In-situ comparisons of moored acoustic Doppler profilers with conventional VACM and VMCM current meters

Irish, James D.; Plueddemann, A. J.; Lentz, Steven J.

doi:10.1109/ccm.1995.516151

Cited by 5 publications

(12 citation statements)

References 6 publications

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“…The vector measuring current meter (VMCM; Weller and Davis 1980) and the acoustic Doppler current profiler (ADCP; Pinkel 1980;Gordon 1996) are two instruments that have been extensively used by oceanographers during the past decade. In particular, these instruments have proven to be reliable instruments for obtaining quality ocean current data from moorings for scientific studies (Halpern et al 1981;Beardsley 1987;Irish et al 1995;Dickey et al 1998a).…”

Section: Introductionmentioning

confidence: 99%

An Intercomparison of Current Measurements Using a Vector Measuring Current Meter, an Acoustic Doppler Current Profiler, and a Recently Developed Acoustic Current Meter

Gilboy

Dickey

Sigurdson

et al. 2000

J. Atmos. Oceanic Technol.

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Horizontal current measurements were obtained simultaneously with a vector measuring current meter (VMCM), an acoustic Doppler current profiler (ADCP), and the recently developed Falmouth Scientific, Inc., acoustic current meter (ACM) during a 110-day period from the Bermuda Testbed Mooring (BTM). The BTM site is located approximately 80 km southeast of Bermuda at 31Њ44ЈN, 64Њ10ЈW in waters of about 4550-m depth. The ACM is a relatively small, lightweight instrument, which can be deployed relatively close to the ocean surface or bottom as well as at intermediate depths. Prior to the present study, in situ data and knowledge concerning the ACM performance were quite limited. Zonal, meridional, and horizontal current speed data were obtained and time series were computed for each instrument. Several analyses were done to evaluate and intercompare instrument performance. The ACM results compared favorably with those of the VMCM and ADCP for 36-h filtered data. The ADCP typically recorded the largest horizontal current speed and the ACM typically recorded the smallest values. The strongest correlation was seen between the VMCM and ADCP data; however, the lowest correlation for all intercomparisons (by component and speed) was r ϭ 0.95 with most values of r ϭ 0.98 or greater. Directional error/bias is a primary factor in limiting current component measurement accuracy. In particular, the ACM direction was up to 20Њ-30Њ offset from those of the other two instruments. After rotating or ''correcting'' the ACM components with respect to the VMCM direction, ACM mean current component differences with respect to the other instruments' values were less than about 2 cm s Ϫ1. Based upon the spectral analysis, both the ACM and VMCM have better performance characteristics than the ADCP in the higher-frequency portion of the spectral domain. The authors' analysis indicates that the three different systems provide generally similar results in terms of coherence and phase with significant departures occurring only with respect to the ADCP at frequencies greater than 0.01 cph. The present study indicates that the ACM provides another viable means of obtaining accurate current measurements.

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Section: Introductionmentioning

confidence: 99%

An Intercomparison of Current Measurements Using a Vector Measuring Current Meter, an Acoustic Doppler Current Profiler, and a Recently Developed Acoustic Current Meter

Gilboy

Dickey

Sigurdson

et al. 2000

J. Atmos. Oceanic Technol.

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“…In this study velocities near 72-m depth measured by a VMCM, an ACM, and an acoustic Doppler current profiler (ADCP) were compared and found to be in agreement within statistical error except for a 20°-30°d irection discrepancy attributed to the ACM. The reader is also referred to the review of modern current measuring techniques given in Dickey et al (1998) and to a comparison of the ADCP with a VACM and VMCM reported by Irish et al (1995).…”

Section: Introductionmentioning

confidence: 99%

Performance of a New Generation of Acoustic Current Meters

Hogg

Frye

2007

Journal of Physical Oceanography

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As part of a program aimed at developing a long-duration, subsurface mooring, known as Ultramoor, several modern acoustic current meters were tested. The instruments with which the authors have the most experience are the Aanderaa RCM11 and the Nortek Aquadopp, which measure currents using the Doppler shift of backscattered acoustic signals, and the Falmouth Scientific ACM, which measures changes in travel time of acoustic signals between pairs of transducers. Some results from the Doppler-based Sontek Argonaut and the travel-time-based Nobska MAVS are also reported. This paper concentrates on the fidelity of the speed measurement but also presents some results related to the accuracy of the direction measurement. Two procedures were used to compare the instruments. In one, different instruments were placed close to one another on three different deep-ocean moorings. These tests showed that the RCM11 measures consistently lower speeds than either a vector averaging current meter or a vector measuring current meter, both more traditional instruments with mechanical velocity sensors. The Aquadopp in use at the time, but since updated to address accuracy problems in low scattering environments, was biased high. A second means of testing involved comparing the appropriate velocity component of each instrument with the rate of change of pressure when they were lowered from a ship. Results from this procedure revealed no depth dependence or measurable bias in the RCM11 data, but did show biases in both the Aquadopp and Argonaut Doppler-based instruments that resulted from low signal-to-noise ratios in the clear, low scattering conditions beneath the thermocline. Improvements in the design of the latest Aquadopp have reduced this bias to a level that is not significant.

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“…Acoustic Doppler velocimeters (ADV) Ball and Schaffranek [8] Wetland 0.15 to 0.66 USGS (2004) [31] Wetland 0.26 to 2.43 Schaffranek and Riscassi [25] Wetland 0.53 to 0.62 Lee and Carter [11] Wetland 0.2 to 1.2 Lightbody and Nepf [26] Wetland/estuary 1.2 to 3.7 Chanson et al [27] Estuary 0 to 28 Nepf [21] Hydraulic flume 2.2 to 15 Nepf [1] Hydraulic flume N/A Rehmel (2007) [32] Streamflow gauging stations 13 to 60 Acoustic Doppler current meters (ADCP) Genereux and Slater [12] Canal 9 to 40 Irish et al (1995) [33] Tidal bay 0 to 22 Vermeyen [13] Lake 0.1 to 5 Laser Doppler velocimeter (LDV)…”

Section: Devicementioning

confidence: 99%

Low flow regime measurements with an automatic pulse tracer velocimeter (APTV) in heterogeneous aquatic environments

Chang

Crawford

Mohiuddin

et al. 2015

Flow Measurement and Instrumentation

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In-situ comparisons of moored acoustic Doppler profilers with conventional VACM and VMCM current meters

Cited by 5 publications

References 6 publications

An Intercomparison of Current Measurements Using a Vector Measuring Current Meter, an Acoustic Doppler Current Profiler, and a Recently Developed Acoustic Current Meter

An Intercomparison of Current Measurements Using a Vector Measuring Current Meter, an Acoustic Doppler Current Profiler, and a Recently Developed Acoustic Current Meter

Performance of a New Generation of Acoustic Current Meters

Low flow regime measurements with an automatic pulse tracer velocimeter (APTV) in heterogeneous aquatic environments

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