Publication Date:
2019-07-17
Description:
Coloured, dissolved organic matter (CDOM), which represents a fraction of dissolved organic carbon (DOC),contributes strongly to the absorption of blue light in Baltic waters. This makes the Baltic an idealtest site for deriving DOC concentrations from ocean colour imagery. Two hundred and five high resolution(1.3km) SeaWiFS images were processed using SeaDAS v.4.0 and combined into monthly composites of reflectance.A simple, in situ-generated reflectance ratio algorithm was used to derive CDOM absorption at 440nm (ag440),and an algorithm from the literature was applied to derive DOC concentrations, with a constant CDOM spectralslope coefficient of 0.019nm{^-1} to extrapolate to the required DOC-algorithm wavelength. Temporalresolution was restricted by cloud cover and by solar illumination conditions: only monthly composites fromMarch to October were practical. Surface DOC concentrations ranged between 4 and 5mgl^{-1}, with elevatedvalues in the cloudiest months (March and October). An increase in surface DOC lagged behind the annualcyanobacterial bloom, which peaked in July, by one month. Assuming a constant DOC profile, basin-integratedDOC estimates for the Baltic of 0.3{/pm}0.04Tg were obtained. The major contributions to error in thistechnique were evaluated.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
