Abstract

In the region 250-175 nm the penetration of solar radiation into the atmosphere is controlled by the absorption cross sections of O₂ bands. Part of the radiation transmitted in this vacuum ultraviolet wavelength region is available to photodissociate minor species including NO. The molecular absorption processes and parameters related to the absorption of ultraviolet solar radiation in the terrestrial middle atmosphere have been discussed by a number of authors. For accurate modelling of this important process, the computations involving O₂ and minor species must be performed on a line-by-line basis; laboratory-measured photoabsorption cross sections, with resolution sufficient to yield true cross sections (i.e. undegraded by instrumental effects), are required for both molecules. For most of the Schumann-Runge (S-R) bands of ¹⁶O₂ and its important isotopic variants, such measurements have been successfully completed [Yoshino et al. , 1983; 1987; 1990].

© 1995 Optical Society of America