Lower mantle viscosity constraints from Earth tides, nutation, and seculardeceleration of rotation

Modern data on the amplitudes and phases of the Earth's forced nutation yie ld reliable estimates of the dynamic flattening and viscosity of the liquid core, as well as the mechanical Q factor of the lower mantle. As is shown in this work, new data on the dynamic flattening of the liquid core and on the secular deceleration of the diurnal rotation of the Earth provide const raints on the lower mantle viscosity for processes with periods of a few hu ndreds of millions of years.