The time-varying gravitational potential field of a massive, deformable body

The internal as well as the external gravitational field of the Earth is co mputed under the assumption that (i) the mass distribution of the deformabl e body as well as (ii) the heights of the topographic surface and the depth s of the interfaces ('dynamic isostasy') vary in time. In order to represen t those shape variations properly, the topographic masses as well as the in terface masses are regarded as condensed following a proposal by F.R. Helme t (1884, p. 149-163). Accordingly time-varying simple layer mass densities are generated Basic results are collected in 4 boxes.