Fig. 4.From: On the possibility of extending the IGRF predictive secular variation model to a higher SH degreePower spectra of the degree 8 IGRF-10 predictive secular variation model (solid) and of the degree 13 EIGRF secular variation model (dashes). Also shown (dots) is the power spectrum of the difference between these two models. All spectra are plotted at Earth’s surface.Back to article page