Abstract
Abstract. In addition to scattering coefficients, the light absorption coefficients of particulate and dissolved materials are the main factors determining the light propagation of the visible part of the spectrum and are, thus, important for developing ocean color algorithms. While these absorption properties have recently been documented by a few studies for the Arctic Ocean (e.g., Matsuoka et al., 2007, 2011; Ben Mustapha et al., 2012), the data sets used in the literature were sparse and individually insufficient to draw a general view of the basin-wide spatial and temporal variations in absorption. To achieve such a task, we built a large absorption database of the Arctic Ocean by pooling the majority of published data sets and merging new data sets. Our results show that the total nonwater absorption coefficients measured in the eastern Arctic Ocean (EAO; Siberian side) are significantly higher than in the western Arctic Ocean (WAO; North American side). This higher absorption is explained by higher concentration of colored dissolved organic matter (CDOM) in watersheds on the Siberian side, which contains a large amount of dissolved organic carbon (DOC) compared to waters off North America. In contrast, the relationship between the phytoplankton absorption (aϕ(λ)) and chlorophyll a (chl a) concentration in the EAO was not significantly different from that in the WAO. Because our semianalytical CDOM absorption algorithm is based on chl a-specific aϕ(λ) values (Matsuoka et al., 2013), this result indirectly suggests that CDOM absorption can be appropriately derived not only for the WAO but also for the EAO using ocean color data. Based on statistics, derived CDOM absorption values were reasonable compared to in situ measurements. By combining this algorithm with empirical DOC versus CDOM relationships, a semianalytical algorithm for estimating DOC concentrations for river-influenced coastal waters of the Arctic Ocean is presented and applied to satellite ocean color data.
Highlights
The Arctic Ocean faces dramatic changes in physical environments driven by ongoing global warming
Recent papers showed that an increase in primary production (PP) is significantly and positively correlated with open water area (Arrigo and van Dijken, 2011), suggesting that autochthonous dissolved organic carbon (DOC) resulting from the increased PP could be a nonnegligible source for open waters (Wheeler et al, 1996)
The higher aCDOM(443) of the eastern Arctic Ocean (EAO) was partly responsible for the higher atw(443) compared to that of the western Arctic Ocean (WAO) (relative contribution to atw(443) of 85 ± 7 % and 67 ± 19 %, respectively; Fig. 3)
Summary
The Arctic Ocean faces dramatic changes in physical environments driven by ongoing global warming. Decreases in both sea ice extent and thickness (Comiso et al, 2008; Kwok, 2007; Stroeve et al, 2008) facilitate the propagation of light into the water column, creating favorable conditions for phytoplankton’s photosynthetic processes when. In terms of the DOC budget, DOC concentrations in river-influenced coastal waters are much higher than for open waters (Benner et al, 2005; Stedmon et al, 2011; Amon et al, 2012, Matsuoka et al, 2012). A comprehensive method for quantifying and continuously monitoring DOC concentrations, which takes into account their temporal and geographical variability for river-influenced coastal waters of the Arctic Ocean, is presently not available
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