Constraints on magnetic energy and mantle conductivity from the forced nutations of the Earth

Abstract

Observations of the Earth's nutations are used to explore the possible presence of a conducting layer at the base of the mantle. Evidence in favor of a conducting layer is found in the effects of ohmic dissipation which cause the amplitude of the Earth's nutation to be out-of-phase with tidal forcings. The additional effects of ohmic dissipation enhanced by the presence of a thin conducting layer at the CMB, are sufficient to reconcile theory and observation. -from Author