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| Titel |
Light absorption and partitioning in Arctic Ocean surface waters: impact of multiyear ice melting |
| VerfasserIn |
S. Bélanger, S. A. Cizmeli, J. Ehn, A. Matsuoka, D. Doxaran, S. Hooker, M. Babin |
| 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 ; 10, no. 10 ; Nr. 10, no. 10 (2013-10-11), S.6433-6452 |
| Datensatznummer |
250085360
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| Publikation (Nr.) |
 copernicus.org/bg-10-6433-2013.pdf |
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| Zusammenfassung |
| Ice melting in the Arctic Ocean exposes the surface water to more
radiative energy with poorly understood effects on
photo-biogeochemical processes and heat deposition in the upper
ocean. In August 2009, we documented the vertical variability of
light absorbing components at 37 stations located in the
southeastern Beaufort Sea including both Mackenzie River-influenced
waters and polar mixed layer waters. We found that melting
multiyear ice released significant amount of non-algal particulates
(NAP) near the sea surface relative to subsurface waters. NAP
absorption coefficients at 440 nm (aNAP(440))
immediately below the sea surface were on average 3-fold (up to
10-fold) higher compared to subsurface values measured at
2–3 m depth. The impact of this unusual feature on the
light transmission and remote sensing reflectance (Rrs)
was further examined using a radiative transfer model. A 10-fold
particle enrichment homogeneously distributed in the first meter of
the water column slightly reduced photosynthetically available and
usable radiation (PAR and PUR) by ∼6 and
∼8%, respectively, relative to a fully homogenous water
column with low particle concentration. In terms of Rrs,
the particle enrichment significantly flattered the spectrum by
reducing the Rrs by up to 20% in the blue-green
spectral region (400–550 nm). These results highlight the
impact of meltwater on the concentration of particles at sea
surface, and the need for considering non-uniform vertical
distribution of particles in such systems when interpreting remotely
sensed ocean color. Spectral slope of aNAP spectra
calculated in the UV (ultraviolet) domain decreased with depth suggesting that
this parameter is sensitive to detritus composition and/or
diagenesis state (e.g., POM (particulate organic matter) photobleaching). |
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