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ITP Recovery: Getting it back out of the ice

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    Typically after a year in the field, an ITP in summer will be found sitting in a melt pond.  Here, cruise personnel are starting to stage for a recovery operation.  The orange float and flag in the background were installed during a previous reconnaissance helicopter flight in order to facilitate relocation. 
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    Helicopters are frequently used to transport the deployment/recovery gear to the ITP site.  Here, the water heating unit is being delivered.
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    Kris Newhall beginning to assemble the water heating unit.
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    More bits and pieces.
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    Key to the recovery operation is use of a hot water melt ring.  The ring (consisting of a loop of metal tubing attached to a frame) fits over the ITP surface buoy and is held in place by the mooring technicians.  Hot water is pumped through the tubing, causing the ice adjacent to the ring to melt. 
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    Close up of the melt ring at work. 
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    Rick, Kris and Jim posing with the melt ring apparatus.
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    Closeup of the melt ring at work.
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    Checking the settings on the water heater and pump.
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    Rigged for recovery.  The melt ring has freed the ITP from its supporting ice floe and been removed.  The deployment/recovery tripod has been set up over the ITP and rigged with a power block.  By now the icebreaker has arrived on scene.
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    Beginning to lift the ITP system out of the water, together with the remaining cylindrical chunk of ice surrounding the tether left by the melt ring.
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    Chipping away at the cylindrical chunk of ice left by the melt ring. 
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    More power!  Using a chain saw to cut away the remaining chunk of ice surrounding the tether.
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    The top 5-m segment of the ITP tether is now clear of the water.  Note the grounding plate for the sea water return of the inductive modem telemetry link just at the junction between the reinforced top wire segment and normal wire-rope tether below.  (Follow the white line that is wrapped around the plate.) 
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    Surface buoy and top 5-m tether segment recovered.  Starting to rig the wire rope tether on the power block.
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    Using the power block to haul up the wire rope tether. 
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    The 790 m of wire rope is simply flaked on the ice floe for later bundling and transport to the icebreaker and disposal.  Due to corrosion, re-use of recovered tethers isn't deemed prudent. 
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    Here the ITP profiling vehicle surfaces, lifted along with the wire by the bottom stop attached to the wire just above the end weight. 
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    The ITP profiling vehicle ready to detach from the tether.  The shackle visible above the wire guide was attached during recovery to control the wire position.
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    Closeup of the CTD on the ITP after 2 years in the Arctic Ocean. 
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    Here the end weight of the ITP tether has been lifted clear of the water.  Kris is removing the bottom stop on the wire -- put there to prevent the ITP profiling vehicle from impacting the wire termination flange (orange object just above the weight) and possibly getting stuck.  The recovery operation is completed by breaking down the tripod and transporting all the components back to the icebreaker.

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