POSTER Session 3

EXAMINATION OF BEST PRACTICES AND SOLID ABSORPTION CALIBRATION METHODS FOR THE POINT SOURCE INTEGRATED CAVITY ABSORPTION METER

A rigorous examination of the uncertainties in PSICAM (Point Source Integrated Cavity Absorption Meter) measurements is conducted. Multiple sources of error can influence the accuracy of PSICAM absorption measurements: measurement noise, spectrometer stability, light source stability, calibration, and external verification of the standard are among the sources of errors investigated. Measurement noise can be mitigated through repetitive measurements. Using more than 300 averages for each measurement provided repeatability of measurements with a mean absolute difference of less than 0.001 m-1 across the visible spectra. Measurement protocols are presented to minimize the potential for bubbles and other contaminants. The stability of the spectrometer over time and temperature is explored. Non-linearity and wavelength registration within the array spectrometer are also considered to reduce errors. Broadband light source stability and output with respect to time are also discussed. Due to its compact size, the PSICAM is utilized both in the lab and at sea. Accurate absorption values necessitate an absorption standard solution to account for the reflectivity of the sphere. Currently, nigrosine dye is employed to measure the reflectivity and requires a priori knowledge of the absorption of the dye. An assessment of the stability of nigrosine dye is conducted for both filtered and non-filtered dye. A solid standard is proposed to enhance the determination of reflectivity in the sphere.

Christopher Strait, Harbor Branch Oceanographic Institute, Florida Atlantic University, USA, [email protected], https://orcid.org/0000-0002-5134-823X

Alberto Tonizzo, Sunstone Scientific, USA, [email protected]

Rüdiger Röttgers, Helmholtz-Zentrum Hereon, Germany, [email protected]

Wayne Slade, Harbor Branch Oceanographic Institute, Florida Atlantic University, USA, [email protected]

Michael Twardowski, Harbor Branch Oceanographic Institute, Florida Atlantic University, USA, [email protected]

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