A tentative model of the equilibrium height distribution of nitric oxide in the high atmosphere and the resulting D-layer

Abstract

An attempt is made to derive a tentative model for the equilibrium distribution of nitric oxide in the height range 50–100 km by considering some of the possible photochemical reactions involving ozone, nitrogen and oxygen (both molecular and atomic) and nitrous oxide. The distribution depends markedly on the types of O and N₂O distributions assumed. In general, under the conditions of photochemical equilibrium, the maximum of NO concentration occurs within 85–95 km with a maximum concentration not exceeding a value of about 2 × 10¹²/cm³. The problem of the formation of the D-layer by photoionization of NO by L_α is then discussed in some detail. With the NO distributions obtained in this work and the recombination coefficient model given by Mitra and Jones, the process is found to yield adequate ionization for the D-layer.