| This dissertation reports on the global temporal variations of the oxygen airglow emissions from the analysis of seven years of WINDII (Wind Imaging Interferometer) satellite data. To interpret the emission signatures, the observations are compared with the simulations of NCAR's TIME-GCM general circulation model that includes atmospheric photochemistry and dynamics. The nighttime O(1S), O2( b1S+g ), and OH airglow emissions originate from the recombination of atomic oxygen, which acts as a tracer of atmospheric motions. Variations of these emissions thus provide information on wave activity and on the large-scale circulation in the mesosphere and lower thermosphere (MLT).;Further, the long-term trend variation is examined. The emissions at all latitudes follow the variation of F10.7 flux and are in phase with the solar cycle. They also have a two-year period variation that may be caused by the quasi-biennial oscillation. All these emission variations could be ultimately explained in terms of vertical motion. Vertical motion is observed directly as a universal inverse relationship of the airglow emission rate and emission altitude.;Finally, the anomalous WINDII airglow profiles with multiple peaks are investigated. Their occurrences coincide with steep emission rate gradients associated with the diurnal tide. Moreover, the multiple peak may be an artificial structure produced during the WINDII inversion because the assumption of horizontal homogeneity for the limb-viewing is not fully satisfied, for instances when the atmosphere is perturbed by waves. A 1-D numerical model shows that localized gravity waves could produce the horizontal variation but would appear as a secondary peak in the WINDII airglow profile.;The study focuses on the seasonal climatology of the emission rate for various latitude regions. In the tropics, a dramatic semi-annual variation exists but only for limited local times. The onset of the variation is consistent with the propagating tidal wave. At mid-latitudes, both semi-annual and annual variations occur. They are subject to local time variations, which again manifest the tidal influence. At higher latitudes, an annual behaviour becomes dominant. It may also result from upward and downward motions associated with the large-scale general circulation. However, a mid-summer peak is superimposed, indicating other influences. |
