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| Titel |
Remote sensing of size structure of phytoplankton communities using optical properties of the Chukchi and Bering Sea shelf region |
| VerfasserIn |
A. Fujiwara, T. Hirawake, K. Suzuki, S.-I. Saitoh |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 12 ; Nr. 8, no. 12 (2011-12-08), S.3567-3580 |
| Datensatznummer |
250006241
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| Publikation (Nr.) |
 copernicus.org/bg-8-3567-2011.pdf |
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| Zusammenfassung |
| Recent ocean warming and subsequent sea ice decline resulting from climate
change could affect the northward shift of the ecosystem structure in the
Chukchi Sea and Bering Sea shelf region (Grebmeier et al., 2006b). The size
structure of phytoplankton communities provides an index of trophic levels
that is crucial to understanding the mechanisms underlying such ecosystem
changes and their implications for the future. This study proposes a new
ocean color algorithm for deriving this characteristic by using the region's
optical properties. The size derivation model (SDM) estimates the
phytoplankton size index FL on the basis of size-fractionated
chlorophyll-a (chl-a) using the light absorption coefficient of phytoplankton,
aph(λ), and the backscattering coefficient of suspended particles
including algae, bbp(λ). FL was defined as the ratio of algal biomass
attributed to cells larger than 5 μm to the total. It was expressed by
a multiple regression model using the aph(λ) ratio,
aph(488)/aph(555), which varies with phytoplankton pigment
composition, and the spectral slope of bbp(λ), γ, which is an index of the
mean suspended particle size. A validation study demonstrated that 69% of
unknown data are correctly derived within FL range of ±20%. The
spatial distributions of FL for the cold August of 2006 and the warm
August of 2007 were compared to examine application of the SDM to satellite
remote sensing. The results suggested that phytoplankton size was responsive
to changes in sea surface temperature. Further analysis of satellite-derived
FL values and other environmental factors can advance our understanding
of ecosystem structure changes in the shelf region of the Chukchi and Bering
Seas. |
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