Improved determination of particulate absorption from combined filter pad and PSICAM measurements

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Lefering, Ina and Röttgers, Rüdiger and Weeks, Rebecca and Connor, Derek and Utschig, Christian and Heymann, Kerstin and McKee, David (2016) Improved determination of particulate absorption from combined filter pad and PSICAM measurements. Optics Express, 24 (22). pp. 24805-24823. ISSN 1094-4087 (https://doi.org/10.1364/OE.24.024805)

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Abstract

Filter pad light absorption measurements are subject to two major sources of experimental uncertainty: the so-called pathlength amplification factor, β, and scattering offsets, o, for which previous null-correction approaches are limited by recent observations of non-zero absorption in the near infrared (NIR). A new filter pad absorption correction method is presented here which uses linear regression against point-source integrating cavity absorption meter (PSICAM) absorption data to simultaneously resolve both β and the scattering offset. The PSICAM has previously been shown to provide accurate absorption data, even in highly scattering waters. Comparisons of PSICAM and filter pad particulate absorption data reveal linear relationships that vary on a sample by sample basis. This regression approach provides significantly improved agreement with PSICAM data (3.2% RMS%E) than previously published filter pad absorption corrections. Results show that direct transmittance (T-method) filter pad absorption measurements perform effectively at the same level as more complex geometrical configurations based on integrating cavity measurements (IS-method and QFT-ICAM) because the linear regression correction compensates for the sensitivity to scattering errors in the T-method. This approach produces accurate filter pad particulate absorption data for wavelengths in the blue/UV and in the NIR where sensitivity issues with PSICAM measurements limit performance. The combination of the filter pad absorption and PSICAM is therefore recommended for generating full spectral, best quality particulate absorption data as it enables correction of multiple errors sources across both measurements.

ORCID iDs

Lefering, Ina ORCID logoORCID: https://orcid.org/0000-0003-1167-2227, Röttgers, Rüdiger, Weeks, Rebecca, Connor, Derek ORCID logoORCID: https://orcid.org/0000-0003-2540-1380, Utschig, Christian, Heymann, Kerstin and McKee, David ORCID logoORCID: https://orcid.org/0000-0001-8023-5923;
  • Item type:Article
    ID code:58740
    Dates:
    Date
    Event
    17 October 2016
    Published
    22 September 2016
    Accepted
    Notes:© 2016 Optical Society of America.]. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.
    Subjects:Science > Physics > Optics. Light
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:17 Nov 2016 16:14
    Last modified:11 Nov 2024 11:33
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/58740
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