Non-global recovery of gravity anomalies from a combination of terrestrial and satellite altimetry data
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Date
1974-07
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Ohio State University. Division of Geodetic Science
Abstract
Two methods for recovery of gravity anomalies are described. Of those, the indirect method, based on the use of the Stokes' formula is chosen for its flexibility in combining any a priori information available on the anomalies and in filtering out any systematic error that may be inherent in the observations. A truncation theory developed for the Molodenskii (Inverse of Stokes') formula forms the basis for implementing the indirect method in a non-global solution. This method is tested with simulated data for the recovery of 2° x 2° and 1° x 1° anomalies. Weighted constraints for parameters are necessary for any realistic results. The anomalies appear to be recoverable with an accuracy of about 8 mgals for 2° x 2° and of 19 mgals for 1° x 1° blocks from altimetry data with 1m accuracy. The minimum requirement for the density of observations is shown to be one per block. The performance of this procedure, to an extent, depends on the cap sizes chosen for both the Stokes' and Molodenskii formulas. The magnitude of the remote zone contributions for both these formulas have been evaluted for various cap sizes and highest degree of the potential coefficients used and graphs to aid in cap selection are plotted. The minimal effect of an observation in one block on the determination of the anomalies in the neighboring blocks suggests that the cap size for the Molodenskii integral need not be more than 1 or 2 degrees for the accuracies obtainable in this procedure.