Presenter: Ryunosuke Akiba (National Oceanic and Atmospheric Administration, Center for Operational Oceanographic Products and Services)

Description:
The National Oceanic and Atmospheric Administration (NOAA) Center for Operational Oceanographic Products and Services (CO-OPS) manages the National Current Observation Program (NCOP), which provides observations and predictions of currents to support maritime commerce and environmental needs. There are emerging needs for shallow water current measurements at sites where significant bottom morphology limits the use of bottom mount options that position an ADCP on the seafloor. There is also a desire to deploy and recover a system including its anchor from a small vessel. Driven by these evolving measurement requirements, CO-OPS designed, developed, and tested a new mooring configuration: the subsurface ellipsoid ADCP buoy (SEABY). SEABY consists of an ellipsoid buoy with an upward looking ADCP suspended by a short wire cable to an acoustic release and float pop-up system on the anchor. A CTD may be clamped to the cable. Initial modeling was conducted in 2020 to predict buoy tilt and drawdown under current forcing and determine the required anchor weight. In May 2021, a three-week field test was conducted in the south Chesapeake Bay to evaluate the performance of SEABY with a reference system, an ADCP in a trawl resistant bottom mount (TRBM) with both systems equipped with a CTD. The systems were successfully deployed and recovered from a small vessel with a davit crane and manual winch. The field test captured a robust data set with several storm events. Data from SEABY showed good performance throughout the field test, staying well within the 15 degree tilt threshold with small vertical motion. The current profiles obtained from the ADCP on SEABY compared well to those observed by the TRBM reference system. Results from this field test suggest that SEABY meets performance requirements for NCOP. The first operational deployment of SEABY is underway as part of the NCOP Delaware Bay & River Tidal Current Survey, from which SEABY initial results will be presented.