The Global Geodetic Observing System: The two meanings of GGOS

The acronym GGOS has two very distinct meanings, which should not be confused:

• the "organization GGOS" consisting of components such as committees, panels, working groups, etc., and
• the "observation system GGOS" comprising the infrastructure of many different instrument types, satellite missions, and data and analysis centers. While GGOS as an organization has established its structure from essentially new entities and will, over the next years, add new entities where needed, the observational infrastructure for GGOS as the system is being largely provided by the IAG Services.

While the components of the GGOS organization are fully under the control of the International Association of Geodesy (IAG), the same is not true for all the components contributing to GGOS the observing system. Many parts of the infrastructure are provided by other organizations not even loosely affiliated with IAG. For example, the GPS system, which is crucial for the IGS, is operated and maintained by the U.S. Department of Defence. Many of the relevant satellite missions including satellite altimetry, gravity, and InSAR missions are under the control of space agencies, while GGOS only can utilize the observations.