Visualization and WKB analysis
of the internal gravity wave in the QBO experiment

Naohito Otobe  (Department of Geophysics, Kyoto Univ.)
Satoshi Sakai (School of Earth Sciences, IHS, Kyoto Univ.)
Shigeo Yoden (Department of Geophysics, Kyoto Univ.)
Masato Shiotani (Graduate School of Environmental Earth Science, Hokkaido Univ.)

We carried out an experiment to analyze the QBO observed in the tropical stratosphere. The QBO-like flow oscillation is visualized along with the gravity wave that causes the oscillation. The gravity wave is visualized by the moíre method. By WKB approximation, propagation of the internal gravity wave was calculated using the mean flow obtained experimentally, and was compared to that observed in the experiment. The patterns of the internal gravity wave agreed fairly well with each other. Also, the estimated momentum flux convergence agrees with the acceleration of the mean flow. These results show the validity of the WKB approximation, even in cases where the structure of the mean flow is relatively small compared to the wavelength.
  • Introduction
  • The apparatus
  • Visualization-The Flow
  • Visualization-The internal gravity wave
  • Result-The oscillation of average flow
  • Result-The internal gravity wave
  • Result-Comparison with WKB analysis
  • Conclusion
  • Appendix
  • Preparation of stratified salt water
  • Making floaters
  • Image processing
  • WKB analysis
  • Figure List
  • Reference
  • Acknowledgements
  • Authors' Address
  • Received 27 January, 1998; in revised form 27 April, 1998

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