Contruction of gravity charts without observed gravity data

INTROCASO A.- CROVETTO C. – INTROCASO B.- RUIZ F.

Bollettino di Geodesia e Scienze Affini

Istituto Geografico Militare

Lugar: Firenze; Año: 2007 vol. 4 p. 189 - 209

Summary. - Gravity anomalies ∆g and geoid undulations N have the same origin: the anomalous masses. It is possible to obtain gravity anomalies from geoid undulations and geoid undulations from gravity anomalies. From observed geoid undulations N= h –H` (h: ellipsoidal height, GPS and H': height from geometric levelling), or from height anomalies ξ, (≈N) = h – HN (HN: normal height), gravity anomalies can be obtained without using gravimeters. The aim of this work is to evaluate and compare five different known and unknown methods to solve this problem: the planar Stokes' integral solved by a system of equations, the planar Stokes' integral solved by Fourier Transform, the use of equivalent sources, the numerical derivation of the perturbing potential through a vertical upward continuation solved by equivalent sources, and the numerical derivation of the perturbing potential through a vertical upward continuation solved using the Fourier Transform. The five methods are tested through a theoretical and a real example on the Salado Basin (Argentina), showing the same global performances. The fastest methods are the ones that involve Fourier Transform techniques, in spite of being the most sensitive to edge effects; the ones that involve equivalent sources are very sensitive to the depth of the sources.