Variometric approach for displacement analysis using Galileo data

The Variometric Approach for Displacement Analysis Standalone Engine (VADASE)* was successfully applied for seismological and monitoring purposes using GPS observations. The Galileo system, recently entered in the Initial Services operation phase, supplies GPS inter-operable and specific observations that can be used by VADASE. In this work, the Galileo derived VADASE solutions are inspected to evaluate the impact of the European system. In particular, the combined GPS and Galileo variometric model has been improved in order to consider two receiver clock variations for both the systems. VADASE solutions were, at first, computed using single and iono-free observations from a set of IGS-MGEX sites in order to evaluate the sensitivity of the solutions with respect a static scenario. After, real displacements were investigated using U-blox single frequency receivers. The comparison with the GPS derived solutions was carried out selecting GPS constellations with the same number of satellites and the closest PDOP values to that of the Galileo constellations inspected. The analysis was carried out using broadcast and precise orbits. Standard statistics of the Galileo derived solutions are provided and commented. In general, the solutions are of good quality and essentially comparable to or better than the GPS derived solutions. The preliminary results enhance the contribution of Galileo system and pave also the way to a wider use of low-cost single frequency receivers for monitoring applications. Furthermore, a WebApp version of the VADASE software is presented in order to give to the scientific community the possibility to run the variometric approach on RINEX files.