<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "https://jats.nlm.nih.gov/nlm-dtd/publishing/3.0/journalpublishing3.dtd">
<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article" specific-use="SMUR" dtd-version="3.0" xml:lang="en">
<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-2026-3730</article-id>
<title-group>
<article-title>Evaluating CH&lt;sub&gt;4&lt;/sub&gt; retrieval methods for hyperspectral images from EnMAP</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Scheidweiler</surname>
<given-names>Leonie Olivia</given-names>
<ext-link>https://orcid.org/0009-0001-2869-9277</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>Jandl</surname>
<given-names>Ida</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Häffner</surname>
<given-names>Lukas</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 contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Knapp</surname>
<given-names>Marvin</given-names>
<ext-link>https://orcid.org/0000-0001-8012-5759</ext-link>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
<xref ref-type="aff" rid="aff6">
<sup>6</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Resch</surname>
<given-names>Lennart</given-names>
<ext-link>https://orcid.org/0000-0003-1843-5005</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>Löw</surname>
<given-names>Benedikt</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>Mielke</surname>
<given-names>Christian</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>Vardag</surname>
<given-names>Sanam N.</given-names>
<ext-link>https://orcid.org/0000-0003-4959-9336</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff7">
<sup>7</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Butz</surname>
<given-names>André</given-names>
<ext-link>https://orcid.org/0000-0003-0593-1608</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff7">
<sup>7</sup>
</xref>
<xref ref-type="aff" rid="aff8">
<sup>8</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Melbourne, Australia</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>CSIRO Environment, Aspendale, Melbourne, Australia</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>German Environment Agency, Dessau-Roßlau, Germany</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Environmental Defense Fund, New York, USA</addr-line>
</aff>
<aff id="aff6">
<label>6</label>
<addr-line>School of Engineering and Applied Science, Harvard University, Cambridge, USA</addr-line>
</aff>
<aff id="aff7">
<label>7</label>
<addr-line>Heidelberg Center for the Environment (HCE), Heidelberg University, Heidelberg, Germany</addr-line>
</aff>
<aff id="aff8">
<label>8</label>
<addr-line>Interdisciplinary Center for Scientific Computing, Heidelberg University, Heidelberg, Germany</addr-line>
</aff>
<pub-date pub-type="epub">
<day>17</day>
<month>07</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>30</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Leonie Olivia Scheidweiler 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-2026-3730/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3730/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3730/egusphere-2026-3730.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3730/egusphere-2026-3730.pdf</self-uri>
<abstract>
<p>The Environmental Mapping and Analysis Program (EnMAP) satellite carries a hyperspectral instrument that is able to measure methane (CH&lt;sub&gt;4&lt;/sub&gt;) plumes of localized hotspot sources from which facility-scale emission rates can be estimated. Here, we implement and evaluate three retrieval techniques for scenes with different complexity and source strengths and discuss the differences and implications for emission estimation. These techniques are (i) RemoTeC, a physics-based retrieval that relies on pixel-wise radiative transfer calculations; (ii) a matched-filter retrieval that exploits the spectral covariance of a scene to detect CH&lt;sub&gt;4&lt;/sub&gt; enhancements; and (iii) a hybrid retrieval that incorporates spectral covariance information into RemoTeC, thereby combining the strengths of approaches i) and ii).&lt;/p&gt;
&lt;p&gt;RemoTeC and the hybrid method yield similar emission estimates, with the hybrid method exhibiting lower statistical noise. The enhancements retrieved by the matched filter have the lowest statistical noise. For sources with emission rates larger than &amp;sim; 3 t h&lt;sup&gt;&amp;minus;1&lt;/sup&gt;, the matched filter yields source strength estimates similar to the physics-based retrievals. For weaker sources, the matched filter estimates larger emission rates than the physics-based retrievals, with deviations being on the order of the emission rate itself. While the matched filter effectively suppresses regular and recurring spectral albedo structures, its performance degrades in the presence of statistically rare spectral features. In contrast, the hybrid retrieval more reliably accounts for such albedo-induced artifacts.&lt;/p&gt;
&lt;p&gt;Our results demonstrate that retrieval methodology can significantly influence methane emission estimates, particularly in challenging scenes. The matched filter is well suited for rapid quantification of strong emission sources, whereas the physics-based approaches provide greater robustness under difficult observational conditions and for weak emitters. The hybrid retrieval offers the best overall performance by combining the mechanistic rigor of radiative transfer modeling with the noise-reduction benefits of covariance-based methods.</p>
</abstract>
<counts><page-count count="30"/></counts>
<funding-group>
<award-group id="gs1">
<funding-source>Bundesministerium für Forschung, Technologie und Raumfahrt</funding-source>
<award-id>FKZ 50EE2232</award-id>
</award-group>
</funding-group>
</article-meta>
</front>
<body/>
<back>
</back>
</article>