Temporal Variability of Ocean Colour Derived Products in the European Seas
The ten-year record of ocean colour data provided by the SeaWiFS mission is an important asset for monitoring and research activities conducted on the optically-complex European seas. This study mainly makes use of the SeaWiFS data set of normalized water leaving radiances LWN to study the major characteristics of temporal variability associated with optical properties across the entire European domain. Specifically, the time series of LWN, band ratios, diffuse attenuation coefficient Kd(490) and concentration of chlorophyll a Chla are decomposed into terms representing a fixed seasonal cycle, irregular variations and trends, and the contribution of these components to the total variance is described for the various basins. The diversity of the European waters is fully reflected by the range of results varying with regions and wavelengths. Generally, the Mediterranean and Baltic seas appear as two end-members with, respectively, high and low contributions of the seasonal component to the total variance. The existence of linear trends affecting the satellite products is also explored for each basin. The interpretation of the trends observed for LWN and band ratios is not straightforward, but it circumvents the limitations resulting from the levels of uncertainty, very variable in space and often high, that characterize derived products such as Chla in European waters. Results for Kd(490) and Chla are also analyzed. Statistically significant, and in some cases large, trends are detected in the Atlantic Ocean west of the European western shelf, the central North Sea, the English Channel, the Black Sea, the northern Adriatic, and various regions of the Mediterranean Sea and the northern Baltic Sea, revealing changes in the concentrations of optically significant constituents in these regions.
VANTREPOTTE Vincent;
MELIN Frederic;
2008-12-02
OPOCE
JRC48490
1018-5593,
EUR 23579 EN,
https://publications.jrc.ec.europa.eu/repository/handle/JRC48490,
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