INTERGEO Agenda - english

GNSS coordinate time series are widely used to monitor climate-driven surface deformation caused by atmospheric, hydrological, and oceanic loading. However, these products may contain constellation-specific artefacts related to orbit modelling, observation geometry, and processing strategies. Understanding the consistency of climate-related signals across individual GNSS constellations is therefore important for geodetic climate studies. This study investigates system-specific coordinate time series derived from GPS, GLONASS, Galileo, BeiDou, and combined multi-GNSS solutions produced by the European Space Agency (ESA). The dataset includes stations with at least four years of observations from 2020 to 2025. The GNSS-derived displacements are compared with atmospheric, hydrological, and oceanic loading models. Correlations, amplitude differences, and regional variability are analysed to assess the consistency between individual constellations and geophysical loading signals. Preliminary results reveal clear constellation-specific spectral signatures associated with orbital periods and their aliases, particularly for GLONASS and BeiDou. Relative annual amplitude differences reveal generally good agreement between GPS, Galileo, and multi-GNSS solutions, with median differences of 8–9%, whereas larger discrepancies are observed for BeiDou (11%) and especially GLONASS, whose annual amplitudes are typically 60% smaller than those derived from GPS. While individual systems exhibit distinct artifacts, multi-GNSS solutions substantially reduce long-period orbital signals and show the best agreement with loading models. The analysis also indicates regional differences in the magnitude of system-specific effects. The results provide new insights into the suitability of individual GNSS constellations for climate applications and highlight the benefits of multi-GNSS integration for monitoring environmentally driven surface deformation.