dc.contributor.author Dickinson, A en dc.contributor.author White, Nicholas en dc.contributor.author Caulfield, Colm-cille en dc.date.accessioned 2018-02-06T15:06:47Z dc.date.available 2018-02-06T15:06:47Z dc.date.issued 2017-12-01 en dc.identifier.issn 2169-9275 dc.identifier.uri https://www.repository.cam.ac.uk/handle/1810/271734 dc.description.abstract Bright reflections are observed within the upper 1000~m of the water column along a seismic reflection profile that traverses the northern margin of the Gulf of Mexico. Independent hydrographic calibration demonstrates that these reflections are primarily caused by temperature changes associated with different water masses that are entrained into the Gulf along the Loop Current. The internal wave field is analyzed by automatically tracking 1171 reflections, each of which is greater than 2~km in length. Power spectra of the horizontal gradient of isopycnal displacement, $\phi_{\xi_x}$, are calculated from these tracked reflections. At low horizontal wavenumbers ($k_x < 10^{-2}$ cpm), $\phi_{\xi_x} \propto k_x^{-0.2 \pm 0.6}$, in agreement with hydrographic observations of the internal wave field. The turbulent spectral subrange is rarely observed. Diapycnal diffusivity, $K$, is estimated from the observed internal wave spectral subrange of each tracked reflection using a fine-scale parametrization of turbulent mixing. Calculated values of $K$ vary between $10^{-8}$ and $10^{-4}$~m$^{2}$~s$^{-1}$ with a mean value of $K \sim 4 \times 10^{-6}$~m$^{2}$~s$^{-1}$. The spatial distribution of turbulent mixing shows that $K \sim 10^{-7}$~m$^{2}$~s$^{-1}$ away from the shelf edge in the upper 300~m where stratification is strong. Mixing is enhanced by up to four orders of magnitude adjacent to the shoaling bathymetry of the continental slope. This overall pattern matches that determined by analyzing nearby suites of CTD casts. However, the range of values recovered by spectral analysis of the seismic image is greater as a consequence of significantly better horizontal resolution. dc.language.iso en en dc.title Spatial Variation of Diapycnal Diffusivity Estimated From Seismic Imaging of Internal Wave Field, Gulf of Mexico en dc.type Article prism.endingPage 9854 prism.issueIdentifier 12 en prism.publicationDate 2017 en prism.publicationName Journal of Geophysical Research: Oceans en prism.startingPage 9827 prism.volume 122 en dc.identifier.doi 10.17863/CAM.18695 dcterms.dateAccepted 2017-11-07 en rioxxterms.versionofrecord 10.1002/2017JC013352 en rioxxterms.version VoR en rioxxterms.licenseref.uri http://www.rioxx.net/licenses/all-rights-reserved en rioxxterms.licenseref.startdate 2017-12-01 en dc.contributor.orcid Dickinson, A [0000-0001-7184-927X] dc.contributor.orcid White, Nicholas [0000-0002-4460-299X] dc.contributor.orcid Caulfield, Colm-cille [0000-0002-3170-9480] dc.identifier.eissn 2169-9291 rioxxterms.type Journal Article/Review en pubs.funder-project-id NERC (1508938) pubs.funder-project-id EPSRC (EP/K034529/1) cam.orpheus.success Thu Jan 30 13:04:25 GMT 2020 - The item has an open VoR version. * rioxxterms.freetoread.startdate 2100-01-01
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