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dc.contributor.authorWollschläger, Jochen
dc.contributor.authorRöttgers, Rüdiger
dc.contributor.authorPetersen, Wilhelm
dc.contributor.authorZielinski, Oliver
dc.identifier.citationWollschläger, J.; Röttgers, R.; Petersen, W. and Zielinski, O. (2019) Stick or Dye: Evaluating a Solid Standard Calibration Approach for Point-Source Integrating Cavity Absorption Meters (PSICAM). Frontiers in Marine Science, 5:534. 13pp. DOI: 10.3389/fmars.2018.00534en_US
dc.description.abstractTogether with scattering, the process of absorption determines the propagation of light within the water column. It is influenced by the concentration and composition of optically active substances (phytoplankton, chromophoric-dissolved organic matter, and non-living particles). For this reason, the absorption coefficients of a water sample can provide corresponding information. However, the accurate determination of absorption coefficients in natural waters is often difficult due to the usually low concentration of absorbing material and the errors that scattering on particles introduce in the measurements. These problems can be overcome by instruments based on integrating cavities like the point-source integrating-cavity absorption meter (PSICAM). The accuracy of PSICAM measurements is to a large degree related to the accuracy of the measurement of the reflectivity inside its cavity, as this determines its mean optical path length. A reflectivity measurement (“calibration”) is usually carried out by measuring a liquid dye (nigrosin) with known absorption coefficients, followed by bleaching and rinsing of the cavity. The procedure requires additional equipment like spectrophotometers and handling of a liquid standard. Therefore, it might be difficult or at least non-convenient under field conditions and is additionally a major obstacle for a potential automation of these systems. In the present study, an alternative calibration approach for a PSICAM is evaluated, taking advantage of a solid standard. The standard is characterized and its suitability for calibration is compared to that of a conventional, nigrosin-based reflectivity measurement. Furthermore, the application in an automated flow-through PSICAM system (HyAbS) used in the field is tested. The results show that the performance of the solid standard calibration is comparable to that of the nigrosinebased calibration. Furthermore, it improves the measurements of the automated system. Thus, due to its simplicity, the solid standard calibration might foster the use of PSICAM systems, which allow a more accurate determination of absorption coefficients in natural water samples compared to conventional spectrophotometric techniques. Furthermore, it will potentially facilitate further approaches to automate these instrumentsen_US
dc.rightsAttribution 4.0*
dc.subject.otherAbsorption coefficienten_US
dc.subject.otherIntegrating cavityen_US
dc.subject.otherInstrument calibrationen_US
dc.subject.otherSolid standarden_US
dc.subject.otherParticle scatteringen_US
dc.titleStick or Dye: Evaluating a Solid Standard Calibration Approach for Point-Source Integrating Cavity Absorption Meters (PSICAM) .en_US
dc.typeJournal Contributionen_US
dc.subject.parameterDisciplineParameter Discipline::Chemical oceanographyen_US
dc.bibliographicCitation.titleFrontiers in Marine Scienceen_US
dc.bibliographicCitation.issueArticle 534
dc.description.maturitylevelTRL 8 Actual system completed and "mission qualified" through test and demonstration in an operational environment (ground or space)en_US

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Except where otherwise noted, this item's license is described as Attribution 4.0