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  • Article
  • Open Access

Some results of S-transform analysis of the transient planetary-scale wind oscillations in the lower thermosphere

  • 1Email author,
  • 1,
  • 2,
  • 3,
  • 4,
  • 5,
  • 6,
  • 6 and
  • 7
Earth, Planets and Space201451:BF03353229

https://doi.org/10.1186/BF03353229

Received: 28 July 1998

Accepted: 20 April 1999

Published: 26 June 2014

Abstract

Technique appropriate to the analysis of lower thermospheric wind data recorded by global-scale networks of ground-based instruments are discussed. The S-transform technique is shown to be effective in the analysis of the main features of travelling planetary waves and this method is applied to the time series of horizontal-velocity data obtained during the DYANA campaign (January–March, 1990). The analysis reveals strongly transient behavior of the day-to-day lower thermosphere wind variations, as well as their specific longitudinal structure. In particular, it was found that the revealed quasi-15 day and quasi-5 day wind oscillations may be described as transient westwardpropagating waves with zonal wavenumber s = 1, while an oscillation with the a period near 7 days is tentatively identified as having a wavenumber s = 0.

Keywords

  • Continuous Wavelet Transform
  • Planetary Wave
  • Meridional Component
  • Longitudinal Structure
  • Lower Thermosphere

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