Underwater sound propagation in a range-dependent environment

Abstract

For an ocean sound channel whose environmental parameters depend not only on depth, but in a gradual fashion also on range, the wave equation may be separated by the adiabatic range variation method of Pierce. For cases of less gradual range dependence, the range equations (and hence the modes) become coupled, and may be solved by diagonalization methods. This approach is used here to calculate underwater sound propagation in a channel with arbitrarily given range dependence, and also with arbitrary depth dependence of the sound velocity profiles, by employing Airy function solutions of segmentwise linearized problems. (For the coupling aspects, the simplification of segmentwise constant problems is made.) Our results are illustrated for a realistic deep water case with profiles from the Western North Atlantic, as well as a shallow water example from the Norwegian Sea, and are compared against the experimental transmission-loss data, and the results of calculations using other methods for the same cases. [Supported in part by NRL Code 8120.]