The Kaiserslautern multiscale geopotential model SWITCH-03 from orbit perturbations of the satellite CHAMP and its comparison to the models EGM96, UCPH2002_02_0.5, EIGEN-1s and EIGEN-2

Observed orbit perturbations of the near- Earth orbiting satellite CHAMP are analysed to recover the long- wavelength features of the Earth's gravitational potential. More precisely, by tracking the low- flying satellite CHAMP using the high- flying satellites of the Global Positioning System (GPS) the kinematic orbit of CHAMP is obtainable from GPS tracking observations, i. e. the ephemeris in Cartesian coordinates in an Earth- fixed coordinate frame (WGS84) becomes available. In this study we are concerned with two tasks: first we present new methods for preprocessing, modelling and analysing the emerging tracking data. Then, in a first step we demonstrate the strength of our approach by applying it to simulated CHAMP orbit data. In a second step we present results obtained by operating on a data set derived from real CHAMP data. The modelling is mainly based on a connection between non- bandlimited spherical splines and least- square adjustment techniques to take into account the non- sphericity of the trajectory. Furthermore, harmonic regularization wavelets for solving the underlying satellite- to- satellite tracking (SST) problem are used within the framework of multiscale recovery of the Earth's gravitational potential leading to SWITCH- 03 (Spline and Wavelet Inverse Tikhonov regularized CHamp data). Further we show how regularization parameters can be adapted adequately to a specific region thereby improving a globally resolved model. Finally we compare the developed model with the EGM96 model, model UCPH2002_02_0.5 from the University of Copenhagen and the GFZ models EIGEN- 1s and EIGEN- 2.