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Ref. No. [UMCES] CBL 2015-013
ACT VS15-06
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 °C to 10.2 °C.
Photo 6.
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 14. 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 (RBR Solo and SBE26) 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 1.38
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 SAMI-pH operated successfully from March 12 through April 1 and generated 1842
observations based on its 15 minute sampling interval. Time series results of the SAMI-pH and
corresponding reference pH results are given in figure 15. From April 1-10, there were 175 no
data returns and the remaining 714 reported observations showed increasing deviations from the
reference results. Ambient pH measured by the SAMI from March 12 through April 1 ranged
from 8.121 to 8.479, compared to the range captured by the reference measurements of 8.024 to
8.403. The bottom panel presents the time series of the difference between the two results for
each matched pair (N=89 observations). The average and standard deviation of the measurement
difference for the period up to April 1 was 0.041 ±0.033 (n=69), with the total range of
differences between -0.086 to 0.114.
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