Isotopic composition of stratospheric ozone

Using recently measured rates for isotopic variants of the ozone formation reaction , we derive expressions for the enrichment of symmetric and asymmetric and in stratospheric ozone and calculate total enrichments of 123‰ and 107‰ for and , respectively. We compare the calculations with measurements made with the Smithsonian Astrophysical Observatory far-infrared spectrometer during seven balloon flights which took place between 1989 and 1997. We find that the calculations are in reasonable agreement with the average observed enrichments of ‰ and ‰ for and , respectively, where the errors indicate the estimated accuracy; we also find that our measurements are in agreement with other recent stratospheric and tropospheric measurements. Using our measurements of the enrichment of the asymmetric and symmetric forms of and , we estimate branching ratios of and ! " # for production of the symmetric isotopomer by the reaction of $&% O with and , respectively.