FY 1997

Using echo intensity to correct moored ADCP data for fish-bias errors at 0°, 170°W

Plimpton, P.E., H.P. Freitag, M.J. McPhaden, and R.H. Weisberg

NOAA Tech. Memo. ERL PMEL-111, NTIS: PB97-201537, 163 pp (1997)

Acoustic Doppler current profilers (ADCPs) have been deployed on both subsurface and taut-line surface moorings to measure upper ocean currents in the equatorial Pacific. The moored ADCP velocity measurements are included as part of the data base from the Tropical Atmosphere Ocean (TAO) array, which provides measurements of upper ocean and atmospheric variability in support of climate studies. Surface moorings tend to attract pelagic fish, which sometimes school around the mooring and bias the ADCP velocity measurements. Therefore the fish-bias velocity errors, which have been as large as 80 cm s^–1 in the surface moored ADCP data, must be eliminated as much as possible from the ADCP velocity time series. In situ mechanical current meter (MCM) data have been used to correct the fish-bias velocity errors in the surface moored ADCP data at 0