Comments on "Mode coupling by internal waves for multimegameter acoustic propagation in the ocean"

The results of numerical simulation presented in the subject paper shows th at sound pulses carried by individual high modes in an underwater acoustic waveguide at ranges of a few thousand km are severely distorted due to inho mogeneities induced by random internal waves. At the same time, the total w ave field reveals a rather coherent pattern, where raylike wavefronts are e vident. Here, comment is made on this interesting result from the viewpoint of ray-mode relations in a waveguide with large-scale refractive index inh omogeneities. It is shown that when very distorted mode arrival patterns ar e synthesized together, the result is a much less distorted ray-arrival pat tern. (C) 1999 Acoustical Society of America. [S0001-4966(99)03107-0].