A quantitative comparison of horizontal and vertical acoustic sounding with in-situ measurements

Abstract

In this paper, we present some results on an experiment to test the accuracy and utility of a horizontally-aimed acoustic sounder. A high-frequency, high-resolution mini-sounder was mounted on the mast of the Boulder Atmospheric Observatory aimed in the cross-wind direction. Measurements of C$, wind velocity and temperature and velocity variances were obtained under both stable and unstable conditions. These measurements were found to be in agreement with the equivalent values obtained, where appropriate, by the tower-fixed instrumentation and a vertically-pointed sounder, confirming the accuracy of the horizontal sounder. In addition, some information into the horizontal structure of plumes and gravity waves was obtained along with evidence of lack of excess attenuation at least for lengths within the unambiguous range of mini-sounders.

Mini-acoustic sounding?A powerful tool for ABL applications: Recent advances and applications of acoustic mini-sodars

“…Their work covered different operating frequencies and antenna configurations, indicating also some small size and light weight acoustic antenna design operating at relatively high frequencies (normally higher than 2.5 Hz), with very good directional capabilities. Following this work several miniature systems appeared in the field during different experimental campaigns and in some occasions unusual applications of the technique were employed (e.g., horizontal acoustic sounding, Moulsley et al 1985).…”

Effects of stability on the profiles of vertical velocity and its variance in katabatic flow

“…In a similar vein, Mursch-Radlgruber and Rengarijan (1994) mounted a minisodar near the top of a forest canopy t o sample the boundary layer above the canopy in the boreal forest. Surfacebased measurements have established the existence of thermal roots well within the surface layer (Moulsley et al, 1985). Coulter and Li (1995) used wavelet transforms of the vertical velocity field in convective conditions t o determine characteristic scale sizes of thermal plumes; using the principal scale size, they showed that in-thermal vertical velocities can serve as a measure of the convective velocity scale, LO*.…”

Excess attenuation of an acoustic beam by turbulence

“…[9][10][11][12][13][14][15] Haugen et al 11 found that the difference between the sodar and the tower instrumentation measurements was large, and attributed it to attenuation from scattering by turbulence and beam bending. Neff 9 and Asimakopoulos 10,13 have similar opinions.…”