High Precision Gravity Anomaly And Sea Surface Height Estimation From GEOS-3/SEASAT Satellite Altimeter Data
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Date
1989-07
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Ohio State University. Division of Geodetic Science
Abstract
The global prediction of gravity anomalies and sea surface heights and their rigorous accuracy estimates from satellite altimeter data were carried out in the ocean area covering φ, = 72° to -72° and λ = 0° to 360°. The data used is the OSU existing combined Geos- 3/Seasat data, which was updated by introducing sea surface topography correction, equatorial radius correction, height bias correction and permanent tidal corrrection and OSU86E reference field to degree 180 for this study. The use of the supercomputer, incorporating with the vectorization technique, has significantly reduced the computer time and a total of 12 CPU hours (on CRAY) was consumed by the production work. The global prediction was carried out in such a way that the sea surface heights were first adjusted by the cross-over arcs method and then the predictions were made by the least squares collocation method. From the tests focusing on various issues, we conclude that the local arc adjustment can remove the biases of arcs with wavelength of 400-500 km and the optimal altimeter data density is 400 points within a prediction cell of 0°.5 with 0°.25 border. A total of 2,322,080 point values with 1/8° grid interval were predicted. The mean standard deviations are 12.11 mgals for anomaly and 8 cm for sea surface height. The comparison of the predicted and ship measured anomalies at the 2011 points in the Bermuda area has an RMS difference fo 15.9 mgals. The plots of anomalies show that many undetected gravity signatures in Rapp's (1985) work now have been recovered.