JPL's Reanalysis of Historical GPS Data for the Second IGS Reanalysis Campaign

As an analysis center of the International GNSS Service (IGS), the Jet Propulsion Laboratory has participated in the second IGS reanalysis campaign for its contribution to the 2013 International Terrestrial Reference Frame. While the IGS campaign requests products starting in 1994, our products span August 16, 1992 to present. Our contributions to the IGS includes orbit and clock solutions for the Global Positioning System (GPS) constellation of satellites, GPS station positions, Earth orientation parameters, and estimates of zenith troposphere delay. Our satellite clock contributions are at 5-minute intervals for the entire period, but we also provide clock solutions at 30-second intervals for the period May 5, 2000 onward. For our entire reanalysis period, our products also include information from the network solutions on the phase biases for the widelane data combination. This information enhances precise point positioning for single receivers, by enabling integer resolution of the GPS carrier phase biases without the need for nearby reference stations. In this paper we present the processing strategy that we have used for this campaign, as well as results from the evaluation of precision and accuracy of our estimates of orbit positions, clocks, and Earth orientation parameters. This reanalysis of historical GPS data is the third that we have performed over the last 7 years. We show the evolution of the products from each campaign, highlighting the impact of successive changes to our processing approach. The most significant improvements in our most recent reanalysis occurs for the periods from 2008 onward, with 3-D orbit and clock precision reaching 2 cm and 50 picoseconds, respectively. We also show the evolution of GPS-based reference frame realization from our successive reanalyses, where stabilities of < 0.5 mm/year have been achieved in each component of the translation parameters.