The global characteristics of atmospheric emissions in the lower thermosphere and their aeronomic implications

Abstract

The green line (557.7 nm) of atomic oxygen and the Herzberg bands of molecular oxygen (measured between 250 and 280 nm) as observed from the Ogo 4 airglow photometer from August 1967 through January 1968 are discussed in terms of their spatial and temporal distributions and their relation to the atomic oxygen content in the lower thermosphere. Daily maps of the distribution of emissions show considerable structure (cells, patches, and bands) with appreciable changes from day to day. When data are averaged over periods of several days in length, the resulting patterns have only occasional tendencies to follow geomagnetic parallels. The seasonal variation is characterized by maxima in both the northern and the southern hemispheres in October, the northern hemisphere having substantially higher emission rates. These maxima tend to move toward the poles, leaving very low values of emission at low latitudes in December and January. Noting the similarity of the atomic oxygen profiles in the lower thermosphere to the profile of a Chapman distribution, formulae are derived relating the vertical column emission rates of the green line and the Herzberg bands to the atomic oxygen peak density. Global averages for the time period for these data (August 1967 to January 1968), when expressed in terms of maximum atomic oxygen densities near 100 km, have a range of 2.0 X 10 • cm -3 to 2.7 X 10 • cm -3. Their variation closely follows the phase of the semiannual variation in total density observed at higher altitudes from the analysis of satellite drag data.

Equinox transition in wind and airglow observations

“…Fukuyama (1977) made an extensive analysis of the seasonal variation from ground-based observations. For satellite results there are O( 1 S) observations by Donahue et al (1973), from Ogo-6 Reed and Chandra (1975), from Ogo-4, and Cogger et al (1981) from ISIS-II measurements. The latter o er the most complete annual coverage, and were modelled by Garcia and Solomon (1985), based on the seasonal e ect of breaking gravity waves on eddy di usion.…”

The emission of oxygen green line and density of O atom determined by using ISUAL and SABER measurements

“…(2) below. This is the way Reed and Chandra (1975) and Melo et al (2001) have reported their distributions for the mesospheric O atoms.…”

“…(2) below. This is the way Reed and Chandra (1975) Based on results shown in Fig. (4a), the O atom distribution can be fitted with a Chapman profile as described in Eq.…”

WINDII on UARS: A View of Upper Mesosphere and Lower Thermosphere Dynamics.

“…The OGO 4 satellite employed nadir viewing to obtain global maps ofthe 557.7 nm emission, which showed large scale patchiness (Reed and Chandra, 1975). The OGO 6 satellite made limb scanning measurements, and discovered a trough in green line emission at the equator (Donahue et al, 1974).…”