Design and initial results of a bottom stationing ocean profiler

The benefits of untethered or drifting buoys and platforms have been well documented over the past decade. Study of physical, chemical and biological processes in the ocean can often be optimized using systems that profile and/or drift. However, it is at times useful to station a sensing system so that measurements are made only after or during specific conditions, e.g. a storm, an algae bloom, or underwater geologic event. A new autonomous platform has been developed that can provide the benefits of an untethered drifter while also providing the benefits of a stationary buoy. The Bottom Stationing Ocean Profiler (BSOP) is an instrument platform that stations itself on the sea floor and ascends and descends autonomously to gather water column profile data. While at the surface the BSOP transmits acquired data via the ORBCOMM satellite system to provide researchers with a near real-time observation of the study area. The BSOP unit is designed to remain at sea for extended periods up to several months. It uses an oil-based buoyancy control system to ascend and descend at speeds up to 0.5 meters per second. The unit is low cost, easy to deploy and recover using only light duty gear and can support a wide variety of sensors. Command scripts are downloadable while the unit is in communication with a satellite ground station; this permits reprogramming of mission parameters if needed. The unit has an integral global positioning system receiver to accurately identify surface position. This is important to the scientific mission but is also used for recovery operations. BSOP design and early results are presented.