Optimal estimation of high degree gravity field from a global set of 1° x 1° anomalies to degree and order 250
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Date
1984-08
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Ohio State University. Division of Geodetic Science
Abstract
An algorithm developed by Colombo (1981) for the optimal estimation of potential coefficients has been implemented with global 1° x 1° gravity anomalies. The reformulation of the algorithm, and the modifications, have been described. The effect of change in anomaly error estimates, and change in the anomaly data, on the optimally estimated potential coefficients has been examined. Potential coefficients were estimated complete to degree and order 250 with present realistic anomaly error estimates, and also with idealized anomaly error estimates. A comparison with the current set of potential coefficients (Rapp, 1981) complete to degree and order 180 shows a realistic coefficient percentage improvement of about 8% at degree 60, increasing to about 33% at degree 180. The cumulative undulation and anomaly difference to degree 180 is 1.51 meters and 2.7 mgals respectively. The present coefficient error estimates are better by a factor of about two when compared to the current coefficient error estimates. In the optimally estimated potential coefficients from 1° x 1° anomalies, the undulation and anomaly magnitudes per degree decrease to about 1 cm and 0.5 mgals respectively near degree 250. The coefficient percentage error per degree exceeds 80% near degree 250. A global set of 30' x 30' gravity anomalies would be needed for estimating the potential coefficients beyond degree 250.