Chirality of the Geodynamo from the Core’s buoyancy and Sense of Spinning

Abstract

<p>The geodynamo inside the liquid core is part of the Earth’s rotation. We discovered that electric currents in the heat exchanging liquid core need to follow the handedness of the spiraling liquids given by Coriolis force. Coriolis force splits the buoyant heat exchanging liquid into the two, north and south hemispheres, each with its unique handedness of spiraling convection systems. Convection spiraling model of the core fluid revealed that any planetary dynamo with a liquid conducitng core must have a two-component bimodal structure magnetic contribution, where, for Earth, the southern hemisphere is always associated with a dominating normal polarity component and northern hemisphere with a dominating component of reverse magnetic polarity. We show that the geodynamo would have a non-random distribution of the probability of generation of dynamo’s magnetic polarity, depending on a difference in a degree of buoyancy vigorousness between the two hemispheres.  In this work, the individual treatment of normal and reversed polarity durations revealed that while before 80 Ma geodynamo was generating predominantly normal polarity durations, after the Tertiary transition at ~ 60 Ma, the geodynamo produced predominantly reverse polarity durations. This observation of predominance of magnetic polarity durations is constrained by the existing temperature models near the core/mantle boundary (CMB) and we show a novel connection how a lower mantle temperature distribution may reorganize its convection pattern in the core and change the stability of the dipolar field in favor of a specific polarity.</p>