Satellite observations of wave disturbances caused by moving solar terminator

Abstract

Wave disturbances caused by moving solar terminator were studied using in situ satellite measurements. Neutral species densities measured by low-latitude satellite Atmosphere Explorer-E in the altitude range of 250–400km were used for analysis. Wave disturbances of neutral species density with amplitudes of 2–4% were observed during few hours after passing the terminator, predominantly in time intervals of 6–9 LST and 20–23 LST. These disturbances were interpreted as the acoustic-gravity waves. Spatial scales of such waves range from few hundred to few thousand kilometers, major part of wave spectral power being concentrated in the horizontal wavelength range from 1000km to 1200km. It was shown that vertical and horizontal components of phase velocity of these waves coincide with vertical and horizontal components of terminator velocity, i.e. observed wave are synchronized with the terminator.