In a recent paper Nijs and Wapenaar [J. Acoust. Am. 87, 1987-1998 (1990)] have developed a method for solving for the effects of horizontal winds on sound propagation in the atmosphere. In this development, Nijs and Wapenaar neglect terms containing the density gradient of the atmosphere which in their notation are comparable to the effects of the adiabatic temperature lapse rate on the sound-speed gradient. Their method represents a significant improvement over the use of an effective sound-speed gradient to express the effects of the wind only for high propagation angles. For these situations, one would expect errors due to the change in ambient pressure and density to be greatest. In this letter, a numerically attractive method to incorporate horizontal winds and a hydrostatic density gradient into a two-dimensional transform solution for sound propagation in the atmosphere is developed. In addition, Nijs and Wapenaar approximate the two-dimensional Fourier transforms by a single one-dimensional transform with little justification. Conditions are discussed under which such an approximation may be valid and it is demonstrated that these conditions are unlikely to be met by the two-dimensional kernal of Nijs and Wapenaar.
ASJC Scopus subject areas
- Arts and Humanities (miscellaneous)
- Acoustics and Ultrasonics