Authors: Fengler M.J.; Freeden W.; Michel V.

Source: Geophysical Journal International, Volume 157, Number 2, May 2004 , pp. 499-514(16)

Publisher: Wiley-Blackwell

Abstract:

SUMMARY

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 pre-processing, 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.

Keywords: CHAMP post-processed science orbit data; regional gravitational field recovery; spherical splines; Tikhonov wavelet regularization

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1365-246X.2004.02209.x

Publication date: 2004-05-01

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