Impact of Albedo Modeling on GNSS Satellite Orbits and Geodetic Time Series

GNSS is a vital space technique for reference system realization. While GNSS is important for densification as well as for tying together the networks of the other space geodetic techniques, navigation satellite orbits do not contribute to the definition of the datum of the International Terrestrial Reference Frame. The reasons reside in the sensitivity of the large satellite structures to direct and indirect solar radiation pressure. Differently than gravitational accelerations, perturbations due to incident radiation represent the largest source of uncertainty for GNSS orbits and obscure information on geocenter location and scale. GNSS orbit modeling deficiencies cause peculiar patterns observed in Satellite Laser Ranging (SLR) residuals. In addition, orbit related frequencies are identified in geodetic time series such as apparent geocenter motion and station displacements derived from GNSS tracking data. A probable candidate for radiation pressure mismodeling is related to Earth albedo radiation consisting of visible light and infrared emission. Earth albedo affects the orbit scale and causes characteristic orbit patterns similar to those observed with SLR. We demonstrate the impact of albedo models of different complexity levels on GNSS orbits and investigate the effect of albedo models on geodetic time series based on the analysis of several years of global IGS tracking data.