Fluctuation of noise attenuation above different ground surfaces under similar meteorological conditions

摘要

Simultaneous measurements of outdoor noise propagation and meteorology up to several tenrnmeters by a captive balloon were carried out above different ground surfaces, asphalt and grasscoveredrnground, on calm sunny days in winter season. Excess attenuations observed above bothrnground surfaces varied primarily at medium and high frequencies from hour to hour, and thernfluctuations of excess attenuation became larger especially at further receivers. However,rndegrees of the fluctuation attenuation of noise throughout the measurements were smaller abovernthe asphalt, even though the meteorological conditions were generally similar. In the paper, wernfocus on the degree of attenuation fluctuation, and in order to examine the difference thernmeasured results are compared with theoretical prediction made using the meteorologicalrnparameters observed.