Abstract
In the paper sound waves propagation in a coastal wedge with sound speed profile (the presence of thermocline) is studied. In down- and up-slope propagation each adiabatic waveguide mode is transformed from the “bottom—surface reflected” shape to the “bottom-bottom refracted” one at some distance from the edge, depending on mode number. Analysis of mode composition and the corresponding spatial variability of the sound field is carried out using Parabolic Equation with the following decomposition of the field over adiabatic modes. It is shown, that there is significant change of amplitudes of adiabatic modes which is interpreted as manifestation of mode coupling. It is shown that mode coupling has local character, at the definite distance from the source, where two range dependent eigenvalues convergent to each other. This phenomenon is analog to the so called quasi crossing of states in atomic physics (Landau–Zener theory of nonadiabatic transitions in two-level system). This leads to sequential excitation of more and more higher modes in down-slope propagation and even creation of higher modes which did not exist at the position of the source. Results of modeling are presented, possible experimental observations are discussed. [Work was supported by RFBR, Grant 20-55-S52005.]
Published Version
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