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Ref. No. [UMCES] CBL 2016-014
ACT VS16-05
5
temperature ranged from 21.0
o
C at the surface to 13.5
o
C in the hypolimnion, with corresponding
DO concentrations of 7.8 and 2.8 mg/L, respectively. In Lake Michigan, the temperature ranged
from 21.0
o
C at the surface to 4.1
o
C in the hypolimnion, with corresponding DO concentrations of
8.6 and 12.6 mg/L, respectively. Two profiling trials were conducted at each location. The first
trial involved equilibrating test instruments at the surface (3m) for ten minutes and then collecting
three Niskin bottle samples at one minute intervals. Following the third sample, the rosette was
quickly profiled into the hypolimnion where samples were collected immediately upon arrival and
then each minute for the next 6 minutes. The second trial was performed in the reverse direction.
In Muskegon Lake, the temperature ranged from 21.0
o
C at the surface to 13.5
o
C in the
hypolimnion, with corresponding DO concentrations of 7.8 and 2.8 mg/L, respectively. In Lake
Michigan, the temperature ranged from 21.0
o
C at the surface to 4.1
o
C in the hypolimnion, with
corresponding DO concentrations of 8.6 and 12.6 mg/L, respectively. For Muskegon Lake, the
range in measurement differences between instrument and reference was -0.07 to 0.16 mg/L for
cast 2 and -0.38 to 0.11 mg/L for cast 3 (cast 1 was aborted and redone as cast 3). For both
profiling transitions the HL4 appeared to equilibrate to the new ambient DO conditions by the third
sample. For Lake Michigan, the range in measurement differences between instrument and
reference was -0.05 to 0.54 mg/L for cast 1 and -0.14 to 0.32 mg/L for cast 2. The equilibration
rate differed among the two profiling directions at this site, occurring by 3 minutes for cast 1, but
continual drift through the 7
th
minute during cast 2.
BACKGROUND AND OBJECTIVES
Instrument performance verification is necessary so that effective existing technologies can
be recognized so that 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
Optical dissolved oxygen sensors in Hydrolab Series 5 (Models MS5, DS5, & DS5X) and
HL Series (Models HL4 & HL7) multi-parameter sondes use Hach LDO (Luminescent Dissolved