Open AccessObservations of strong inertial oscillations after the passage of Tropical Cyclone Ofa
Author(s) -
Firing Eric,
Lien RenChieh,
Muller Peter
Publication year - 1997
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/96jc03497
Subject(s) - amplitude , inertial wave , geology , tropical cyclone , wind shear , mixed layer , atmospheric sciences , geophysics , geodesy , physics , wind speed , climatology , wave propagation , oceanography , longitudinal wave , mechanical wave , quantum mechanics
One week after Tropical Cyclone Ofa passed near Samoa, near‐inertial oscillations of almost 1 m s −1 in amplitude were observed with a shipboard acoustic Doppler current profiler (ADCP). The velocity was nearly 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 oscillations, 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 measurements. 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.