Study of lateral attenuation under meteorological conditions for airport noise modeling

摘要

This paper describes the result of examination on the validity of equations for lateral attenuation of over-ground sound propagation during aircraft flyover under various meteorological conditions, using long-term unattended noise monitoring at Narita Airport. The well-known SAE/AIR 1751 equation was said to bring a little overestimation. Thus, we examined the validity of the equation by following the procedure to construct AIR 1751. As a result, we found that lateral attenuation changes dramatically dependent on meteorological conditions and that lateral attenuation using AIR 1751 corresponds to upwind conditions. Based on these, we proposed a modified equation (1751M) applicable under various meteorological conditions, and decided to use it in the case of wind calm and temperature gradient neutral conditions for long term average noise prediction. Since first using it, a lot of new types of aircraft have been introduced, and comparing noise predictions with measurements suggests that 1751M gives a bit of underestimation. Aside from these, another new equation (SAE/AIR 5662) gives a bit higher value of lateral attenuation. Thus, we made this study to check the validity of lateral attenuation equations, following the same procedure we used when constructing 1751M. This paper describes the result as well as discusses further issues related to lateral attenuation in airport noise modeling.