 |
| Titel |
Long-term observation of mass-independent oxygen isotope anomaly in stratospheric CO2 |
| VerfasserIn |
S. Kawagucci, U. Tsunogai, S. Kudo, F. Nakagawa, H. Honda, S. Aoki, T. Nakazawa, M. Tsutsumi, T. Gamo |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 8, no. 20 ; Nr. 8, no. 20 (2008-10-24), S.6189-6197 |
| Datensatznummer |
250006422
|
| Publikation (Nr.) |
 copernicus.org/acp-8-6189-2008.pdf |
|
|
|
|
|
| Zusammenfassung |
| Stratospheric and upper tropospheric air samples were collected during
1994–2004 over Sanriku, Japan and in 1997 over Kiruna, Sweden. Using these
archived air samples, we determined the triple oxygen-isotope composition of
stratospheric CO2 and the N2O mixing ratio. The maximum Δ17OCO2
value of +12.2‰, resembling that observed previously in
the mesosphere at 60 km height, was found in the middle stratosphere over
Kiruna at 25.6 km height, suggesting that upper stratospheric and
mesospheric air descended to the middle stratosphere through strong downward
advection. A least-squares regression analysis of our observations on a
δ18OCO2−δ17OCO2
plot (r2>0.95)
shows a slope of 1.63±pm0.10, which is similar to the reported value of
1.71±0.06, thereby confirming the linearity of three isotope
correlation with the slope of 1.6–1.7 in the mid-latitude lower and middle
stratosphere. The slope decrease with increasing altitude and a curvy trend
in three-isotope correlation reported from previous studies were not
statistically significant. Using negative linear correlations of Δ17OCO2
and δ18OCO2 with the N2O mixing
ratio, we quantified triple oxygen-isotope fluxes of CO2 to the
troposphere as +48‰ GtC/yr (Δ17OCO2) and +38‰ GtC/yr
(δ18OCO2) with ~30% uncertainty. Comparing recent
model results and observations, underestimation of the three isotope slope
and the maximum Δ17OCO2 value in the model were clarified,
suggesting a smaller O2 photolysis contribution than that of the model.
Simultaneous observations of δ18OCO2, δ17OCO2, and N2O mixing ratios can elucidate triple oxygen
isotopes in CO2 and clarify complex interactions among physical,
chemical, and photochemical processes occurring in the middle atmosphere. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|