A Reexamination of Acoustic Scattering in the Atmosphere Using an Improved Model for the Turbulence Spectrum
Abstract
Sound waves propagating near the ground are scattered by random fluctuations in the velocity of temperature fields. We revisit the problem of scattering of sound by turbulence using an improved von Karman-type model for the atmospheric turbulence spectrum. The new model incorporates large boundary-layer scale eddies generated by atmospheric convection, as well as smaller height-scale eddies generated by surface-layer shear. We show that velocity fluctuations- ions from the large convective eddies are typically the cause of random signal behavior for low acoustical frequencies and line-of-sight propagation. For higher frequencies and scattering angles, the shear turbulence becomes more important, with the relative importance of scattering by temperature and velocity fluctuations depending on the degree of atmospheric convection. By applying the new model to monostatic solar systems, we find that solar measurements of the temperature structure parameter can be systematically contaminated by the velocity structure parameter in strong wind conditions. We also discuss how the new model can be used to determine appropriate baselines for direction-finding arrays when there is significant degradation of signal coherence caused by turbulence.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1998
- Accession Number
- ADA388573
Entities
People
- D. K. Wilson
- Vladimir E. Ostashev
Organizations
- New Mexico State University