Semi-empirical correction algorithm for AC-9 measurements in a coccolithophore bloom

David J.C. McKee, Alex Cunningham, Susanne E. Craig

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Values for the coefficients of absorption (a) and attenuation (c) obtained from AC-9 measurements in coccolithophore blooms do not provide satisfactory inputs for radiance transfer models. We have therefore modified the standard AC-9 scattering correction algorithm by including an extra term, F(λ, λr), which allows for possible wavelength dependence in the scattering phase function. We estimated the magnitude of F(λ, λr), which is unity in the standard algorithm, by adjusting the absorption and scattering values in Hydrolight radiance transfer calculations until the depth profiles of downward irradiance (Ed) and upward radiance (Lu) matched those measured in situ. The modified algorithm was tested with data from a phytoplankton bloom dominated by the coccolithophore Emiliania huxleyi, which occurred in the western English Channel in May 2001. In this paper, we only have sufficient data to adequately constrain the radiance transfer model in one wave band centered on 488 nm. A single value of F(λ, λr) = 1.4 was found to produce satisfactory agreement between modeled and observed profiles at four widely spaced stations within the bloom. Measurements of the ratio of backscattering (bb) to total scattering (b) showed significant wavelength dependence at these stations.
LanguageEnglish
Pages4369-4374
Number of pages5
JournalApplied Optics
Volume42
Issue number21
DOIs
Publication statusPublished - 20 Jul 2003

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radiance
alternating current
scattering
English Channel
stations
phytoplankton
profiles
irradiance
wavelengths
unity
backscattering
attenuation
adjusting
coefficients

Keywords

  • correction algorithm
  • coccolithophore bloom
  • english channel
  • wavelength dependence
  • optics

Cite this

McKee, David J.C. ; Cunningham, Alex ; Craig, Susanne E. / Semi-empirical correction algorithm for AC-9 measurements in a coccolithophore bloom. In: Applied Optics. 2003 ; Vol. 42, No. 21. pp. 4369-4374.
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Semi-empirical correction algorithm for AC-9 measurements in a coccolithophore bloom. / McKee, David J.C.; Cunningham, Alex; Craig, Susanne E.

In: Applied Optics, Vol. 42, No. 21, 20.07.2003, p. 4369-4374.

Research output: Contribution to journalArticle

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