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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-2026-37</article-id>
<title-group>
<article-title>Implementation of the ORACLE (v1.0) organic aerosol composition and evolution module into the EC-Earth3-AerChem model</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Kakavas</surname>
<given-names>Stylianos</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>Myriokefalitakis</surname>
<given-names>Stelios</given-names>
<ext-link>https://orcid.org/0000-0002-1541-7680</ext-link>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Tsimpidi</surname>
<given-names>Alexandra P.</given-names>
<ext-link>https://orcid.org/0000-0001-8773-4987</ext-link>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Karydis</surname>
<given-names>Vlassis A.</given-names>
<ext-link>https://orcid.org/0000-0002-1616-9746</ext-link>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Pandis</surname>
<given-names>Spyros N.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Institute of Chemical Engineering Sciences, Foundation for Research and  Technology Hellas, Patras, Greece</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Institute for Environmental Research and Sustainable Development (IERSD),  National Observatory of Athens, Penteli, Greece</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Institute for Energy and Climate Research, IEK-8 Troposphere, Forschungszentrum  Jülich GmbH, Jülich, Germany</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Department of Chemical Engineering, University of Patras, Patras, Greece</addr-line>
</aff>
<pub-date pub-type="epub">
<day>22</day>
<month>01</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>39</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Stylianos Kakavas 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-2026-37/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-37/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-37/egusphere-2026-37.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-37/egusphere-2026-37.pdf</self-uri>
<abstract>
<p>Simulating the composition and evolution of organic aerosol (OA) in Earth System Models (ESMs) presents significant challenges due to the high computational demands of detailed chemical mechanisms. The computationally efficient ORACLE module employs the volatility basis set framework and can simulate secondary organic aerosol (SOA) formation from a range of precursors, including volatile (VOCs), intermediate-volatility (IVOCs), semi-volatile (SVOCs), and low-volatility organic compounds (LVOCs). In this study, a lite configuration of the ORACLE v1.0 module (ORACLE-lite) is implemented into the TM5-MP global chemical transport model (CTM), which represents the chemistry-transport component of the EC-Earth3-AerChem ESM. SOA formation from anthropogenic VOCs is neglected to reduce the number of surrogate species and further improve computational efficiency. For the standalone TM5-MP simulation, the global annual mean surface total OA concentration using ORACLE-lite is approximately 1.1 &amp;mu;g m&lt;sup&gt;&amp;minus;3&lt;/sup&gt;, representing a 25 % increase compared to the previous version of the model. The annual atmospheric OA burden also increases by 50 %, reaching 3.67 Tg. Corresponding predictions from EC-Earth3-AerChem are slightly higher, with a surface total OA concentration of 1.16  &amp;mu;g m&lt;sup&gt;&amp;minus;3 &lt;/sup&gt;and an atmospheric burden of 3.83 Tg, representing increases of 30 % and 60 %, respectively, compared to the previous version of the model. Comparison of monthly measured PM&lt;sub&gt;2.5&lt;/sub&gt; OA concentrations from Europe and the US with the corresponding predictions shows that the models bias is reduced by approximately half in the standalone TM5-MP simulation and by a factor of three in EC-Earth3-AerChem when ORACLE-lite is implemented. These enhancements enable more accurate and computationally feasible assessments of the climate impacts of individual organic aerosol components in future ESM studies.</p>
</abstract>
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<funding-group>
<award-group id="gs1">
<funding-source>Hellenic Foundation for Research and Innovation</funding-source>
<award-id>15155</award-id>
<award-id>11504</award-id>
</award-group>
</funding-group>
</article-meta>
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