Glossary

Co-located grids

One or more grids that have grid points are at exactly the same locations. This property is important when performing operations like adding and subtracting grid values since they must be located at the same geographical locations.

Geocentric gravitational constant

The multiplication of the total mass of a reference ellipsoid and the gravitational constant. Often represented as \(GM\).

Gravity disturbance

The gravity disturbance is the difference between the magnitude of observed gravity and the magnitude of normal gravity evaluated at the same point [HofmannWellenhofMoritz2006]: \(\delta g(\lambda, \phi, h) = \|\vec{g}(\lambda, \phi, h)\| - \|\vec{\gamma}(\lambda, \phi, h)\|\)

Gravitational potential

The potential \(V\) due solely to gravitational accelerations (not including the centrifugal potential) [HofmannWellenhofMoritz2006]. By convention, it is positive and decreases with the distance to the masses.

Gravity potential

The combined gravitational and centrifugal potential \(U = V + \Phi\) [HofmannWellenhofMoritz2006].

Normal gravity

The magnitude of the gradient of the gravity potential of a reference ellipsoid.

Reference ellipsoid

An ellipsoid with geometric and physical properties used to best approximate a given planetary body (the Earth or others). See Wikipedia.