Calibration of satellite gradiometer data aided by ground gravity data

Parametric least squares collocation was used in order to study the detecti on of systematic errors of satellite gradiometer data. For this purpose, si mulated data sets with a priori known systematic errors were produced using ground gravity data in the very smooth gravity field of the Canadian plain s. Experiments carried out at different satellite altitudes showed that the recovery of bias parameters from the gradiometer "measurements" is possibl e with high accuracy, especially in the case of crossing tracks. The mean v alue of the differences (original minus estimated bias parameters) was rela tively large compared to the standard deviation of the corresponding second -order derivative component at the corresponding height. This mean value al most vanished when gravity data at ground level were combined with the seco nd-order derivative data set at satellite altitude. In the case of simultan eous estimation of bias and tilt parameters from partial derivative(2)T/par tial derivative z(2) "measurements", the recovery of both parameters agreed very well with the collocation error estimation.