This study examines the basin-wide adjustment process associated with El Ni
no-Southern Oscillation (ENSO) in terms of oceanic waves using the Cane-Zeb
iak model. The Rossby waves induce not only the meridional mass divergence
in the ocean interior but also the incoming zonal mass flux at the western
boundary, which generally overcompensates the interior meridional divergenc
e. Therefore, the Rossby waves alone cannot make a negative feedback. Howev
er, the outgoing zonal mass flux associated with the reflected Kelvin wave
at the western boundary reduces the incoming boundary mass flux associated
with the Rossby waves, resulting in the tendency of equatorial basin-wide h
eat content varying in phase with the meridional divergence. Also shown is
that the nonequilibrium adjustment of the tropical Pacific Ocean is mainly
due to the free Kelvin waves reflected at the western boundary.