Characterization of periodic signals and noises of Geocenter motion from space geodesy techniques data

Abstract

The purpose of this work was to characterize the signals and noises of Geocenter variations time series obtained from different space geodesy techniques as Global Positioning System (GPS), Doppler Orbitography and Radiopositioning Integrated on Satellite (DORIS), and Satellite Laser Ranging (SLR). The methodology proposed is based on the estimation of periodic signals by performing the frequency analysis using FAMOUS software (Frequency Analysis Mapping On Unusual Sampling) and evaluation of noises level and type by Allan variance technique. The available data covers 13 years (from 1993 to 2006) of weekly series of Geocenter residuals components, according to ITRF2000. The results obtained are more accurate according to GPS and SLR of about 2-8 mm than DORIS of about 8-42 mm. The estimated seasonal signals amplitudes are of about of few mm per technique with centimeter level for Z Geocenter coordinate of DORIS. The Geocenter motion derived from the SLR technique is more accurate and close to the geodynamic models. The noise analysis shows a dominant white noise in the SLR and DORIS solutions at level of 0.6-1 mm and 10- 40 mm, respectively. However, the GPS solution is characterized by a flicker noise at the millimetre level, relating to mismodelling systematic errors.