Revisiting non-tidal atmospheric and oceanic gravity corrections for terrestrial gravimetry

Mass redistribution within Earth’s atmosphere and oceans affects gravity time series recorded by precise superconducting and quantum gravimeters at a multitude of temporal scales. While the largest component of the systematic disturbances is attributed to tides mainly in the oceans, the solid Earth, and to a smaller extent also the atmosphere, synoptic weather features also cause non-negligible gravity anomalies. The accurate description of these effects requires a high-resolution representation of certain components of the instantaneous Earth system state, namely the 3D atmospheric density and the ocean bottom pressure distribution. In this contribution, we calculate gravity anomalies induced by the Newtonian attraction of the mass anomalies and the loading effect they exert on Earth’s crust, employing the state-of-the-art meso-beta scale numerical weather model ERA5 reanalysis from ECMWF. We compare the ERA5-derived gravity anomalies to those provided by ATMACS, a service that features weather-driven gravity anomaly corrections for most superconducting gravimeter sites based on the operational model ICON-global, from the German Weather Service. In this work, we place our focus on non-tidal contributions only, while tidal signatures are estimated based on the gravity anomaly time series. The ocean state is based on a recent MPIOM simulations forced consistently from ERA5 which is also the basis of the latest GRACE/GRACE-FO non-tidal atmosphere-ocean dealiasing product AOD1B RL07. To assess the effectiveness of the modelling strategy as well as the quality of the mass anomaly fields, we apply the ERA5 and ATMACS-retrieved models to a few selected superconducting gravimeter time series with a focus on sites with unusual orography such as on the small island of Helgoland located in the North Sea, and assess the band-pass filtered residuals to assess the quality of the various correction models available.