Electromagnetic induction effects by the solar quiet magnetic field at satellite altitude

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 field 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 representing 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 and dusk and appears static when sampled by a satellite such as MAGSAT. This induced anomaly field could explain some of the weak oceanic static anomalies observed in satellite global magnetic anomaly maps.