Global atmospheric loading and gravity

The purpose of this paper is to model atmospheric pressure effects on surface gravity. Pressure corrections are usually done with the help of an empirical trans fer function called barometric admittance between pressure and gravity both measured locally. We show the validity of this local approach with the help of spectral coherency between air pressure and gravity residuals after subtraction from the superconducting gravimeter observations in Strasbourg (France) of luni-solar tides, polar motion and instrumental drift contributions. We compute the atmospheric surface loading effects using a Green's function formalism and global surface pressure data provided by the European Centre for Medium Range Weather Forecasts (ECMWF). We model a specific oceanic response to atmospheric loading which incorporates interactions between ocean, atmosphere and solid Earth and differs from the classical inverted or non-inverted barometer hypotheses. We investigate the contribution of this global pressure correction in a 3000 day (1987-1996) tidal analysis of the French superconducting gravimeter. (C) 1998 Elsevier Science B.V. All rights reserved.