Reports

Carbon Dioxide and Oxygen Isotope Anomalies in the Mesosphere and Stratosphere

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Science  10 Nov 1995:
Vol. 270, Issue 5238, pp. 969-972
DOI: 10.1126/science.270.5238.969

Abstract

Isotopic (δ17O and δ18O) measurements of stratospheric and mesospheric carbon dioxide (CO2) and oxygen (O2), along with trace species concentrations (N2O, CO, and CO2), were made in samples collected from a rocket-borne cryogenic whole air sampler. A large mass-independent isotopic anomaly was observed in CO2, which may in part derive from photochemical coupling to ozone (O3). The data also require an additional isotopic fractionation process, which is presently unidentified. Mesospheric O2 isotope ratios differed from those in the troposphere and stratosphere. The cause of this isotopic variation in O2 is presently unknown. The inability to account for these observations represents a fundamental gap in the understanding of the O2 chemistry in the stratosphere and mesosphere.