The Role of Core and Co-location Sites and the Activities Underway to Improve the Global Space Geodesy Network

Abstract

The Global Geodetic Observing System (GGOS) was established by the IAG to integrate the three fundamental areas of geodesy (Earth’s shape, gravity field, and rotation) and to monitor geodetic parameters and their temporal variations in a global reference frame with a target relative accuracy of 10E-9 or better (See GGOS 2020). The goals were to provide products and services with the geodetic accuracy necessary to address important geophysical questions and societal needs and to provide the robustness and continuity of service which will be required of this system in order to meet future needs and make intelligent long-range decisions. GGOS is constituted mainly from the Services (IERS, IDS, IGFS, IGS, ILRS, IVS, etc.) and its main focus at the moment is the International Terrestrial Reference Frame (ITRF), but we expect other data products requiring multi-technique observations will emerge.