5 / 53
Ref. No. [UMCES] CBL 2016-012
ACT VS16-03
5
users with an independent and credible assessment of instrument performance in a variety of
environments and applications. To this end, the data and information on performance
characteristics were focused on the types of information users most need.
The fundamental objectives of this Performance Verification were to: (1) highlight the
potential capabilities of particular in situ DO sensors by demonstrating their utility in a range of
coastal environments; (2) verify the claims of manufacturers on the performance characteristics of
commercially available DO sensors when tested in a controlled laboratory setting, and (3) verify
performance characteristics of commercially available DO sensors when applied in real world
applications in a diverse range of coastal environments.
INSTRUMENT TECHNOLOGY TESTED
The HydroCAT CTD with optical dissolved oxygen (ODO) Sensor is part of the model 37
family of moored sensors from Sea-Bird Scientific. It was released by Sea-Bird in 1997 and to date
over 10,000 instruments have been deployed. In 2012 Sea-Bird released the SBS63 which is an
optical dissolved oxygen sensor. The HydroCAT is designed for long duration deployment at
fixed-sites.
The optical dissolved oxygen sensor on the HydroCAT is individually calibrated in a
temperature-controlled bath. Bath temperatures are varied at each of 4 oxygen values, providing a
comprehensive 24-point calibration. Two reference sensors in each bath are standardized against
Winkler titrations. Response time tests are conducted on each sensor using gas. Salinity and
pressure impacts on sensor response are each checked at two separate points. By locating the ODO
sensor in the flow path the optimum correlation with the CTD measurements can be achieved. The
elapsed time between the CTD and associated oxygen measurement is easily quantified, and
corrected for in post-processing. The plumbing’s black tubing blocks light and further reduces in-
situ algal growth. Due to the stable sensor technology and comprehensive factory calibration the
HydroCAT does not require user calibration. Factory calibration is recommended every 1 – 2
years.
With its on-board data storage capability, internal battery pack and anti-foulant cartridges,
the HydroCAT can operate autonomously over long-term deployments. Data can be output in real-
time via SDI-12 or RS232.
The supplied
Universal Coastal Interface (UCI)
software provides easy set-up and
configuration, graphical real-time data display for pre-deployment checks and interactive sampling.
UCI can also be used with other sensors such as the SUNA V2 and HydroCAT-EP.
PERFORMANCE EVALUTION TEST PLAN
Laboratory Tests
Laboratory tests of accuracy, precision, response time, and stability were conducted at
Moss Landing Marine Lab. All tests were run under ambient pressure (logged hourly from a
barometer at the laboratory) and involved the comparison of dissolved oxygen concentration
reported by the instrument versus Winkler titration values of water samples taken from the test
baths. All tests were run in thermally controlled tanks at specific temperature, salinity, and DO