Dispatch 11: The First Ice Station     Print

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Hugo Sindelar

September 17, 2018

Location: 76° 28' N 137° 37' W

Weather: -9°C (16°F), Mostly sunny, seas ice covered, Northwest winds at 9 knots, seawater temperature 0.2°C (32.4°F)

Sea Ice: Variable from complete coverage to mostly covered.

You’re always supposed to find something more interesting to talk about than the weather, right?  Well, I am going to do it, and I won’t be making any apologies for it.  The weather up here plays a key role in what we can do and when we can do it, and so far Mother Nature has sure given us a run of perfect weather (fingers crossed it keeps up and my writing about it doesn’t change our fortune).  This morning we awoke to clear blue skies and little wind.  The perfect day to get out on the ice for our first ice station.  The icing on the cake came from a thick ice floe the ship found (in consultation with the WHOI team) for the station.  Having a thick floe right next to the CCGS Louis S. St-Laurent meant we could use the gangway–think stairs you can lower to the ice.  Pretty convenient if you ask me.  As soon as the gangway was in place, the science started in earnest.  We had two parallel operations going today.

First, the WHOI team was installing an Ice-Tethered Profiler (ITP).  An ITP station is a much shorter version of the moorings the WHOI team installs in deeper water.  The biggest difference is the buoy is placed into a hole in the sea ice, “locking” the buoy in place.  It is actually much safer for the buoy to move with the ice than in open water.  Unfortunately, as more sea ice melts each summer due to climate change, the buoys often melt out of the ice.  Thus, the reason we spent some time earlier in the trip recovering wayward buoys.  The ITP has cable that goes down to a depth of 730 meters, and an Ice-Tethered Profiler, essentially a modified McLane Mooring Profiler (MMP), patrols the cable to measure Conductivity, Temperature, and Depth (CTD).  Just below the surface buoy sits a Submersible Autonomous Mooring Instrument (SAMI), which measures pH and dissolved CO₂.  As I mentioned before, these parameters help scientists track ocean acidification, one of the ramifications of climate change.  Finally, inside the buoy goes the surface package.

While it is nice to recover the ITPs, they are actually designed to be one-time use.  The surface package allows the MMP and SAMI to send data back to WHOI using satellites.  It also allows WHOI to track the location of each ITP over time.  The surface package contains a fascinating piece of electronics that I had never heard about–the inductive modem.  The inductive modem allows the surface package to collect data from the ITP and SAMI, which it then relays to WHOI.  It accomplishes this feat by sending a signal through the steel cable the ITP is attached to.  Only problem is that the steel cable isn’t a complete circuit, but it turns out that seawater because of its high salinity is quite conductive.  The steel cable is exposed to the ocean at its top and bottom, completing the circuit through the seawater and allowing the surface package to talk to an instrument hundreds of meters below it!

The second parallel operation was JOIS scientists conducting ice measurements and drilling ice cores.  However, I did not get to spend time with them today as I was focused on the WHOI team’s work.  I am a one-man band after all, and try as I might, I just can’t keep track of all the concurrent science going on during these different operations.  Despair not, JOIS fans.  There is a second ice station to come mid-week, and I will be spending the whole day with the JOIS scientists as they conduct their work.  I’ll have the scoop for you, I promise.