Global atmospheric loading and gravity

The purpose of this paper is to model atmospheric pressure effects on surfa ce gravity. Pressure corrections are usually done with the help of an empir ical trans fer function called barometric admittance between pressure and g ravity both measured locally. We show the validity of this local approach w ith the help of spectral coherency between air pressure and gravity residua ls after subtraction from the superconducting gravimeter observations in St rasbourg (France) of luni-solar tides, polar motion and instrumental drift contributions. We compute the atmospheric surface loading effects using a G reen's function formalism and global surface pressure data provided by the European Centre for Medium Range Weather Forecasts (ECMWF). We model a spec ific oceanic response to atmospheric loading which incorporates interaction s between ocean, atmosphere and solid Earth and differs from the classical inverted or non-inverted barometer hypotheses. We investigate the contribut ion of this global pressure correction in a 3000 day (1987-1996) tidal anal ysis of the French superconducting gravimeter. (C) 1998 Elsevier Science B. V. All rights reserved.