Geodetic standards and conventions are essential for ensuring the consistency, accuracy, reliability, and interoperability of geodetic data and results. Different geodetic techniques observe the same Earth system but are sensitive to different signals and operate at different spatial and temporal resolutions, with different sensitivities and latencies. Consequently, observations from different techniques can only be consistently combined and interpreted if they are processed and analysed within a common framework of standards and conventions. The use of consistent standards and conventions is particularly important for distinguishing genuine changes in the Earth system from apparent changes arising from inconsistencies in data preparation, processing, modelling, or analysis. Unified standards and conventions therefore provide the foundation for generating high-quality geodetic products, integrating observations from different techniques, ensuring interoperability, and enabling the consistent modelling and reliable interpretation of geodetic results.
The following geodetic products are key to realising, monitoring and applying this Essential Geodetic Variable:
Numerical Standards in Geodesy (NSG)Numerical Standards in Geodesy (NSG): such as speed of light, geocentric gravitational constant, reference-level ellipsoid, potential value of the geoid, geometric-size parameters of the Earth (e.g., equatorial radius and flattening factor), dynamical form factor of the Earth, mean equatorial gravity, atomic time scales, transformation between permanent-tide concepts, etc.
Conventional Background Models (CBM)Conventional Background Models (CBM): a priori models used for data processing. They are regarded as known and are expected to be at least as accurate as the geodetic observation data. Examples include corrections for phase centre variations in emitting and receiving antennas, tidal corrections for the solid Earth tide, permanent tide, and solid Earth pole tide, ocean and atmospheric tide loading effects, a priori tropospheric zenith delays, etc.
IAG as part of the IUGG
IAG Related Organisations
IAG collaborates closely with numerous organizations within geodesy and beyond. See the list for details.
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