A 1973 Gravimetric Geoid of Africa

Summary Results of a preliminary gravimetric geoid computed on the Geodetic Reference System of 1967 (GRS67) are given in the form of undulation and deflection maps. For the computations, 1°× 1° mean free-air gravity anomalies formed the inner zone and 5° equal area values the outer zone around each computation point. Some of the required 1°× 1° means, together with their accuracies, were obtained by statistical prediction methods using an auto-covariance function derived from the known 1°× 1° values. The results confirm the general south-easterly down slope of the geoid undulations. The average computed standard errors are about 3·6 m in the undulations and 0·“6 in the deflections.