Long Range Sound Propagation in a Turbulent Atmosphere Within the Parabolic Approximation

The characteristics of acoustic waves propagating in the atmosphere are mainly determined by the environment. Acoustic signals vary both in space and time, and the dominant source of this variability is the turbulence of the atmospheric boundary layer. The influence of temperature and velocity random fluctuations have been demonstrated in many experimental studies. During the last decade significant progress have been made in the modelling of sound propagation over distances ranging from hundreds meters to kilometers, and the agreement between calculated and measured fields have been greatly improved. New developments appear in two domains: the numerical simulation of random fields and the parabolic-equation method. We will evaluate these new wide-angle parabolic equations through a series of numerical experiments. Different types of velocity fields will be used in these evaluations: a profile of sound speed combined with a velocity distribution, and a velocity field having random spatial fluctuations over a range of spatial scales. The objective is to determine the effect of using a more accurate PE in modelling acoustic propagation in inhomogeneous moving media.