Development of a European Combined Geodetic Network (ECGN)

To ensure the long-time stability of the terrestrial reference system with an accuracy of 10‑9 in the global and continental scale, the interactions between different time-dependent influences of the system Earth to the terrestrial reference system and the related observation has to be considered in the evaluation models. It is proposed to establish a kinematic European Combined Geodetic Network (ECGN) and to integrate the spatial and height reference system into the Earth gravity field parameter estimation. This plan is in agreement with the foreseen IAG project of an Integrated Global Geodetic Observation System (IGGOS). In selected European stations ECGN will establish the combination of time series of spatial/geometric GNSS observations, precise levelling and tide gauge records with gravity field related observations (gravity, Earth tides). Observations are complemented with meteorological parameters, surrounding information of the stations, e.g. eccentricities and ground water level. A first call for participation in the project was directed to the implementation of the ECGN stations. These stations include the standard observation techniques GNSS (GPS/GLONASS—permanent), gravity (super conducting gravimeter and/or absolute gravimeter—permanent or repeated), levelling connections to nodal points of the European levelling network (UELN) (repeated) and meteorological parameters (permanent). A basic constituent of the ECGN stations is a local network for controlling the eccentricities at the 1 mm accuracy level in all three spatial components. For the contributing observation techniques, guidelines have been agreed upon to ensure equal observation principles