Determination of the absorption coefficient of chromophoric dissolved organic matter from underway spectrophotometry

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Dall'Olmo, Giorgio and Brewin, Robert J. W. and Nencioli, Francesco and Organelli, Emanuele and Lefering, Ina and McKee, David and Röttgers, Rüdiger and Mitchell, Catherine and Boss, Emmanuel and Bricaud, Annick and Tilstone, Gavin (2017) Determination of the absorption coefficient of chromophoric dissolved organic matter from underway spectrophotometry. Optics Express, 25 (24). A1079-A1095. ISSN 1094-4087 (https://doi.org/10.1364/OE.25.0A1079)

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Abstract

Measurements of the absorption coefficient of chromophoric dissolved organic matter (ay) are needed to validate existing ocean-color algorithms. In the surface open ocean, these measurements are challenging because of low ay values. Yet, existing global datasets demonstrate that ay could contribute between 30% to 50% of the total absorption budget in the 400–450 nm spectral range, thus making accurate measurement of ay essential to constrain these uncertainties. In this study, we present a simple way of determining ay using a commercially-available in-situ spectrophotometer operated in underway mode. The obtained ay values were validated using independent collocated measurements. The method is simple to implement, can provide measurements with very high spatio-temporal resolution, and has an accuracy of about 0.0004 m−1 and a precision of about 0.0025 m−1 when compared to independent data (at 440 nm). The only limitation for using this method at sea is that it relies on the availability of relatively large volumes of ultrapure water. Despite this limitation, the method can deliver the ay data needed for validating and assessing uncertainties in ocean-colour algorithms.

ORCID iDs

Dall'Olmo, Giorgio, Brewin, Robert J. W., Nencioli, Francesco, Organelli, Emanuele, Lefering, Ina ORCID logoORCID: https://orcid.org/0000-0003-1167-2227, McKee, David ORCID logoORCID: https://orcid.org/0000-0001-8023-5923, Röttgers, Rüdiger, Mitchell, Catherine, Boss, Emmanuel, Bricaud, Annick and Tilstone, Gavin;
  • Item type:Article
    ID code:62275
    Dates:
    Date
    Event
    31 October 2017
    Published
    24 October 2017
    Accepted
    Notes:© 2017 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
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:07 Nov 2017 16:38
    Last modified:22 Nov 2024 23:11
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/62275
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