IMPROVED OBSERVATIONS OF PERIODIC UT1 VARIATIONS CAUSED BY OCEAN TIDES

The recent determination of ocean tidal waves in UT1 (Brosche et al. 1991) has been improved using more accurate radio source positions and station coordinates as well as applying nutation corrections. A new set of 38 geodetic VLBI experiments from 1988 with time intervals of 2 and 3 h was used, the 3 h intervals giving more stable results. The presence of the M2 and O1 waves is confirmed. The K1 and S2 waves are also detected, although S2 only marginally. The phase angles and amplitudes of all four tides M2, S2, K1, O1 agree reasonably well with the theoretical values. The disturbing large amplitude at the K1 frequency in the previous paper has disappeared.