Consistent Combination of Satellite and Terrestrial Gravity Field Observations in Regional Geoid Modeling: A Case Study for Austria

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 short-wavelength 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.