Abstract
Zonal modes of mantle deformation may couple with the Earth's rotational motion. Increases of the LOD (slowing down of the Earth's rotational speed) suggest a coupling with increases of the vertical in the low latitude zone. This relation may be due to the angular momentum redistribution in the mantle associated with motions in the fluid core. Thermal core-mantle interaction is proposed to explain the coupling between the fluid motion near the CMS and the elastic mantle in a simple model valid at the equator near the CMB. Transport of mass in the fluid core near the CMB along the north direction can be large enough to explain the observed values of the variation of the vertical.
