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AGU: Geophysical Research Letters

 

Keywords

  • Kelvin-Helmholtz billow
  • deep-ocean mixing
  • internal waves

Index Terms

  • Oceanography: Physical: Internal and inertial waves
  • Oceanography: Physical: Turbulence, diffusion, and mixing processes
  • Oceanography: General: Benthic boundary layers

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 37, L03605, 5 PP., 2010
doi:10.1029/2009GL041890

A deep-ocean Kelvin-Helmholtz billow train

Hans van Haren

Royal Netherlands Institute for Sea Research, Den Burg, the Netherlands

Louis Gostiaux

Coriolis, LEGI, CNRS, Grenoble, France

Detailed overturning is observed between 0.5 and 50 m above the sloping side of Great Meteor Seamount, Canary Basin, using 100 moored temperature sensors, 1 mK accurate, sampling at 1-Hz. While previously reported frontal bores of 40-m amplitude can form with vigorous near-bottom motions and sediment resuspension at the beginning of the upslope phase of large, e.g., tidal, carrier waves, the downslope phase presented here is more “permanently” turbulent away from the bottom. This turbulence is inferred from high-resolution temperature space-time series, which reveal ubiquitous “finger-like” structures. It occurs during the clear-water tidal phase, with low amounts of acoustic scatterers. The high-frequency finger-like motions σ ≫ N, N the buoyancy frequency, are observed simultaneously with local mode-2 near-N inertio-gravity waves and overall shear ∣S∣ ≈ N. They show large temperature variations, 5–10 m vertical amplitudes and occasionally develop Kelvin-Helmholtz billows. The typical (Eulerian) period of these firstly observed deep-ocean billows amounts 50 ± 10 s.

Received 23 November 2009; accepted 14 January 2010; published 6 February 2010.

Citation: van Haren, H., and L. Gostiaux (2010), A deep-ocean Kelvin-Helmholtz billow train, Geophys. Res. Lett., 37, L03605, doi:10.1029/2009GL041890.

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