Coupling an Inviscid Core to an Electrically Insulating Mantle

Abstract

The torque exerted on the mantle is examined with emphasis on purely mechanical topographic or pressure core-mantle coupling. Pressure perturbations accompanying tangentially geostrophic, frozen-flux core flow acting on core-mantle boundary topography can exert an “enormous” torque on the mantle if thermal core-mantle interactions drive such flow. Conditions for growing or changing a dipole and correlating its fluctuations with those in the length of the day are analyzed.