:25:52Z
dc.date.issued 2009-12
dc.date.submitted 2008-07
dc.identifier.issn 0739-0572
dc.identifier.issn 1520-0426
dc.identifier.uri http://hdl.handle.net/1721.1/64409
dc.description.abstract Variability in sea surface height (SSH) can be decomposed into two contributions: one from changes in mass in the water column (barotropic) and the other from purely steric changes (baroclinic). Both contributions can be determined from data recorded by a pressure sensor–equipped inverted echo sounder (PIES). PIES data from the Agulhas South Atlantic Thermohaline Experiment (ASTTEX) were used, collected in the Cape Basin off South Africa, along 1000 km of an eddy corridor where Agulhas eddies carry cores of warm, salty Indian Ocean waters into the South Atlantic. The paper presents in detail the method used to convert PIES measurements into barotropic, baroclinic, and total SSH, and discusses the error budget. The baroclinic contribution is geopotential height (reference 4500 dbar), which can be determined from the measured vertical acoustic travel time together with a lookup curve based on the regional hydrography. The main error source is scatter about this curve that depends on the extent to which water masses advecting along each geopotential streamline may derive from different ocean regions. The barotropic contribution can be determined from the bottom pressure measurements of the mass variation in the water column and has an uncertainty due to sensor calibration drift in two years corresponding to 1-cm water column height. The barotropic component accounts for 20% of the overall SSH variance and 47% during large signal intervals exceeding 15 cm. PIES data demonstrate via the two measurements that barotropic and baroclinic contributions may work independently or in concert in different mesoscale eddies. The combined structure need not be equivalent barotropic. In particular, deep barotropic eddies exhibit mesoscale spatiotemporal scales and may or may not be systematically tilted or aligned in space or time relative to baroclinic eddies. en_US
dc.description.sponsorship National Science Foundation (U.S.) (Grant OCE-0095572) en_US
dc.description.sponsorship National Science Foundation (U.S.) (Grant OCE-0099177) en_US
dc.description.sponsorship National Science Foundation (U.S.) (Grant OCE-0221008) en_US
dc.description.sponsorship United States. National Aeronautics and Space Administration en_US
dc.language.iso en_US
dc.publisher American Meteorological Society en_US
dc.relation.isversionof http://dx.doi.org/10.1175/2009jtecho659.1 en_US
dc.rights Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. en_US
dc.source PNAS en_US
dc.title Measurements of Sea Surface Height Variability in the Eastern South Atlantic from Pressure Sensor-Equipped Inverted Echo Sounders: Baroclinic and Barotropic en_US
dc.type Article en_US
dc.identifier.citation Baker-Yeboah, Sheekela, D. Randolph Watts, and Deirdre A Byrne. “Measurements of Sea Surface Height Variability in the Eastern South Atlantic from Pressure Sensor–Equipped Inverted Echo Sounders: Baroclinic and Barotropic Components.” Journal of Atmospheric and Oceanic Technology 26.12 (2009) : 2593-2609. c2009 American Meteorological Society en_US
dc.contributor.department Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences en_US
dc.contributor.approver Baker-Yeboah, Sheekela
dc.contributor.mitauthor Baker-Yeboah, Sheekela
dc.relation.journal Journal of Atmospheric and Oceanic Technology en_US
dc.identifier.mitlicense PUBLISHER_POLICY en_US
dc.eprint.version Final published version en_US
dc.type.uri http://purl.org/eprint/type/JournalArticle en_US
eprint.status http://purl.org/eprint/status/PeerReviewed en_US
dspace.orderedauthors Baker-Yeboah, Sheekela; Watts, D. Randolph; Byrne, Deirdre A. en


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