ИСТИНА

The GRACE and GRACE-FO satellites provide data on the Earth's gravitational field changes and are among the most successful NASA/DLR geodetic missions in recent decades. We use multichannel singular spectral analysis (MSSA) to filter JPL Level 2 release 6.3 data on gravity field and apply river basins masks from Simulated Topological Network (STN-30p) database. We obtained principal components of mass changes since 2002 till now for the rivers flowing into the Caspian Sea. By comparison with altimetry data, we tried to estimate trends and role of these rivers. The trend for the Volga River of -2.7 km3/year for GRACE and -4.8 km3/year for GRACE-FO epochs is found to be important, but not the only reason of the Caspian Sea level (SL) drop. We estimated effect from the ICE-6G GIA model, showing small uplift of the sea bottom with positive contribution of +0.1 cm/year to the Caspian SL. The approximate influence on Earth rotation velocity (increase) is at the level of 1 microsecond per 10 cm of SL drop.