Photodissociation of isotopically heavy O 2 as a source of atmospheric O 3

Abstract

18O16O is the sixth most abundant gas in the atmosphere after 14N14N, 16O16O, Ar, 15N14N and H2O. From available data on line positions in the Schumann‐Runge (S‐R) bands (175 < λ < 205 nm) of 18O16O we estimate its atmospheric photodissociation rates. In the high stratosphere and mesosphere this proposed source of O and O3 could be significant compared to photodissociation of 16O16O although our estimates are subject to several uncertainties that are discussed. We calculate the transmission of solar radiation through the S‐R bands of 18O16O and 16O16O with transmission functions averaged over individual S‐R bands. Line‐by‐line calculations will be needed to refine our estimates but certain spectroscopic data are not yet available. © 1980 by the Chinese Geophysical Society