Seasonal variations of atomic oxygen in the lower thermosphere

The seasonal variations of the vertical profiles of the atomic oxygen concentration are analyzed. The balance equation for the concentration of atomic oxygen, the reaction equations determining the velocity of chemical losses, the expression for the barometric distribution of atomic oxygen concentration, and the basic balance equation for the region above the turbopause are used in the analysis. Profiles were obtained for the atomic oxygen concentration in winter and summer conditions. Both graphs are at a 75 degree zenith angle to the sun and are similar in shape. The maximum in the vertical distribution of the concentration lies at about 96 km in winter and 92 km in summer, a result due to the stronger summer sunshine raising the equilibrium concentration of atomic oxygen to higher values. The profiles can be used as a sui generis continuation of the MSIS model at heights of 120 km or less.