Fig. 3From: A model of Earth’s magnetic field derived from 2 years of Swarm satellite constellation dataResiduals of differences (“gradient”) between Swarm Alpha and Charlie at non-polar latitudes and for non-sunlit conditions. Blue curves show monthly means; shaded blue area indicates \(\pm 1 \sigma \). The dashed red and blue vertical lines indicate the satellites are at dusk or dawn local timeBack to article page