First comparison of GRACE-FO-derived gravity variations and  superconducting gravity observations at the Argentine-German Geodetic Observatory (AGGO)

Abstract

Continuous monitoring of gravity variations has been contributing to the study of a wide range of geophysical and geodynamic phenomena. In particular, satellite gravity missions such as GRACE and its follow-up mission, GRACE-FO, play an essential role not only for the development of global gravity models but also for the analysis of temporal variations of the Earth's gravity field related to, for example, climate change. On the other hand, superconducting gravimeters (SGs) allow for a precise and stable monitoring of gravity variations at particular stations. In this sense, SGs have a great potential as a ground-truth observation useful for the validation of satellite-derived products. In this study, a first comparison of nine different satellite gravity solutions from GRACE-FO with the SG time series recorded at the Argentine-German Geodetic Observatory (AGGO) is performed. Spherical harmonic coefficients from GRACE-FO were used to derive gravity variations at AGGO's location after applying different isotropic and non-isotropic de-striping filters. Results show correlations up to 80\% between the SG time series and several GRACE-FO solutions. A spectral analysis complemented by an Empirical Orthogonal Function (EOF) analysis shows that annual signals are well represented especially by non-isotropic solutions. Longer periods are also present in both observations, although the SG presents larger amplitudes, which could be related to local effects not captured by the lower spatial resolution of GRACE-FO.