Evaluation of archeo- and paleomagnetic field models and their common features

Abstract

Archeo- and paleomagnetic field models show a wide range of temporal variability and of spatial content. While the temporal variability may reflect true geomagnetic field variation, the different spatial content of individual models could be explained by different modeling strategies and data sources, but mostly by data uncertainties. To overcome these data uncertainties, we derive averaged models over the last 100 kyrs from a large suite of different archeo- and paleomagnetic field models using different average techniques. The averaged models allow us to evaluate the robustness and the significance of spatial features of these models throughout time. It is utilized to compute structural criteria that quantify the axial dipole dominance, the equator-symmetry of magnetic field, its zonality and other important measures of weak field regions and control of the geodynamo by heterogeneous heat flux at the lowermost mantle. These criteria are used to quantify the Earth-likeness of numerical dynamo simulations. Over 100 kyrs the criteria show larger fluctuations than previously assumed, which implies a wider range of numerical dynamo simulations to be considered Earth-like.