Nine years of very long baseline interferometry (VLBI) observations ha
ve been analyzed to determine the magnitudes of the tidal variations i
n UT1 for periods between 5 and 35 days. Corrections for variations in
atmospheric angular momentum (AAM) significantly reduce the scatter o
f the measured amplitudes across both time and frequency. The AAM corr
ections are found to reduce the scatter in the observed tidal amplitud
es by as much as 60% for periods as short as 5.6 days; in contrast, ea
rlier studies have shown a loss of coherence between AAM and length-of
-day (LOD) for periods shorter than about 10 days. The tidal amplitude
measurements place bounds on both the nonequilibrium ocean and mantle
anelasticity effects. The in-phase k/C determination is found to agre
e to better than 0.5% with the value of 0.944 from Yoder et al. (1981)
. The out-of-phase values are found to have a frequency dependence tha
t can only be explained by nonequilibrium ocean effects. The observed
slope is larger than the theoretical by about 3 times the expected err
or. This result may indicate that the ocean is farther out of equilibr
ium for the higher frequencies than present models permit. Significant
improvements are needed in both ocean and atmosphere modeling to expl
oit the full capability of the VLBI observations.