One of the most important and unique task of space geodesy is a development and control of the global terrestrial reference coordinate frame ndash; ITRF, accurate and stable within millimeter level. Small movements of the ITRF origin geocenter, which conventionally coincides with the Earth's center of mass, provide important information about mass redistribution in the Earth system. An accuracy of the geocenter position estimation is strongly dependent on the geodetic network size and stations distribution over the Earth's surface. From this point of view Doppler Orbit determination and Radiopositioning Integrated on Satellites DORIS system has an advantage, as its ground network of beacons consists of about 70 sites, equally distributed over the Earth's surface. The IDC Analysis Center of the Institute of astronomy, RAS, performs DORIS data analysis since 1995. Estimated amplitudes of annual and semiannual variations of the geocenter positions are in the limits of 2ndash;10nbsp;mm for horizontal components and 8ndash;30nbsp;mm for vertical component. The first attempt to develop a mathematical model of the geocenter motion has been made with the use of Dynamic Regression Modelling approach for spectral analysis of the long set 16nbsp;years of geocenter coordinates, estimated by DORIS measurements at the Institute of Astronomy of the Russian Academy of Sciences INASAN. In the issue of these studies a possibility to predict the preliminary geocenter positions with the accuracy about 2ndash;4nbsp;mm seems feasible over time period up to 10 weeks by the use of mathematical models. Further improvement of the contemporary ITRF could be possible only with dense and equally distributed tracking networks equipped with different measurement techniques. A development of the precise fundamental geodetic network, based on the combined use of GNSS, SLR and VLBI measurements, is now carried out in Russia. Monitoring of secular movements velocities of the permanent GPS-stations, located in Russia, already provided an improvement of the reference coordinate frame for North Eurasia. Studies of the seismic belts of Eurasia and velocities of the crust movement, estimated with the use of GPS measurements, showed that only a northern part of the continent could be classified as an indivisible lithosphere plate. It could be named the North Eurasian Plate unlike the Eurasian Plate, which doesn't exist now as an indivisible tectonic block.
ITRF origin estimation, space geodesy, monitoring tectonic movements
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