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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-2026-5300</article-id>
<title-group>
<article-title>Physics-Guided Diagnosis of CYGNSS Wind Mismatch under Tropical-Cyclone Wind&amp;ndash;Wave Disequilibrium</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Masum</surname>
<given-names>S. M. Injamamul Haque</given-names>
<ext-link>https://orcid.org/0009-0009-0640-1431</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>Akande</surname>
<given-names>Ahmed Wasiu</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>Yang</surname>
<given-names>Dongkai</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>Islam</surname>
<given-names>Mohammad Shohidul</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>Shah</surname>
<given-names>Syed Shahid</given-names>
<ext-link>https://orcid.org/0009-0000-7160-8986</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>School of Electronic and Information Engineering, Hangzhou International Innovation Institute of Beihang University,  Hangzhou 311115, China</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>International School, Hangzhou International Innovation Institute of Beihang University, