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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>
<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-2026-6638</article-id>
<title-group>
<article-title>NO&lt;sub&gt;x&lt;/sub&gt; emissions changes from 2019 to 2021 in Eastern China as estimated through variational inversions and TROPOMI satellite data</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Abeed</surname>
<given-names>﻿Rimal</given-names>
<ext-link>https://orcid.org/0000-0002-1176-0529</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff9">
<sup>9</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Fortems-Cheiney</surname>
<given-names>Audrey</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>Broquet</surname>
<given-names>Grégoire</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>Plauchu</surname>
<given-names>Robin</given-names>
<ext-link>https://orcid.org/0009-0004-7165-7736</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>Pison</surname>
<given-names>Isabelle</given-names>
<ext-link>https://orcid.org/0000-0001-5471-7785</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>Berchet</surname>
<given-names>Antoine</given-names>
<ext-link>https://orcid.org/0000-0001-6709-0125</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>Potier</surname>
<given-names>Elise</given-names>
<ext-link>https://orcid.org/0000-0003-1823-2101</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>Zheng</surname>
<given-names>Bo</given-names>
<ext-link>https://orcid.org/0000-0001-8344-3445</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>Dufour</surname>
<given-names>Gaëlle</given-names>
<ext-link>https://orcid.org/0000-0001-8847-2165</ext-link>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Coman</surname>
<given-names>Adriana</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>Savas</surname>
<given-names>Dilek</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>Siour</surname>
<given-names>Guillaume</given-names>
<ext-link>https://orcid.org/0000-0002-5940-4902</ext-link>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Eskes</surname>
<given-names>Henk</given-names>
<ext-link>https://orcid.org/0000-0002-8743-4455</ext-link>
</name>
<xref ref-type="aff" rid="aff6">
<sup>6</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Revilla-Romero</surname>
<given-names>Beatriz</given-names>
</name>
<xref ref-type="aff" rid="aff7">
<sup>7</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Delavois</surname>
<given-names>Antony</given-names>
</name>
<xref ref-type="aff" rid="aff8">
<sup>8</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Ciais</surname>
<given-names>Philippe</given-names>
<ext-link>https://orcid.org/0000-0001-8560-4943</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ, Gif-sur-Yvette, France</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Science Partners, Quai de Jemmapes, 75010 Paris, France</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Shenzhen Key Laboratory of Ecological Remediation and Carbon Sequestration, Institute of Environment and Ecology,  Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Université Paris Cité and Univ Paris Est Créteil, CNRS, LISA, F-75013 Paris, France</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Univ Paris Est Créteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, France</addr-line>
</aff>
<aff id="aff6">
<label>6</label>
<addr-line>Royal Netherlands Meteorological Institute (KNMI), De Bilt, the Netherlands</addr-line>
</aff>
<aff id="aff7">
<label>7</label>
<addr-line>GMV, Remote Sensing and Geospatial Analytics Division, Madrid, Spain</addr-line>
</aff>
<aff id="aff8">
<label>8</label>
<addr-line>European Space Agency (ESA), Rome, Italy</addr-line>
</aff>
<aff id="aff9">
<label>9</label>
<addr-line>now at: The Cyprus Institute, Climate and Atmosphere Research Center, 2121 Nicosia, Cyprus</addr-line>
</aff>
<pub-date pub-type="epub">
<day>10</day>
<month>11</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>27</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 ﻿Rimal Abeed 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-2026-6638/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-6638/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-6638/egusphere-2026-6638.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-6638/egusphere-2026-6638.pdf</self-uri>
<abstract>
<p>China is one of the largest emitters of nitrogen oxides NO&lt;sub&gt;x&lt;/sub&gt; (= NO + NO&lt;sub&gt;2&lt;/sub&gt;) worldwide, and up-to-date estimates are crucial as the country faces rising pressure to curb emissions. We estimate NO&lt;sub&gt;x&lt;/sub&gt; emissions over Eastern China (101.75&amp;ndash;132.25&amp;deg; E; 17.75&amp;ndash;50.25&amp;deg; N) from 2019 to 2021, focusing on the impacts of COVID-19 and the Chinese Lunar New Year (LNY). Using high-resolution NO&lt;sub&gt;2&lt;/sub&gt; observations from TROPOMI, onboard the Sentinel-5 Precursor satellite, our estimates are at the regional, national, and provincial scales. They are produced using the Community Inversion Framework (CIF), coupled to the CHIMERE regional chemistry transport model at 0.5&amp;deg; resolution. Our results show a drop in NO&lt;sub&gt;x &lt;/sub&gt;emissions of -35 % during February 2020, as compared to 2019. The drop in NO&lt;sub&gt;x&lt;/sub&gt; emissions is driven mostly by lockdown-related mobility restrictions and LNY festivities. Provincial reductions amounted to -15 %, -16 %, -17 % in Hubei, Shanghai and Jiangsu respectively. Anthropogenic NO&lt;sub&gt;x&lt;/sub&gt; emissions over Eastern China fell by 0.4 TgNO&lt;sub&gt;2&lt;/sub&gt;/year in 2020 vs. 2019, and by 0.2 TgNO&lt;sub&gt;2&lt;/sub&gt;/year in 2021 compared to 2020. The yearly budget of NO&lt;sub&gt;x&lt;/sub&gt; emissions for 2019, 2020 and 2021 are 18.3, 17.9, and 17.7 TgNO&lt;sub&gt;2&lt;/sub&gt; respectively. Our estimates of recent past years offer insights to guide future strategies and policies to reduce NO&lt;sub&gt;x&lt;/sub&gt; emissions in China and its provinces. These results highlight the advantages of combining high dimensional variational inversion methods with high-resolution satellite data, to strengthen air quality monitoring and support more effective regulations.</p>
</abstract>
<counts><page-count count="27"/></counts>
<funding-group>
<award-group id="gs1">
<funding-source>Agence Nationale de la Recherche</funding-source>
<award-id>ANR-19-CE01-0007</award-id>
</award-group>
<award-group id="gs2">
<funding-source>Centre national d&apos;études spatiales</funding-source>
<award-id>2162D0010</award-id>
</award-group>
<award-group id="gs3">
<funding-source>European Space Agency</funding-source>
<award-id>World Emission Project</award-id>
</award-group>
</funding-group>
</article-meta>
</front>
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