Effects of large-scale wind-driven turbulence on sound propagation

A large‐scale wind‐driven turbulence model is put forth to account for long‐term (1–5 min) phase variations observed in outdoor sound propagation experiments. The long‐term variations experimentally observed cannot be explained with small‐scale turbulence models. Fourier analysis of phase variations show outer scales of 200 m and greater, which corresponds to turbulence in the energy‐containing subrange. Turbulence in this region corresponds to turbule sizes as large as the planetary boundary layer. The large‐scale turbulence in the boundary layer is assumed to be elongated longitudinal vortex pairs roughly aligned with the mean wind. Large‐scale turbulence is a range‐dependent problem that is best handled by the parabolic equation. The parabolic equation is a solution to the one‐way wave equation that is applicable to sound propagation where back‐scattered energy is negligible. The algorithm computes the pressure and phase at a receiver as the vortex pair traverses the propagation path with the mean wind speed. The model provides good results with the same trends and variations in the magnitudes of the phase observed experimentally.A large‐scale wind‐driven turbulence model is put forth to account for long‐term (1–5 min) phase variations observed in outdoor sound propagation experiments. The long‐term variations experimentally observed cannot be explained with small‐scale turbulence models. Fourier analysis of phase variations show outer scales of 200 m and greater, which corresponds to turbulence in the energy‐containing subrange. Turbulence in this region corresponds to turbule sizes as large as the planetary boundary layer. The large‐scale turbulence in the boundary layer is assumed to be elongated longitudinal vortex pairs roughly aligned with the mean wind. Large‐scale turbulence is a range‐dependent problem that is best handled by the parabolic equation. The parabolic equation is a solution to the one‐way wave equation that is applicable to sound propagation where back‐scattered energy is negligible. The algorithm computes the pressure and phase at a receiver as the vortex pair traverses the propagation path with the mean wind...