Atmospheric Acoustic and Gravity Wave Studies. Part A. Acoustic Propagation Studies. Boundary Layer Fluctuation Effects on Sound Propagation.
Rept. no. 13 (Final, Part A), Jul 70-Jun 74,
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH AND PLANETARY SCIENCES
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Amplitude and phase variation measurements of sound waves propagating through the boundary layer have been made to study the boundary layer fluctuations. The ray paths penetrated 100 to 300 meters above the surface and travelled horizontal distances of up to 10 kilometers. The wind velocity fluctuations inferred from the sound propagation were only about 20 of the 50 meter wind fluctuations for periods of 30-60 seconds and about 50 for fluctuation periods of 250-900 seconds. The fluctuation cells were inferred to be greatly flattened with vertical scales of 100-200 meters relatively independent of the horizontal scale.