Dispatch 7: The Ice Tethered Profiler (ITP)     Print

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Fred Marin

September 18, 2019

Location: 78° 52’ N 137° 35’ W

Sea Conditions: 3718m water depth; patchwork of ice floes, calm seas.

Today was a particularly exciting day as we broke from our routine of CTD-rosette casts, plankton net tows, and XCTD launches as we continue to connect the dots between sampling stations across the beautiful Beaufort Sea.  Don’t get me wrong, we still sampled the water column and collected jars of plankton, but we also deployed our first Ice Tethered Profiler for this year’s expedition!  This deployment was in open water, which is unusual because ideally ITPs are deployed on the ice, so we had to work over the side of the ship utilizing the vessels forward A-frame and crane.

What exactly is an ITP? Glad you asked! ITP stands for “Ice Tethered Profiler”.  It consists of a surface package which is attached to an 800m jacketed steel cable that has anchors which hang freely in the water column to keep the cable taut.  On this cable is a profiler which patrols up and down the cable collecting data on pressure, temperature, and conductivity.  Sometimes, the profiler is outfitted with extra instruments such as optical instruments measuring Color Dissolved Organic Material (CDOM), or an Acoustic Current Meter (ACM) to measure the waters speed and direction.  Additional instruments (i.e., SAMI-CO2) are sometimes attached in fixed positions to the top of the cable mooring.  Through an inductive loop, the profiler and auxiliary instruments send data back to the surface package which calls home via Iridium satellite twice daily to send data and its GPS location to a special server storing the data from every ITP ever deployed.  The surface package is placed in a yellow foam buoy which keeps the unit upright and from falling through the ice, or afloat in open water so that it doesn’t drop to the bottom of the sea.  A typical ITP profiler will make a trip up the wire and then down the wire each day, and it can do this every day for 12-24 months, or more!

When it comes to instruments like the ITP, testing reaches a new level of importance because once it is in the ice or in today’s case, open water, that is it.  You don’t get to fix a problem, or correct a mistake later down the road.  The instruments undergo rigorous testing back at the Woods Hole Oceanographic Institute (WHOI) where they are built, again onboard the ship, and twice when they are deployed.  In today’s open water deployment, the instruments communications were tested once the whole unit was in the water where it will remain for the months or years to come.

Thank you for joining us again today for a window into life aboard the CCGS Louis S. St-Laurent as we continue our Arctic expedition.  Check in again with us tomorrow as we attempt to locate a solid ice floe and set up our first ice station!