Fig. 5From: Geomagnetic core field models and secular variation forecasts for the 13th International Geomagnetic Reference Field (IGRF-13)The temporally averaged secular variation spectra of Models 1 and 2 at Earth’s surface (left) and at the core surface (right). Same line styles are applied as in Fig. 3. The vertical bars indicate the range, i.e., the temporal variability of the individual spectraBack to article page