Altitude profile of the infrared atmospheric system of oxygen in the dayglow

Abstract

The altitude profile of the infrared atmospheric system of oxygen at 1.27 μ in the dayglow has been measured using a two-channel filter photometer flown to an altitude of 128 km over White Sands, New Mexico, at a solar elevation of 14.5° in October 1966. The emission peaks at 49.5 km and the maximum volume emission rate is 1030 kR/km. The total emission intensity of 21 MR is in agreement with that of balloon-borne observations. The main emission layer agrees well with that predicted from an excitation mechanism of the photolysis of ozone in the Hartley continuum. There is some excess emission above 80 km, and three possible explanations are considered: additional ozone, enforced fluorescence via the ¹Σ level, and recombination of atomic oxygen. A combination of these can explain the observations, but which ones are most important cannot be decided. The amounts of metastable O2 observed above 70 km are sufficient to provide an important source of ionization and of NO in the lower D region.