Similarity Modeling for Atmospheric Acoustics
ARMY RESEARCH LAB ADELPHI MD
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Acoustic propagation in the atmosphere depends on several environmental parameters. One of the parameters is the atmospheric profile which consists of temperature, vector wind speed, humidity, and pressure from the ground to some height in the planetary boundary layer. The problem is many times there are no atmospheric profiles available for the time, location, or season of interest. One method to obtain an atmospheric profile is to use a similarity model to generate a temperature and wind speed profile. However, the parameters to construct a similarity profile such as the friction velocity, temperature scale, virtual temperature scale, humidity scale, and Monin-Obukhov length are not easily obtained by the average user. An approach has been developed to construct similarity-based atmospheric profiles using readily available data feeding a surface energy budget model. The atmospheric profiles created using this method are valid for performing calculations of acoustic propagation over short ranges less than 5 km. The similarity-based profiles are only valid for the surface layer, which limits the propagation range. Even with this limitation, similarity-based generated profiles allow users to perform estimates on the attenuation of sound by the environment.