Publication Date:
2022-05-26
Description:
Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography: Methods 15 (2017): 495-502, doi:10.1002/lom3.10177.
Description:
An Aanderaa Data Instruments 4831 Oxygen optode was configured on an underwater
glider such that the optode extended into the atmosphere during each glider surface interval
enabling in situ calibration of the sensor by directly measuring the known partial pressure of the
atmosphere. The approach, which has previously been implemented on profiling floats but not on
gliders, was tested during a 15-day deployment at the New England shelf break in June 2016, a
productive period during which surface O2 saturation averaged 110%. Results were validated by
shipboard Winkler O2 calibration casts, which were used to determine a sensor gain factor of 1.055
± 0.004. Consistent with profiling float observations, air measurements contain contamination
from splashing water and/or residual seawater on the sensor face. Glider surface measurements
were determined to be a linear combination of 36% of surface water and 64% atmospheric air.
When correcting air measurements for this effect, a sensor gain correction of 1.055 ± 0.005 was
calculated based on comparing glider air measurements to the expected atmospheric pO2
calculated from atmospheric pressure and humidity data from a nearby NOAA buoy. Thus, the
two approaches were in agreement and were both demonstrated to be accurate to within ±0.5%.
We expect uncertainty in the air-calibration could be further reduced by increasing the vertical
positioning of the optode, lengthening deployment time, or operating in waters with surface O2
saturation closer to equilibrium.
Keywords:
Dissolved oxygen
;
Autonomous platform
;
Slocum glider
;
Optode
;
Calibration
;
Ocean
;
Ocean observing
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
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