A buoy-based observatory that uses acoustic communication to retrieve data from water column and seafloor instruments has been developed and deployed in 2362 m of water offshore Vancouver Island. The system uses high-rate (5000 bps) acoustic modems that are power-efficient (on order 1000 bits per joule) to telemeter data from an ocean bottom seismometer and a sensor monitoring a cold seep site near the Nootka fault. The buoy includes a Linux-based embedded controller, the modem base station and meteorological sensors. Data is off-loaded from the buoy using ftp, and remote login capability allows the acoustic communication schedule to be modified when instruments are added or removed from the network. The system has been operational for one year, typically transferring more than 500 Kbytes of data per day from two seafloor instruments.

A data delivery system was developed for the Northern Gulf of Mexico Littoral Initiative that allows access to data from bottom mounted instrumentation. The system consists of two parts, a trawl resistant sub-surface component and a separate surface buoy. The sub-surface component employs a Trawl Resistant Bottom Mount containing an Acoustic Doppler Current Profiler equipped with a Micro-Modem (muModem.) The surface expression consists of a buoy equipped with an acoustic receiver (Utility Acoustic Modem, or UAM), a system controller and an Argos transmitter (PTT.) The muModem acoustically telemeters data from the ADCP on an hourly schedule to the UAM on the nearby (similar to500m) surface buoy. Data from the acoustic receiver is forwarded via the controller to the Argos transmitter. To maximize data throughput of the Argos link the controller loads a circular buffer containing the most recent eight hours of data into the PTT each hour. This data is continuously transmitted until the next hourly update. The controller also performs resynchronization of the acoustic system in the event acoustic communications are lost. One particular benefit of this system is the ability to perform measurements in high traffic locations while maintaining the surface buoy at a safe distance from navigation aids. One system is currently deployed in a high traffic area, in Horn Island Pass, due south of Pascagoula, MS. This paper describes the overall system and presents data from initial deployments.