Application of the WKBJ Green’s function to acoustic propagation in horizontally stratified oceans

The Green’s function (response to an impulsive point source) for ocean acoustic propagation is found using the WKBJ seismogram technique [Chapman, Geophys. J. R. Astron. Soc. 54, 481–518 (1978)]. It is shown that the WKBJ Green’s function reduces to geometric ray theory; in the vicinity of caustics it gives the well-known Airy function range dependence of each harmonic component of the acoustic field. Arrival patterns constructed using the WKBJ Green’s function are in excellent agreement with a solution to the parabolic equation (PE) except when the source and/or receiver depth is near the turning depth of a geometric ray. Agreement with a measured arrival pattern is also found to be good.