Inter-comparison and evaluation of a single-point, acoustic Doppler current sensor mounted on a TABS II spar buoy

The Geochemical and Environmental Research Group of Texas A&M University conducted a thirty-day field experiment to compare and evaluate a single-point, Doppler current sensor for use on the Texas Automated Buoy System (TABS) spar buoys. Two spar buoys were deployed within 200 m of each other approximately 22 nmi. southwest of Galveston, Texas, in the Gulf of Mexico. One buoy was equipped with a Marsh-McBirney model 585 electromagnetic sensor and the other with an Aanderaa model DCS3500R single-point acoustic Doppler sensor. The sensors were located 2.5 m below the surface. A 300 kHz RD Instruments Workhorse Sentinel was moored in an upward-looking mode between the two buoys. Statistical comparison of the data from the three sensors shows that they performed well and measured vector components of similar magnitudes. Data from the Aanderaa DCS3500R tracked the bottom-mounted ADCP more closely than did the MMI585. The experiment indicates that both the MMI585 and the Aanderaa DCS3500R are suitable sensors for spar buoy deployment in a near surface dynamic environment. Of the three sensors, the MMI585 was most sensitive to fouling