Diurnal and long-term behavior of the exospheric temperature as observed by incoherent scatter sounding in the F2 region


  • D. Alcayde


A spectral analysis has been performed on the exospheric temperature derived from incoherent scatter data gathered at St. Santin for two unusually long observation campaigns. It is found that the main components of the oscillations are diurnal and semidiurnal, with amplitudes of respectively 10 and 2.5% of the steady component. Based on this evidence the bulk of the data, corresponding to 84 shorter experiments of only about 40 hr, has been Fourier-analyzed in terms of the abovementioned components. The long-term variations of the characteristics of each steady state and of the oscillation components are then analyzed and their implications for the temperature structure are discussed.