Krzysztof Sośnica

The time series of station coordinates derived using Global Navigation Satellite Systems (GNSS) are affected by several technique errors, influencing the studies of the geophysical processes and phenomena. Using different GNSS constellations leads to the appearance of various artificial signals with amplitudes up to several millimeters. The presence of the GNSS system‐specific artifacts is demonstrated using the 2‐year long series of station coordinates and zenith total delay parameters for 15 stations using Precise Point Positioning algorithms. The most dominant orbital artifacts for Galileo appear with periods of 14.08 hr, 17.09 hr, 34.20 hr, 2.49 days, and ∼3.4 days. The corresponding signals for GLONASS appear with periods of 5.63 hr, 7.36 hr, 10.64 hr, 21.26 hr, 3.99 days, and ∼8 days. Moreover, when estimating discrete 24‐hr solutions from high‐rate GNSS data, high‐frequency signatures are under‐sampled, resulting in long‐term aliased periodic signals. Galileo is less vulnerable to the orbital signals than GPS or GLONASS. The difference is visible mainly for the East coordinate. The Galileo‐based daily estimates are up to 55% and 36% better than those delivered from GLONASS and GPS. The GPS orbital signals arise at the periods corresponding to the harmonics of the K 1 tide, which leads to the inconsistency of the GPS‐based products with geophysical models reaching on average 12 mm for the K 2 tidal term in the Up component. The magnitude of the orbital signals depends on the geographical location of the station and the geometry of the satellites' flybys. Finally, using a combination of GPS and Galileo increases the precision of estimates by 10% compared with the best‐case Galileo‐only solution.