ASA 125th Meeting Ottawa 1993 May

5aPA4. Prediction of the sound-speed profiles and the index of turbulence associated with various meteorological conditions.

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.