The satellite-only gravity field model GOCO2025s

Abstract. GOCO2025s is a global gravity field model represented by spherical harmonic coefficients up to degree and order 300, with constrained secular, annual, and semi-annual variations up to degree and order 200. It is derived from 23 years of satellite data, incorporating observations from the dedicated gravity field missions Gravity field and steady-state Ocean Circulation Explorer (GOCE), Gravity Recovery and Climate Experiment (GRACE), and GRACE Follow-On (GRACE-FO), as well as kinematic orbits of 18 low Earth orbit satellites and satellite laser ranging observations to 9 passive geodetic satellites. The complementary measurement principles of the different satellite missions and their strengths in determining specific parts of the spherical harmonic spectrum were exploited by combining the data at the normal equation level, with emphasis on the stochastic modeling of each contribution. Particular focus was placed on the inclusion of GRACE-FO laser ranging interferometer (LRI) data, which provided the dominant contribution to the estimation of the spherical harmonic coefficients between degrees 70 and 200. All processing steps, except for the determination of the GOCE normal equations, were carried out at the Institute of Geodesy at Graz University of Technology (TUG) employing up-to-date background models. The consistent in-house processing of nearly all satellite data, using the Gravity Recovery Object Oriented Programming System (GROOPS) software package, minimized errors arising from inconsistencies of different algorithms or models being applied. 

The individual files of the GOCO2025s model (Öhlinger et al., 2025) are available at the TUG repository and identified with the following DOI: 10.3217/f48p8-8h651. They comprise the static and time-dependent gravity field coefficients and their respective uncertainty information, all parts of the normal equation system of the static gravity field, and the gravitational potential of non-tidal atmospheric and ocean masses already included in GOCO2025s.