Feasibility studies for the prediction of the gravity disturbance vector in high altitudes
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Date
1981-03
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Ohio State University. Division of Geodetic Science
Abstract
The accuracy of the gravity disturbance vector in high altitude (30 000 - 200 000), predicted from a surface-covering set of mean gravity anomalies, is estimated. Two methods are used and found to provide estimates which differ by less than 10%, the least-squares collocation and the integral solution; for the integral solution, the estimation of the representation error has been performed in the frequency domain. For the collocation solution an optimal algorithm has been developed which takes advantage of the regular data distribution and is up to 64 times faster than a non-optimized solution. The results indicate that the radial component of the gravity disturbance vector can be estimated with an accuracy of ±1 mgal at an altitude of about 50 000 ft. on the basis of the available data sets; in order to achieve the same accuracy at 30 000 ft. altitude, the data error, particularly that of 5' x 5' anomalies, has to be reduced by some 60%; the available data distributions are adequate. The prediction error drops quickly with increasing altitude. The situation is considerably different for the horizontal component: with the best available data distribution an accuracy of ±2.3 mgal at 30 000 ft. altitude can be achieved; (this corresponds to ±0."5 in the direction of the gravity vector). An accuracy of ±1 mgal requires a block size reduction by a factor or 2 not only in the innermost zone, but also up to a spherical distance of about 30°; in addition, the overall data error needs to be reduced by some 30%. The prediction error decreases only slowly with increasing altitude. [Some mathematical expressions are not fully represented in the metadata. Full text of abstract available in document.]