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Ref. No. [UMCES] CBL 2015-008
ACT VS15-01
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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 to 14.3 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 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 CSI operated successfully over the entire 30 day deployment measuring at 15 minute
intervals. However, a programming error initiated by ACT personnel during set-up resulted in
the shutter being closed during every other observation, so the useable number of observations
was reduced from 2756 to 1378. No comparative data with reference samples were lost due to
this programming error. Time series results of the CSI and corresponding reference pH results
are given in figure 15. Ambient pH measured by the CSI ranged from 7.693 to 7.979, 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 CSI and reference pH for each matched pair (n=107
observations). The average and standard deviation of the measurement difference was -0.398
±0.040, with the total range of differences from -0.472 to -0.316.