Tidal distortion of terrestrial planet resulting from gravitational forcing of host star. The planet structure is composed of a solid part of radius R_c and a thin uniform ocean of external radius R_p rotating as a solid body at the spin rotation rate Ω. The tidal responses of the two layers are coupled together and characterised by different frequency behaviours. The corresponding angular lags are designated by δ_c and δ_oc, and the surface displacements by ξ_c and ξ_oc. The ocean depth modified by solid and oceanic tides is denoted by h. Reference frames introduced in Sect. 2 are drawn in purple.