Validation of the state-of-the-art static gravity models using GRACE-FO laser ranging interferometer measurements

Global static gravity field models are used for various applications such as determination of geoid height (i.e., vertical datum), satellite orbits, and ocean circulation models. Such static gravity models are obtained by combination of various satellite gravimetry data such as GRACE and GOCE, altimetry measurements over the oceans and terrestrial gravity measurements. These datasets have different error characteristics as well as spatial and spectral contents, which makes the data combination in model production very challenging. Therefore, it is very important to validate the global static gravity field models using independent observations not used in those models. Laser ranging interferometer (LRI) measurements acquired by the GRACE-FO show extraordinary sensitivity to small-scale static gravity signals down to 100 km. We use one year of GRACE LRI observations in 2019 to validate six state-of-the-art global static gravity models: GGM05C, GGM05S, ITSG-Grace2018s, GOCO-TIM-R06e, EIGEN-6C4, and GOCO06s. Our comprehensive analysis leads to detection of the spectral (spherical harmonic) band and spatial regions where these models suffer from errors. We discuss inefficacies of each model as well as their potential causes. Our unique study helps inform the model developers about the spectral band and spatial regions where their models need improvement.