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  • Author or Editor: W. D. Hall x
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F. F. Hall Jr. and W. D. Neff

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R. J. Wyckoff, D. W. Beran, and F. F. Hall Jr.

Abstract

Temperature profiles measured with a radiosonde are compared with returns from an acoustic echo sounder throughout the height range 50–700 m. In general, the sounder records indicate the temperature inversion to be somewhat lower than do the radiosonde records. Reasons for this apparent discrepancy and the advantage of the sounder, in being able to monitor continuously the inversion structure and undulations produced by wind shear, are discussed. It was proved feasible to operate the acoustic sounder in a noisy commercial district with little detrimental effect on the ability to detect atmospheric temperature structure. It is concluded from this preliminary investigation that the combination of the radiosonde and the acoustic echo sounder provides a much more valuable tool for monitoring structure in the stable planetary boundary layer than either device used alone.

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F. F. Hall Jr., J. G. Edinger, and W. D. Neff

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The turbulent temperature structure and winds in thermal convective plumes over prairie grassland have been investigated with an acoustic echo sounder system. Three spaced acoustic antennas, with two inclined at 45° elevation, were used to provide plume shape information and Doppler-derived total wind-vector patterns between heights of 70 and 500 m. Supporting in situ measurements were made on a 15 m tower, with a tethered balloon-supported Boundary Layer Profiler, and from a light aircraft. The most probable orientation of the plumes was nearly vertical, but frequent upwind and downwind tilts were also observed. Maximum positive vertical velocities in the plumes at midday were near 2 m s−1, while maximum downward currents were one-half this value. Acoustic echoes from regions above the mixed layer, corresponding in height to an elevated temperature inversion, correlate well with regions of maximum wind shear.

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