Editorial Type:
Article
Article Type:
Research Article

Internal Tide Reflection and Turbulent Mixing on the Continental Slope

Jonathan D. Nash College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon

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Eric Kunze Applied Physics Laboratory, University of Washington, Seattle, Washington

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John M. Toole Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

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Ray W. Schmitt Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

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Print Publication:
01 May 2004
DOI:
https://doi.org/10.1175/1520-0485(2004)034<1117:ITRATM>2.0.CO;2
Page(s):
1117–1134
Restricted access

Abstract

Observations of turbulence, internal waves, and subinertial flow were made over a steep, corrugated continental slope off Virginia during May–June 1998. At semidiurnal frequencies, a convergence of low-mode, onshore energy flux is approximately balanced by a divergence of high-wavenumber offshore energy flux. This conversion occurs in a region where the continental slope is nearly critical with respect to the semidiurnal tide. It is suggested that elevated near-bottom mixing (Kρ ∼ 10−3 m2 s−1) observed offshore of the supercritical continental slope arises from the reflection of a remotely generated, low-mode, M2 internal tide. Based on the observed turbulent kinetic energy dissipation rate ϵ, the high-wavenumber internal tide decays on time scales O(1 day). No evidence for internal lee wave generation by flow over the slope's corrugations or internal tide generation at the shelf break was found at this site.

Corresponding author address: Dr. Jonathan Nash, College of Oceanic and Atmospheric Sciences, Oregon State University, 104 COAS Admin Bldg., Corvallis, OR 97331. Email: nash@coas.oregonstate.edu

Abstract

Observations of turbulence, internal waves, and subinertial flow were made over a steep, corrugated continental slope off Virginia during May–June 1998. At semidiurnal frequencies, a convergence of low-mode, onshore energy flux is approximately balanced by a divergence of high-wavenumber offshore energy flux. This conversion occurs in a region where the continental slope is nearly critical with respect to the semidiurnal tide. It is suggested that elevated near-bottom mixing (Kρ ∼ 10−3 m2 s−1) observed offshore of the supercritical continental slope arises from the reflection of a remotely generated, low-mode, M2 internal tide. Based on the observed turbulent kinetic energy dissipation rate ϵ, the high-wavenumber internal tide decays on time scales O(1 day). No evidence for internal lee wave generation by flow over the slope's corrugations or internal tide generation at the shelf break was found at this site.

Corresponding author address: Dr. Jonathan Nash, College of Oceanic and Atmospheric Sciences, Oregon State University, 104 COAS Admin Bldg., Corvallis, OR 97331. Email: nash@coas.oregonstate.edu

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