The axial component of the oceanic tidal angular momentum (OTAM) has b
een demonstrated to be responsible for most of the diurnal and semidiu
rnal variations in Earth's rotational rate. In this paper we study the
equatorial components of OTAM and their corresponding effects on the
orientation of Earth's rotational axis, or polar motion. Three ocean t
ide models derived from TOPEX/Poseidon satellite altimetry are employe
d to predict the polar motion excited by eight major diurnal/semidiurn
al tides (Q(1), O-1, P-1, K-1, N-2, M(2), S-2, K-2). The predictions a
re compared with geodetic measurements of polar motion from both long-
term observations and during the intensive campaign Cont94. The progra
de diurnal and prograde and retrograde semidiurnal periods are treated
, whereas the retrograde diurnal polar motion is not treated (because
it cannot be observed directly and uniquely.) The comparison shows gen
erally good agreement, with discrepancies typically within 10-30 micro
-arc-seconds for the largest tides. The eight tides collectively expla
in nearly 60% of the total variance in subdaily polar motion during Co
nt94. This establishes the dominant role of OTAM in exciting the diurn
al/semidiurnal polar motion and paves the way for detailed studies of
short-period nontidal polar motion. The present accuracy, however, is
inadequate to shed light on the prograde diurnal polar libration.