Correlation study of the annual signal in GPS and DORIS station positions with atmospheric and hydrology loading effects

Abstract

In this paper, the origin of the annual signal observed in the position time series of the GPS (Global Positioning System) and DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) co-located stations is investigated, by studying its correlation with atmospheric and hydrological pressure loading signals. The data used are the residual position time series of 11 well-observed GPS-DORIS co-located stations, expressed in the local (North, East and Up) reference frame, and referred to ITRF2014. For the atmospheric and hydrological loading at the 11 selected sites, we used the time series of displacements (North, East and Up) estimated from the atmospheric models ECMWF-IB, ECMWF-TUGO-m barotropic and ERA interim, and from the hydrology models GLDAS/Noah, ERA interim and MERRA2. The annual signal in the analysed position time series is determined by means of the wavelet multi-resolution analysis. The results reveal that the average amplitude of the extracted annual signal in, respectively, North, East and Up components is about 0.55, 0.54 and 1.70 mm for GPS stations, and 4.39, 4.56 and 4.06 mm for DORIS stations. The correlations computed between the extracted annual signal and all atmospheric and hydrological loading models used are low for all analysed GPS stations and significant for only a few components of some DORIS stations.