Gulf of Maine Ocean Observing System (GoMOOS): current measurement approaches in a prototype integrated ocean observing system

The Gulf of Maine Ocean Observing System (GoMOOS) was established in the summer of 2001 as a real-time pilot integrated observing system that includes a comprehensive array of moored physical and optical sensors, shore based long-range HF radar systems, circulation and wave modeling, satellite observations, and Web delivery of data and data products. The system is automated and operational. The GoMOOS moored buoy array presently consists of 10 solar-powered, automated buoy systems that telemeter data hourly via cellular/iridium phone and GOES satellite transmitters. The operational protocol is that 20 buoys and instrument suites are rotated through the 10 locations on a six-month cycle. Current measurements are made at 2 m depth using Aanderaa RCM9 in situ Doppler current meters, and subsurface currents are made with downward-looking RIM Doppler profilers. In addition, near-surface currents in the Gulf of Maine are being measured using a 5-megahertz long-range HF radar system manufactured by CODAR Ocean Systems Inc. Comparisons of the three current measurement systems are presented, and the operational logistics of current monitoring using these technologies in the challenging Gulf of Maine environment is discussed.