From satellite antenna Centers of Phase to the Center of the Earth: a study in improving the modeling of SLR/DORIS antenna phase centers and of the geocenter
Event: 2018 Ocean Surface Topography Science Team Meeting
Session: Precision Orbit Determination
Presentation type: Type Oral
The computed altimeter satellite orbit defines the reference frame of the altimeter observation, and continues to be the largest component of the error budget for altimeter measurements. Analysis of SLR/DORIS tracking data residuals and Jason orbits suggest significant improvements can be further achieved in modeling of the SLR/DORIS antenna phase centers and of the Earth’s center of mass. Imperfect knowledge of the SLR/DORIS antenna centers of phase contributes to error in the satellite center-of-mass location and results in the degradation in the quality of the orbit and of estimates for geodetic parameters. Analysis of SLR residuals suggests considerable error remains in SLR phase center modeling of over 15 mm for TOPEX/Poseidon and up to 8 mm for the Jason satellites. Analysis of DORIS residuals suggests that multi-path presents a considerable source of error. Our results suggest antenna phase center azimuth-elevation maps can serve as the most practical incremental correction to the current modeling. The altimeter measurement frame origin should be aligned to the center of mass of the total Earth (CM). Tests have shown that the current POD standard Ries (2013) annual CM model moderately improves alignment of the Jason-2 SLR+DORIS orbit origin with the instantaneous geocenter. GSFC and other CM models derived from LAGEOS and Jason-2 SLR and DORIS are compared, and the impact of improvements to modeling Earth tides, tidal EOP, and other corrections evaluated. There is some variation between the available CM models, but there is no consensus for the criteria to be used in selecting the best model. Our test of Jason orbit centering, which relies on the sensitivity of SLR and DORIS tracking, will be presented as a possible objective approach for such evaluation.