An analysis of absolute mean hourly values of the three geomagnetic elements H, D and Z at Alibag for the period 1932-1972 has revealed clear and significant L(O1), the geomagnetic lunar daily variation associated with the lunar atmospheric tide 01. Partial tides are small in comparison with the phase law tides, suggesting that the variation resulting from the atmospheric tide O1 and higher harmonics of ionospheric conductivity contribute little to L(O1) at Alibag. Separation of L(O1) into parts of oceanic and ionospheric origin shows that (i) primary source of L(O1) in Z is the oceanic dynamo; (ii) smaller amplitude of the first harmonic of L(O1) compared to that of the second, contrary to expectation, is not due to the influence of oceanic dynamo contribution on L(O1). It is inferred that even yearly L(O1) contains some contribution from L(M2), lunar variation associated with the atmospheric tide M2. Next, by applying the formulae due to Winch, the seasonal harmonics of L(O1) and L(M2) are corrected for the possible contamination of one by the other. It is found that seasonal progression of L(O1) and L(M2) prior to and after the removal of the effect of one from the other remains the same.