Fig. 1: Summary of magnetic field behaviour from representative geodynamo simulations and Earth.
From: Quantitative estimates of average geomagnetic axial dipole dominance in deep geological time
The dynamo simulations (first three columns) show the tendency of AD/NADmedian to increase as VGP dispersion decreases. The first row is a snapshot of radial field at the Earth’s surface taken from a timestep with AD/NAD close to its median for the time series shown in the second row (median shown as red line; note the semi-log scale). The third row represents palaeosecular variation as presented in studies of ancient time periods (but with far more data); the red line represents the best Model G fit (parameters a and b provided) to the entire data set of 500 randomly drawn timesteps (blue circles) sampled at each of 324 regularly placed locations (see the “Methods” section). Final column: equivalent plots for observational geomagnetic models11,63 and a palaeosecular variation dataset from last 10 Myr19. Note that AD/NAD for IGRF2015 is 9.6 and AD/NADmedian for gufm1 is 16.4. The red shaded area around the Model G fit to the empirical data represents 95% confidence bounds.
