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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-2026-2458</article-id>
<title-group>
<article-title>Ice nucleating properties of &amp;alpha;-pinene- and limonene-derived secondary organic aerosol under cirrus conditions</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Rapp</surname>
<given-names>Christopher N.</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>Niu</surname>
<given-names>Sining</given-names>
<ext-link>https://orcid.org/0000-0002-3389-0076</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>Surratt</surname>
<given-names>Jason D.</given-names>
<ext-link>https://orcid.org/0000-0002-6833-1450</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>Zhang</surname>
<given-names>Yue</given-names>
<ext-link>https://orcid.org/0000-0001-7234-9672</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>Cziczo</surname>
<given-names>Daniel J.</given-names>
</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, Atmospheric and Planetary Sciences, Purdue University, West Lafayette, Indiana, 47906-2051, USA</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Department of Atmospheric Sciences, Texas A&amp;M University, College Station, Texas, 77843-3150, USA</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North  Carolina, 27599-7400, USA</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>30</day>
<month>04</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>30</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Christopher N. Rapp 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-2026-2458/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-2458/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-2458/egusphere-2026-2458.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-2458/egusphere-2026-2458.pdf</self-uri>
<abstract>
<p>The contribution of biogenic secondary organic aerosol (BSOA) to cirrus cloud formation remains unresolved, contributing to uncertainty in aerosol-cloud interactions in global climate models. Laboratory studies report highly variable ice nucleating efficiencies for BSOA, suggesting that these particles may act as either homogeneous or moderately effective heterogeneous ice nuclei. Here, we investigate the deposition ice nucleating properties of &amp;alpha;-pinene- and limonene-derived BSOA, including both self-nucleated particles and BSOA coatings on ammonium sulfate and ammonium bisulfate seed particles. Deposition ice nucleation relevant to cirrus clouds (&amp;minus;45 &amp;deg;C, &amp;minus;40 &amp;deg;C, &amp;minus;35 &amp;deg;C; 1.0 &amp;le; &lt;em&gt;S&lt;/em&gt;&lt;sub&gt;ice&lt;/sub&gt; &amp;le; 1.6) was measured using the SPectrometer for Ice Nucleation (SPIN). Bulk physicochemical properties relevant to ice nucleation were characterized using aerosol mass spectrometry (AMS) and volatility distributions. Pre-cooling was applied to modulate phase state as inferred from glass transition temperature (&lt;em&gt;T&lt;/em&gt;&lt;sub&gt;g&lt;/sub&gt;).&lt;/p&gt;
&lt;p&gt;BSOA ice nucleating properties were strongly precursor dependent (&lt;em&gt;p &lt;/em&gt;&amp;lt; 0.001). &lt;em&gt;T&lt;/em&gt;&lt;sub&gt;g&lt;/sub&gt; was an unreliable predictor of freezing behavior, correctly anticipating freezing mode for only two of eleven particle combinations. Limonene-derived BSOA nucleated ice almost exclusively via heterogeneous freezing, with &lt;em&gt;S&lt;/em&gt;&lt;sub&gt;ice&lt;/sub&gt; onsets as low as 1.27&amp;plusmn;0.07 at -39.8&amp;plusmn;0.3 &amp;deg;C. &amp;alpha;-pinene-derived BSOA predominantly nucleated ice homogeneously. BSOA coatings on ammonium bisulfate shifted freezing from homogeneous to heterogeneous, while the role of acid-catalyzed multiphase chemistry in ice nucleation remained inconclusive due to experimental limitations. These results demonstrate that cirrus-relevant BSOA parameterizations must explicitly account for precursor specific chemistry and broad classifications of BSOA ice nucleating abilities are inappropriate.</p>
</abstract>
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<funding-group>
<award-group id="gs1">
<funding-source>National Science Foundation</funding-source>
<award-id>2131369</award-id>
<award-id>2131370</award-id>
<award-id>2131371</award-id>
</award-group>
<award-group id="gs2">
<funding-source>National Oceanic and Atmospheric Administration</funding-source>
<award-id>NA23OAR4310300</award-id>
</award-group>
</funding-group>
</article-meta>
</front>
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