A Field Trial on the Influence of Range-Dependent Meteorology on Outdoor Sound Propagation

This paper reports on the findings of a field trial programme to investigate the effect of range-dependent meteorology on sound propagation in the atmosphere. Comparisons are made with predictions derived from a PE model utilising the rangedependent meteorology and terrain data derived from the field trail. An experiment is described in which range-dependent meteorological and acoustical data were simultaneously measured during the onset of stable nighttime conditions. A Doppler LIDAR measured winds in scans above the length of the 1km acoustical array rising from the bottom of a valley. Vertical winds, temperatures and turbulence were determined in a column at one point on the array by a combined SODAR, RASS and sonic anemometer system. Wind profiles were also measured using a SODAR positioned 250 metres along the receiving array within the valley. Experimental results are presented investigating the effects of variable meteorology on propagation with distance, and significant intermittent episodes of depressed and elevated sound levels are considered.