Résumé
We compute Green functions relating mantle mass heterogeneities to geoid undulations using both incompressible and radially compressible mantle rheologies. Our results differ from those previously published by Forte & Peltier (1991) and Thoraval, Machetel & Cazenave (1994). This is due to two factors. Instead of taking gravity as constant throughout the mantle, we compute it self-consistently with the radial density profile. Secondly, we show that in the mathematical formulation of the compressible case, stresses are not continuous through a density jump. We then point out that the presence of a surface ocean has no additional effect on the geoid signal associated with internal mantle mass anomalies. We apply this formalism to a geodynamic model of mantle density variations and show that an excellent fit to the observed geoid can be obtained.