Knowledge Bank

The equatorial radius (a) of the earth and the potential (Wo) of the geoid may be determined from four, essentially independent, parameters: equatorial gravity, ve, from terrestrial gravity measurements; KM determined from lunar probes; the flattening, f, from close-orbit satellite analysis; and the rotational velocity of the earth. With these parameters defining a mean earth ellipsoid it is possible to find the zero-order undulation (No ) that must be added to the undulation obtained from the Stokes' equation in order to yield an absolute undulation with respect to a given reference ellipsoid. [Full text of abstract available in document.]