Kopelevich O.V., Sahling I.V.
The article presents the results of an analysis of inter-annual changes in the monthly means of bio-optical characteristics in the surface layer of the Barents, Kara, White, Baltic, Black and Caspian Seas for the period 1998–2018, calculated from data satellite color scanners. As the main parameters, the chlorophyll-a concentration, Chl and particle backscattering coefficient, b bp = b bp (555), characterizing the variability of phytoplankton and suspended matter, are discussed. The other characteristics, such as the absorption coefficient of colored organic substance a g = a g (440) as an indicator of river runoff, the parameters that characterize the phytoplankton bloom (coccolithophore blooms in the Barents and Black Seas, of blue-green algae in the Baltic Sea) are also considered. The monthly means of sea surface temperature, SST by MODIS-Aqua data are presented as a parameter characterizing climate change. Most of the bio-optical characteristics were calculated using regional algorithms, derived from field measurements carried out in the considered seas and reflecting their regional features.
The presented data revealed significant changes in bio-optical characteristics that occurred in the considered seas in 2016–2018, in most cases they were associated with phytoplankton blooms. Systematization and analysis of extreme changes in bio-optical characteristics over the entire observation period found a record change in the southern part of the Caspian Sea in July 2001 after the invasion of the ctenophore Mnemiopsis — the chlorophyll concentration increased by more than an order. Another factor contributing to the record variability of bio-optical characteristics is river runoff.
The obtained results provided quantitative data on changes in bio-optical characteristics in the period 1998–2018 for six seas, different in their natural conditions, and provided the basis for further analysis aimed at identifying the processes and factors that caused these changes.