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Long-term observation of mass-independent oxygen isotope anomaly in stratospheric CO2

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Title: Long-term observation of mass-independent oxygen isotope anomaly in stratospheric CO2
Authors: Kawagucci, S. Browse this author
Tsunogai, U. Browse this author
Kudo, S. Browse this author
Nakagawa, F. Browse this author
Honda, H. Browse this author
Aoki, S. Browse this author
Nakazawa, T. Browse this author
Tsutsumi, M. Browse this author
Gamo, T. Browse this author
Issue Date: 24-Oct-2008
Publisher: Copernicus Publications
Journal Title: Atmospheric Chemistry and Physics
Volume: 8
Issue: 20
Start Page: 6189
End Page: 6197
Publisher DOI: 10.5194/acp-8-6189-2008
Abstract: 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.
Type: article
URI: http://hdl.handle.net/2115/44836
Appears in Collections:雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 角皆 潤

 

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