Impact of new Earth’s time-variable gravity field models on orbits of altimetry satellites

Gravitational forces are the major forces acting on near-Earth orbiting (e.g., altimetry) satellites. Recently published Earth’s gravity field models used within the satellite precise orbit determination (POD) comprise observations of GRACE (Gravity Recovery And Climate Experiment) and GRACE-FO (GRACE-Follow-On), gravity field satellite missions between 2002 until 2017 and since 2018, respectively. In this presentation, we perform a review of selected Earth’s time-variable gravity field models developed in the past ten years (2014-2023). We analyze also the POD results obtained for selected altimetry satellites, namely, TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 at the time interval from 1992 to 2023 using various Earth’s gravity field models. A special focus is put on the CNES/GRGS mean gravity field models of releases 2 to 5, including the latest CNES_GRGS.RL05MF_COMBINED_GRACE_SLR_DORIS model. The impact of these models is assessed for different orbit parameters as well as the root-mean-square and mean values of Satellite Laser Ranging observation residuals and orbit differences. Furthermore, the impact of these models on altimetry (single- and multi-satellite) sea surface height crossover differences is investigated. From these crossover differences, radial errors and geographically-correlated mean errors are derived and analyzed. The results are used to conclude on the accuracy of current Earth’s time-variable gravity field models when used for the POD of altimetry satellites.