MORPHOLOGICAL STUDIES OF ATOMIC OXYGEN 557.7MN AND 630.0NM DAYGLOW EMISSIONS

Abstract

The Mesosphere Lower Thermosphere (MLT) dynamics is considerably governed by the solar UV radiation. The EUV component of sunlight is primarily absorbed in lower thermosphere and the UV component in the mesosphere. This absorption of solar radiation governs the photochemistry and airgiow emission of this part of the atmosphere. A number of measurements of solar UV and EUV fluxes have been reported in the literature (Mahajan et al., 1998, Tobiska 1991, Hinteregger et al., 1981). Airglow emissions are faint luminescence of the atmosphere that are being caused by air molecules and atoms selective absorption of solar ultraviolet and X-radiations and these are a feature of most planetary atmospheres. The emissions consist of atomic and molecular lines, band, and continuum systems of atmospheric constituents, both neutral and ionized. As many of the emission features are measurable at the earth's surface, airgiow investigations provide valuable source of information about the composition of our own as well as other planetary atmosphere long before the era of direct investigation by rocket probes and satellites. Other emission features are absorbed by the terrestrial atmosphere, and thus require instrumentation on space vehicle for their study. These airglow investigations continue to assist in the interpretations of the photochemistry and dynamics of planetary atmospheres.