Shore-Based Video Observations of Nonlinear Internal Waves across the Inner Shelf Public Deposited


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  • Shore-based video remote sensing is used to observe and continually monitor nonlinear internal waves propagating across the inner shelf. Month-long measurements of velocity from bottom-mounted acoustic Doppler current profilers and temperature from thermistor chains at the 10- and 20-m isobaths are combined with sea surface imagery from a suite of cameras (Argus) to provide a kinematic description of 11 borelike internal waves as they propagate across the central Oregon inner shelf. The surface expression of these waves, commonly seen by eye as alternating rough and smooth bands, are identified by increased pixel intensity in Argus imagery (average width 39 ± 6 m), caused by the convergence of internal wave-driven surface currents. These features are tracked through time and space using 2-min time exposure images and then compared to wave propagation speed and direction from in situ measurements. Internal waves are refracted by bathymetry, and the measured wave speed (~0.15 m s⁻¹) is higher than predicted by linear theory (< 0.1 m s⁻¹). Propagating internal waves are also visible in subsampled Argus pixel time series (hourly collections of 17 min worth of 2-Hz pixel intensity from a subset of locations), thus extending the observational record to times without an in situ presence. Results from this 5-month record show that the preferred sea state for successful video observations occurs for wind speeds of 2–5 m s⁻¹. Continued video measurements and analysis of extensive existing Argus data will allow a statistical estimate of internal wave occurrence at a variety of inner-shelf locations.
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Date Available
Date Issued
  • Suanda, S. H., Barth, J. A., Holman, R. A., & Stanley, J. (2014). Shore-Based Video Observations of Nonlinear Internal Waves across the Inner Shelf. Journal of Atmospheric and Oceanic Technology, 31(3), 714-728. doi:10.1175/JTECH-D-13-00098.1
Journal Title
Journal Volume
  • 31
Journal Issue/Number
  • 3
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Funding Statement (additional comments about funding)
  • Support for this work comes from NSF Grants OCE-0851486 and OCE-1155863. The Argus program is supported by ONR Littoral Geosciences and Optics Grant N00014-09-10121. This work is supported by the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO), funded by the David and Lucile Packard Foundation and the Gordon and Betty Moore Foundation.
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