Living Reference Work Entry

Encyclopedia of Geodesy

pp 1-9

Date: Latest Version

Gravity Anomalies

  • Georges BalminoAffiliated withBureau Gravimétrique International (BGI)CNES/Geosciences Environnement Toulouse (GET) Email author 
  • , Sylvain BonvalotAffiliated withBureau Gravimétrique International (BGI)Institut de Recherche pour le Développement (IRD)/Geosciences Environnement Toulouse (GET)

Definition

Gravity anomaly. Difference between the measured gravity and the theoretical gravity derived from a reference body, after some corrections.

Introduction: Basic Quantities of Physical Geodesy

The shape of the Earth is well approximated by an ellipsoid of revolution, and similarly its gravity field is close to the field of such an ellipsoid. This reference body being precisely defined as we will see below is therefore natural to describe the Earth gravity field (and any related quantity) as departures, or anomalies, with respect to the ellipsoid.

The reference ellipsoid is defined from geometrical and dynamical quantities. Centered at the Earth’s center of mass, it has the mass, M, of the Earth (including the atmosphere); a semimajor axis, a, equal to the (conventional) Earth’s equatorial radius; a flattening f equal to the Earth’s flattening (or equivalently the polar radius b); and the same (mean) angular rotation rate ω. The surface of the ell ...

This is an excerpt from the content