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Quality Controlling Surf Zone Acoustic Doppler Velocimeter Observations to Estimate the Turbulent Dissipation Rate

Quality Controlling Surf Zone Acoustic Doppler Velocimeter Observations to Estimate the Turbulent... High-quality measurements of the turbulent dissipation rate ϵ are required to diagnose field surf-zone turbulence budgets. Quality control (QC) methods are presented for estimating surf zone ϵ with acoustic Doppler velocimeter (ADV) data. Bad ADV velocity data points are diagnosed with both the ADV signal strength (SS) and correlation (CORR). The fraction of bad SS data points ( δ SS ) depends inversely upon the wave-amplitude-normalized transducer distance below the mean sea surface. The fraction of bad CORR data points δ CORR can be elevated when δ SS is low. The δ CORR depends inversely upon the wave-amplitude-normalized sensing volume distance below the mean sea surface, and also increases with increased wave breaking, consistent with turbulence- and bubble-induced Doppler noise. Velocity spectra derived from both “patched” and “interpolated” time series are used to estimate ϵ . Two QC tests, based upon the properties of a turbulent inertial subrange, are used to reject bad ϵ data runs. The first test checks that the vertical velocity spectrum’s power-law exponent is near . The second test checks that a ratio R of horizontal and vertical velocity spectra is near 1. Over all δ CORR , 70% of the patched and interpolated data runs pass these tests. However, for larger δ CORR > 0.1 (locations higher in the water column), 50% more patched than interpolated data runs pass the QC tests. Previous QC methods designed for wave studies are not appropriate for ϵ QC. The results suggest that ϵ can be consistently estimated over the lower 60% of the water column and >0.1 m above the bed within a saturated surf zone. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Atmospheric and Oceanic Technology American Meteorological Society

Quality Controlling Surf Zone Acoustic Doppler Velocimeter Observations to Estimate the Turbulent Dissipation Rate

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References (49)

Publisher
American Meteorological Society
Copyright
Copyright © 2010 American Meteorological Society
ISSN
1520-0426
DOI
10.1175/2010JTECHO783.1
Publisher site
See Article on Publisher Site

Abstract

High-quality measurements of the turbulent dissipation rate ϵ are required to diagnose field surf-zone turbulence budgets. Quality control (QC) methods are presented for estimating surf zone ϵ with acoustic Doppler velocimeter (ADV) data. Bad ADV velocity data points are diagnosed with both the ADV signal strength (SS) and correlation (CORR). The fraction of bad SS data points ( δ SS ) depends inversely upon the wave-amplitude-normalized transducer distance below the mean sea surface. The fraction of bad CORR data points δ CORR can be elevated when δ SS is low. The δ CORR depends inversely upon the wave-amplitude-normalized sensing volume distance below the mean sea surface, and also increases with increased wave breaking, consistent with turbulence- and bubble-induced Doppler noise. Velocity spectra derived from both “patched” and “interpolated” time series are used to estimate ϵ . Two QC tests, based upon the properties of a turbulent inertial subrange, are used to reject bad ϵ data runs. The first test checks that the vertical velocity spectrum’s power-law exponent is near . The second test checks that a ratio R of horizontal and vertical velocity spectra is near 1. Over all δ CORR , 70% of the patched and interpolated data runs pass these tests. However, for larger δ CORR > 0.1 (locations higher in the water column), 50% more patched than interpolated data runs pass the QC tests. Previous QC methods designed for wave studies are not appropriate for ϵ QC. The results suggest that ϵ can be consistently estimated over the lower 60% of the water column and >0.1 m above the bed within a saturated surf zone.

Journal

Journal of Atmospheric and Oceanic TechnologyAmerican Meteorological Society

Published: Mar 16, 2010

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