Influence of short-term variations of meteorological parameters on sound propagation outdoors

Abstract

Predicting long-range sound propagation over a nonurban site with complex propagation media requires the knowledge of micrometeorological fields in the lower part of the atmospheric boundary layer. In the framework of road traffic noise characterization there is a need for reliable sound pressure level predictions for specific propagation conditions that must be representative of time and space (small scale and site effects) characteristics of the acoustic situation. Outdoor measurements involving roughly 100 meteorological and acoustic sensors have been carried out during 3 months in 2005 in the southwest of France. This large database enables us to study the variability of meteorological parameters (wind speed, temperature, etc.) on different time scales. Scaling parameters in the atmospheric surface layer (such as the friction velocity and the Monin-Obukhov length) are estimated every 15 min, which allows looking at relatively short-term variations. Some longer-term effects, from days to months, are studied too. These include occurrences of meteorological configurations and variation of ground parameters. The effect of meteorological variability on sound propagation is studied using parabolic equation simulations. Comparisons between numerical predictions and experimental data will be discussed.