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Ref. No. [UMCES] CBL 2016-014
ACT VS16-05
29
Michigan Tech Great Lakes Research Center Field Deployment Site
A
15 week deployment under ice took place from January 9 through April 22 in the Keweenaw
Waterway adjacent to the Great Lakes Research Center in Houghton, MI. The deployment site
was located at 47.12° N, 88.55° W, at the end of the pier at the Great Lakes Research Center
docks. This site is located on the south side of the Keweenaw Waterway, and is connected to Lake
Superior in both the NW and SE directions. The instrumentation rack was lowered off of the end of
the pier with a ½ ton crane and rested on the bottom, under the ice, in 4.5m of water. A small
shelter was constructed at the end of the pier to provide shelter for processing the reference
samples during winter sampling efforts.
Photo 1.
Aerial view of the Keweenaw Waterway (left) and dockside mooring deployment (right).
Time series results of ambient conditions for temperature and specific conductivity are
given in figure 1. Temperature ranged from 0.04 - 5.3
o
C and specific conductivity from 87 - 137
µS/cm over the duration of the field test. The bottom panel displays the maximum difference
recorded between all reference thermistors mounted at the same depth as the sensors sampling
intakes as well as a meter above, at different locations across the mooring rack. The average
temperature difference observed across the space of the mooring rack was 0.01
°
C with a maximum
of 0.98
o
C. Differences between instrument and reference readings resulting from this variability
should be minimized as the sampling bottle integrates across the mooring space.
During the pre-tank test the HL4 started reporting errors, the manufacturer was notified but
could not get another sensor to Houghton in time for deployment. It was decided to try the
malfunctioning instrument, but it returned no data. The DS5X was also not supplied to this site for
testing so no instrument results are available for this field test.