Optimum frequency for propagation of sound in shallow sound channels was studied using two acoustic transmission loss models. The split-step Parabolic Equation model (a full-wave model) and the Fast Asymptotic Coherent Transmission loss model, version 9H (a ray-tracing model) were tested against experimental data collected by Dosso and Chapman in the northeast Pacific Ocean. The models were found to be valid predictors of optimum frequency for the shallow sound channel observed by Dosso and Chapman. Both models were then used to predict optimum frequency for two sound velocity profiles obtained in a high-latitude deep ocean basin under summer conditions, exhibiting shallow sound channels. As expected, the split-step Parabolic Equation (PE) model adequately predicted optimum frequencies for these cases. The Fast Asymptotic Coherent Transmission loss model, version 9H (FACT 9H) model did not produce reasonable results for optimum frequencies.

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http://archive.org/details/optimumfrequency1094521475

Lieutenant Commander, United States Navy