Weather-Dependent Airport Noise Contour Prediction Concept Based on Ray Tracing

Abstract

The most frequently used excess attenuation method for noise contour models is called the lateral attenuation correction. This empirical method disregards varying atmospheric conditions. It is known that varying atmospheric conditions can lead to large discrepancies for single-event cases. This paper studies these atmospheric effects for a longer period, thus involving multi-event calculations. A European Civil Aviation Conference Document 29 compliant noise model is used with the extended functionality to apply results from a ray-tracing excess attenuation calculation. Results are shown for monthly and yearly noise contours around an example airport using three different modeling options: the standard Document 29 methodology, the standard methodology augmented by varying atmospheric absorption, and the ray-tracing excess attenuation method. The differences found in excess attenuation between the standard Document 29 method and ray tracing are small. It is argued that the main differences are related to varying atmospheric absorption and ground attenuation. For the case considered, wind effects are of minor importance when modeling monthly or yearly contours. In conclusion, the empirical lateral attenuation model, used to estimate the average excess attenuation in a varying atmosphere, provides a practical and realistic estimate for yearly and monthly noise contours for the used atmosphere.