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A Balloonborne Acoustic Sounder

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  • 1 Department of Physics (RAAF Academy), University of Melbourne, Victoria 3186 Australia
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Abstract

An account is given of the design and construction of an experiment in which a monostatic acoustic sounder was mounted beneath a gondola carried by a freely ascending polyethylene balloon. By interrogating a volume of the atmosphere directly below the ascending gondola, a vertical profile of acoustic scattering structures could be obtained from the ground, up through the tropopause and into the lower stratosphere. In a series of six flights, a considerable number of atmospheric acoustic scattering structures were observed from the ground up to altitudes greater than 15 km. More complex, intense and closely-spaced structures were observed near and below the tropopause. Measurement of the coefficient of total attenuation for sound at a frequency of 1250 Hz gave values between 0.005 and 0.01 dB m−1, in general agreement with those made in the free atmosphere by Delsasso and Leonard (1953).

Abstract

An account is given of the design and construction of an experiment in which a monostatic acoustic sounder was mounted beneath a gondola carried by a freely ascending polyethylene balloon. By interrogating a volume of the atmosphere directly below the ascending gondola, a vertical profile of acoustic scattering structures could be obtained from the ground, up through the tropopause and into the lower stratosphere. In a series of six flights, a considerable number of atmospheric acoustic scattering structures were observed from the ground up to altitudes greater than 15 km. More complex, intense and closely-spaced structures were observed near and below the tropopause. Measurement of the coefficient of total attenuation for sound at a frequency of 1250 Hz gave values between 0.005 and 0.01 dB m−1, in general agreement with those made in the free atmosphere by Delsasso and Leonard (1953).

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