Study on oxygen atmospheric band dayglow: global and seasonal variations deduced from high-resolution Doppler imager observations

Abstract

The atmospheric band of O 2 mapped by high resolution Doppler imager instrument on board of upper atmospheric research satellite during the years 1992–1998 are analyzed to investigate the diurnal, monthly, seasonal, and latitudinal variations. In the equatorial regions, the emission rates are strongest in the spring and fall equinoxes, carrying a semiannual oscillation mode (SAO), which can be linked with the solar influences. In the mid latitudes, the emission rates are strong only in the winter months, showing an annual oscillation mode. The correlation between the emission rate with mesopause temperature is discussed. The intensity and height of the peak emission rates in the northern hemisphere are slightly different from those of southern hemisphere. Similarly, the ozone at 90 km , taken from halogen occultation experiment data also shows a positive correlation with the emission rates. This suggests a strong link with the photochemically produced O atoms. With a Lomb Scargle harmonic analysis, we show that the emission rate has the strongest 182-day oscillation followed by the annual and seasonal oscillations. The relative amplitude depends on the latitude.