Direct breaking of the internal tide near topography : Kaena Ridge, Hawaii
MetadataShow full item record
Barotropic to baroclinic conversion and attendant phenomena were recently examined at the Kaena Ridge as an aspect of the Hawaii Ocean Mixing Experiment. Two distinct mixing processes appear to be at work in the waters above the 1100-m-deep ridge crest. At middepths, above 400 m, mixing events resemble their open-ocean counterparts. There is no apparent modulation of mixing rates with the fortnightly cycle, and they are well modeled by standard open-ocean parameterizations. Nearer to the topography, there is quasi-deterministic breaking associated with each baroclinic crest passage. Large-amplitude, small-scale internal waves are triggered by tidal forcing, consistent with lee-wave formation at the ridge break. These waves have vertical wavelengths on the order of 400 m. During spring tides, the waves are nonlinear and exhibit convective instabilities on their leading edge. Dissipation rates exceed those predicted by the open-ocean parameterizations by up to a factor of 100, with the disparity increasing as the seafloor is approached. These observations are based on a set of repeated CTD and microconductivity profiles obtained from the research platform (R/P) Floating Instrument Platform (FLIP), which was trimoored over the southern edge of the ridge crest. Ocean velocity and shear were resolved to a 4-m vertical scale by a suspended Doppler sonar. Dissipation was estimated both by measuring overturn displacements and from microconductivity wavenumber spectra. The methods agreed in water deeper than 200 m, where sensor resolution limitations do not limit the turbulence estimates. At intense mixing sites new phenomena await discovery, and existing parameterizations cannot be expected to apply.
Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 380-399, doi:10.1175/2007JPO3728.1.
Showing items related by title, author, creator and subject.
South China Sea internal tide/internal waves-impact on the temporal variability of horizontal array gain at 276 Hz Orr, Marshall H.; Pasewark, Bruce H.; Wolf, Stephen N.; Lynch, James F.; Schroeder, Theodore; Chiu, Ching-Sang (IEEE, 2004-10)The temporal variability of the spatial coherence of an acoustic signal received on a bottomed horizontal array has been calculated for 276-Hz narrow-band signals. A conventional plane wave beamformer was applied to the ...
Acoustic travel time perturbations due to an internal tide and internal wave field in the Barents Sea Ray, Douglas S. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1993-08)Travel time perturbations of adiabatic normal modes due to an internal tide and internal mode field in the Barents Sea are examined. A formalism for the travel time perturbation due to a change in sound speed is presented. ...
A science plan for a collaborative international research program on the coupled North Atlantic-Arctic system, a report of a Planning Workshop for an International Research Program on the Coupled North Atlantic-Arctic System developed from a workshop held in Arlington, VA 14-16 April 2014 Hofmann, Eileen E.; St. John, Mike; Benway, Heather M. (Ocean Carbon & Biogeochemistry Program, 2015)This North Atlantic-Arctic science plan is derived from an international workshop held in April 2014 with support from the National Science Foundation Division of Ocean Sciences and the European Union (EU). The workshop ...