The aim of this letter is to discuss the virtual identity of two recent tidal theories : our creep tide theory and one Maxwell model recently developed .
It includes the discussion of the basic equations of the theories , which , in both cases , include an elastic and an anelastic component , and shows that the basic equations of the two theories are equivalent and differ by only a numerical factor in the anelastic tide .
It also includes a discussion of the lags : the lag of the full tide ( geodetic ) , dominated by the elastic component , and the phase of the anelastic tide .
In rotating rocky bodies not trapped in a spin-orbit resonance ( e.g . , the Earth ) the geodetic lag is close to zero and the phase of the semidiurnal argument in the anelastic tide is close to 90 degrees .
The results obtained from combining tidal solutions from satellite tracking data and from the Topex/Poseidon satellite altimeter data are extended to determine the phase of the semi-diurnal argument in the Earth ’ s anelastic tide as \sigma _ { 0 } = 89.80 \pm 0.05 degrees .