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Ref. No. [UMCES] CBL 2015-010
ACT VS15-03
Moored Deployment at Chesapeake Biological Laboratory (CBL)
A month-long moored field test was conducted in Chesapeake Bay from March 3 to April
10, 2014. The deployment was located at 38.32°N, 76.45°W attached to the end of a pier at the
mouth of the Patuxent River (Photo 6.) The average water depth of the test site was 2.2 m. The
site was brackish with salinity ranging from 9.1 PSU to 14.3 PSU during the deployment and
temperature ranging from 3.3 to 10.2 °C.
Photo 5.
Aerial view of CBL deployment site (left) and duplicate sampling at mooring rack.
Time series results of ambient conditions for tidal height, temperature, and salinity are
given in figure 12. Temperature ranged from 3.4 to 10.1 and salinity from 9.3 to 14.0 over the
duration of the field test. The bottom panel displays the maximum difference recorded between
all reference thermistors mounted at the same depth and different locations across the mooring
rack. The average temperature difference observed across the space of the mooring rack was
0.04 ±0.06
o
C with a maximum of 01.38
o
C. As noted above, it is not possible to quantify the
exact difference between the averaged reference temperature and that measured by the test
instrument, but differences resulting from this variation and variation in the chemistry of the
water across will be minimized because the sampling bottle integrates across the mooring space.
The Idronaut 305 Plus operated continuously for the first four days of the deployment and
generated 372 pH measurements at 15 minute intervals. This represented approximately 13% of
the total possible data return. Time series results of the 305 Plus and corresponding reference pH
results are given in figure 13. Ambient pH measured by the Idronaut ranged from 7.798 to
8.135, compared to the range from reference measurements of 8.024 to 8.403. The bottom panel
presents the time series of the difference between the instrument and reference pH for each
matched pair (n=18, out of a total of 107 possible). The average of the measurement difference
was -0.366 ±0.042, with the total range of -0.425 to -0.247.
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