On the role of magnetostrophic waves in geodynamo

Abstract

It is shown that magnetostrophic waves which are generated in the equatorial plane of the Earth’s core due to the instability of the equatorial jet and which propagate almost transversely to the rotational axis off the tangent cylinder, have a negative helicity in the northern hemisphere and positive helicity in the southern hemisphere. When the wave trains propagate through the regions with a constant azimuthal magnetic field caused by the Ω-effect, this helicity distribution induces an electromotive force (emf) (due to the α-effect), which may lead to the maintenance of the initial dipole field by the scenario of the α-Ω dynamo.