Evidence for Altitude-dependent photolysis-induced 18O isotopic fractionation in stratospheric ozone

Authors

Vanessa E. Haverd, University of WollongongFollow
Geoffrey C. Toon, California Institute of Technology
David W. Griffith, University of WollongongFollow

RIS ID

12300

Publication Details

Haverd, V. E., Griffith, D. W. & Toon, G. (2005). Evidence for Altitude-dependent photolysis-induced 18O isotopic fractionation in stratospheric ozone. Geophysical Research Letters, 32 (22), 1-4. Copyright 2005 the American Geophysical Union.

Abstract

We present vertical profiles of ¹⁸O fractionations in ozone, measured by balloon-borne infrared remote sensing between 15 and 40 km. The magnitudes of the ¹⁶O¹⁶O¹⁸O (⁶⁶⁸O₃) and ¹⁶O¹⁸O¹⁶O (⁶⁸⁶O₃) fractionations are 13.5 +/- 2.7% and 7.7 +/- 2.2%, averaged over the 20-35 km altitude range, in good agreement with previous atmospheric measurements by mass spectrometry and both infrared and far infrared remote sensing spectroscopy. We use our fractionation profiles, together with known fractionation effects of the ozone formation reaction, to deduce fractionations attributable to photolysis. These photolytic fractionation profiles show significant increases with altitude (3.5 +/- 2.2% and 4.0 +/- 1.6% for ⁶⁶⁸O₃ and ⁶⁸⁶O₃ respectively over the 20-35 km altitude range), indicating that the ozone formation reaction alone does not account for the observed enrichments.