Tidally driven processes leading to near-field turbulence in a channel at the crest of the Mendocino Escarpment*

TitleTidally driven processes leading to near-field turbulence in a channel at the crest of the Mendocino Escarpment*
Publication TypeJournal Article
Year of Publication2016
AuthorsMusgrave R.C, MacKinnon JA, Pinkel R, Waterhouse A.F, Nash J.
JournalJournal of Physical Oceanography
Volume46
Pagination1137-1155
Date Published2016/04
Type of ArticleArticle
ISBN Number0022-3670
Accession NumberWOS:000372812000002
KeywordsAtm/Ocean Structure/ Phenomena; circulation; Circulation/ Dynamics; dissipation; internal waves; internal-tide; lee waves; Mixing; model; ocean; ridge; simulations; stratified flow; tides; topographic effects; topography; wave breaking
Abstract

In situ observations of tidally driven turbulence were obtained in a small channel that transects the crest of the Mendocino Ridge, a site of mixed (diurnal and semidiurnal) tides. Diurnal tides are subinertial at this latitude, and once per day a trapped tide leads to large flows through the channel giving rise to tidal excursion lengths comparable to the width of the ridge crest. During these times, energetic turbulence is observed in the channel, with overturns spanning almost half of the full water depth. A high-resolution, nonhydrostatic, 2.5-dimensional simulation is used to interpret the observations in terms of the advection of a breaking tidal lee wave that extends from the ridge crest to the surface and the subsequent development of a hydraulic jump on the flanks of the ridge. Modeled dissipation rates show that turbulence is strongest on the flanks of the ridge and that local dissipation accounts for 28% of the energy converted from the barotropic tide into baroclinic motion.

DOI10.1175/jpo-d-15-0021.1
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