Comments on “Mode coupling by internal waves for multimegameter acoustic propagation in the ocean” [J. Acoust. Soc. Am. 100, 3607–3620 (1996)]

The results of numerical simulation presented in the subject paper shows that sound pulses carried by individual high modes in an underwater acoustic waveguide at ranges of a few thousand km are severely distorted due to inhomogeneities induced by random internal waves. At the same time, the total wave field reveals a rather coherent pattern, where raylike wavefronts are evident. Here, comment is made on this interesting result from the viewpoint of ray-mode relations in a waveguide with large-scale refractive index inhomogeneities. It is shown that when very distorted mode arrival patterns are synthesized together, the result is a much less distorted ray-arrival pattern.