Stratospheric ozone isotope enrichments-revisited

Ozone isotope data for O-49(3) and O-50(3) are presented, that were obtaine d from 28 stratospheric samples collected over 10 years onboard balloon pay loads. Enrichments for O-49(3) range from 7 to 9% in the middle stratospher e. This is in very good agreement with laboratory-derived isotope predictio ns. For O-50(3) most enrichments are between 7 and 11%, a few, however, are too high to be of atmospheric origin. Arguments are presented that stratos pheric ozone isotope data are consistent with enrichments determined in lab oratory studies when pressure and temperature dependence of the isotope eff ect is included. Results from recent remote sensing experiments support the values obtained during balloon-borne sample collections. Very high enrichm ents occasionally measured in the past should be disregarded.