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<front>
<journal-meta>
<journal-id journal-id-type="publisher">EGUsphere</journal-id>
<journal-title-group>
<journal-title>EGUsphere</journal-title>
<abbrev-journal-title abbrev-type="publisher">EGUsphere</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">EGUsphere</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub"></issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/egusphere-2026-1236</article-id>
<title-group>
<article-title>Developing tracer interrelationships to derive stratospheric age of air from satellite observations of nitrous oxide</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Castillo</surname>
<given-names>Ariana Elena</given-names>
<ext-link>https://orcid.org/0009-0002-4446-2066</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Linz</surname>
<given-names>Marianna</given-names>
<ext-link>https://orcid.org/0000-0002-3241-5062</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Ray</surname>
<given-names>Eric</given-names>
<ext-link>https://orcid.org/0000-0001-8727-9849</ext-link>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Saunders</surname>
<given-names>Laura N.</given-names>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Walker</surname>
<given-names>Kaley A.</given-names>
<ext-link>https://orcid.org/0000-0003-3420-9454</ext-link>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Stiller</surname>
<given-names>Gabriele P.</given-names>
<ext-link>https://orcid.org/0000-0003-2883-6873</ext-link>
</name>
<xref ref-type="aff" rid="aff6">
<sup>6</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Mooring</surname>
<given-names>Todd A.</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>Bourguet</surname>
<given-names>Stephen</given-names>
<ext-link>https://orcid.org/0000-0002-3520-4519</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Department of Earth and Planetary Sciences, Harvard University, Cambridge, USA</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>School of Engineering and Applied Sciences, Harvard University, Cambridge, USA</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Chemical Sciences Laboratory, Earth Systems Research Laboratory, NOAA, Boulder, USA</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, USA</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Department of Physics, University of Toronto, Toronto, Canada</addr-line>
</aff>
<aff id="aff6">
<label>6</label>
<addr-line>Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany</addr-line>
</aff>
<pub-date pub-type="epub">
<day>19</day>
<month>03</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>30</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Ariana Elena Castillo et al.</copyright-statement>
<copyright-year>2026</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1236/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1236/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1236/egusphere-2026-1236.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1236/egusphere-2026-1236.pdf</self-uri>
<abstract>
<p>Chemistry-climate models predict a strengthening of the Brewer-Dobson Circulation (BDC) in response to climate change, which has implications for global atmospheric composition, radiation, and climate. This predicted acceleration has not been confirmed with observations, and models also disagree about the mean stratospheric circulation and mixing strength. The BDC impacts the distribution of long-lived tracers and their empirical relationships with one another. Age of air is an important diagnostic for changes in the BDC, and it can be derived from long-lived trace gases, such as sulfur hexafluoride (SF&lt;sub&gt;6&lt;/sub&gt;) and nitrous oxide (N&lt;sub&gt;2&lt;/sub&gt;O). We introduce an updated technique to calculate age of air using satellite observations of N&lt;sub&gt;2&lt;/sub&gt;O. We (1) compute tracer interrelationships of age of air and N&lt;sub&gt;2&lt;/sub&gt;O (Age:N&lt;sub&gt;2&lt;/sub&gt;O) and demonstrate that they vary with latitude, and then (2) use these relationships to calculate a new N&lt;sub&gt;2&lt;/sub&gt;O-derived age timeseries that takes this latitude variability into account from 2005 to 2012. The tracer interrelationships and their variability with latitude provide a better understanding of the structure and seasonality of the BDC. In particular, latitudinally-resolved Age:N&lt;sub&gt;2&lt;/sub&gt;O relationships reflect the relative importance of photochemical loss of N&lt;sub&gt;2&lt;/sub&gt;O in different regions and enable hemispheric structural comparisons. The N&lt;sub&gt;2&lt;/sub&gt;O-age product has more extensive spatial coverage than previous counterparts. Additionally, N&lt;sub&gt;2&lt;/sub&gt;O and SF&lt;sub&gt;6&lt;/sub&gt;-age compare well, showing that Age:N&lt;sub&gt;2&lt;/sub&gt;O relationships are robust on seasonal and interannual time scales. While this timeseries is only 7 years long, this manuscript lays the groundwork for calculating a longer record of N&lt;sub&gt;2&lt;/sub&gt;O-age to understand long-term variability and shifts of the BDC.</p>
</abstract>
<counts><page-count count="30"/></counts>
<funding-group>
<award-group id="gs1">
<funding-source>Earth Sciences Division</funding-source>
<award-id>80NSSC21K0943</award-id>
</award-group>
<award-group id="gs2">
<funding-source>Earth Sciences Division</funding-source>
<award-id>80NSSC23K1005</award-id>
</award-group>
<award-group id="gs3">
<funding-source>National Science Foundation</funding-source>
<award-id>2239242</award-id>
</award-group>
</funding-group>
</article-meta>
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