Atmospheric Motions from Sodium Cloud Drifts at Four Locations

Atmospheric motions from 54 sodium cloud firings are examined in the 80-200-km. height region. To gain an insight into various types of motion that are presumably present in the total observed wind, an oscillatory component assigned to internal gravity waves, and the residual motion containing tides and prevailing wind, are studied. Data from apparent movements of ionospheric irregularities seem, in many respects, consistent with sodium drift measurements and are utilized to estimate the prevailing wind and the 24-hr. and 12-hr. periodic variations. Only inferential results can be obtained from many parts of this analysis, but there is a strong suggestion that a slowly varying prevailing wind has a substantial role in these motions; the magnitude of this wind appears to be 45 m./sec. in the 100-115-km. layer and 65 m./sec. near 160 km. At three stations located within the 30"-40' N. latitudes, both the observed and the derived motions are very similar, as if a well organized circulation existed at all heights from 80 to 180 km. Fort Churchill data indicate that farther north this circulation may be considerably stronger.