Concept and Status of the ECGN Project

In order to ensure the long-time stability of the terrestrial reference system with an accuracy of 10 in the global and continental scale, the interaction 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. The EUROPEAN COMBINED GEODETIC NETWORK (ECGN) integrates the spatial and height reference system into the Earth gravity field parameter estimation. This is in agreement with the planned IAG project of an Integrated Global Geodetic Observation System (IGGOS). In geodetic fundamental stations the ECGN will establish a European network for the continuation of time series of spatial/geometric observations (GNSS GPS/GLONASS and in the future GALILEO), precise levelling and tide gauge records with gravity field related observations and parameters (gravity, Earth tides), complemented with supplementary information (meteorological parameters, surrounding information of the stations e.g. eccentricities and ground water level). The 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 and in future GALILEO), gravity (super conducting gravimeter and/or absolute gravimeter), levelling connections to nodal points of the European levelling network (UELN) and meteorological parameters. 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. All ECGN stations are part of the European GPS Permanent Network (EPN). For the contributing observation techniques, guidelines have been agreed upon to ensure equal observation principles.