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Effects of Meteorology on propogation

Abstract - Honington 2001

A fundamental investigation of the effects of range-dependent meteorology on outdoor sound propagation

  • Field campaigns
    • Experimental techniques
    • SODAR
    • LIDAR
  • Comparisons with predictions
  • Limitations in theoretical modelling

Introduction

  • Influence of weather on a particular measurement depends upon the determination of the prevailing meteorological conditions over the propagation path
  • Application of research into outdoor noise propagation to practical environmental noise measurement and prediction
  • Three principal mechanisms of refraction, atmospheric absorption and scattering

Schematic of Field Trial

Schematic of Field Trial

The loudspeaker structure

Experimental Method: Meteorology

  • Wind profiles
    • SODAR
      • 250 metres along array
    • Doppler LIDAR
      • Scanning in three-dimensions
      • Radial wind velocities from a single location
      • 900 metres perpendicular array
    • Radar wind profiler
      • 28km southeast of site
      • Augment data at highest altitudes
  • Automatic weather stations
    • 2m and 10m at source and furthest position

Aerial view of bunker trial

Aerial view of bunker trial

Multi-Azimuth Parabolic Equation Predictions

Multi-Azimuth Parabolic Equation Predictions 

Conclusion

  • Meteorological changes may exert significant influence
    • High-level sources and long distances
  • Downwind
    • Noise levels may increase by a few dB
    • Depends on wind speed
  • Measurement normally preferred downwind
    • More conservative since deviation is smaller
  • Upwind or sidewind level
    • Decreases in excess of 20 dB
  • Temperature gradients under with no wind
    • Variations of same order as strong vector winds

Acknowledgements

  • The SODAR team was led by Prof Bradley and Prof Collier led the LIDAR team
  • We would like to thank D Humpheson and R Beaman of RAF Henlow, Group Captain Anderton of RAF Honington, and CL Murray of QinetiQ Malvern
  • This work was kindly funded by the EPSRC under grant GR/M71459

Contact

Dr David Waddington