Diurnal atmospheric tide and induced gravity variations

The gravity loading effects induced by the diurnal (S1) air tide are investigated. We compare worldwide superconducting gravimeter records belonging to the GGP (Global Geodynamics Project) network with loading predictions computed from recent air and oceanic tidal models. Although discrepancies between the observations and models are large, the global tidal models allow a significant reduction of gravity residuals compared with the classical and empirical local pressure correction as well as with the loading computed with surface pressure provided by meteorological centers under the assumption of an inverted barometer response of the ocean to pressure forcing.