Construction of Earth's gravitational field model from CHAMP, GRACE and GOCE data

The basic principle of spectral combination method is discussed, and the general expressions of the spectral weight and spectral combination of the united-processing of various types of gravimetric data are shown. What's more, based on degree error RMS of potential coefficients, the detailed expressions of spectral combination formulae and the corresponding spectral weights in the Earth's gravitational field model(EGM) determination using GOCE + GRACE and CHAMP + GRACE + GOCE are derived. The fundamental situation that ulux-champ2013s, tongji-GRACE01, go-cons-gcf-2-tim-r5 constructed respectively by CHAMP, GRACE, GOCE data and go-cons-gcf-2-dir-r5 constructed by syncretic processing of GRACE, GOCE and LAGEOS data are explained briefly, the degree error RMS, cumulative geoid height error and cumulative gravity anomaly error of these models are calculated. A syncretic model constructed from CHAMP, GRACE and GOCE data, which is expressed by champ + grace + goce, is obtained based on spectral combination method. Experimentation results show that the precision of CHAMP data model is the lowest in satellite-only models, so it is not needed in the determination of syncretic models. The GRACE data model can improve the GOCE data model in medium-long wavelength, so the overall precision of syncretic model can be improved. Consequently, as many types of gravimetric data as possible should be combined together in the data processing in order to strengthen the quality and reliability with widening scope and improve the precision and spatial resolution of the computational results.