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Abstract

A central task of the IAG sub-commission 1.3a for Europe, EUREF, is the provision and maintenance of terrestrial reference systems for Europe, namely the European Vertical Reference System (EVRS) and the European Terrestrial Reference System 1989 (ETRS89). One objective of EUREF, which provides reference frames for ETRS and EVRS, is to provide uniform reference frames for use within European countries. The latest realisation of the EVRS, the European Vertical Reference Frame (EVRF), is the EVRF2019 and it is realised through the Unified European Levelling Network (UELN). The realisation of the ETRS89, the European Terrestrial Reference Frame (ETRF), is following the most recent realisation of the International Terrestrial Reference System (ITRS) and is implemented through the EUREF Permanent Network (EPN). Currently, the ETRF2020 is under development, compliant with and derived from the latest release of the International Terrestrial Reference Frame, ITRF2020 by similarity transformation. A missing link between both European frames is a European geoid, which is under investigation in the 2021 established Working Group “European Unified Height Reference”. For the realisation of the International Height Reference System (IHRS) into an International Height Reference Frame (IHRF), the implementation in Europe will include to establish a precise and well-defined relation between IHRF and EVRF.