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Unexpected quasi-independence of coloured dissolved organic matter absorption from chlorophyll-a concentration in the Southern Ocean.

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Title: Unexpected quasi-independence of coloured dissolved organic matter absorption from chlorophyll-a concentration in the Southern Ocean.
Authors: Li, Juan1,2,3 (AUTHOR) juan.li@takuvik.ulaval.ca, Antoine, David1,3 (AUTHOR), Huot, Yannick4 (AUTHOR)
Source: Biogeosciences. 2026, Vol. 23 Issue 9, p3073-3090. 18p.
Subject Terms: *Absorption coefficients, *Chlorophyll in water, *Dissolved organic matter, *Biogeochemical cycles, *Ocean color, *Optical oceanography, *Ocean
Geographic Terms: Antarctic Ocean
Abstract: The absorption coefficient of coloured dissolved organic matter (CDOM), ay , plays a critical role in driving ocean optical properties and thereby light attenuation and light-dependent biogeochemical cycles. In the Southern Ocean (SO), however, ay remains poorly documented because of the scarcity of in situ measurements and the absence of suitable bio-optical models. To address this gap, we derived ay in surface waters from the diffuse attenuation coefficient (Kd) derived from radiometric measurements performed by Biogeochemical-Argo floats. Sensitivity analyses using Monte Carlo simulations indicated that the uncertainty of our estimates is mainly driven by the uncertainty in Kd , and is overall ∼ 18 % for ay at 380 and 412 nm. Our derived ay vs. chlorophyll- a concentration (Chl) relationships for low-latitude waters are consistent with previously published relationships. They, however, diverge in the SO, with a larger relative contribution of ay to the absorption budget for clear waters (Chl < ∼ 0.2 mg m−3) and the opposite for greener waters, leading to a weaker dependence of ay on Chl. Lower-than-expected CDOM absorption mostly happens during the austral summer, suggesting significant photobleaching or lower biologically-mediated production. The relative contributions of CDOM and phytoplankton to the absorption budget are also found to diverge from what bio-optical models predict, with implication for interpretation of satellite ocean colour observations in the SO. [ABSTRACT FROM AUTHOR]
Database: Energy & Power Source
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Header DbId: enr
DbLabel: Energy & Power Source
An: 193976265
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
PreciseRelevancyScore: 0
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  Label: Title
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  Data: Unexpected quasi-independence of coloured dissolved organic matter absorption from chlorophyll-a concentration in the Southern Ocean.
– Name: Author
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  Data: &lt;searchLink fieldCode=&quot;AR&quot; term=&quot;%22Li%2C+Juan%22&quot;&gt;Li, Juan&lt;/searchLink&gt;&lt;relatesTo&gt;1,2,3&lt;/relatesTo&gt; (AUTHOR)&lt;i&gt; juan.li@takuvik.ulaval.ca&lt;/i&gt;&lt;br /&gt;&lt;searchLink fieldCode=&quot;AR&quot; term=&quot;%22Antoine%2C+David%22&quot;&gt;Antoine, David&lt;/searchLink&gt;&lt;relatesTo&gt;1,3&lt;/relatesTo&gt; (AUTHOR)&lt;br /&gt;&lt;searchLink fieldCode=&quot;AR&quot; term=&quot;%22Huot%2C+Yannick%22&quot;&gt;Huot, Yannick&lt;/searchLink&gt;&lt;relatesTo&gt;4&lt;/relatesTo&gt; (AUTHOR)
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  Data: &lt;searchLink fieldCode=&quot;JN&quot; term=&quot;%22Biogeosciences%22&quot;&gt;Biogeosciences&lt;/searchLink&gt;. 2026, Vol. 23 Issue 9, p3073-3090. 18p.
– Name: Subject
  Label: Subject Terms
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  Data: *&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Absorption+coefficients%22&quot;&gt;Absorption coefficients&lt;/searchLink&gt;&lt;br /&gt;*&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Chlorophyll+in+water%22&quot;&gt;Chlorophyll in water&lt;/searchLink&gt;&lt;br /&gt;*&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Dissolved+organic+matter%22&quot;&gt;Dissolved organic matter&lt;/searchLink&gt;&lt;br /&gt;*&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Biogeochemical+cycles%22&quot;&gt;Biogeochemical cycles&lt;/searchLink&gt;&lt;br /&gt;*&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Ocean+color%22&quot;&gt;Ocean color&lt;/searchLink&gt;&lt;br /&gt;*&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Optical+oceanography%22&quot;&gt;Optical oceanography&lt;/searchLink&gt;&lt;br /&gt;*&lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Ocean%22&quot;&gt;Ocean&lt;/searchLink&gt;
– Name: SubjectGeographic
  Label: Geographic Terms
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  Data: &lt;searchLink fieldCode=&quot;DE&quot; term=&quot;%22Antarctic+Ocean%22&quot;&gt;Antarctic Ocean&lt;/searchLink&gt;
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: The absorption coefficient of coloured dissolved organic matter (CDOM), ay , plays a critical role in driving ocean optical properties and thereby light attenuation and light-dependent biogeochemical cycles. In the Southern Ocean (SO), however, ay remains poorly documented because of the scarcity of in situ measurements and the absence of suitable bio-optical models. To address this gap, we derived ay in surface waters from the diffuse attenuation coefficient (Kd) derived from radiometric measurements performed by Biogeochemical-Argo floats. Sensitivity analyses using Monte Carlo simulations indicated that the uncertainty of our estimates is mainly driven by the uncertainty in Kd , and is overall ∼ 18 % for ay at 380 and 412 nm. Our derived ay vs. chlorophyll- a concentration (Chl) relationships for low-latitude waters are consistent with previously published relationships. They, however, diverge in the SO, with a larger relative contribution of ay to the absorption budget for clear waters (Chl &lt; ∼ 0.2 mg m−3) and the opposite for greener waters, leading to a weaker dependence of ay on Chl. Lower-than-expected CDOM absorption mostly happens during the austral summer, suggesting significant photobleaching or lower biologically-mediated production. The relative contributions of CDOM and phytoplankton to the absorption budget are also found to diverge from what bio-optical models predict, with implication for interpretation of satellite ocean colour observations in the SO. [ABSTRACT FROM AUTHOR]
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RecordInfo BibRecord:
  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.5194/bg-23-3073-2026
    Languages:
      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 18
        StartPage: 3073
    Subjects:
      – SubjectFull: Absorption coefficients
        Type: general
      – SubjectFull: Chlorophyll in water
        Type: general
      – SubjectFull: Dissolved organic matter
        Type: general
      – SubjectFull: Biogeochemical cycles
        Type: general
      – SubjectFull: Ocean color
        Type: general
      – SubjectFull: Optical oceanography
        Type: general
      – SubjectFull: Ocean
        Type: general
      – SubjectFull: Antarctic Ocean
        Type: general
    Titles:
      – TitleFull: Unexpected quasi-independence of coloured dissolved organic matter absorption from chlorophyll-a concentration in the Southern Ocean.
        Type: main
  BibRelationships:
    HasContributorRelationships:
      – PersonEntity:
          Name:
            NameFull: Li, Juan
      – PersonEntity:
          Name:
            NameFull: Antoine, David
      – PersonEntity:
          Name:
            NameFull: Huot, Yannick
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          Dates:
            – D: 01
              M: 05
              Text: 2026
              Type: published
              Y: 2026
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            – Type: issn-print
              Value: 17264170
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              Value: 23
            – Type: issue
              Value: 9
          Titles:
            – TitleFull: Biogeosciences
              Type: main
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