A. L'Esperance
G.A.U.S., Mech. Eng. Dept., Univ. de Sherbrooke, Sherbrooke, PQ J1K 2R1, Canada
Y. Gabillet
Ctr. Sci. et Tech. du Batiment de Grenoble, 38400 Saint-Martin d'Heres, France
Sound propagation over the ground is greatly influenced by the sound-speed profiles and the atmospheric turbulence, and there exist a number of models taking these effects into account. However, for practical outdoor sound propagation studies, it appears to be unrealistic to measure the effective sound-speed profiles (SSP) and turbulence index <(mu)[sup 2]> to obtain acoustical predictions. For a complete prediction model, these parameters should therefore be estimated from general atmospheric conditions. To fulfill the needs of acoustical prediction models, a meteorological model was developed to estimate SSP and <(mu)[sup 2]>. This model is based on estimations of the roughness length and the Monin--Obukhov length, which define the shape of the wind-speed profiles, temperature profiles, and the index of turbulence [Panofski and Dutton, Atmospheric Turbulence (Wiley, New York, 1984)]. The roughness length is estimated according to the surface of the site, and the Monin--Obukhov length using an empirical relation proposed by Golder [Bound. Layer. Meteorol. 3, 47--58 (1972)]. To verify the precision and the limitation of this model, the theoretical SSP and <(mu)[sup 2]> were compared to experimental results for various meteorological conditions. These comparisons show the capability and the limitation of this meteorological model, which may limit the accuracy of a complete acoustical prediction scheme.