Laboratory and field measurements with a broad band ADCP

Appell, G.; Williams, Robert G.

doi:10.1109/oceans.1993.326126

Cited by 4 publications

(1 citation statement)

References 3 publications

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“…Appell and Williams (1993) suggest that the time constants associated with the ADCP's internal compass and pitch/roll sensors are inappropriate for accurate operation under dynamic conditions. While the effect of the pitch-and-roll correction transfers some of the variance of the horizontal velocity into the vertical, a comparison of the magnitudes of total velocities (Fig.…”

Section: Comparisonsmentioning

confidence: 99%

Comparison of Buoy-Mounted and Bottom-Moored ADCP Performance at Gray’s Reef

Seim

Edwards

2007

Journal of Atmospheric and Oceanic Technology

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Simultaneous ADCP profile measurements are compared over a 2-month period in late 2003. One set of measurements comes from a National Data Buoy Center (NDBC) buoy-mounted ADCP, the other from a bottom-mounted, upward-looking ADCP moored roughly 500 m from the buoy. The study was undertaken to evaluate the proficiency of an experimental configuration by NDBC; unfortunately, the ADCP was not optimally configured. The higher temporally and vertically resolved bottom-mounted ADCP data are interpolated in time and depth to match the buoy-mounted ADCP measurements. It is found that the two ADCP measurements are significantly different. The buoy-mounted measurements are affected by highfrequency (Ͻ10 h period) noise that is vertically coherent throughout the profiles. This noise results in autospectra that are essentially white, unlike the classic red spectra formed from the bottom-mounted ADCP observations. The spectra imply a practical noise floor of 0.045 m s Ϫ1 for the buoy-mounted system. Contamination by surface waves is the likely cause of this problem. At tidal frequencies the buoy-mounted system underestimates major axis tidal current magnitude by 10%-40%; interference from the buoy chain and/or fish or plankton are considered the most likely cause of the bias. The subtidal velocity field (periods greater than 40 h) is only partially captured; the correlation coefficient for the east-west current is 0.49 and for the north-south current is 0.64.

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Section: Comparisonsmentioning

confidence: 99%