Improved quality of National Data Buoy Center (NDBC) Acoustic Doppler Current Profiler (ADCP) measurements

Abstract

Abstract. In 2006, NOAA's National Data Buoy Center (NDBC) began an effort to add ocean sensors (directional waves, surface currents, current profiles, and ocean temperature and salinity) to its fleet of weather buoys. In this paper, we report on the improvements in the quality of ocean currents collected from the Acoustic Doppler Current Profiler (ADCP).Initially, the ADCP was deployed in a cage that was suspended below the bridle of the buoy. It was an effort to remove the motion of the surface buoy from the current record. Measurements were made at intervals of 30 to 45 seconds over an hour's time and averaged. The cage required a lengthy cable to carry the current information to the payload within the buoy. The movement (twisting, swinging, and upand-down motion) of the cage put stress on the cable, which was also exposed to long line gear and other fishing tackle, and the failure rate was high. Several iterations of cable were attempted, but the failure rate of the real-time currents remained high. Because of the averaging method, the currents were under-sampled and represented a considerable period of the changing tidal current.The ADCP was moved inside the bridle just below the buoy to shorten the exposure of the cable to the environment. An additional result of this method is to sample closer to the ocean surface. The algorithms test for echo amplitude, percent good beams, error velocity, and horizontal velocities. Additionally, a test to determine the presence of the surface or bottom allows these bins to be included in the data stream as the tide changes. These algorithms have been implemented into NDBC's realtime processing stream

Properties and Mechanisms of Seawater Exchange in Marian Cove, King George Island, West Antarctic Peninsula

“…We applied the value used by Cowley et al. (2008) and Crout and Riley (2010) as the threshold for quality control (QC) of the obtained ADCP data. For QC, the ratio of error data was less than 1% near the bottom region.…”

“…The seabed depth at the mooring position was 109 m and SBE-37SM observed time-series variations in seawater temperature and salinity at a depth of 92 m. The current velocity of each layer from the ADCP, located at a depth of 79 m from the surface, was observed at 4 m intervals. We applied the value used by Cowley et al (2008) and Crout and Riley (2010) as the threshold for quality control (QC) of the obtained ADCP data. For QC, the ratio of error data was less than 1% near the bottom region.…”