On the resolution of density within the Earth

Roughly 30 years have passed since the last publication of a linear resolution calculation of density inside the Earth. Since that time, the data set of free oscillation degnerate frequencies has been completely re-estimated taking into account the biassing effects of splitting and coupling due to 3D structure. This paper presents a new resolution analysis based on the new data and focuses on two particular issues: (1) the density jump at the inner-core boundary which is important in discussions of the maintenance of the geodynamo; and (2) a possible density excess in the lowermost mantle which might be indicative of a “hot abyssal layer”. We find that the density jump at the inner-core boundary is 0.82±0.18 Mg m−3 which is significantly larger than previously thought. We also find little support for an excess density in the lowermost mantle though an increase of 0.4% is possible.