P. Tarits et N. Grammatica, Electromagnetic induction effects by the solar quiet magnetic field at satellite altitude, GEOPHYS R L, 27(24), 2000, pp. 4009-4012
We show that magnetic fields induced by a near-earth ionospheric source can
produce, at a satellite altitude of 400 km, an induced magnetic anomaly fi
eld with an amplitude of 2-3 nT at dawn and dusk local times and 3-4 nT at
noon local time. Our results are based on an earth model which has an upper
4 km thick shell with a laterally varying electrical conductivity represen
ting the distribution of continents and oceans. The upper shell overlies a
one-dimensional mantle with a radially varying electrical conductivity. In
some regions, the induced anomaly field does not change sign between dawn a
nd dusk and appears static when sampled by a satellite such as MAGSAT. This
induced anomaly field could explain some of the weak oceanic static anomal
ies observed in satellite global magnetic anomaly maps.