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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-2026-3864</article-id>
<title-group>
<article-title>First comparison of XCO&lt;sub&gt;2&lt;/sub&gt; products from DQ-1 ACDL and passive optical satellites</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Wang</surname>
<given-names>Yike</given-names>
<ext-link>https://orcid.org/0009-0006-1987-5052</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>Han</surname>
<given-names>Ge</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</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>Zhang</surname>
<given-names>Hongyuan</given-names>
<ext-link>https://orcid.org/0000-0002-9159-5550</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>Huang</surname>
<given-names>Yiyang</given-names>
<ext-link>https://orcid.org/0009-0008-9362-1725</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>Zhou</surname>
<given-names>Kangjie</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>Gong</surname>
<given-names>Wei</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Hubei Key Laboratory of Quantitative Remote Sensing of Land and Atmosphere, School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430079, China</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan  University, Luoyu Road No.129, Wuhan 430079, China</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Perception and Effectiveness Assessment for Carbon-neutrality Efforts, Engineering Research Center of  Ministry of Education, Institute for Carbon Neutrality, Wuhan University, Wuhan, China</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Electronic Information School, Wuhan University, Wuhan, China</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Wuhan Institute of Quantum Technology, Wuhan, China</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>39</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Yike Wang 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-2026-3864/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3864/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3864/egusphere-2026-3864.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3864/egusphere-2026-3864.pdf</self-uri>
<abstract>
<p>Spaceborne active CO&lt;sub&gt;2&lt;/sub&gt; IPDA lidar provides an active remote-sensing approach for XCO&lt;sub&gt;2&lt;/sub&gt; observations that differs from passive NIR/SWIR remote sensing. However, comparisons between DQ-1 ACDL and passive optical satellite XCO&lt;sub&gt;2&lt;/sub&gt; products remain limited. Here we compare DQ-1 ACDL with OCO-2, OCO-3, GOSAT, and GOSAT-2 XCO&lt;sub&gt;2&lt;/sub&gt; products from June 2022 to December 2024 using a unified framework that combines CAMS-based spatiotemporal coherence assessment, satellite sampling availability, daily 2&amp;deg; aggregation, spatiotemporal collocation, and XCO&lt;sub&gt;2&lt;/sub&gt; column-definition correction. The results show that DQ-1 is broadly consistent with OCO-2 and OCO-3 over coherent and well-sampled regions, with mean differences mostly below 0.5 ppm and similar spatial distributions, meridional structures, and regional monthly variations. Nighttime DQ-1 XCO&lt;sub&gt;2&lt;/sub&gt; is also consistent with CAMS-derived XCO&lt;sub&gt;2&lt;/sub&gt;, indicating stable performance relative to an external model reference. Independent validation against TCCON shows that daytime DQ-1 XCO&lt;sub&gt;2&lt;/sub&gt; has a correlation coefficient of 0.92, a mean bias of 0.21 ppm, and an RMSE of 1.49 ppm, with statistics comparable to GOSAT. Regional results further indicate that DQ-1 does not simply duplicate existing passive satellite observations, but provides complementary XCO&lt;sub&gt;2&lt;/sub&gt; observational coverage under high aerosol loading, at high latitudes, and in regions where passive observations are limited. Overall, DQ-1 ACDL is comparable to passive satellite XCO&lt;sub&gt;2&lt;/sub&gt; products under the unified framework, and can serve as an important complement to existing passive satellite XCO&lt;sub&gt;2&lt;/sub&gt; observations, supporting future active&amp;ndash;passive joint XCO&lt;sub&gt;2&lt;/sub&gt; constraints, regional carbon flux inversions, and emission monitoring.</p>
</abstract>
<counts><page-count count="39"/></counts>
<funding-group>
<award-group id="gs1">
<funding-source>National Natural Science Foundation of China</funding-source>
<award-id>42475144</award-id>
</award-group>
<award-group id="gs2">
<funding-source>National Key Research and Development Program of China</funding-source>
<award-id>2024YFB3910203</award-id>
</award-group>
<award-group id="gs3">
<funding-source>Natural Science Foundation of Beijing Municipality</funding-source>
<award-id>L211045</award-id>
</award-group>
<award-group id="gs4">
<funding-source>Fundamental Research Funds for the Central Universities</funding-source>
<award-id>2042025kf0036</award-id>
</award-group>
</funding-group>
</article-meta>
</front>
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