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Abstract:
The International Height Reference System (IHRS) was introduced by the International Association of Geodesy (IAG) in 2015 to provide a global standard for the precise determination of physical heights. The IHRS is based on the combination of a geometric component given by coordinates X referring to the International Terrestrial Reference Frame (ITRF), and a physical component given by the determination of potential values W at the positions P defined by the ITRF coordinates. The primary vertical coordinate is the geopotential number (CP =W0‐WP), which may be converted to a metric (orthometric or normal) height. The IHRS vertical datum is given by the equipotential surface of the Earth's gravity field defined by the conventional value W0 = 62 636 853.4 m2s‐2. The realisation of the IHRS is the International Height Reference Frame (IHRF). The IHRF realises the IHRS in two ways: physically, by a set of globally distributed reference stations, and mathematically, by the precise determination of potential values at the reference stations. Thanks to a strong international cooperation hosted by the IAG, the station selection for the IHRF reference network is completed. Present efforts concentrate on the determination of the potential values at the global IHRF reference stations. After evaluating different approaches, a standard procedure to infer potential values from existing regional and global gravity field models was compiled and applied to release a first IHRF solution.
