Marine Optical Buoy - Function

Function

Light from the Sun crosses space, enters and travels through the Earth's atmosphere, then enters the Earth's oceans. In the atmosphere and in the oceans, this light reflects from, refracts around, and absorbs into molecules and other objects. Some of this light leaves the water to again travel through the atmosphere and out into space, carrying the color of whatever it struck.

At the sea surface, light coming down through the atmosphere enters the collector at the top of MOBY's antenna column. Each of MOBY's three submerged standoff arms has a pair of light collectors: one on top of the arm to collect downward moving light; and one underneath the arm to collect upward moving reflected light. Light entering the collectors travels through optical fibers and the optical multiplexer to the CCD detectors and spectrographs. The spectrographs record the light signals, and a computer stores the measurement data. The communications system aboard MOBY daily transmits much of the light measurement data to operators on shore.

There is one Marine Optical Buoy operating in the water, and another in maintenance on shore. Every 3 to 4 months, a team exchanges the two buoys. The team calibrates each MOBY while it is in maintenance, both before deploying the buoy and after recovering it. Additionally, a team visits the MOBY in the water monthly, to clean algae, barnacles, and other organisms off the light collectors; and to generate independent comparison data using portable reference light sources. Each MOBY has internal reference light sources, as well, for continuous but not independent comparison. The MOBY calibration data traces to National Institute of Standards and Technology (NIST) radiometric standards directly, as opposed to using intermediate standards.