24 / 59
Ref. No. [UMCES] CBL 2016-013
ACT VS16-04
24
Winkler reference samples drawn at level of sensor foil in well-mixed test tanks.
Bottom Panel
:
Corresponding offset between instrument reading and Winkler DO reference sample during
exposure trial. Dotted line represents zero offset from reference. Instrument reads were adjusted
to bath salinity using HOBOware’s DO Assistant processing feature.
The global response of the HOBO U26 for all nine temperature-salinity trials is shown in
figure J. This plot includes all instrument-reference comparisons. In general instrument readings
were well correlated across the entire range of DO concentrations (hypoxic to supraoxic) covering
all temperature and salinity ranges tested. A linear regression of the instrument versus reference
measurements (n=358; r
2
= 1.00; p<0.0001) produced a slope of 1.037 and intercept of -0.084
Figure J.
Concordance of the Onset HOBO logger with RDO (sn 10603120) oxygen measures
paired with discrete Winkler DO reference samples. In general readings are well correlated across
a range of DO concentrations (hypoxic to supraoxic). Offsets in instrument readings increase at
higher DO levels and with salinity. Dotted line represents perfect agreement between the two
measures.