A Theoretical Model of Acoustic Propagation Around a Conical Seamount
The ocean around a conical seamount is an acoustic waveguide whose depth increases linearly with range measured out from the apex, As a result of horizontal refraction, the field created by an harmonic point source in such a channel is three-dimensional in character. A full solution for this 3-D field, derived from the inhomogeneous Helmholtz equation, is discussed in this paper. The solution, giving both amplitude and phase of the field, consists of a sum of uncoupled normal modes, which are functions of the angular depth about the apex. The range and azimuthal dependence of the field is contained in the mode coefficients. These coefficients exhibit three features which are characteristic of 3-D fields in general: acoustic shadowing in the horizontal; strong spatial variations within each mode (intra-mode interference); and apparent bearing shifts in the source position, due to ray curvature in the horizontal.
KeywordsRefraction Azimuth Acoustics
Unable to display preview. Download preview PDF.
- Buckingham, M. J., 1984, Acoustic propagation in a wedge-shaped ocean with perfectly reflecting boundaries, in: “Hybrid Formulation of Wave Propagation and Scattering”, L.B. Felsen, ed., Martinus Nijhoff, Dordrecht.Google Scholar
- Buckingham, M. J., 1986a, Theory of acoustic propagation around a conical seamount, to be published in J, Acoust, Soc, Am.Google Scholar
- Buckingham, M. J., 1986b, Theory of three-dimensional acoustic propagation in a wedge-like ocean with a penetrable bottom, to be submitted for publication in J. Acoust. Soc. Am.Google Scholar
- Buckingham, M.J., Jones, S.A.S., and Harriman, P.N., 1986, Stationary phase evaluation of the acoustic field around a conical seamount, to be published in J. Acoust.Soc. Am.Google Scholar
- Menard, H.V., and Ladd, H.S., 1963, Oceanic islands, seamounts, guyots and atolls, in: “The Sea”, vol.3, pp. 365–387, M.N. Hill, ed., Interscience Publishers, New York.Google Scholar