Reference Frame ITRF

The International Terrestrial Reference Frame (ITRF) is the global geodetic reference frame that gives station coordinates and velocities for the whole Earth, realized by the IERS from VLBI, SLR, GNSS, and DORIS observations. Each version, such as ITRF2014 and ITRF2020, fixes the origin at the Earth system center of mass, the scale, and the orientation, and provides the millimeter-level positions and the plate and GIA velocities behind precise positioning. Tide-gauge benchmarks, GNSS stations, and altimeter orbits are all tied to it, so sea-level trends are geocentric and mutually comparable. It is the spatial backbone for separating ocean change from vertical land motion.