OPTIMUM PROPAGATION IN OCEAN: THE COMPARISON BETWEEN NORMAL MODE AND EMPIRICAL FRANCOIS-GARRISON FORMULA

Abstract

There are not only theory but also the empirical formula to deal with the problem of sound propagation in ocean. As such the Normal mode and Francois-Garrison are typical methods. Optimum sound propagation in ocean is the way we unify these two methods. In this paper, we investigate the transmission losses of both Normal mode and Francois- Garrison at some frequencies (170Hz, 800Hz, 100 KHz) at shallow water conditions (Tonkin gulf). The calculated and simulation results show that the optimum is achieved when the Normal mode is used at low frequencies whereas the Francois-Garrison is used at high frequencies.