Turbulence Measurements from Compliant Moorings. Part II: Motion Correction

Kilcher, Levi F.; Thomson, Jim; Harding, Samuel; Nylund, Sven

doi:10.1175/JTECH-D-16-0213.1

Title: Turbulence Measurements from Compliant Moorings. Part II: Motion Correction

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Abstract

Acoustic Doppler velocimeters (ADVs) are a valuable tool for making high-precision measurements of turbulence, and moorings are a convenient and ubiquitous platform for making many kinds of measurements in the ocean. However, because of concerns that mooring motion can contaminate turbulence measurements and that acoustic Doppler profilers make middepth velocity measurements relatively easy, ADVs are not frequently deployed from moorings. This work demonstrates that inertial motion measurements can be used to reduce motion contamination from moored ADV velocity measurements. Three distinct mooring platforms were deployed in a tidal channel with inertial-motion-sensor-equipped ADVs. In each case, motion correction based on the inertial measurements reduces mooring motion contamination of velocity measurements. The spectra from these measurements are consistent with other measurements in tidal channels and have an f^–5/3 slope at high frequencies - consistent with Kolmogorov's theory of isotropic turbulence. Motion correction also improves estimates of cross spectra and Reynolds stresses. A comparison of turbulence dissipation with flow speed and turbulence production indicates a bottom boundary layer production-dissipation balance during ebb and flood that is consistent with the strong tidal forcing at the site. Finally, these results indicate that inertial-motion-sensor-equipped ADVs are a valuable new tool for making high-precision turbulence measurements frommore » moorings.« less

Authors:

Kilcher, Levi F. ^[1]; Thomson, Jim ^[2]; Harding, Samuel ^[3]; Nylund, Sven ^[4]

National Renewable Energy Laboratory, Golden, Colorado
Applied Physics Laboratory, University of Washington, Seattle, Washington
Pacific Northwest National Laboratory, Richland, Washington
Nortek AS, Rud, Norway

Publication Date:: Wed May 17 00:00:00 EDT 2017

Research Org.:: National Renewable Energy Lab. (NREL), Golden, CO (United States)

Sponsoring Org.:: USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:: 1364677

Alternate Identifier(s):: OSTI ID: 1373672

Report Number(s):: NREL/JA-5000-67282
Journal ID: ISSN 0739-0572

Grant/Contract Number:: AC36-08GO28308

Resource Type:: Published Article

Journal Name:: Journal of Atmospheric and Oceanic Technology

Additional Journal Information:: Journal Name: Journal of Atmospheric and Oceanic Technology Journal Volume: 34 Journal Issue: 6; Journal ID: ISSN 0739-0572

Publisher:: American Meteorological Society

Country of Publication:: United States

Language:: English

Subject:: 16 TIDAL AND WAVE POWER; turbulence; acoustic measurements/effects; buoy observations; in situ oceanic observations; instrumentation/sensors; renewable energy

Citation Formats


                    Kilcher, Levi F., Thomson, Jim, Harding, Samuel, and Nylund, Sven. Turbulence Measurements from Compliant Moorings. Part II: Motion Correction.  United States: N. p., 2017. 
Web.  doi:10.1175/JTECH-D-16-0213.1.

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                    Kilcher, Levi F., Thomson, Jim, Harding, Samuel, & Nylund, Sven. Turbulence Measurements from Compliant Moorings. Part II: Motion Correction.  United States.  https://doi.org/10.1175/JTECH-D-16-0213.1

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                    Kilcher, Levi F., Thomson, Jim, Harding, Samuel, and Nylund, Sven. Wed .  
"Turbulence Measurements from Compliant Moorings. Part II: Motion Correction".  United States.  https://doi.org/10.1175/JTECH-D-16-0213.1.

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@article{osti_1364677,

  title        = {Turbulence Measurements from Compliant Moorings. Part II: Motion Correction},

  author       = {Kilcher, Levi F. and Thomson, Jim and Harding, Samuel and Nylund, Sven},

  abstractNote = {Acoustic Doppler velocimeters (ADVs) are a valuable tool for making high-precision measurements of turbulence, and moorings are a convenient and ubiquitous platform for making many kinds of measurements in the ocean. However, because of concerns that mooring motion can contaminate turbulence measurements and that acoustic Doppler profilers make middepth velocity measurements relatively easy, ADVs are not frequently deployed from moorings. This work demonstrates that inertial motion measurements can be used to reduce motion contamination from moored ADV velocity measurements. Three distinct mooring platforms were deployed in a tidal channel with inertial-motion-sensor-equipped ADVs. In each case, motion correction based on the inertial measurements reduces mooring motion contamination of velocity measurements. The spectra from these measurements are consistent with other measurements in tidal channels and have an f–5/3 slope at high frequencies - consistent with Kolmogorov's theory of isotropic turbulence. Motion correction also improves estimates of cross spectra and Reynolds stresses. A comparison of turbulence dissipation with flow speed and turbulence production indicates a bottom boundary layer production-dissipation balance during ebb and flood that is consistent with the strong tidal forcing at the site. Finally, these results indicate that inertial-motion-sensor-equipped ADVs are a valuable new tool for making high-precision turbulence measurements from moorings.},

  doi          = {10.1175/JTECH-D-16-0213.1},

  journal      = {Journal of Atmospheric and Oceanic Technology},

  number       = 6,

  volume       = 34,

  place        = {United States},

  year         = {Wed May 17 00:00:00 EDT 2017},

  month        = {Wed May 17 00:00:00 EDT 2017}

}

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Turbulence Measurements from Compliant Moorings. Part II: Motion Correction

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