Reciprocal travel time scintillation analysis

Authors

  • D. Menemenlis Electr. Eng., Victoria Univ., BC, Canada
  • D.M. Farmer Electr. Eng., Victoria Univ., BC, Canada

Keywords:

acoustic wave velocity, oceanographic regions, sea ice, underwater sound, Arctic boundary layer, acoustical reciprocal transmissions, line-averaged velocity measurements, high frequency velocity fluctuations, advection, turbulent velocity fine structure, sonic anemometers, spectral transfer functions, dimensionless wavenumber

Abstract

During a study of the Arctic boundary layer. Menemenlis and Farmer used acoustical reciprocal transmissions to obtain line-averaged velocity measurements along 200 m horizontal paths in the mixed layer beneath ice. The present discussion is motivated by a desire to interpret the observed high frequency velocity fluctuations in terms of the advection and evolution of turbulent velocity fine structure. Kaimal et al. (1968) discussed the problem of line-averaging in the context of extending the useful range of sonic anemometers to scales shorter than the acoustic paths. They derived transfer functions that relate measured and ideal one-dimensional power spectra. The present authors investigate the asymptotic behaviour of the spectral transfer functions, as the length of the measuring baseline is increased, and derive analytic expressions. The spectral transfer functions are shown to vary with dimensionless wavenumber and with angle between the measuring baseline and the mean velocity. The analysis is extended to anisotropic and inhomogeneous flows. Finally, some experimental data taken in the boundary layer beneath ice is compared with the theory

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Published

1992-09-01

How to Cite

1.
Menemenlis D, Farmer D. Reciprocal travel time scintillation analysis. Canadian Acoustics [Internet]. 1992 Sep. 1 [cited 2021 Dec. 8];20(3):71-2. Available from: https://jcaa.caa-aca.ca/index.php/jcaa/article/view/741

Issue

Section

Proceedings of the Acoustics Week in Canada