Combination Service for Time-variable Gravity Fields (COST-G): operations and new developments

Since its start of operations in July 2019, IAGâ?Ts Combination Service for Time-variable Gravity fields (COST-G) is providing a complete time-series of combined monthly GRACE gravity fields and a regularly updated time-series of monthly gravity fields derived from kinematic Swarm orbits. Starting from October 2020, the COST-G product line is complemented by a time-series of operationally combined and monthly updated GRACE-FO gravity fields. All these combinations are performed by variance component estimation on the solution level. We report on new developments, i.e., a planned extension of COST-G to include Chinese analysis centers of GRACE and GRACE-FO data, a re-consideration of the combination strategy to better focus on the range of spherical harmonic coefficients most relevant for the users, and the potential application of COST-G products for orbit determination of altimeter satellites.