Length of day variations due to zonal tides for an inelastic earth in non-hydrostatic equilibrium

We present a refined theoretical model for length-of-day (lod) variations i nduced by the zonal part of the tide-generating potential. The model is com puted from a numerical integration, from the Earth's centre up to the surfa ce, of the equation of motion, the rheological equation of state and Poisso n's equation. The Earth is modelled as a three-layered body, with an inelas tic inner core, an inviscid fluid core and an inelastic mantle sustaining c onvection, which,induces deviations from hydrostatic equilibrium. The model also incorporates ocean corrections deduced from dynamic ocean models. It is shown that the non-hydrostatic structure inside the Earth has an effect of less than 0.1 per cent on the transfer functions, while the different mo dellings of mantle inelasticity (different combinations of possible values for the inelastic parameters) can lead to a wide range of results. Finally, we show that the precision of the geodetic observations of UT1 and the pre cision of the oceanic and atmospheric corrections are not yet sufficient to obtain information about mantle inelasticity from the comparison between t heoretical models and geodetic observations.