• Agrawal, Y. C., , and Aubrey D. G. , 1992: Velocity observations above a rippled bed using laser Doppler velocimetry. J. Geophys. Res., 97 , 2024920259.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bendat, J. S., , and Piersol A. G. , 2000: Random Data: Analysis and Measurement Procedures. 3rd ed. Wiley, 594 pp.

  • Benilov, A. Y., , and Filyushkin B. N. , 1970: Application of methods of linear filtration to an analysis of fluctuations in the surface layer of the sea. Izv. Acad. Sci. USSR Atmos. Oceanic Phys. Engl. Transl., 6 , 810819.

    • Search Google Scholar
    • Export Citation
  • Bromirski, P. D., , Cayan D. R. , , and Flick R. E. , 2005: Wave spectral energy variability in the northeast Pacific. J. Geophys. Res., 110 .C03005, doi:10.1029/2004JC002398.

    • Search Google Scholar
    • Export Citation
  • Dean, R. G., , and Dalrymple R. A. , 1991: Water Wave Mechanics for Engineers and Scientists. World Scientific, 353 pp.

  • Dewey, R. K., , and Crawford W. R. , 1988: Bottom stress estimates from vertical dissipation rate profiles on the continental shelf. J. Phys. Oceanogr., 18 , 11671177.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Feddersen, F., , and Williams A. J. III, 2007: Direct estimation of the Reynolds stress vertical structure in the nearshore. J. Atmos. Oceanic Technol., 24 , 102116.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fugate, D. C., , and Chant R. J. , 2005: Near-bottom shear stresses in a small, highly stratified estuary. J. Geophys. Res., 110 .C03022, doi:10.1029/2004JC002563.

    • Search Google Scholar
    • Export Citation
  • Gross, T. F., , and Nowell A. R. M. , 1983: Mean flow and turbulence scaling in a tidal boundary layer. Cont. Shelf Res., 2 , 11091126.

  • Herbers, T. H. C., , and Guza R. T. , 1993: Comment on “Velocity observations above a rippled bed using laser Doppler velocimetry” by Y. C. Agrawal and D. G. Aubrey. J. Geophys. Res., 98 , C11. 2033120334.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Howarth, M. J., , and Souza A. J. , 2005: Reynolds stress observations in continental shelf seas. Deep-Sea Res. II, 52 , 10751086.

  • Lohrmann, A., , Hackett B. , , and Røed L. P. , 1990: High resolution measurements of turbulence, velocity, and stress using a pulse-to-pulse coherent sonar. J. Atmos. Oceanic Technol., 7 , 1937.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lu, Y., , and Lueck R. G. , 1999: Using a broadband ADCP in a tidal channel. Part II: Turbulence. J. Atmos. Oceanic Technol., 16 , 15681579.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nidzieko, N. J., , Fong D. A. , , and Hench J. L. , 2006: Comparison of Reynolds stress estimates derived from standard and fast-ping ADCPs. J. Atmos. Oceanic Technol., 23 , 854861.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • RD Instruments, 2005: Workhorse acoustic Doppler current profiler technical manual. RD Instruments P/N957-6150-00, 196 pp.

  • Reidenbach, M. A., , Monismith S. G. , , Koseff J. R. , , Yahel G. , , and Genin A. , 2006: Boundary layer turbulence and flow structure over a fringing coral reef. Limnol. Oceanogr., 51 , 19561968.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rippeth, T. P., , Williams E. , , and Simpson J. H. , 2002: Reynolds stress and turbulent energy production in a tidal channel. J. Phys. Oceanogr., 32 , 12421251.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rippeth, T. P., , Simpson J. H. , , Williams E. , , and Inall M. E. , 2003: Measurement of the rates of production and dissipation of turbulent kinetic energy in an energetic tidal flow: Red Wharf Bay revisited. J. Phys. Oceanogr., 33 , 18891901.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Shaw, W. J., , and Trowbridge J. H. , 2001: The direct estimation of near-bottom turbulent fluxes in the presence of energetic wave motions. J. Atmos. Oceanic Technol., 18 , 15401557.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Souza, A. J., , and Howarth M. J. , 2005: Estimates of Reynolds stress in a highly energetic shelf sea. Ocean Dyn., 55 , 490498.

