The vertical distribution of atomic oxygen in the upper atmosphere

The spectra from auroras and from the night sky prove that atomic oxygen is permanently present in the lower ionosphere. Oxygen molecules are dissociated photo-chemically by ultra-violet radiation. The atoms recombine in a three-body collision. The rate of change of oxygen atoms during day and night has been derived, in addition to the vertical distribution for the equilibrium state. The numerical calculations have been carried through using different values for incoming radiation (effective temperature of a black body varying between 5000° and 6000°K), zenith-distance of the sun, and rate-constant of the three-body collision. From the data obtained, it is concluded that the thickness of the transition layer is about 10 km. Due to the uncertainty of the constants involved, its mean height can be confirmed only between 100 and 110 km; no more accurate value can be given. The transition layer is definitely below the E-layer. Differences caused by the use of different intensities of incoming radiation are large; variations of the rate-constant have about the same influence, whereas different zenith-distances are of little importance. Height and shape of the transition layer are more or less equal all over the globe. The assumed atmospheric density-distribution influences the results considerably. The findings are compared with the investigations by other authors. During the night, when the dissociative agent is absent, the concentration of oxygen atoms undergoes small changes. It is negligible above 120 km and largest at about 100 km. Within 12 hours the largest changes which occur are less than 16 per cent, with the equilibrium amount depending on the value of rate-constant. The amount of atoms recombined during the night is exactly formed anew during the day. Therefore, the equilibrium is maintained, and the assumptions made are justified. The height of the transition layer is constant during day and night. Recombination during the night has no appreciable influence on the vertical distribution of atomic oxygen.