Terry E. Ewart
Appl. Phys. Lab. and School of Oceanogr., Univ. of Washington, Seattle, WA 98105
Stochastic acoustic models of acoustic phase propagation were used to validate ocean internal wave models in Ewart and Reynolds [SPIE Press, PM09 (April 1993)]. In that work Rytov modeling of the phase variability provided very accurate agreement with a linear ocean internal wave model. Such tests require extreme accuracy in the phase measurements and hence very accurate position stability in the acoustic arrays. In the AIWEX acoustic transmission experiment the phase variability was so small that millimeters of motion of the array were significant in the phase variance. When the propagation is in the Rytov regime for both the phase and log amplitude variability, the amplitude should be equally usable to test stochastic ocean models. In this work we develop the Rytov model for the case of variability in the sound velocity profile and a nonconstant Vaisala frequency profile where the scintillation index of the acoustic fluctuations indicates that Rytov models hold. Simulated linear internal wave fields and PE propagation are used to generate the complex wave fields. The stochastic inverse for the phase and log amplitude is compared with the input transverse spectrum of internal waves. The regimes of applicability of these methods, the directions of further research, and the incorporation of these techniques in the conduct of traditional oceanographic measurements to enhance our ability to interpret the internal wave environment will be discussed.