Chapter 16 Satellite-derived flow characteristics of the Caspian Sea

Abstract

Abstract Mesoscale dynamics of the Caspian Sea are analyzed with satellite data to capture rapid submesoscale motions not sufficiently resolved by in-situ measurements. A combination of Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ocean color data and Advanced Very-High Resolution Radiometer (AVHRR) sea surface temperature (SST) measurements provide a novel evaluation of marine biogeochemical and physical processes and their forcing mechanisms. The main feature of the Caspian Sea is higher pigment concentration with respect to other basins in the Mediterranean region. SeaWiFS detects riverine sediments introduced into the Caspian Sea by the Ural, Terek, Volga, and other rivers, and planktonic flora created in the Caspian Sea by nutrient-rich river runoff. The influence of river flow into the north-northwestern shelf area is especially evident after springtime flooding. Runoff from the Volga River has a major impact on the biomass in the northern Caspian Sea. Eddies and river plumes in coastal waters transport materials and momentum into the Caspian's northern and middle basins. In winter, the cyclonic (counterclockwise) circulation leads to much higher SST in the eastern part of the Caspian than in the west. In summer, wind-induced upwelling yields a pronounced decrease in temperature and higher biomass in the upper layer of the eastern Caspian Sea. In spring, cold water is formed over the entire northern Caspian Sea.