A calibration equation for oxygen optodes based on physical properties of the sensing foil

McNeil, Craig; D’Asaro, Eric A.

doi:10.4319/lom.2014.12.139

Cited by 24 publications

(25 citation statements)

References 42 publications

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“…In reality, optodes deviate from a linear Stern-Volmer behavior and a number of parametric models exist to relate sensor data (phase shift and temperature) to oxygen (e.g., Aanderaa high-order polynomials; Uchida et al 2008;McNeil and D'Asaro 2014). While numbers vary somewhat with the choice of the model, the drift characteristic ( Fig.…”

Section: A Drift Characteristicmentioning

confidence: 99%

Tackling Oxygen Optode Drift: Near-Surface and In-Air Oxygen Optode Measurements on a Float Provide an Accurate in Situ Reference

Bittig

Körtzinger

2015

Journal of Atmospheric and Oceanic Technology

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A yet unexplained drift of (some) oxygen optodes during storage/transport and thus significant deviations from factory/laboratory calibrations have been a major handicap for autonomous oxygen observations. Optode drift appears to be systematic and is predominantly a slope effect due to reduced oxygen sensitivity. A small contribution comes from a reduced luminophore lifetime, which causes a small positive offset. A reliable in situ reference is essential to correct such a drift. Traditionally, this called for a ship-based reference cast, which poses some challenges for opportunistic float deployments. This study presents an easily implemented alternative using near-surface/in-air measurements of an Aanderaa optode on a 10-cm stalk and compares it to the more traditional approaches (factory, laboratory, and in situ deployment calibration). In-air samples show a systematic bias depending on the water saturation, which is likely caused by occasional submersions of the standardheight stalk optode. Linear regression of measured in-air supersaturation against in-water supersaturation (using ancillary meteorological data to define the saturation level) robustly removes this bias and thus provides a precise (0.2%) and accurate (1%) in situ correction that is available throughout the entire instrument's lifetime.

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Section: A Drift Characteristicmentioning

confidence: 99%

Tackling Oxygen Optode Drift: Near-Surface and In-Air Oxygen Optode Measurements on a Float Provide an Accurate in Situ Reference

Bittig

Körtzinger

2015

Journal of Atmospheric and Oceanic Technology

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“…These models include high-order polynomials (e.g., Aanderaa Data Instruments AS, 2009, Appendix 6), parametric models inspired by Stern-Volmer (Uchida et al, 2008(Uchida et al, , 2010Sea-Bird Electronics, 2013; this work), and two-site physics (McNeil and D'Asaro, 2014). Their output can either be an oxygen concentration c O 2 (Uchida et al, 2008;Aanderaa Data Instruments AS, 2009;Sea-Bird Electronics, 2013) or an oxygen partial pressure pO 2 (Bittig et al, 2012;McNeil and D'Asaro, 2014;this work), which both can be converted using temperature and salinity . More details about these calculations can be found in section 5.2.…”

Section: O 2 and Temperature Dependencementioning

confidence: 99%

Oxygen Optode Sensors: Principle, Characterization, Calibration, and Application in the Ocean

et al. 2018

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Recently, measurements of oxygen concentration in the ocean-one of the most classical parameters in chemical oceanography-are experiencing a revival. This is not surprising, given the key role of oxygen for assessing the status of the marine carbon cycle and feeling the pulse of the biological pump. The revival, however, has to a large extent been driven by the availability of robust optical oxygen sensors and their painstakingly thorough characterization. For autonomous observations, oxygen optodes are the sensors of choice: They are used abundantly on Biogeochemical-Argo floats, gliders and other autonomous oceanographic observation platforms. Still, data quality and accuracy are often suboptimal, in some part because sensor and data treatment are not always straightforward and/or sensor characteristics are not adequately taken into account. Here, we want to summarize the current knowledge about oxygen optodes, their working principle as well as their behavior with respect to oxygen, temperature, hydrostatic pressure, and response time. The focus will lie on the most widely used and accepted optodes made by Aanderaa and Sea-Bird. We revisit the essentials and caveats of in-situ in air calibration as well as of time response correction for profiling applications, and provide requirements for a successful field deployment. In addition, all required steps to post-correct oxygen optode data will be discussed. We hope this summary will serve as a comprehensive, yet concise reference to help people get started with oxygen observations, ensure successful sensor deployments and acquisition of highest quality data, and facilitate post-treatment of oxygen data. In the end, we hope that this will lead to more and higher-quality oxygen observations and help to advance our understanding of ocean biogeochemistry in a changing ocean.

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“…It evolved from a polynomial approach (e.g., Aanderaa Data Instruments 2009, appendix 6) over variants of a Stern-Volmer inspired, parametric function (Uchida et al 2008(Uchida et al , 2010Sea-Bird Electronics 2013) to a model approximating two-site physics (McNeil and D'Asaro 2014). The calculated oxygen quantity is either the (freshwater) c O 2 (Aanderaa Data Instruments 2009; Uchida et al 2008;Sea-Bird Electronics 2013), which requires subsequent salinity correction, or the pO 2 (Bittig et al 2012;McNeil and D'Asaro 2014), which can be converted to concentration via the oxygen solubility c O 2 * (Garcia and Gordon 1992) [see Eq. (6) in section 2a].…”

Section: Introductionmentioning

confidence: 99%

Pressure Response of Aanderaa and Sea-Bird Oxygen Optodes

Fiedler

Fietzek

Körtzinger

2015

Journal of Atmospheric and Oceanic Technology

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This study investigated the effect of hydrostatic pressure of up to 6000 dbar on Aanderaa and Sea-Bird oxygen optodes both in the laboratory and in the field. The overall pressure response is a reduction in the O 2 reading by 3%-4% per 1000 dbar, which is closely linear with pressure and increases with temperature. Closer inspection reveals two superimposed processes with an opposite effect: an O 2 -independent pressure response on the luminophore that increases optode O 2 readings and an O 2 -dependent change in luminescence quenching that decreases optode O 2 readings. The latter process dominates and is mainly due to a shift in the equilibrium between the sensing membrane and seawater under elevated pressures. If only the dominant O 2 -dependent process is considered, then the Aanderaa and Sea-Bird optodes differ in their pressure response. Compensation of the O 2 -independent process, however, yields a uniform O 2 dependence for Aanderaa optodes with standard foil and fast-response foil as well as for Sea-Bird optodes. A new scheme to calculate optode O 2 from raw data is proposed to account for the two processes. The overall uncertainty of the optode pressure correction amounts to 0.3% per 1000 dbar, which is mainly due to variability between the sensors.

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A calibration equation for oxygen optodes based on physical properties of the sensing foil

Cited by 24 publications

References 42 publications

Tackling Oxygen Optode Drift: Near-Surface and In-Air Oxygen Optode Measurements on a Float Provide an Accurate in Situ Reference

Tackling Oxygen Optode Drift: Near-Surface and In-Air Oxygen Optode Measurements on a Float Provide an Accurate in Situ Reference

Oxygen Optode Sensors: Principle, Characterization, Calibration, and Application in the Ocean

Pressure Response of Aanderaa and Sea-Bird Oxygen Optodes

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