Development of a Practical Coherent Acoustic Doppler Current Profiler

Cabrera, R.; Deines, K.L.; Brumley, B.; Terray, Eugene A.

doi:10.1109/oceans.1987.1160903

Cited by 32 publications

(39 citation statements)

References 6 publications

(5 reference statements)

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“…Weak scatters, indicated by low beam correlations (Cabrera et al, 1987;Lhermitte and Lemmin 1994), can reduce the ADV return signal strength to the level of background noise (Elgar et al, 2005) and lead to inaccurate velocity estimates (Zedel et al, 1996). The ADV correlation signal (ranging from 0 to 1.0) is therefore used to diagnose data quality (Zedel et al, 1996;SonTek, 2004).…”

Section: Low Particles Content and Adv Beam Correlation Thresholdmentioning

confidence: 99%

Assessing benthic oxygen fluxes in oligotrophic deep sea sediments (HAUSGARTEN observatory)

Donis

Mcginnis

Holtappels

et al. 2016

Deep Sea Research Part I: Oceanographic Research Papers

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a b s t r a c tBenthic oxygen fluxes, an established proxy for total organic carbon mineralization, were investigated in oligotrophic deep sea sediments. We used three different in situ technologies to estimate the benthic oxygen fluxes at an Arctic deep sea site (2500 m depth, HAUSGARTEN observatory) with limiting conditions of low oxygen gradients and fluxes, low turbulence and low particle content in the benthic boundary layer. The resolved eddy covariance turbulent oxygen flux ( À 0. ). The agreement between these different techniques revealed that microbial-mediated oxygen consumption was dominant at this site. The average benthic flux equals a carbon mineralization rate of 4.3 g C m À 2 yr À 1 , which exceeds the annual sedimentation of particulate organic matter measured by sediment traps. The present study represents a detailed comparison of different in situ technologies for benthic flux measurements at different spatial scales in oligotrophic deep sea sediments. The use of eddy covariance, so far rarely used for deep sea investigations, is presented in detail.

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Section: Low Particles Content and Adv Beam Correlation Thresholdmentioning

confidence: 99%

Assessing benthic oxygen fluxes in oligotrophic deep sea sediments (HAUSGARTEN observatory)

Donis

Mcginnis

Holtappels

et al. 2016

Deep Sea Research Part I: Oceanographic Research Papers

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“…where Δθ is the bistatic angle, the angle bisector between the transmitter and receiver (15° for Vectrino ADV), and U c is the cross-beam or transverse velocity component (<V> The uncertainty due to residence time can be calculated from the following equation (Cabrera et al 1987):…”

Section: Recommendations For Future Workmentioning

confidence: 99%

“…Voulgaris and Trowbridge (1998) B t is due to turbulent scales on the order of the sampling volume or smaller, which cause the particles to have a distribution of velocities within the sampling volume. This quantity can be estimated to be (Cabrera et al 1987):…”

Section: Appendix A: Sources Of Error and Uncertainty Analysismentioning

confidence: 99%

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Effect of background turbulence on an axisymmetric turbulent jet

2013

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The effect of background turbulence on a turbulent jet was investigated experimentally. The primary objective of this work was to study the effect of different levels of the background turbulence on the dynamics and mixing of an axisymmetric turbulent jet at different Reynolds numbers. The secondary objective, which arose during the experiments, was to improve the acoustic Doppler velocimetry measurements which were found to be inaccurate when measuring turbulence statistics.In addition to acoustic Doppler velocimetry (ADV), flying hot-film anemometry was employed in this study. To move the hot-film probe at constant speeds, a high precision traversing mechanism was designed and built. A data acquisition system and LabVIEW programs were also developed to acquire data and control the traversing mechanism. The experiments started by benchmarking the two measurement techniques in an axisymmetric turbulent jet. Comparing the results with those of the other studies validated the use of flying hot-film anemometry to estimate the mean and the root-mean square (RMS) velocities.The experiments also validated the use of ADV for measurement of the mean velocities (measured in three Cartesian directions) and the RMS velocity (measured in the z-direction only). RMS velocities measured by the ADV along the x-and y-direction of the probe were overestimated.Attempts to improve the turbulence statistics measured by the ADV using the post-processing and noise-reduction methods presented in the literature were undertaken. However, the RMS velocities remained higher than the accepted values. In addition, a noise-reduction method was presented in this study which reduced the RMS velocities down to the accepted values. It was also attempted to relate Doppler noise to current velocity, and thus improve the results by iv subtracting the Doppler noise from the measured RMS velocities in the jet. However, no relationship was found between the Doppler noise and the mean velocity.The effect of different levels of background turbulence on the dynamics and mixing of an axisymmetric turbulent jet at different Reynolds numbers was then investigated. The background turbulence was generated by a random jet array. To confirm that the turbulence is approximately homogeneous and isotropic and has a low mean flow, the background flow was first characterized. Velocity measurements in an axisymmetric jet issuing into two different levels of background turbulence were then conducted. Three different jet Reynolds

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“…2에서 (Cabrera et al, 1987;Brumley et al, 1987;Hackett et al, 1987) (Fig. 9(a) 전체적으로 보면, 바닥으로부터 0.1m 이상에서 측정된 유속은 일부 수심층에서 나타나는 이상치를 제외하면 P-vK 대수분포와 비교적 일치하고 있다.…”

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Development of an Acoustic Velocity Profiler by Using Pulse Repetition Frequency Technique

Lee¹,

Kim²,

Lee³

et al. 2011

Journal of Korea Water Resources Association

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An acoustic velocity profiler is developed, which is able to be used for open-channel flow measurement. It measures flow velocity based Doppler effect on acoustic signals, which is estimated by using pulse repetition frequency technique. Laboratory and field tests were made to verify velocity measuring performance of the developed device. It is confirmed that the acoustic velocity profiler can normally measure vertical velocity profile in the range above 0.1 m from the bottom and has equivalent performance to commercial acoustic velocity measuring devices.

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Development of a Practical Coherent Acoustic Doppler Current Profiler

Cited by 32 publications

References 6 publications

Assessing benthic oxygen fluxes in oligotrophic deep sea sediments (HAUSGARTEN observatory)

Assessing benthic oxygen fluxes in oligotrophic deep sea sediments (HAUSGARTEN observatory)

Effect of background turbulence on an axisymmetric turbulent jet

Development of an Acoustic Velocity Profiler by Using Pulse Repetition Frequency Technique

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