| Abstract: | Due to the successful operation of dedicated satellite gravity missions, nowadays high-accuracy global gravity field models
have become available. This triggers the challenge to optimally combine this long to medium wavelength gravity field information
derived from space-borne data with high-resolution terrestrial gravity data. In this paper, the least squares collocation
concept is revised with the attempt to consistently unify the combination procedure in such a way that the full information
contained in both data sets is merged. For example, in local or regional geoid determination the remove-restore method is
usually applied only partially taking into account the accuracy of the global model coefficients used for the long-wavelength
reduction. The key advantage of the extended formulation is the fact that it automatically accounts for the error covariance
of all data types involved. The applicability, feasibility and performance of the proposed method is investigated in the frame
of numerical closed-loop simulations. The two main fields of application, i.e., the improvement of a global gravity field
model by terrestrial gravity field data, and, vice versa, the support to a regional geoid solution by the incorporation of
a global gravity field model, have been analyzed and assessed. Although applied under simplified conditions, it could be shown
that the method works and is practically applicable. |
