Fig. 3.

Maps of geomagnetic field intensity (F) at Earth’s surface and radial field (B_r) at the CMB based on model averages of (A and B) COV-OBS.x2 at 2020 CE and (C and D) pfm9k.2 at 600 BCE. The geomagnetic field at 600 BCE serves as a potential ancient analog to the present. The projection in B and D maps (600 BCE) has been rotated 100${}^{°}$ toward the east to align the eccentric dipole axis location with A and C (red star in Fig. 2B). (C and D) Gray shaded areas, which represent regions where the model SD exceeds 5 and 120 µT, respectively, are added to highlight the large model uncertainties, particularly in the Southern Hemisphere field predictions. Movies S1 and S2 have more detailed information on the model uncertainties.