Update of the Atmospheric Attraction Computation Service (Atmacs) for High-Precision Terrestrial Gravity Observations

Abstract

AbstractThe Atmospheric attraction computation service (Atmacs) of BKG provides atmospheric corrections for terrestrial high-precision gravity measurements based on operational weather models of the German Weather Service (DWD). In Atmacs, Newtonian attraction and deformation contributions to atmospheric loading are computed separately. The attraction component benefits from the discrete 3D distribution of air masses around the station, while deformation effects are derived from surface atmospheric pressure changes assuming that the oceans respond to atmospheric forcing as an 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 was 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 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 signal recorded by high-precision terrestrial gravimeters.