Re-Analysis of a Decade of Continuous GPS Data at the Scripps Orbit and Permanent Array Center: Implications for Terrestrial Reference Frame Stability

The Scripps Orbit and Permanent Array Center serves as a global archive and analysis center for the International GPS Service, since it inception. Recently, we have completed a re-analysis of our entire archive of continuous GPS data spanning more than a decade in a consistent manner with the GAMIT/GLOBK software suite. We have produced new orbital solutions, EOP parameters, site coordinates, and SINEX files in the ITRF97 reference frame which have replaced our (inconsistently-analyzed) long-term operational products on the SOPAC Web Site. The terrestrial reference frame is realized by the adoption of a set of epoch coordinates and velocities for a set ot global tracking stations. We describe a time series analysis of the site coordinate solutions that provides insight into the long-term stability of the terrestrial reference frame defined by GPS. In particular, we characterize the noise in the time series, identify periodic signals, and investigate non-linear effects that complicate the assignment of a velocity and a velocity uncertainty for global tracking sites.