A NUMERICAL-MODEL FOR SOUND-PROPAGATION THROUGH A TURBULENT ATMOSPHERE NEAR THE GROUND

In this paper a series of numerical simulations of the effect of turbu lence on the propagation of acoustic waves in the atmosphere are prese nted. First the technique of representing the turbulence as a set of r ealizations of a random field generated by a limited number of Fourier modes is described. Through each individual realization, the acoustic waves are propagated in a wide-angle parabolic approximation to obtai n the sound-pressure level. Ensemble averaging is then performed to co mpute the statistical properties of the acoustic held: mean sound-pres sure level, intensity fluctuations, and amplitude distributions. The m ethod is applied first to a nonrefractive atmosphere, both in the pres ence of a rigid boundary and of an impedance ground, and then to an up ward refractive atmosphere with an impedance ground. The model, which contains no adjustable parameters, is tested using the experimental da ta of Parkin and Scholes, Daigle, and Wiener and Keast. Good agreement between numerical simulations and experiments is obtained. (C) 1996 A coustical Society of America.