Dispatch 8: The First Ice Station     Print

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Fred Marin

September 19, 2019

Location: 80° 55’ N 135° 32’ W

Sea Conditions: 3673m water depth; virtually complete ice coverage.

On this sunny nearly windless day, we had a BIG day, as an ice floe suitable for establishing an ice station was located early in the morning.  We discovered the floe earlier than expected which was great! Because this meant that instead of deploying a single Ice Tethered Profiler (ITP), the prototype Tethered Ocean Profiler (TOP) would also be deployed along with a Seasonal Ice Mass Balance buoy (SIMB).  Opportunities like this do not always present themselves, so when they do, we capitalize on them!

Safety first! So, before anybody wandered out onto the ice, the bear guard established himself and made sure there were no Polar bears around to share our ice floe with.  The ice floe was ~1m thick and we were fortunate to be able to use the ship’s gang way and cranes to walk out onto the ice, and to lower our heavy equipment. 

For the ITP deployment, we drilled a 11” hole through the meter of ice.  A special winch and tripod with an overhead block was then set up around the ice hole.  Anchors were assembled, and the ITP profiler was attached to its mooring cable.  A test of the profiler’s communications was conducted prior to spooling the 800m of cable into the water column below.  At the end of the spool, the load was transferred from the block to a “yale grip”.  Once the Submersible Autonomous Moored Instrument - CO2 (SAMI-CO2), surface package, buoy, and grounding plate were attached to the other end of the cable.  The “yale grip” was then slipped until the load was transferred to the ITPs bail.  The bail was then carefully lowered until the buoy rested flush against the ice.  The ITP was now tethered in the ice as it was designed to be.  A quick test of the profiler’s communications ensured the system was working properly before moving on to the next deployment of the day.

TOPs deployment into the ice was very similar to the procedure followed for the ITP, but with a few differences.  The first being that the TOP climbs a thinner jacketed steel cable that is only 200m in length (it is much lighter to transport).  Secondly, there is no reinforced hose for the first 4m out of the buoy like with an ITP, so there is no room for a grounding plate on the wire since the TOPs profiler can climb right up to the ice ceiling.  In place of a grounding plate, an aluminum rod is placed through the floating surface buoy alongside the surface package and mooring cable to complete the inductive loop.  This grounding is essential for the profiler to be able to send its data to the surface package where it is then sent home via Iridium satellite.  This is the first Tethered Ocean Profiler to ever be deployed.  This new generation of autonomous profilers is unique in that it is able to climb its mooring, and touch the bottom of the ice sheet to which the instrument is tethered.  This measurement of water properties right up to the ice/sea interface by an autonomous profiler is a first of its kind!

There were other science activities happening on the ice today. Stephen Page and Peter Van Buren from the Institute of Ocean Sciences (IOS) were busily deploying the SIMB buoy through an 11” hole they drilled in the ice at a location between the ITP and TOP.  Installing the SIMB is a delicate procedure as it is important to minimally disturb the ice and snow around it.  Kazu Tateyama, from the Kitami Institute of Technology lead his team of students in establishing transect lines across the ice sheet to characterize the ice and snow coverage, and to take samples and ice cores to study the history, physics, chemistry, and biology of the floe.

Thank you again for taking the time to read about our day in the beautiful Beaufort Sea!  In the upcoming days, we will continue with another ice station and talk more about how these stations are selected, and the science being conducted to examine the ice floes themselves!