Tidal studies from the perturbations in satellite orbits

Tidal perturbations in the orbits of close Earth satellites permit the Love number K2 and the phase lag ε2 of the tidal effective Earth to be estimated. These parameters differ significantly from the nominal values of K2 = 0.30 and ε2 < 0.5° that would be expected if only the solid tide was important. This difference is due to the contribution of the oceans to the total tidal potential. This contribution is less well known than the solid tide potential and the study of the orbital perturbations permits an estimation of some of the long wavelength variations in the ocean tide. In this paper we discuss the method and the results obtained from two satellites for the S2 and M2 ocean tide. These tidal parameters are compared with and combined with numerical models of these tides to give improved parameters to be used in any orbital theory.