Basin-scale internal wave tomography: Some first steps
John Colosi
Woods Hole Oceanographic Institution
High frequency fluctuations in basin-scale acoustic transmissions offer intriging possibilities for inferring average statistical characteristics of the ocean internal wave field. For the 1000-km slice89 experiment Monte-Carlo numerical simulations using the Garrett-Munk (GM) internal wave model were used to infer the average nternal wave energy as a function of depth. This technique has the dvantage of treating the forward problem very accurately, yet due to the computational intensity of the technique only variation of internal wave energy could be studied. To fully explore the parameter space of the GM model a simplified forward model based on a geometrical optics calculation of the phase structure function, D, is proposed which treats the acoustic observables of travel time variance, depth and time coherence. Vertical coherence is sensitive to the GM parameters of internal wave vertical wave number bandwidth and vertical wavenumber spectral slope. Temporal coherence is sensitive to the GM frequencyspectrum slope. This approach is being applied to the ATOC vertical line array data, and some preliminary results will be shown. For acoustic energy which samples the upper ocean the GM model is not appropriate and a substitute model is needed.
