Reexamination of Fluid Motion in the Earth's Core Derived from Geomagnetic Field Data. Is the .OMEGA.-Effect Really Strong in the Core?

Abstract

Fluid motion in the Earth's outer core has been derived from geomagnetic field data on the presumption that a strong ω-effect is operative in the core. In this case, it is important to properly estimate differential rotation which is expected to generate strong zonal toroidal magnetic fields. So far, we have relied on a physically simplified model in terms of virtual displacement of fluid particles. We here attempt to solve both the induction and the Navier-Stokes equations. The basic standpoint is that the non-axisymmetric poloidal magnetic field is maintained by the interaction between the strong zonal toroidal magnetic fields and a large-scale fluid motion within the outer core.