An Icy CTD Cast

August 16, 2009 · Filed Under 2009, Journey

Andy Armstrong, NOAA’s Office of Coast Survey, Co-chief scientist aboard USCGC Healy

USCGC Healy continues to break ice for the Canadian Coast Guard Ship Louis S. St-Laurent, which is following astern of us. We are obtaining valuable multibeam bathymetry in parts of the Arctic Ocean that have never been mapped, but multichannel seismic profiling from the Louis S. St-Laurent remains the primary goal for now. On Friday and Saturday, we were on an eastward upslope track toward the Canadian shelf. Last night we reached the end of that track and turned southwestward to profile and sound back down the slope. Tomorrow we expect to turn northwestward toward the areas of more interest to the U.S.

At the end our eastward line last night, we stopped briefly for engineering maintenance on both ships, and some maintenance on the seismic equipment. While stopped, we were able to complete a CTD cast – a deployment of an instrument that measures the conductivity (salinity), temperature, and depth. The readings from the CTD create a sound speed profile, which we compare to the multibeam echosounder depth results. This CTD cast through the ice was a first for me, but is one of the things Healy does fairly routinely.

One of the remarkable aspects of this cruise is the cooperation and collaboration between the U.S. and Canada. Both nations need these seismic profiles for our respective Extended Continental Shelf projects, but they are almost impossible to obtain with the single icebreaker each of us has available. By operating jointly, we can both get the data we need.

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