Space gravity GRACE and GRACE Follow-On (GRACE-FO) missions have been measuring the temporal mass variations at the Earth’s surface and within the mantle since 2002. GRACE products enable to study continental hydrology, oceanic and atmospheric loading, post-glacial rebound, glaciers, earthquakes and other phenomena that involve mass variations. The Earth’s interior, particularly the Earth’s fluid outer core possesses a broad dynamics of processes involving mass variations. Theoretical modeling indicates that low degrees of the gravity field might indeed contain some inter-annual signals of core origin. We can mention for instance dynamic pressure changes at the Core Mantle Boundary (CMB) associated with core flows reconstructed from geomagnetic observations, reorientation of the inner core controlled by gravitational coupling with the mantle. We also consider the hypothetical effects due to some dissolution/crystallization at the CMB introducing a time-varying roughness of the interface. For the first time, we investigate the density changes obtained from magneto-hydro-dynamics (MHD) simulations and accompanying geomagnetic jerks.

To verify the capacity of detecting Earth’s core signature into GRACE time series, we generate synthetic core signals that we incorporate into GRACE gravity products. Then, we aim to retrieve these synthetic signals through different analysis methods. We use decomposition methods such as wavelet and Empirical Orthogonal Function analyses. In the case of gravity-field perturbation due to geomagnetic jerks, we consider an approach based on the correlation with the geomagnetic field observations. We then discuss the required amplitudes for a possible detection in space-gravity time-series in regards with uncertainties linked to other sources of mass variations that we removed from GRACE data.

Finally, we expose the current limitations in the search for the Earth’s core signature in space gravity records.