Quality Assessment of GOCE Gradients

To meet the accuracy requirements of the GOCE mission, the gradiometer has to be calibrated and validated internally as well as externally. An internal quality assessment of the observed GOCE data is possible by comparisons of observations at the same satellite position, i.e. at satellite track cross-overs. Due to the orbit characteristics of the mission, satellite ground track cross-overs have to be used instead of identical repeat positions. Therefore, an appropriate reduction concept has to be applied to consider the differences caused by different satellite altitudes and orientations. It is shown here, that present global gravity field models meet the accuracy and resolution requirements for the reduction concept, and hence for the relative validation of GOCE gradients.