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| Titel |
MERIS-based ocean colour classification with the discrete Forel–Ule scale |
| VerfasserIn |
M. R. Wernand, A. Hommersom, H. J. Woerd |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 9, no. 3 ; Nr. 9, no. 3 (2013-05-02), S.477-487 |
| Datensatznummer |
250018073
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| Publikation (Nr.) |
 copernicus.org/os-9-477-2013.pdf |
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| Zusammenfassung |
| Multispectral information from satellite borne ocean colour sensors is at
present used to characterize natural waters via the retrieval of
concentrations of the three dominant optical constituents; pigments of
phytoplankton, non-algal particles and coloured dissolved organic matter. A
limitation of this approach is that accurate retrieval of these constituents
requires detailed local knowledge of the specific absorption and scattering
properties. In addition, the retrieval algorithms generally use only a
limited part of the collected spectral information. In this paper we present
an additional new algorithm that has the merit of using the full spectral
information in the visible domain to characterize natural waters in a simple
and globally valid way. This Forel–Ule MERIS (FUME) algorithm converts the
normalized multiband reflectance information into a discrete set of numbers
using uniform colourimetric functions. The Forel–Ule (FU) scale is a sea colour
comparator scale that has been developed to cover all possible natural sea
colours, ranging from indigo blue (the open ocean) to brownish-green (coastal
water) and even brown (humic-acid dominated) waters. Data using this scale
have been collected since the late nineteenth century, and therefore, this
algorithm creates the possibility to compare historic ocean colour data with
present-day satellite ocean colour observations. The FUME algorithm was
tested by transforming a number of MERIS satellite images into Forel–Ule
colour index images and comparing in situ observed FU numbers with
FU numbers modelled from in situ radiometer measurements. Similar
patterns and FU numbers were observed when comparing MERIS ocean colour
distribution maps with ground truth Forel–Ule observations. The FU
numbers modelled from in situ radiometer measurements showed a good
correlation with observed FU numbers (R2 = 0.81 when full
spectra are used and R2 = 0.71 when MERIS bands are used). |
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