Fluctuations of CW phase caused by time-varying multipath interference are simulated with fully coherent ray propagation models. Fixed-system measurements of fluctuations of CW transmission are presented and compared for three ocean ranges. When the sound-speed perturbation used for model inputs are adjusted to give the same statistics of transmission-loss fluctuations (decorrelation time, variance, and mean-square bandwidth) as observed, then the associated fluctuations of CW phase also have the same statistics as the experimental results. Phase fluctuations are shown to be strongly influenced by the nonlinear multipath process. For low-frequency internal waves (less than 1 cycle/h), and especially for internal tides, linear or direct fluctuations influence the phase spectrum, but for higher frequencies it seems likely that nonlinear effects dominate. Therefore, the possibility of a direct linear relationship between the internal-wave spectrum and the spectrum of phase fluctuations is unlikely.
ASJC Scopus subject areas
- Arts and Humanities (miscellaneous)
- Acoustics and Ultrasonics