OBSERVATIONS OF STRONG INERTIAL OSCILLATIONS AFTER THE PASSAGE OF TROPICAL CYCLONE OFA

One week after Tropical Cyclone Ofa passed near Samoa, near-inertial o scillations of almost 1 m s(-1) in amplitude were observed with a ship board acoustic Doppler current profiler (ADCP). The velocity was nearl y uniform with depth in the upper 80 m. The strongest currents in this layer were found about 300 km from Ofa's track, farther than expected from previous observations and models. Below 80 m was a layer 50-100 m thick in which the shear exceeded 0.01 s(-1) Strong near-inertial os cillations, with currents over 0.6 m s(-1) from 130 to 200 m, extended through the shear layer to at least 300 m, the limit of the ADCP meas urements. The phase of the oscillations propagated upward, consistent with downward propagation of energy. A simple slab model driven by an idealized wind field approximately matches the observed amplitude and phase of the oscillations in the surface layer within 150 km of Ofa's track, but not the stronger current 300 km from the track.