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Direct measurements of neutral wave characteristics in the thermosphere

Authors

  • W. E. Potter,

  • D. C. Kayser,

  • K. Mauersberger


Abstract

Waves in the neutral upper atmosphere have been measured by the open source neutral mass spectrometer (Oss) during both the elliptical and the circular phases of the Atmosphere Explorer-C mission. Typical peak-to-peak wave amplitudes seen in [N2] are 30%, although amplitudes of 55% have been recorded. The amplitudes are mass dependent, Ar showing the largest perturbation. Helium is typically found to be out of phase with the heavier constituents. A survey of Oss data from 338 circular orbits shows that the highest wave amplitudes and the greatest number of occurrences are found in both the northern and the southern high-latitude regions. The near-simultaneous measurements of waves in both hemispheres at high latitudes also point toward a source related to conjugate phenomena. A possible second class of lower-amplitude waves peaks at high latitudes; however, a secondary peak near ±25° magnetic latitude may be due to waves generated near the equatorial region. A study of wave amplitudes and occurrences during a magnetic storm shows a possible transpolar propagation of waves from a magnetically active region near local midnight. The assumption of horizontal propagation would explain the observed high-latitude distribution of large-amplitude waves. The results of this study are compared with previous measurements of neutral wave structure.

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