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The floats
are autonomous : they are programmed before launch for their mission, which
they pursue automatically and repeatedly. After
launch, the float sinks to a predetermined depth, called the parking depth,
where it drifts with the ocean current for
about 10 days.
During that descent it may or may not collect temperature and salinity
data. At a preset time it dives to
a maximum depth (about 1500 or 2000 m), and then ascends to the surface while
measuring temperature and salinity as a function of pressure (equivalent to
depth). At the surface, the float
transmits the stored data, via satellite (the ARGOS system) to a land station,
whence it is forwarded for processing to the Coriolis
data center. After 4 to 8 hours at
the surface, the floats dives again to start a new cycle. The cycle
length is 10 days, and it is anticipated that each float should perform about
100 cycles, i.e. a life-time of 1000 days (almost 3 years). Floats used in the project are manufactured by Martec and Webb Research Corporation Gyroscope uses two types of floats : the PROVOR and the APEX.
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