CoAuthors

Nikita Zelensky (SGT Inc., U.S.A); Alexandre Belli (NPP/USRA @ NASA GSFC, U.S.A.); Taylor Thomas (Emergent Space Technologies, USA); Brian Beckley (SGT Inc., U.S.A.); Douglas Chinn (SGT Inc., U.S.A.); Despina Pavlis (ESSIC, University of Maryland @ College Park,, USA); Jean-Paul Boy (EOST/IPGS, University of Strasbourg, France)

Orbit error remains a major component in the overall error budget of all altimeter satellite missions. Error sources include terrestrial reference frame and station positions, systematic and unaccounted-for errors in the satellite tracking measurements, mismodeling of nonconservative forces, and incomplete modeling of time-variable gravity. The agreement between the SLR/DORIS and GPS-reduced-dynamic orbits is at the level of 6-9 mm radial RMS, however we continue to observe systematic signatures in the orbits and in the tracking data. This paper presents a status report on the development of new orbit standards. We seek to address important issues, including improved modeling of the Laser Retroflector Arrays (LRAs) as well as better a priori modeling of geocenter. We re-examine the internal weighting of the SLR stations, as well as the overall weighting with respect to DORIS data in light of recent re-analyses (e.g. ITRF2014). We evaluate the impact of improvements to DORIS data modeling for Jason-2 and Jason-3, taking advantage of the results of the Jason-2 T2L2 experiment. We describe the implementation of the most recent static and time-variable models for the Earth’s geopotential as well as other improvements to the dynamical orbit model. As an operational validation, we describe the comparison of the SLR/DORIS orbits with GPS orbits constructed with similar standards for the Jason satellites, also computed at NASA GSFC with the NASA Orbit Determination and Geodetic Parameter Estimation program (GEODYN).
We present the altimeter measurement calibration with tide gauges for the new sets of orbits as well as comparisons of the GSFC orbits are compared with orbits from other analysis centers, including the CNES, JPL, ESA, and other