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<front>
<journal-meta>
<journal-id journal-id-type="publisher">ACP</journal-id>
<journal-title-group>
<journal-title>Atmospheric Chemistry and Physics</journal-title>
<abbrev-journal-title abbrev-type="publisher">ACP</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1680-7324</issn>
<publisher><publisher-name>Copernicus GmbH</publisher-name>
<publisher-loc>GÃ¶ttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/acp-8-6189-2008</article-id>
<title-group>
<article-title>Long-term observation of mass-independent oxygen isotope anomaly in stratospheric CO&lt;sub&gt;2&lt;/sub&gt;</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Kawagucci</surname>
<given-names>S.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Tsunogai</surname>
<given-names>U.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Kudo</surname>
<given-names>S.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Nakagawa</surname>
<given-names>F.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Honda</surname>
<given-names>H.</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Aoki</surname>
<given-names>S.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Nakazawa</surname>
<given-names>T.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Tsutsumi</surname>
<given-names>M.</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Gamo</surname>
<given-names>T.</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Earth and Planetary System Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Japan Aerospace Exploration Agency, Sagamihara, Japan</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Center for Atmospheric and Oceanic Studies, Graduate School of Science, Tohoku University, Sendai, Japan</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Dept. of Chemical Oceanography, Ocean Res. Ins., Univ. of Tokyo, Nakano-ku, Tokyo, Japan</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>present address: Dept. of Chemical Oceanography, Ocean Res. Ins., Univ. of Tokyo, Nakano-ku, Tokyo, Japan</addr-line>
</aff>
<pub-date pub-type="epub">
<day>24</day>
<month>10</month>
<year>2008</year>
</pub-date>
<volume>8</volume>
<issue>20</issue>
<fpage>6189</fpage>
<lpage>6197</lpage>
<permissions>
<license xlink:type="simple">
<license-p>This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.</license-p>
</license>
</permissions>
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<abstract>
<p>Stratospheric and upper tropospheric air samples were collected during
1994â€“2004 over Sanriku, Japan and in 1997 over Kiruna, Sweden. Using these
archived air samples, we determined the triple oxygen-isotope composition of
stratospheric CO&lt;sub&gt;2&lt;/sub&gt; and the N&lt;sub&gt;2&lt;/sub&gt;O mixing ratio. The maximum &amp;Delta;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;CO&lt;sub&gt;2&lt;/sub&gt;&lt;/sub&gt;
value of +12.2&amp;permil;, 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
&amp;delta;&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;CO&lt;sub&gt;2&lt;/sub&gt;&lt;/sub&gt;&amp;minus;&amp;delta;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;CO&lt;sub&gt;2&lt;/sub&gt;&lt;/sub&gt; 
plot (&lt;i&gt;r&lt;/i&gt;&lt;sup&gt;2&lt;/sup&gt;&gt;0.95)
shows a slope of 1.63&amp;plusmn;pm0.10, which is similar to the reported value of
1.71&amp;plusmn;0.06, thereby confirming the linearity of three isotope
correlation with the slope of 1.6â€“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 &amp;Delta;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;CO&lt;sub&gt;2&lt;/sub&gt;&lt;/sub&gt;
and &amp;delta;&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;CO&lt;sub&gt;2&lt;/sub&gt;&lt;/sub&gt; with the N&lt;sub&gt;2&lt;/sub&gt;O mixing
ratio, we quantified triple oxygen-isotope fluxes of CO&lt;sub&gt;2&lt;/sub&gt; to the
troposphere as +48&amp;permil; GtC/yr (&amp;Delta;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;CO&lt;sub&gt;2&lt;/sub&gt;&lt;/sub&gt;) and +38&amp;permil; GtC/yr
(&amp;delta;&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;CO&lt;sub&gt;2&lt;/sub&gt;&lt;/sub&gt;) with ~30% uncertainty. Comparing recent
model results and observations, underestimation of the three isotope slope
and the maximum &amp;Delta;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;CO&lt;sub&gt;2&lt;/sub&gt;&lt;/sub&gt; value in the model were clarified,
suggesting a smaller O&lt;sub&gt;2&lt;/sub&gt; photolysis contribution than that of the model.
Simultaneous observations of &amp;delta;&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;CO&lt;sub&gt;2&lt;/sub&gt;&lt;/sub&gt;, &amp;delta;&lt;sup&gt;17&lt;/sup&gt;O&lt;sub&gt;CO&lt;sub&gt;2&lt;/sub&gt;&lt;/sub&gt;, and N&lt;sub&gt;2&lt;/sub&gt;O mixing ratios can elucidate triple oxygen
isotopes in CO&lt;sub&gt;2&lt;/sub&gt; and clarify complex interactions among physical,
chemical, and photochemical processes occurring in the middle atmosphere.</p>
</abstract>
<counts><page-count count="9"/></counts>
</article-meta>
</front>
<body/>
<back>
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