TESTS FOR THE RECOVERY OF 5-DEGREES MEAN GRAVITY-ANOMALIES IN LOCAL AREAS FROM ATS 6-GEOS 3 SATELLITE TO SATELLITE RANGE-RATE OBSERVATIONS

The prediction of 5o mean gravity anomalies is considered by collocation from ATS 6/Geos 3 satellite to satellite range-rate observations. The auto- and cross-covariances of the residual line of sight accelerations R from Geos 3 to ATS 6 are computed rigorously in the anomalous potential field. The raw residual range-rate R values are filtered and smoothed by approximating them in a least-squares sense by a cubic spline function, and the residual accelerations R are obtained as the first derivatives of the spline. Tests are described to fit the raw R values by a spline function with variable knots, and to remove any linear trend from R values due to residual errors in the initial state vectors.-Author