On the Role of the Mesopause in Interaction Studies.

A demonstration that the spatial and temporal behavior of the mesosphere and lower thermosphere can be depicted in a way consistent with empirical data only if they are considered as separate entities. Attempts to derive quantitatively plausible connections between them failed until it was assumed that the mesopause itself was not only a schematic boundary, but also a region exerting a dominant effect on the atmosphere above and below. Sounding rockets have clearly shown that temperature and density in this region vary with latitude and season in a periodic way; satellite reentry observations now seem to indicate that both height and temperature of the mesopause undergo considerable variation, apparently as a function of the eleven-year solar cycle. It thus appears that the mesopause region is the center of interactions between lower and upper atmosphere, where direct solar influences from above combine with the periodic phenomena from below. 25 pp. Bibliog.