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Ref. No. [UMCES] CBL 2015-014
ACT VS15-07
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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 23. 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, and additional differences resulting from variation in the actual
chemistry of the water across this space may exist but will be minimized because the sampling
bottle integrates across the mooring space.
Only one pH sensor was deployed on the EXO sonde for this deployment. The EXO
operated successfully over the entire 30 day deployment measuring at 15 minute intervals and
generated 2759 pH measurements. Time series results of the EXO and corresponding reference
pH results are given in figure 24. Ambient pH measured by the EXO ranged from 8.14 to 8.52,
compared to the range captured from reference measurements of 8.024 to 8.403. The bottom
panel presents the time series of the difference between the EXO and reference pH for each
matched pair (n=107 observations). The average and standard deviation of the measurement
difference was 0.16 ±0.04, with the total range of differences from 0.05 to 0.27.