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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-2025-5012</article-id>
<title-group>
<article-title>Quantifying CH&lt;sub&gt;4&lt;/sub&gt; point source emissions with airborne remote sensing: First results from AVIRIS-4</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Meier</surname>
<given-names>Sandro</given-names>
<ext-link>https://orcid.org/0009-0003-7374-5927</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>Vögtli</surname>
<given-names>Marius</given-names>
<ext-link>https://orcid.org/0000-0002-2674-2788</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>Hueni</surname>
<given-names>Andreas</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>McManemin</surname>
<given-names>Audrey</given-names>
<ext-link>https://orcid.org/0009-0001-1487-0192</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>Brandt</surname>
<given-names>Adam R.</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>Juéry</surname>
<given-names>Catherine</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>Blandin</surname>
<given-names>Vincent</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>Brunner</surname>
<given-names>Dominik</given-names>
<ext-link>https://orcid.org/0000-0002-4007-6902</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>Kuhlmann</surname>
<given-names>Gerrit</given-names>
<ext-link>https://orcid.org/0000-0002-7021-4712</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Empa, Laboratory for Air Pollution / Environmental Technology, Ueberlandstrasse 129, 8600 Duebendorf, Switzerland</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Department of Geography, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Department of Energy Science &amp; Engineering, Stanford University, United States</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Air Quality Laboratory, TotalEnergies, France</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>TotalEnergies Anomalies Detection Initiatives (TADI), TotalEnergies, France</addr-line>
</aff>
<pub-date pub-type="epub">
<day>21</day>
<month>10</month>
<year>2025</year>
</pub-date>
<volume>2025</volume>
<fpage>1</fpage>
<lpage>38</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2025 Sandro Meier et al.</copyright-statement>
<copyright-year>2025</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/2025/egusphere-2025-5012/">This article is available from https://egusphere.copernicus.org/preprints/2025/egusphere-2025-5012/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2025/egusphere-2025-5012/egusphere-2025-5012.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2025/egusphere-2025-5012/egusphere-2025-5012.pdf</self-uri>
<abstract>
<p>Atmospheric concentration of methane (CH&lt;sub&gt;4&lt;/sub&gt;), a critical greenhouse gas, increased significantly since pre-industrial times, with anthropogenic emissions originating primarily from agriculture, fossil fuel use and waste management. However, considerable uncertainties persist in the detection and quantification of anthropogenic CH&lt;sub&gt;4&lt;/sub&gt; emissions. In this study, we present first CH&lt;sub&gt;4&lt;/sub&gt; observations, plume detections and emission estimates from the new state-of-the-art Airborne Visible InfraRed Imaging Spectrometer 4 (AVIRIS-4), which participated in a blind controlled release experiment in September 2024 in southern France. We used an albedo-corrected matched filter to retrieve CH&lt;sub&gt;4&lt;/sub&gt; maps from the spectral images and estimated CH&lt;sub&gt;4&lt;/sub&gt; emission with the Integrated Mass Enhancement (IME) and Cross-Sectional Flux (CSF) methods. Our results demonstrate that AVIRIS-4 can reliably detect emissions as low as 5.5 kg CH&lt;sub&gt;4&lt;/sub&gt; h&lt;sup&gt;&amp;minus;1&lt;/sup&gt; under good weather conditions at low flight altitudes (&amp;lt;1500 m) and 1.45 kg CH&lt;sub&gt;4&lt;/sub&gt; h&lt;sup&gt;&amp;minus;1&lt;/sup&gt; under ideal conditions. While AVIRIS-4 provides highly accurate CH&lt;sub&gt;4&lt;/sub&gt; maps at &amp;lt;0.5 m resolution, emission estimation is limited by the accuracy of the effective wind speed, whose uncertainty and natural variability contribute substantially to the overall uncertainty. Using wind speed at source height performs well for small releases (below 20 kg CH&lt;sub&gt;4&lt;/sub&gt; h&lt;sup&gt;&amp;minus;1&lt;/sup&gt;) (rRMSE = 1.065; rMBE = 0.361) and overall (rRMSE = 0.702; rMBE = -0.204). Using literature-derived effective wind speeds improves the apparent fit between estimated and reported CH&lt;sub&gt;4&lt;/sub&gt; emissions, but degrades performance both in overall agreement (rRMSE = 2.098; rMBE = 0.964) and for low-emission events (rRMSE = 2.367; rMBE = 1.711). Interestingly, the high spatial resolution makes it possible to retrieve the cast shadow of the CH&lt;sub&gt;4&lt;/sub&gt; plume, which can be used to estimate source and plume height, and could provide an approach for better constraining the height-dependency of the effective wind speed. On the bottom line, the controlled release experiment provides critical insights into the sensor&amp;rsquo;s capabilities and guides further improvements to detect and quantify low intensity sources in the fossil fuel and waste management sectors, with implications for more accurate global greenhouse gas monitoring.</p>
</abstract>
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<funding-group>
<award-group id="gs1">
<funding-source>United Nations Environment Programme</funding-source>
<award-id>CCD24-MB7279</award-id>
</award-group>
</funding-group>
</article-meta>
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