Observatory measurements of waves and current

Williams, Antony J.; Fredericks, Janet; Hobart, E.; Carson, Mark; Tierney, C.; Waterbury, A.

doi:10.1109/ccm.2003.1194325

Cited by 3 publications

(2 citation statements)

References 5 publications

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“…Vector velocity measurements of current at a fixed single point near the bottom can measure attenuated surface wave orbits and horizontal velocity measurements combined with pressure measurements can measure surface waves even when the sensor is so close to the bottom that the vertical component of wave velocity is nearly zero [1,2]. Analysis programs exist to project such near bottom measurements back to the surface for directional wave spectra, useful for surface vessel navigation [3].…”

Section: Introductionmentioning

confidence: 99%

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Cross-Spectral Phase Method for Distinguishing Waves from Turbulence in Single-Point Boundary Layer Flow Measurements

Williams

2006

Oceans 2006

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Cross-spectral analysis was applied to fixed singlepoint current measurements obtained using a Modular Acoustic Velocity Sensor (MAVS) from a shallow deployment in a tidal channel in Vineyard Sound south of Woods Hole, Massachusetts. Distinct phase signatures at different frequency bands were found in the cross power spectra between the vector components of velocity and between velocity and pressure. Velocity and pressure data had been obtained in burst samples both during periods when the flow was dominated by tidal currents and during periods when the flow was dominated by surface waves. Our analyses show that the phase signature in the cross power spectra can be used to effectively separate waves from turbulence over a broad range of scales that we sampled. In addition, the phase signature of the Cartesian velocity components has been derived in terms of the acoustic axes that comprise the raw measurements of velocity from MAVS. This association is used to distinguish between turbulence contributions and electronic noise at the intermediate to high frequency bands. By separating flow fluctuations due to turbulence from those due to waves a more accurate and representative observation of boundary layer dynamics can be obtained from a single-point vector flow measurement in the bottom boundary layer. Where these bands can be separated in frequency, Reynolds stress as well as structural eddies can be distinguished from waves.

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Section: Introductionmentioning

confidence: 99%

“…MAVS has been successfully deployed to measure the directional wave spectrum [1] and turbulence [8], and, as part of a large marine observatory, to monitor waves and current [2]. Spectral analysis has been routinely applied to process the measured velocity data and compute the associated power spectrum.…”

Section: Introductionmentioning

confidence: 99%