5:00 PM - 5:15 PM
[G02-6-03] On the practical realization of the fixed GBVP approach for a unification of height systems in Central Europe
By using tide gauge observations, national height reference systems have conventionally been linked to the local mean sea level. Due to variations in the sea surface topography, different tide gauges do not realize the same height reference level in terms of a global equipotential surface. The resulting discrepancies cause height datum offsets with a magnitude of about +- 1-2m at a global scale.
To achieve a height system unification of high precision, an approach based on the solution of the fixed Geodetic Boundary Value Problem (GBVP) is proposed. On the basis of gravity disturbances and their rigorous transformation into gravity anomalies, Hotine's integral formula is solved at GNSS/leveling benchmarks in different height datum zones, which allows to estimate datum offsets as unknown parameters in a least squares adjustment.
Based on the analysis of several case studies, this contribution presents first results of a practical realization of the fixed GBVP approach for a unification of height systems in Central Europe. To this end, several practical aspects have to be considered and taken into account. Due to the limited availability of gravity data of the necessary resolution and accuracy, it is not possible to evaluate Hotine's integral formula to its global extent. Therefore, the integration area is restricted to a near zone around the respective GNSS/leveling benchmarks, where regional high-resolution gravity anomaly data is available. In order to accelerate the convergence rate of the resulting truncation error, a suitable modification of the Hotine-kernel is applied. Furthermore, to reduce systematic errors, the terrestrial gravity data is combined with the information of a satellite-based global geopotential model as well as topographic effects within a remove-compute-restore procedure.
In order to evaluate the obtained height datum offsets, results are compared to the transformation parameters of the unified European Vertical Reference Frame EVRF2007.
To achieve a height system unification of high precision, an approach based on the solution of the fixed Geodetic Boundary Value Problem (GBVP) is proposed. On the basis of gravity disturbances and their rigorous transformation into gravity anomalies, Hotine's integral formula is solved at GNSS/leveling benchmarks in different height datum zones, which allows to estimate datum offsets as unknown parameters in a least squares adjustment.
Based on the analysis of several case studies, this contribution presents first results of a practical realization of the fixed GBVP approach for a unification of height systems in Central Europe. To this end, several practical aspects have to be considered and taken into account. Due to the limited availability of gravity data of the necessary resolution and accuracy, it is not possible to evaluate Hotine's integral formula to its global extent. Therefore, the integration area is restricted to a near zone around the respective GNSS/leveling benchmarks, where regional high-resolution gravity anomaly data is available. In order to accelerate the convergence rate of the resulting truncation error, a suitable modification of the Hotine-kernel is applied. Furthermore, to reduce systematic errors, the terrestrial gravity data is combined with the information of a satellite-based global geopotential model as well as topographic effects within a remove-compute-restore procedure.
In order to evaluate the obtained height datum offsets, results are compared to the transformation parameters of the unified European Vertical Reference Frame EVRF2007.