The possibility of lateral structure inside the core and its implications for nutation and Earth tide observations

Abstract

SUMMARY We show that there can be lateral structure inside the fluid core caused by gravitational forcing from the mantle, from the inner core, or from topography on the core-mantle or inner core-outer core boundaries. We describe a method for calculating the internal structure, given knowledge of the forcing. We discuss the possible effects of this structure on results for the core-mantle boundary topography inferred from observations of the Earth’s forced nutations and diurnal earth tides. We consider the possible implications of a thin, low-density fluid layer at the top of the core.