Composition variations in the lower thermosphere

Abstract

A collection of density and composition data as obtained from rocket experiments is presented for 120-, 150-, and 200-km altitude. The relevant geophysical parameters of the measurements are also included. The data are analyzed for seasonal and diurnal variations of the major constituents in this altitude region. Only minor seasonal changes of N2 and O2 are found. Atomic oxygen, however, exhibits a pronounced density minimum in summer. The diurnal variation of O appears to be comparatively small. Indication of a diurnal variation of the O2 density with a morning maximum is found at 150 km.