Numerical study on lateral attenuation of aircraft noise by using the meteorological effect database developed in JAXA's DREAMS project - Part 2. Ground-to-ground propagation

In DREAMS project conducted by JAXA, the excess attenuation over soft ground under various meteorological conditions was numerically obtained using PE (Parabolic Equation) method. The results were combined into a database for an aircraft prediction model which can take into account meteorological and ground effects. By accessing the database, characteristics of outdoor sound propagation under various meteorological conditions which are defined by 273 kinds of effective sound speed profiles can be discussed including turbulent effects. In the database, the values of excess attenuation in the case that the source height is 2.5 m are also recorded for the prediction of ground-to-ground propagation. In this study, we focus on the over-ground attenuation of aircraft noise and the variation of the attenuation in accordance with meteorological conditions has been investigated by leveraging the excess attenuation recorded in the database. We also discuss about the model of over-ground attenuation defined in SAE/AIR 5662 by comparing with the attenuation values in the database.