The fast analysis of gravity field recovery from the GOCE observations along 979/61 nearly repeated orbit based on the SA method

The SA (Semi-Analytical) approach can recover the potential coefficients from huge satellite gravity observations in short time based on the application of FFT and introduction of the nominal orbit (circular, exact repeat orbit, uninterrupted measurement time series, and constant inclination). We analyzed the gravity field recovery from the GOCE observations along the 979/61 nearly repeated orbit using the lumped coefficient formulation. Lumped coefficients (LC) are obtained from 1D-FFT analysis of the observations along the orbit. The iteration technique is used in the LS procedure to reduce the error of model approximation caused by the non-nominal orbit (real orbit). Based on the 979/61 nearly repeated orbit observations including the SST and SGG with the prior error information, the gravity field model with the degree and order 200 is recovered. Comparing the estimated model with the released GOCE gravity model, several conclusions are presented.