Abstract: GOCE satellite carries a high-sensitivity gradiometer, whose observations are used for recovering high-precision and high-resolution earth gravity field. Based on EIGEN-5C, EGM2008, GGM03S and GOTIM3 global gravity field models, the calibration parameters of the diagonal components(V_xx, V_yy, V_zz) of GOCE gravitational gradient tensor(GGT) were obtained. We analyzed the stability of scale factors. The influences on the calibration parameters and the calibrated observations from different gravity field models, the same model with different maximum degree and order and whether estimating the drift parameters were discussed in detail.The results shows that the stability of scale factors are about 10^-4 and calibrated observations are mainly determined by the low-degree signal of gravity field models. The differences of calibrated observations between EGM2008 and EIGEN-5C up to degree and order 250 are less than 10^-4E, which is far less than the noise level of GOCE GGT. We also find that the effects of whether estimating the drift parameter on the calibrated observations could approach 0.4E when the calibration is carried out every day. At the same time, the PSD(power spectral density) of the observation difference before and after the calibration shows that the low-frequency part of observations V_xx, V_yy, V_zz are mainly calibrated from the low-medium degree part(<150) of the empirical gravity field models. Taking the measurement bandwidth of GOCE gradiometer into account, the calibrated observations could be used for recovering the middle-high frequency signal of gravity field.

Key words: GOCE, satellite gravitational gradient, external calibration, gravity field model, scale factor