Measurement and Prediction of Infrasonic Wind Noise in Forests
Technical Report,15 Sep 2012,14 Apr 2015
The University of Mississippi University United States
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It is well known that infrasonic wind noise levels are lower for arrays placed in forests. In this study, the the wind noise levels, turbulence spectra, wind velocity profiles and convection velocity were measured in and above a pine forest and in a mixed deciduous forest. The wind velocity differ from those in the meteorological literature in having zero displacement length. A prediction of the measured wind noise from the measured meteorological data based on fluid dynamic theory has been developed and compared to the measured wind noise. Very good agreement between measurement and theory was achieved. Low frequency wind noise is due to the turbulence-shear interaction above the trees, while the higher frequency wind noise is due tot he turbulence-turbulence interaction within the tree canopy. Initial measurements demonstrated the necessity of measuring the convection velocity.