In this investigation a consistent combination of the complementary data types of satellite observations and the available terrestrial gravity field measurements in Austria is considered. For this purpose, the well known Remove-Compute-Restore technique is adapted to perform long-and short-wavelength signal reductions. The long-wavelength effect is represented by a global satellite-only model in terms of spherical harmonics. The shortwavelength are modeled by topographic masses in the spatial domain. As the topographic reduction contains also long-wavelength effects a possible double consideration has to be avoided. Alternatively to Least Squares Collocation (LSC) method (Moritz 1980a) a least squares approach with parametrization as Radial Basis Functions (RBF) is applied. The RBF approach has the advantage that an increasing number of observations can be included in the calculations and a downsampling of the available data, as it is required in LSC, will no longer be necessary. Another advantage is that RBF is to able to handle an inhomogeneous input data distribution. The very first outcomes are verified by comparing with independent GPS/leveling observations. instance, with the GOCE mission it is possible to derive a global gravity field model parametrized in terms of a spherical harmonic series expansion up to a degree and order (D/O) of 250 corresponding to a spatial resolution of approximately 80 km half wavelength. The accuracy in terms of geoid height with 100 km spatial resolution is 1-2 cm (Drinkwater et al. 2008). However, for regional applications the spatial resolution of a satellite-only gravity field model is insufficient. Many local and regional applications require a much higher spatial resolution than a satellite-only model can provide. On the other hand, local gravity field models derived from terrestrial and airborne gravity field data e.g. gravity anomalies or deflections of the vertical reflect the small scale features better as the satellite data but lack from long-wavelength information. Therefore a pure gravimetric geoid solution is affected by long-wavelength errors (Pail et al. 2009).
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