The transient Dst electromagnetic induction signal at satellite altitudes for a realistic 3-D electrical conductivity in the crust and mantle

Abstract

Magnetometer data from recent low-orbit satellite missions Ørsted and CHAMP offer an opportunity to improve our knowledge of electrical conductivity of the Earth's mantle. The forward modelling of electromagnetic induction (EM) is conventionally carried out in the frequency domain. We use a time-domain technique to study the electromagnetic response of a realistic 3-D electrical conductivity model based on seismic tomography and laboratory measurements. The model is excited by a Dst signal realistic in time evolution but simplified as spatial dipolar shape. The results show measurable response of simulated satellite time series to mid-mantle conductivity inhomogeneities. The interpretation of satellite magnetic data for the determination of 3-D mantle conductivity inhomogeneities will, however, require a more precise model of external ionospheric and magnetospheric currents. This can be obtained by simultaneous measurements by several satellites.