HR: 1340h
AN: A33B-0909    [Abstracts]
TI: Investigation into the stratosphere by long-term observations of the triple isotopic compositions of stratospheric CO₂
AU: * Kawagucci, S
EM: boss@ep.sci.hokudai.ac.jp
AF: Division of Earth and Planetary Sciences, Graduate School of Science, Hokkaido University, N10 W8, Kita-ku, Sapporo, 060-0810, Japan, sapporo, 060-0810 Japan
AU: Tsunogai, U
A33B-0909 AF: Division of Earth and Planetary Sciences, Graduate School of Science, Hokkaido University, N10 W8, Kita-ku, Sapporo, 060-0810, Japan, sapporo, 060-0810 Japan
AU: Nakagawa, F
A33B-0909 AF: Division of Earth and Planetary Sciences, Graduate School of Science, Hokkaido University, N10 W8, Kita-ku, Sapporo, 060-0810, Japan, sapporo, 060-0810 Japan
AU: Aoki, S
A33B-0909 AF: Center for Atmospheric and Oceanic Studies, Graduate School of Science,Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai, Japan, sendai, 980-8578 Japan
AU: Nakazawa, T
A33B-0909 AF: Center for Atmospheric and Oceanic Studies, Graduate School of Science,Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai, Japan, sendai, 980-8578 Japan
AU: Honda, H
A33B-0909 AF: Japan Aerospace Exploration Agency, Yoshinodai, Sagamihara, Japan, sagamihara, 229-8510
AU: Gamo, T
A33B-0909 AF: Ocean Research Institute, The University of Tokyo, 1-15-1, Minamidai, Nakano-ku, Tokyo, Tokyo, 164-8639 Japan
AB: Triple oxygen isotopic composition (δ¹⁸O, Δ¹⁷O) of stratospheric CO₂ is useful as a tracer to study processes of both chemical reactions and air circulations in the stratosphere. In this study, we quantified triple oxygen isotopic compositions of stratospheric CO₂ sampled over Japan by using a balloon-borne cryogenic sampler, as well as their temporal variations for past 15 years. We found significant oxygen isotope anomalies in stratospheric CO₂, while the temporal and seasonal variation was little in both δ¹⁸O and Δ¹⁷O. Besides, the values coincide well with those reported for lower stratospheric CO₂ sampled over Sweden and France by Laemmerzahl et al. (2002), especially for the relation between δ¹⁸O and Δ¹⁷O. We conclude that our dataset represents the actual triple oxygen isotopic compositions of CO₂ in the lower stratosphere. The anomalous oxygen isotopic compositions of stratospheric CO₂ have been explained by oxygen exchanging reaction between CO₂ and O₃ via O(¹D) [Yung et al., 1991]. However, it is difficult to explain the observed triple oxygen isotopic compositions only by the process, because the observed Δ¹⁷O values are substantially higher than the expected Δ¹⁷O values from each δ¹⁸O value, assuming oxygen exchanging reaction between tropospheric CO₂ and stratospheric O₃, using the reported Δ¹⁷O and δ¹⁸O values for stratospheric O₃ [Mauersberger et al., 2003]. Thus, we conclude that some unknown mass independent fractionation processes by some photochemical reactions in upper stratosphere or mesosphere, such as production and/or decomposition reaction of CO₃ complex, for example, must be more responsible for the origin of the anomalous oxygen isotopic compositions of stratospheric CO₂. That is to say, the mixing of air masses between upper stratosphere and troposphere must be responsible for the anomalous oxygen isotopic compositions of CO₂ in the lower stratosphere, rather than by in-situ photochemical reactions in the lower stratosphere.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0330 Geochemical cycles (1030)
DE: 0340 Middle atmosphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005