DORIS-aided orbit and gravity field determination

The use of satellite tandems allows to form differential DORIS observations, which mitigates some common errors such as tropospheric delay correction errors. Therefore, the gravity field retrieval simulations included solutions based on both absolute and differential DORIS observations. The gravity field retrieval simulations have been conducted for the scenario 3d_H. It was verified that TU Delft and CNES software lead to comparable gravity field retrieval simulation results. The DORIS differential measurement type, even the ideal case tested in the gravity field retrieval simulations, does not provide additional information, i.e. accuracy, to the solution. In reality, the errors in the DORIS differential measurements will be much larger as they will for an important part not cancel out, as was shown with real Sentinel 3A/3B data. The DORIS receiver can therefore only be considered as a back-up instrument for the GNSS receiver in the unlikely event of its failure.