CO2 and SF6 as stratospheric age tracers: consistency and the effect of mesospheric SF6-loss

Mixing ratios of the conserved tracers SF6, and CO2 in air samples collecte d with cryogenic whole-air samplers during two balloon flights in the Arcti c and mid-latitude stratosphere up to 30 km altitude in 1997 are presented. The data are used to derive the mean age of stratospheric air. The calcula ted CO2-ages agree with the corresponding SF6-ages to within 0.5 years. The se results do not confirm the findings previously reported by Harnisch et a l. [1998] but rather suggest that SF6 and CO2 can be regarded as equivalent age tracers. However, evidence is presented that this general agreement ma y not be valid for polar stratospheric air parcels that comprise fractions of mesospheric air.