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Infrasonic wind noise under a deciduous tree canopy
Jeremy Webster1, Richard Raspet2
1National Center for Physical Acoustics, Box 1848, University, Mississippi 38677, USA.
The Journal of the Acoustical Society of America
|May 22, 2015
Summary
This study predicts infrasonic wind noise under deciduous forests. Leaf presence significantly reduces high-frequency noise, making levels similar to pine forests.
Area of Science:
- Acoustics
- Environmental Science
- Atmospheric Physics
Background:
- Infrasonic wind noise in forests is influenced by wind velocity and canopy structure.
- Previous research predicted infrasonic wind noise in pine forests based on wind data.
- Understanding forest acoustics is crucial for environmental monitoring and noise pollution studies.
Purpose of the Study:
- To measure and predict infrasonic wind noise under deciduous forests with and without leaves.
- To investigate the impact of leaf presence on wind noise spectra.
- To analyze the contributions of turbulence-shear and turbulence-turbulence interactions to wind noise.
Main Methods:
- Measurements of infrasonic wind noise and wind velocity spectra within and above deciduous forest canopies.
- Calculation of turbulence-shear and turbulence-turbulence interaction pressures.
- Comparison of predicted noise levels with measured data.
- Simulations of forest effects using meteorological parameters.
Main Results:
- A low-frequency peak in wind noise spectra was predicted by turbulence-shear interactions above the canopy.
- High-frequency wind noise was predicted by turbulence-turbulence interactions near the ground.
- Leaf presence had minimal effect on the low-frequency peak but reduced high-frequency noise by an order of magnitude.
- Wind noise levels in leafy deciduous forests were comparable to those in pine forests.
Conclusions:
- Turbulence-turbulence interactions near the ground are dominant in predicting high-frequency wind noise.
- Leaf presence significantly attenuates high-frequency infrasonic wind noise in forests.
- Forest canopy structure and leaf presence are critical factors in determining infrasonic wind noise characteristics.
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