Reflections on the Geodynamo

Numerical simulations of the geodynamo are beginning to approach a dynamically relevant regime, not least because of the efforts in Paris and Grenoble. It seems timely, therefore, to compare the results of the various simulations with the conceptual cartoons of the geodynamo that have been developed over the decades. One such cartoon is presented here, based in part on helical wave dispersion within the Earth’s core. This cartoon is far from the standard model, but nevertheless seems reasonably consistent with the evidence of the numerical simulations. Of course, understanding the numerical simulations is not at all the same as understanding the geodynamo, but it seems a good place to start.