Recovery of mean gravity anomalies from satellite - satellite range rate data using least squares collocation
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Date
1976-09
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Publisher
Ohio State University. Division of Geodetic Science
Abstract
Range rate data between two satellites can be used to determine acceleration along the connecting line between two satellites by numerically differentiating an analytic representation of this data. Using a reference potential field this acceleration can be interpreted to be a derivative of the disturbing potential along the line of the satellites. Using geometric techniques, the radial component of the disturbing potential can be estimated. This component can then be incorporated in the determination of mean gravity anomalies at the surface of the earth using least squares collocation and theoretical covariance functions. This paper discusses the theoretical basis of the above procedures and describes two simulation studies performed. In the first, postulated data surrounding a 5° equal area block and a 2° x 2° block was used to estimate the accuracy in which the anomaly could be recovered. For example, with acceleration data having an accuracy of ±1 mgal, a 5° anomaly could be determined with an accuracy of ±4 mgals with the low satellite at 250 km, and ±8 mgals with the low satellite at 850 km. A comprehensive simulation experiment was then performed to check the actual recovery of postulated anomalies determined from defined sets of potential coefficients. Assuming known orbits the recovery of the unknown anomalies was accomplished to about ±2 mgals. When orbits errors were introduced the errors increased but could properly be controlled through assignment of data accuracies. The promising results of this study indicate that least squares collocation techniques can be advantageously applied to this type of anomaly recovery avoiding the instability of the downward continuation problem that exists in other methods of anomaly recovery from this data type.