A global CHAMP gravity field by merging of regional refinement patches

The usual way of modeling the global gravity field is by means of spherical harmonics. A disadvantage of this kind of gravity field representation is the lack of flexibility in modeling the inhomogeneous gravity field features in specific regions with different roughness. As an alternative the gravity field can be modeled by space localizing base functions as harmonic splines. The advantage of this method is the possibility of adjusting the spline representation and the recovery procedure according to the regional gravity field structures and the specific data distribution. Subsequently, several regional solutions with global coverage can be merged to obtain a global solution. A spherical harmonic representation, in principle up to an arbitrary maximum degree, can be obtained as well by means of quadrature methods in a direct way avoiding the inverse procedure. Such a global refinement from a combination of regional refinement patches is presented in the following. It is based on our CHAMP gravity field ITG-CHAMP01K derived from one year of kinematical CHAMP orbits. The refinement strategy reveals that a regional recovery technique enables the extraction of additional information out of the given data set and therefore leads to a considerable improvement of the global solution. Citation.A. Eicker, T. Mayer-Guerr, K.H. Ilk: A global CHAMP gravity field by merging of regional refinement patches, CHAMP/GRACE Science Team Meet. 2004, published online, www.gfz-potsdam.de/pb1/JCG, 2005