Cover Journal of Atmospheric and Oceanic Technology
Journal of Atmospheric and Oceanic Technology

  • Buijsman, M. C., and Coauthors, 2014: Three-dimensional double-ridge internal tide resonance in Luzon Strait. J. Phys. Oceanogr., 44, 850–869, doi:10.1175/JPO-D-13-024.1.

    • Search Google Scholar
    • Export Citation

  • Moum, J. N., 1990a: Profiler measurements of vertical velocity fluctuations in the ocean. J. Atmos. Oceanic Technol., 7, 323–333, doi:10.1175/1520-0426(1990)007<0323:PMOVVF>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Moum, J. N., 1990b: The quest for Kρ—Preliminary results from direct measurements of turbulent fluxes in the ocean. J. Phys. Oceanogr., 20, 1980–1984, doi:10.1175/1520-0485(1990)020<1980:TQFRFD>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Moum, J. N., 1996a: Efficiency of mixing in the main thermocline. J. Geophys. Res., 101, 12 057–12 069, doi:10.1029/96JC00508.

  • Moum, J. N., 1996b: Energy-containing scales of turbulence in the ocean thermocline. J. Geophys. Res., 101, 14 095–14 109, doi:10.1029/96JC00507.

    • Search Google Scholar
    • Export Citation

  • Moum, J. N., , and Nash J. D. , 2009: Mixing measurements on an equatorial ocean mooring. J. Atmos. Oceanic Technol., 26, 317–336, doi:10.1175/2008JTECHO617.1.

    • Search Google Scholar
    • Export Citation

  • Peltier, L. J., , Wyngaard J. C. , , Khanna S. , , and Brasseur J. G. , 1996: Spectra in the unstable surface layer. J. Atmos. Sci., 53, 49–61, doi:10.1175/1520-0469(1996)053<0049:SITUSL>2.0.CO;2.

    • Search Google Scholar
    • Export Citation

  • Perlin, A., , and Moum J. N. , 2012: Comparison of thermal variance dissipation rates from moored and profiling instruments at the equator. J. Atmos. Oceanic Technol., 29, 1347–1362, doi:10.1175/JTECH-D-12-00019.1.

    • Search Google Scholar
    • Export Citation

  • Perlin, A., , Moum J. N. , , Klymak J. M. , , Levine M. D. , , Boyd T. , , and Kosro P. M. , 2005: A modified law-of-the-wall applied to oceanic bottom boundary layers. J. Geophys. Res.,110, C10S10, doi:10.1029/2004JC002310.

  • Tennekes, H., , and Lumley J. L. , 1972: A First Course in Turbulence. MIT Press, 300 pp.

  • Wijesekera, H. W., , Paulson C. A. , , and Skylingstad E. D. , 2004: Scaled temperature spectrum in the unstable oceanic surface layer. J. Geophys. Res.,109, C03015, doi:10.1029/2003JC002066.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 78 78 31
PDF Downloads 68 68 23
Editorial Type:
Article

Ocean Speed and Turbulence Measurements Using Pitot-Static Tubes on Moorings

James N. Moum 1
View More View Less
  • 1 College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon
Print Publication:
01 Jul 2015
DOI:
https://doi.org/10.1175/JTECH-D-14-00158.1
Page(s):
1400–1413
© Get Permissions
Restricted access

Abstract

A low-power (<10 mW), physically small (15.6 cm long × 3.2 cm diameter), lightweight (600 g Cu; alternatively, 200 g Al), robust, and simply calibrated pitot-static tube to measure mean speed and turbulence dissipation is described and evaluated. The measurement of speed is derived from differential pressure via Bernoulli’s principle. The differential pressure sensor employed here has relatively small, but significant, adverse sensitivities to static pressure, temperature, and acceleration, which are characterized in tests in the college’s laboratory. Results from field tests on moorings indicate acceptable agreement in pitot-static speed measurements with independent acoustic Doppler current profiler speeds, characterized as linear fits with slope = 1 (95% confidence), ±0.02 m s−1 bias, and root-mean-square error of residuals (observed minus fitted values) = 0.055 m s−1. Direct estimates of are derived from fits of velocity spectra to a theoretical turbulence inertial subrange. From near-bottom measurements, these estimates are interpreted as seafloor friction velocities, which yield drag coefficients consistent with expected values. Noise levels for , based on 40-min spectral fits, are <10–9 m2 s–3. In comparison to the airfoil (or shear) probe, the pitot-static tube provides the full spectrum of velocity, not just the dissipation range of the spectrum. In comparison to acoustic measurements of velocity, the pitot-static tube does not require acoustic scatters in the measurement volume. This makes the sensor a candidate for use in the deep ocean, for example, where acoustic scatterers are weak.

Corresponding author address: James Moum, College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, 104 CEOAS Administration Bldg., Corvallis, OR 97331-5503. E-mail: moum@coas.oregonstate.edu

Abstract

A low-power (<10 mW), physically small (15.6 cm long × 3.2 cm diameter), lightweight (600 g Cu; alternatively, 200 g Al), robust, and simply calibrated pitot-static tube to measure mean speed and turbulence dissipation is described and evaluated. The measurement of speed is derived from differential pressure via Bernoulli’s principle. The differential pressure sensor employed here has relatively small, but significant, adverse sensitivities to static pressure, temperature, and acceleration, which are characterized in tests in the college’s laboratory. Results from field tests on moorings indicate acceptable agreement in pitot-static speed measurements with independent acoustic Doppler current profiler speeds, characterized as linear fits with slope = 1 (95% confidence), ±0.02 m s−1 bias, and root-mean-square error of residuals (observed minus fitted values) = 0.055 m s−1. Direct estimates of are derived from fits of velocity spectra to a theoretical turbulence inertial subrange. From near-bottom measurements, these estimates are interpreted as seafloor friction velocities, which yield drag coefficients consistent with expected values. Noise levels for , based on 40-min spectral fits, are <10–9 m2 s–3. In comparison to the airfoil (or shear) probe, the pitot-static tube provides the full spectrum of velocity, not just the dissipation range of the spectrum. In comparison to acoustic measurements of velocity, the pitot-static tube does not require acoustic scatters in the measurement volume. This makes the sensor a candidate for use in the deep ocean, for example, where acoustic scatterers are weak.

Corresponding author address: James Moum, College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, 104 CEOAS Administration Bldg., Corvallis, OR 97331-5503. E-mail: moum@coas.oregonstate.edu
Save