ALBERT

Description: Our knowledge of the Earth’s liquid core dynamics is based on indirect information sources. One of the crucial information comes from the geomagnetic field observations, which can be used to infer variations of the fluid motion at the top of the core. The dynamic of the fluid core is associated with redistributions of the internal mass, which feature density heterogeneities, and the exchange of angular momentum with the solid Earth. Consequently, these processes occurring in the core can produce signatures in the gravitational field. Previous studies indicate that the leading mode of the global temporal gravity variations can be correlated with the leading mode of secular acceleration of the radial geomagnetic field. In this study, by applying several statistical Blind Source Separation (BSS) methods, we investigate the common space-time variabilities that emerge in the geomagnetic and gravity fields. Oscillations around 6-7 years are present in most of the analyses of both fields. The common areas where both magnetic and gravity field exhibit such variations include the South-Pacific Ocean, the northern part of Africa, and India. We note that 6-7 year oscillation in the geomagnetic field has also been reported in some previous studies as a mode attributed to the Quasi-Geostrophic (QG), Magneto-Coriolis (MC) and Alfvén waves in the liquid core. The possible causes for such oscillations in the gravity field are still under investigation.