The LEO-15 Long-term Ecosystem Observatory: design and installation

The Long-term Ecosystem Observatory (LEO-15) provides scientists with power and telemetry for instruments deployed off the central coast of New Jersey for the Institute of Marine and Coastal Sciences at Rutgers University. The ability to read and control a deployed instrument in real-time allows a researcher to modify experiments or to respond to events of interest as they occur. The observatory provides two nodes deployed in about 15 m depth with diver accessible connectors for guest instruments. The nodes are connected to a shore station through a 9-km, buried, electro-optic cable. The cable power wires and optical fibers are connected between a node base and a node instrument frame via diver mateable connections. This permits the instrument frame to be easily removed for repair or periodic maintenance. The node bases are designed and anchored to withstand anticipated storms that occur in this coastal area. Various means have been employed to limit corrosion and bio-fouling. Each node provides a vertical profiler for making a variety of oceanographic measurements from a buoyant frame attached to a winch deployed cable. Additional guest instruments can connect to one of eight standard ports, or to one of several specialized interfaces. The telemetry system provides unbuffered serial data connections at various speeds between a user's instrument(s) and shore equipment. One video channel is also available from each node. Power and data wires for each instrument are switched under the direction of a computer in the shore station. This computer monitors the instruments for various faults, can disconnect faulted instruments, and will send notification to operators and scientists when problems occur. Several means are provided for a user to request the central computer to turn an instrument on or off, or to report an instrument's status.