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Ref. No. [UMCES] CBL 2016-010
ACT VS16-01
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third sample, the rosette was quickly profiled into the hypolimnion were samples were collected
immediately upon arrival and then each minute for the next 6 minutes. The second trial was performed
in the reverse direction. Note for Muskegon Lake cast 1 was aborted due to bottle misfires and
repeated as cast 3. In Muskegon Lake, the Aro-USB exhibited a negative bias in the colder, low DO
hypolimnion and a positive bias in the warm, high DO surface. Sensor equilibration time was slightly
greater going from surface to hypolimnetic conditions. The range in measurement differences between
instrument and reference was -0.42 to 0.34 mg/L for cast 2 and -0.75 to 0.27 mg/L for cast 3.
In Lake Michigan, the Aro-USB exhibited a positive bias in both portions of the water column
but the magnitude was higher in the cold high DO hypolimnion. Sensor equilibration time was similar
between both trials, whether equilibrated at surface or depth. The range in measurement differences
between instrument and reference was -0.16 to 0.53 mg/L for cast 1 and 0.18 to 0.50 mg/L for cast 2.
BACKGROUND AND OBJECTIVES
Instrument performance verification is necessary so that effective existing technologies can be
recognized and promising new technologies can be made available to support coastal science, resource
management and ocean observing systems. To this end, the NOAA-funded Alliance for Coastal
Technologies (ACT) serves as an unbiased, third party testbed for evaluating sensors and sensor
platforms for use in coastal environments. ACT also serves as a comprehensive data and information
clearinghouse on coastal technologies and a forum for capacity building through workshops on specific
technology topics (visit
www.act-us.info).
As part of our service to the coastal community, ACT conducted a performance verification of
commercially available, in situ dissolved oxygen (DO) sensors through the evaluation of objective and
quality assured data. The goal of ACT’s evaluation program is to provide technology 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
For this performance evaluation both the JFE Advantech RINKO AroUSB and AroW-USB
were tested during all laboratory trials. The AroUSB was additionally evaluated in the profiling field
test in Michigan, and the AroW-USB was evaluated in the three field deployment tests at Michigan,
Maryland, and Hawaii. JFE Advantech RINKO AroUSB and AroW-USB are high-accuracy and
high-resolution optical dissolved oxygen (DO) sensors based on the phosphorescence principle. The
sensors are coated with photo-stimulable phosphor (PSP) on the outside of the pressure-resistant
acrylic optical window, measuring a phosphorescence quenching phase shift. The excitation blue LED
pulse generates a red phosphorescence pulse, which in turn has an inverse correlation with the oxygen
partial pressure in water (DO concentration). Since the method does not consume oxygen, there is no
need for stirring. The instruments offer a user friendly 2-point calibration that compensates the sensing