The GRACE and GRACE Follow-On (GRACE-FO) missions have been providing monthly time-variable gravity field estimates since 2002 with an one-year gap between 2017 and 2018. GRACE satellites monitor mass variations in the Earth system. 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 a gravitational coupling with the mantle and some dissolution/crystallization at the CMB introducing a time-varying roughness of the interface.

To verify the capacity of detecting Earth’s core signature into GRACE time series, we propose to generate some synthetic core signals that we incorporate into GRACE gravity products. Then, we aim to retrieve these synthetic signals through different analysis methods. We test correlations with the geomagnetic field observations and decomposition methods such as wavelet and Empirical Orthogonal Function (EOF) analyses. We then discuss the needed amplitudes for a possible detection with respect to the predicted amplitude and in regards with other sources of mass variations that were originally present in GRACE data.

Finally, we identify the correct methods to search for the Earth’s core signature and their current limitations.