The increasing precision of satellite altimetry in relation to tides justifies making a distinction between the gravitationally generated S-2 tide and its observed values in the ocean, which are affected indirectly by solar radiation. In view of the relatively high noise background, we propose a simplified form of response analysis in which the purely solar semidiurnal harmonics of the gravitational potential are modified by an arbitrary amplitude-factor R* and a phase lag r*. Analysis of a globally representative set of 80 tide-recording stations shows that the observed S-2 constituent is strongly coherent with its gravitational part deduced from lunar tides, with regression constants R* = 0.97, r* = 5.9 degrees. The corresponding 'radiational anomaly has a phase lag of 108 degrees on the gravitational part, with amplitude ratio 0.105, very close to the values associated with the inverse barometric tide. The proposed analytical procedure should yield improved definition of S-2 and K-2 when applied to altimetry from either sun-synchronous or non-sun-synchronous satellites. This result is confirmed by comparing an analysis of 40 cycles of Topex/Poseidon altimetry with 'sea truth' from 30 open-sea tide-gage stations.