Global terrestrial reference systems and their realizations

Geodetic reference systems are fundamental requisites for accurate and reliable geodetic results. Unambiguous reference systems are needed to refer the geodetic observations and estimated parameters to a unique global basis. Highly accurate, consistent and reliable realizations of the terrestrial reference systems are required for measuring and mapping the Earth's surface and its variations in time. These terrestrial reference frames are the basis for many practical applications, such as national and regional geodetic networks, engineering, precise navigation, geo-information systems, etc. as well as for scientific investigations in the Earth's system (e.g., tectonic plate motion, sea level change, seasonal and secular loading signals, atmosphere dynamics and Earth orientation excitation).