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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-2026-5682</article-id>
<title-group>
<article-title>BRONet v1.0: A machine learning approach for BrO profile retrieval using a full-physics inverse model</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Huang</surname>
<given-names>Zhongtao</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>Tian</surname>
<given-names>Xin</given-names>
<ext-link>https://orcid.org/0000-0001-9471-1580</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>Xie</surname>
<given-names>Pinhua</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Wang</surname>
<given-names>Shanshan</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>Huang</surname>
<given-names>Yu</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>Liu</surname>
<given-names>Zhengde</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>Liu</surname>
<given-names>Wenqing</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei,  230031, China</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Institute of Environment, Hefei Comprehensive National Science Center, Hefei, 230031, China</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 101408, China</addr-line>
</aff>
<pub-date pub-type="epub">
<day>09</day>
<month>11</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>24</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Zhongtao Huang 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-2026-5682/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5682/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5682/egusphere-2026-5682.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5682/egusphere-2026-5682.pdf</self-uri>
<abstract>
<p>To address the challenge in retrieving tropospheric BrO profiles using the optimal estimation algorithm for Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS)&amp;mdash;which relies on a priori profiles&amp;mdash;a robust, data-driven retrieval framework, hereafter BRONet v1.0, is developed. First, a comprehensive synthetic dataset comprising 51.5 million samples is generated by coupling physics-based parameterizations of BrO and aerosol profiles with radiative transfer simulations. Second, a hybrid convolutional and long short-term memory neural network (CNN-LSTM) is designed and trained to directly map BrO differential slant column densities (DSCDs) to BrO profiles. This architecture leverages convolutional layers for local feature extraction from multi-angle data and LSTM layers to capture vertical dependencies, enhanced by an attention mechanism for adaptive weighting. The model achieves a coefficient of determination of 0.84 and a root mean square error of 0.36. Finally, the retrieved BrO profiles at Huaniao Island, China, show an average relative deviation of 15.8 % compared with those from the optimal estimation algorithm. Notably, the model completes a single profile retrieval in approximately 0.5 s, representing a 240-fold improvement in computational efficiency over the traditional optimal estimation approach, while delivering an enhanced vertical resolution of 191 layers with 10 m resolution below 1 km within the 0&amp;ndash;4 km range.</p>
</abstract>
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