Impact of the new GFZ RL07 GRACE/GRACE-FO processing standards on the Level-2 gravity field solutions

Abstract

GFZ aims to distribute a reprocessed and improved RL07 Level-2 gravity field time series in the last quarter of 2026. Most of these improvements have been developed within the Research Unit “New Refined Observations of Climate Change from Spaceborne Gravity Missions” (NEROGRAV) funded by the German Research Foundation DFG.When developing the new GFZ RL07 processing standards, the main focus was on an optimized stochastic modeling during the GRACE/GRACE-FO gravity field determination. This includes the extension of the stochastic instrument error models, the optimization of the combination of the different observations in terms of relative weighting, and the inclusion of non-tidal background model error variance-covariance information in the adjustment process. Further changes compared to GFZ RL06 comprise the parameterization as well as the applied background models, e.g., the ocean tide model and the static gravity field model.This presentation provides an overview of the GFZ RL07 performance compared to RL06 with focus at specific processing aspects and its impact on the gravity field solution, such as the ocean tide model update or the influence of stochastic modelling of observation and background model errors. Improvements stemming from the applied advanced processing strategy led to a significant reduction of noise (> 30% relative to GFZ RL06), as well as more realistic formal uncertainties of the estimated gravity field parameters. In addition, a short outlook on the expected performance of LRI-based GRACE-FO gravity field performance is presented.