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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-2026-3196</article-id>
<title-group>
<article-title>Spatiotemporal Distribution of Tropopause Folds over the Arctic during Spring Season: A 24-Year Analysis (2000&amp;ndash;2023)</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Chen</surname>
<given-names>Yiqi</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>Cao</surname>
<given-names>Le</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>Zhu</surname>
<given-names>Xiaochun</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>Xia</surname>
<given-names>Yan</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>Zhang</surname>
<given-names>Tianqi</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>Lei</surname>
<given-names>Xiuli</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>Wang</surname>
<given-names>Mengke</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>Xu</surname>
<given-names>Liqiang</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>Zhao</surname>
<given-names>Tianliang</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>State Key Laboratory of Climate System Prediction and Risk Management, Nanjing University of Information Science and  Technology, Nanjing, 210044, China</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>School of Systems Science, Beijing Normal University, Beijing, 100875, China</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>National Supercomputer Center in Tianjin, Tianjin, 300457, China</addr-line>
</aff>
<pub-date pub-type="epub">
<day>12</day>
<month>08</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>28</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Yiqi Chen 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-2026-3196/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3196/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3196/egusphere-2026-3196.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3196/egusphere-2026-3196.pdf</self-uri>
<abstract>
<p>Springtime tropopause folds facilitate stratosphere&amp;ndash;troposphere exchange and may influence Arctic tropospheric composition, yet their long-term variability and dynamical background over the Arctic remain insufficiently characterized. Here, we use ERA5 reanalysis data and a three-dimensional labeling algorithm to identify tropopause folds over the Arctic during March&amp;ndash;May from 2000 to 2023, with particular focus on four monitoring sites: Alert, Barrow, Villum, and Zeppelin. The results show spatial heterogeneity and depth dependence. Total and shallow folds occur over relatively broad Arctic regions, with high-frequency centers around Greenland, the Greenland&amp;ndash;Barents Sea region, and the North Pacific side of the Arctic. Medium and deep folds are less frequent and are more strongly confined to the lower-latitude Arctic periphery. This spatial structure is dynamically consistent with the 700&amp;ndash;250 hPa layer-mean maximum Eady growth rate, which is larger along the Arctic margins than over the central Arctic. Station-based composites further indicate that deeper folds are associated with stronger 250 hPa geopotential height contrasts, larger horizontal GPH gradient magnitude (&lt;em&gt;G&lt;/em&gt;&lt;sub&gt;&lt;em&gt;Z&lt;/em&gt;&lt;/sub&gt;), and stronger wind speed characteristics. Temporally, total fold frequency shows interannual positive trends at all four stations during 2000&amp;ndash;2023, with the strongest increases at Alert and Villum, mainly contributed by shallow folds. A monthly decline is also found from March to May, with May frequencies only about 20 %&amp;ndash;30 % of March values, whereas diurnal variations are weak. These results provide a climatological framework for understanding Arctic springtime tropopause folds and their potential implications for Arctic tropospheric composition.</p>
</abstract>
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<funding-group>
<award-group id="gs1">
<funding-source>National Key Research and Development Program of China</funding-source>
<award-id>2022YFC3701204</award-id>
</award-group>
<award-group id="gs2">
<funding-source>National Natural Science Foundation of China</funding-source>
<award-id>41705103</award-id>
</award-group>
<award-group id="gs3">
<funding-source>Qinglan Project of Jiangsu Province of China</funding-source>
<award-id>R202302</award-id>
</award-group>
</funding-group>
</article-meta>
</front>
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