Study of seasonal and long-term phytoplankton variability in the Caspian Sea based on remote sensing data.

The patterns of seasonal and long-term variability of phytoplankton in the Caspian Sea have been studied using SeaWiFS and MODIS-Aqua data. Chlorophyll "a" concentrations (CHL) in the Caspian Sea were calculated by the regional algorithm developed using an array of in situ measurements in different seasons of the year. Maps of the average monthly CHL values over a twenty-two-year period and seasonal variability diagrams were constructed for the Northern, Middle and Southern Caspian Sea. The features of seasonal variability of phytoplankton are analyzed using CHL data. The fundamental differences were mentioned in seasonal variability of phytoplankton in the Northern, Caspian Middle and Southern Caspian. The regularities of the spatial dynamics of CHL throughout the sea have been studied according to seasonal succession of phytoplankton. The years with significant deviations of the seasonal dynamics of CHL from the average climatic one were identified.