Frank S. Henyey
Stephen A. Reynolds
Terry E. Ewart
Appl. Phys. Lab., Univ. of Washington, 1013 NE 40th St., Seattle, WA 98105
The Chester, Friedman, and Ursell (CFU) uniform asymptotic expansion near caustics has been implemented as an adjunct to a ray-tracing code. The method is applied to the propagation of 400 Hz sound from a 200-m deep source in a Munk sound-speed profile through a range of 300 km. Making the parabolic approximation in the ray trace, the validity of ``semiclassical'' wave functions with the CFU expansion near caustics can be determined by comparison with a parabolic equation code. Good results for the semiclassical wave function are found. If the CFU expansion is not used, the field is badly inaccurate over hundreds of meters in the vertical. A video of the propagation comparing the Wigner function with the ray depth-angle plot is shown. [Work supported by ONR.]