Modeling the Ocean - Introduction to Wave Propagation in a Turbulent Medium
CENTER FOR NAVAL ANALYSES ALEXANDRIA VA NAVAL WARFARE ANALYSIS GROUP
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The observation fundamental to this work is that the ocean is usually in a state of turbulent motion. Correspondingly, the value of the temperature at every point in the ocean undergoes irregular fluctuations. In particular, since the index of refraction of the ocean is a function of temperature, we shall take the viewpoint that the refractive index is random and assume that the Kolmogorov theory of locally homogeneous and isotropic turbulence provides a sufficiently good description of the refractive index microstructure. To extract information concerning the randomness of an acoustic wave propagating through this turbulent and unbounded ocean, we make use of the wave equation to connect the statistical properties of the random medium to the implied statistical properties of the wave parameters within the framework of a correlation theory. We accomplish this only to first order in perturbation theory, thus restricting the realm of validity of our results to high frequencies and small refractive index fluctuations. The structure function of the logrithmic amplitude we find, generalizes similar results of Tatarski and Chernov away from the transversal, correspondingly longitudinal restrictions inherent in their work.
- Physical and Dynamic Oceanography
- Fluid Mechanics
- Radiofrequency Wave Propagation