  • Stacey, M. T., , Monismith S. G. , , and Burau J. R. , 1999a: Observations of turbulence in a partially stratified estuary. J. Phys. Oceanogr., 29 , 19501970.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Stacey, M. T., , Monismith S. G. , , and Burau J. R. , 1999b: Measurements of Reynolds stress profiles in unstratified tidal flow. J. Geophys. Res., 104 , C5. 1093310949.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Trowbridge, J. H., 1998: On a technique for measurement of turbulent shear stress in the presence of surface waves. J. Atmos. Oceanic Technol., 15 , 290298.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Whipple, A. C., , Luettich R. A. , , and Seim H. E. , 2006: Measurements of Reynolds stress in a wind-driven lagoonal estuary. Ocean Dyn., 56 , 169185.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Williams, E., , and Simpson J. H. , 2004: Uncertainties in estimates of Reynolds stress and TKE production rate using the ADCP variance method. J. Atmos. Oceanic Technol., 21 , 347357.

    • Crossref
    • Search Google Scholar
    • Export Citation
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Extracting Reynolds Stresses from Acoustic Doppler Current Profiler Measurements in Wave-Dominated Environments

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  • 1 Environmental Fluid Mechanics Laboratory, Stanford University, Stanford, California
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Abstract

Surface waves introduce velocity correlations that bias and often dominate Reynolds stress estimates made using the traditional variance method for acoustic Doppler current profilers (ADCPs). This analysis shows that the wave bias is the sum of a real wave stress and an error due to instrument tilt, both of which have a large uncertainty. Three alternative extensions to the variance method for calculating Reynolds stress profiles from ADCP measurements in wavy conditions are analyzed. The previously proposed variance fitting method (Variance Fit) is evaluated and two more general methods that use along- and between-beam velocity differencing with adaptive filtering (Vertical AF and Horizontal AF) are derived. The three methods are tested on datasets containing long-period monochromatic swell (Moorea, French Polynesia) and shorter-period mixed swell (Santa Barbara, California). The Variance Fit method leaves a residual wave bias in beam velocity variances, especially for intermediate waves, but gives physically reasonable Reynolds stress estimates because most of the residual wave bias cancels when the variance method is applied. The new Vertical AF method does not produce inherent wave bias in beam velocity variances, but yields comparable Reynolds stresses to the Variance Fit method. The Horizontal AF method performs poorly for all but monochromatic waves. Error remaining after one of the above methods is applied can be attributed to residual wave error, correlation of turbulence between points chosen for differencing, or correlation between waves and turbulence. A simple procedure is provided for determining the minimum bin separation that can be used.

Corresponding author address: Johanna H. Rosman, Environmental Fluid Mechanics Laboratory, Civil and Environmental Engineering, Stanford University, Stanford, CA 94305-4020. Email: jrosman@stanford.edu

Abstract

Surface waves introduce velocity correlations that bias and often dominate Reynolds stress estimates made using the traditional variance method for acoustic Doppler current profilers (ADCPs). This analysis shows that the wave bias is the sum of a real wave stress and an error due to instrument tilt, both of which have a large uncertainty. Three alternative extensions to the variance method for calculating Reynolds stress profiles from ADCP measurements in wavy conditions are analyzed. The previously proposed variance fitting method (Variance Fit) is evaluated and two more general methods that use along- and between-beam velocity differencing with adaptive filtering (Vertical AF and Horizontal AF) are derived. The three methods are tested on datasets containing long-period monochromatic swell (Moorea, French Polynesia) and shorter-period mixed swell (Santa Barbara, California). The Variance Fit method leaves a residual wave bias in beam velocity variances, especially for intermediate waves, but gives physically reasonable Reynolds stress estimates because most of the residual wave bias cancels when the variance method is applied. The new Vertical AF method does not produce inherent wave bias in beam velocity variances, but yields comparable Reynolds stresses to the Variance Fit method. The Horizontal AF method performs poorly for all but monochromatic waves. Error remaining after one of the above methods is applied can be attributed to residual wave error, correlation of turbulence between points chosen for differencing, or correlation between waves and turbulence. A simple procedure is provided for determining the minimum bin separation that can be used.

Corresponding author address: Johanna H. Rosman, Environmental Fluid Mechanics Laboratory, Civil and Environmental Engineering, Stanford University, Stanford, CA 94305-4020. Email: jrosman@stanford.edu

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