On the Impact of Multi-GNSS Solutions on Satellite Products and Positioning

In Global Navigation Satellite System (GNSS) coordinate time series unrecognised errors and un-modelled (periodic) effects may bias non-linear motions induced by geophysical signals. Those spurious signals can be caused either due to un-modelled long periodic signals or propagation of sub-daily signals into the time series. Understanding and mitigating these errors is vital to reduce biases and on revealing subtle geophysical signals. Mostly, the spurious signals are caused by unmodelled errors which occur due to the draconitic years, satellite ground repeats and absorption into resonant GNSS orbits. Accordingly, different features can be observed in GNSS-derived products from different single-GNSS or combined-GNSS solutions. To assess the nature of periodic signals on station coordinate time series Precise Point Positioning (PPP) solutions are generated using the Bernese GNSS Software V5.2. The solutions consider only GPS, only GLONASS or combined GPS+GLONASS (GNSS) observations. We assess the periodic signals of station coordinates computed using the combined International GNSS Service (IGS) and four of its Analysis Centers (ACs) products.