Experimental study of meteorological and ground effects on outdoor sound propagation for developing aircraft noise prediction model

JAXA has been developing an aircraft noise propagation model by applying the GF-PE method. To predict aircraft noise propagation precisely, it is necessary to assume meteorological condition and ground property in the sound field appropriately. In order to study how to model those conditions in the predictions and to verify the model, outdoor sound propagation experiments were conducted in November 2012 and in July 2013 at Taiki Aerospace Research Field in Hokkaido, Japan. In the experiments, receivers were lined up on the 1000-meter long runway and on the grass-covered flat ground in the test field. An elevated sound source was hanged from a tethered balloon, while other sound sources were placed at ground level. Air-to-Ground and Ground-to-Ground impulse responses were measured under various meteorological conditions. In this paper, we introduce variations in excess attenuation due to the meteorological and ground effects. By comparing the experimental results and the calculation results of the GF-PE method, we also discuss appropriateness of the modeling of meteorological conditions and ground property in the developing aircraft noise prediction model.