Frank Lemoine (NASA GSFC, USA); Stavros Melachroinos (SGT Inc, USA); Brian Beckley (SGT Inc, USA); Despina Pavlis (SGT Inc, USA); Jesse Wimert (SGT Inc, USA)

The satellite orbit defines the reference coordinates of the satellite altimeter observation. Precision orbit determination (POD) using SLR or DORIS tracking data relies on the terrestrial reference frame, within which the tracking station coordinates are defined, for the orbit reference frame definition. The origin of the ITRF2008 SLR/DORIS frame is considered to be the long-term center of mass (CM) of the entire Earth system and whose changes are only described by secular motion. The crust-fixed ITRF tracking station position and secular motion define the ITRF origin. We evaluate the effect of correcting the station positions to the instantaneous CM using an annual model on the SLR+DORIS Jason-2 orbit, as well as correcting the station positions due to atmosphere loading. Both corrections improve the SLR residuals and affect the orbit with an annual signal in Z. Orbit differences with the JPL GPS-based orbits, believed closer to the instantaneous center of mass, are included in the evaluation. Both corrections are being considered for inclusion in the next GSFC POD standards and are evaluated for their possible impact on the analysis of altimeter data, and the determination of mean sea level.