Gravity field of the earth

Abstract

The Earth’s gravitational field, defined as the field generated by the subsurface mass density, embodies a wealth of geophysical information at global and local scales. The global field is often described in terms of a spherical harmonic expansion, where the low-degree harmonics have a definite (though incomplete) interpretation with respect to the moments of the density distribution. The attenuation of the potential in the spherical harmonic (spatial fre-quency) domain is sufficiently gradual that first-and sec-ond-order radial derivatives readily characterize the local, near surface structure of the Earth. Whereas the external gravitational field of the Earth can be modeled in detail on the basis of surface measurements and potential theory, the deeper internal gravitational field model is derived secondarily from density distribution models obtained from other sources, such as seismological data.