Computation of sound fields in a realistic atmosphere

Abstract

The computation of sound fields in realistic atmospheres is demonstrated using a Green’s-function parabolic equation approach [X. Di and K. E. Gilbert, in Proceedings ofthe Sixth International Symposium on Long Range Sound Propagation, Ottawa, Canada, 1994] to handle the effects of ground impedance, refractive sound-speed profiles, and atmospheric turbulence. The calculated sound fields are presented as color-coded screen displays and show various effects, including upward or downward refraction, the ‘‘sky wave,’’ scattering into an acoustic shadow, and the effects of turbulence drift. Another program is used during the acquisition of meteorological data to monitor incoming data, to display the vertical sound-speed profiles obtained using similarity theory, and to display in real time the predictions obtained from a ray tracing algorithm.