Calculating the waveguide invariant for non-ideal waveguides.

Abstract

The waveguide invariant describes striations in a range versus frequency plot of a waveguide’s Green’s function. Analytic expressions for the waveguide invariant only exist for a few select waveguides, but experiments and simulations have shown that the waveguide invariant is approximately equal to unity for almost all realistic shallow-water waveguides. A quasi-analytic method will be presented for estimating the value of the waveguide invariant in waveguides with arbitrary sound speed profiles, including the effects of a bottom fluid halfspace. The method is approximate but allows for an intuitive understanding of why the value of the waveguide invariant does not strongly depend on the details of the sound speed profile.

Shallow Waters Interference Pattern Features and Applications

“…Under the WKB approximation horizontal wavenumber are evaluate solving κ r in the Eq. (5) (Lee et al, 1988;Cockrell & Schmidt, 2010):…”