Functional Description
Gliders typically make measurements such as temperature, conductivity (to calculate salinity), currents, chlorophyll fluorescence, optical backscatter, bottom depth, and (occasionally) acoustic backscatter. They navigate with the help of periodic surface GPS fixes, pressure sensors, tilt sensors, and magnetic compasses. Vehicle pitch is controllable by movable internal ballast (usually battery packs), and steering is accomplished either with a rudder (as in Slocum) or by moving internal ballast to control roll (as in SeaExplorer, Spray and Seaglider). Buoyancy is adjusted either by using a piston to flood/evacuate a compartment with seawater (Slocum) or by moving oil in/out of an external bladder (SeaExplorer, Seaglider, Spray, and Slocum Thermal). Commands and data are relayed between gliders and shore by satellite.
Gliders vary in the pressure they are able to withstand. The Slocum model is rated for 200 meter or 1000 meter depths. Spray can operate to 1500 meters, Seaglider to 1000 meters, SeaExplorer to 700, and Slocum Thermal to 1200. In August 2010, a Deep Glider variant of the Seaglider achieved a repeated 6000-meter operating depth.
Read more about this topic: Underwater Glider
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