On the magnetic field in Earth’s interior

Abstract

Abstract This paper discusses the possible distribution of Earth’s magnetic field in its three main layers. As a first step, using the IGRF-13 model, it was found that the magnetic field energy exterior to the liquid outer core (i.e., inside the mantle and the surrounding Earth’s atmosphere) is about 6 . 7 × 10 18 J (for epoch 2010) while the field strength exactly at the Core-Mantle-Boundary (CMB) is about 0.42 mT (RMS value). These findings can be further considered as reliable reference values among the large dispersion of published data for the total magnetic field in Earth’s interior. Therefore, utilizing the layer breakdown reported in a pioneering paper (Glatzmaier and Roberts [8]) according to which the inner core includes about 10% of the total energy content, it was made possible to validate a previously reported figure (year 1949: 9×1020 J) regarding the total magnetic field energy of the Earth. But due to substantial deviation of the latter from a later reported figure (year 1980: 7×1021 J), this paper continues the investigation for the purpose of clarifying the issue. In this context, two inverse-cubic dipole models and the bar magnet (tiny and cylindrical) model, as well as the IGRF-13 standard were applied and compared in the Earth’s interior. Overall, under certain conditions these findings are successfully compared with literature reports, and eventually (after many assumptions) reached an acceptable compromise regarding the spatial distribution of the magnetic field, while a stimulus for further reflection to other researchers was provided. At the end, a question is posed and somewhat answered whether the available magnetic field energy is abundant to feed the motion of futuristic lightweight electromagnetic vehicles revived in recent literature.