Acoustic-internal wave interaction at long ranges in the ocean

Abstract

Fluctuations in the amplitude and phase of low-frequency sound propagated to long range in the ocean are predicted. Phase fluctuations are attributed to the passage of acoustic radiation through the internal gravity-wave field; predictions are based on measured and modeled internal wave spectra. Ray theory is used to determine phase and amplitude variations as a function of time, space, and acoustic frequency. It is shown and experimentally verified that mean-square phase fluctuations are depth dependent.