No abstract

Large variations occur in actual meteorological conditions according to the time and place, on which the atmospheric absorption of sound depends strongly. To examine the temporal variability of atmospheric sound absorption during the year, the attenuation coefficients for atmospheric absorption were calculated from meteorological data in various world regions. The hourly meteorological data at 10 international airports and the half-daily aerological data obtained at 3 observatories were used in the calculation. The results show that significant differences in atmospheric absorption with the place can be found. The seasonal changes in the attenuation coefficients depend on both the frequency of the sound and the place. In addition, the effects of atmospheric absorption on aircraft noise propagation were examined by performing simple simulated calculations. The Aweighted sound pressure levels and sound spectra of aircraft noise change instantaneously owing to atmospheric absorption, which depends on actual meteorological conditions.