Measurements of tidal oscillations above 120 kilometers

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Studies of the altitude variations of upper atmospheric winds indicate oscillatory components of the horizontal wind motion in the vertical plane. The smaller scales of these oscillatory motions have been shown to be the lengths predicted by the theory of the viscous limited internal gravity waves. Measurements of the large scales in the 120 to 180 km altitude range have shown a marked correlation to the pressure scale height. Analysis of these large-scale vertical wavelengths indicates that the equivalent depth (h) of the atmosphere corresponds to two of the eigenmodes of earth's atmosphere or model atmosphere of the solar semidiurnal tide predicted by the Laplace tidal equation. These are, respectively, the (2, 4) mode which appears to dominate in the summer, and the (2, 6) mode which is dominant in the winter. (Author).