Design and Operation of Automated Ice-Tethered Profilers for Real-Time Seawater Observations in the Polar Oceans
WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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An automated, easily-deployed Ice-Tethered Profiler ITP has been developed for deployment on perennial sea ice in polar oceans to measure changes in upper ocean temperature and salinity in all seasons. The ITP system consists of three components a surface instrument that sits atop an ice floe, a weighted, plastic-jacketed wire-rope tether of arbitrary length up to 800 m suspended from the surface instrument, and an instrumented underwater unit that profiles up and down the wire tether. The profiling underwater unit is similar in shape and dimension to an ARGO float except that the floats variable-buoyancy system is replaced with a traction drive unit. Deployment of ITPs may be conducted either from ice caps or icebreakers, utilizing a self contained tripodwinch system that requires no power. Careful selection of an appropriate multiyear ice floe is needed to prolong the lifetime of the system up to 3 years depending on the profiling schedule. Shortly after deployment, each ITP begins profiling the water column at its programmed sampling interval. After each acquired temperature and salinity profile, the underwater unit PROCON transfers the data and engineering files using an inductive modem to the surface controller SURFCON. SURFCON-also accumulates battery voltages, buoy temperature, and locations from GPS at specified intervals in status files, and queues that information for transmission at the start of each new day. At frequent intervals, an Iridium satellite transceiver in the surface package calls and transmits queued status and CTD data files onto a WHOI logger computer, which are subsequently processed and displayed in near-real time at httpwww.whoi.eduitp. In 2004 and 2005, three ITP prototypes were deployed in the Arctic Ocean. Each system was programmed with accelerated sampling schedules of multiple one-way traverses per day between 10 and 750-760 m depth in order to quickly evaluate endurance and component fatigue.
- Physical and Dynamic Oceanography