Ray Propagation in an Underwater Acoustic Channel with Time-Varying Stratification.
ROSENSTIEL SCHOOL OF MARINE AND ATMOSPHERIC SCIENCES MIAMI FLA
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A ray propagation model is developed which evaluates the influence upon sound propagation in a shallow water channel of ocean fluctuations of large spatial scale. The analysis is restricted to refracted, bottom-reflected rays and to bottomed acoustic sources and receivers. The influence of water depth changes as well as time variations in the channel stratification are investigated. Additional restrictions are that the wave length of the channel fluctuation be long compared to the range between the acoustic source and receiver, and that the period of the channel fluctuation be long compared to the ray travel times. The effects of water currents are neglected. The study has specific application in modeling the influence of surface tides and internal tides upon continuous wave propagation in fixed system shallow water acoustic ranges. A comparison of theoretical results with data from the Straits of Florida Project MIMI Range is qualitatively successful. The study offers an explanation for several outstanding features of these measurements not previously understood within a consistent theoretical framework. It is concluded that diurnal time scale internal fluctuations, principally the internal tides, have a much greater influence upon acoutic propagation than the surface tides. Author
- Physical and Dynamic Oceanography