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Abstract:
The Atmospheric attraction computation service (Atmacs) provides atmospheric corrections for terrestrial high-precision gravity time series based on operational weather models of the German Weather Service (DWD). In Atmacs, Newtonian attraction and deformation contributions to loading are computed separately. The attraction component benefits from the discrete 3D distribution of air mass around the station, while deformation effects are derived from surface atmospheric pressure changes assuming that the oceans behave as a perfect Inverse Barometer (IB).Several improvements in the modelling approach of Atmacs are presented. A revision of the IB hypothesis implementation revealed that the attraction component over oceans is overestimated. A modification of the IB implementation not only resolves this issue but further enhances the compatibility between the atmospheric modelling and ocean models. This allows to complement Atmacs with non-tidal ocean loading (NTOL) effects, here based on the Max-Plank-Institute for Meteorology Ocean Model (MPIOM). These updates allow for a consistent combination of atmospheric and ocean models and a more efficient reduction of the gravity time series.Finally, we evaluate atmospheric corrections derived from both meteorological models currently used by Atmacs: the global and the European solutions of the Icosahedral Nonhydrostatic (ICON) model. In the case of the regional model, non-regional contributions are accounted from the global solution. This comparison is performed for several stations located in Europe, with emphasis on the estimation of tidal parameters and the reduction of gravity residuals.
