Effect of inner core conductivity on planetary dynamo models

Abstract

Various studies have investigated the influence of inner core conductivity in modelling planetary dynamos. Some studies suggest that the finite conductivity of the inner core reduces the frequency of reversals and affects magnetic field morphology while other studies suggest that the inner core conductivity does not have a significant effect on the resulting magnetic fields. Here we investigate numerical dynamo models in Earth-like geometry in order to understand the influence of inner core conductivity. We show that a conducting inner core can reduce the frequency of reversals and produce axial-dipolar dominated fields in our models. We also demonstrate that a strong planetary magnetic field intensity does not imply that the dynamo operates in the strong field regime as is usually presumed. We also investigate the discrepancy between our studies and previous work and find that the combination of thermal boundary conditions and the Rayleigh number play an important role in determining the influence of the inner core’s conductivity on planetary dynamos.