Validation of GOCE-based gravitational gradients grids by spectral combination method

This paper deals with the validation of gravity gradients measured by GOCE using terrestrial data measured in the Czech Republic and Slovakia. In our study, we test the quality of the official GOCE Level 2 product called GRD_SPW_2 and GOCE + Geoxplore II. These are gravitational gradients in a local north-oriented frame at a regular grid at mid-altitude corresponding to the GOCE orbit. These gradients are continued to the points on the Earth's surface at which the gravity measurements were performed and then transformed into gravity failures using the spectral combination method. Since the satellite data contain only band limited information about the Earth's gravity field, a direct comparison with the values ​​measured on the Earth's surface would be incorrect. Therefore, before comparing, we removed from the teresetrial gravity data a shortwave component corresponding to the spherical degrees 250-2190 from the global gravitational potential model EGM2008 and degrees above 2190 were calculated using a residual terrain model.