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Abstract:
Precise calibration of the GOCE gravity gradiometer is one of the premises to determine a state-of-the-art global gravity field model. Provided the center of the gradiometer coincides to the GOCE center of mass, the so-called common-mode accelerometer observations can generally represent the satellite’s non-gravitational accelerations. However, during the satellite flight, it is necessary to consider the possible offset of the gradiometer center with the center of the satellite towards the end of the mission due to orbital maneuvers and other reasons. In this research, the gradiometer calibration model is established by a priori gravity field model with six accelerometer observations and three star trackers’ angular rates. Besides the inverse calibration matrices, it includes the mass center offset as new calibration parameters and the impact of the parameter drifts will be discussed. The feasibility of this method to solve this parameter is verified using the nominal L1b data, and the impact of this offset on GOCE gravity gradient data quality are reduced to a large extent. Furthermore, the analysis of time series of the calibration parameters and the estimated PSD of the gravity gradient trace demonstrate that the accuracy of the calibrated gravity gradients is improved.
