Open Access

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

  • Yu. I. Portnyagin1Email author,
  • E. G. Merzlyakov1,
  • Ch. Jacobi2,
  • N. J. Mitchell3,
  • H. G. Muller4,
  • A. H. Manson5,
  • W. Singer6,
  • P. Hoffmann6 and
  • A. N. Fachrutdinova7
Earth, Planets and Space201451:BF03353229

DOI: 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.