Synchrony between Dipole and Quadrupole During Magnetic Field Reversals and Excursions

Abstract—In contrast to reversals, geomagnetic field excursions can occur at lower convection intensity in the Earth’s core. Since in such geodynamo regimes the magnetic field behavior is still quasi regular, a reduction in the dipole field during excursion may indicate a global failure in the dynamo process. As a consequence, it is possible that during the excursion, not only the dipole component, but also higher harmonics of the field decrease. This hypothesis is tested in a 3D (3D) dynamo model.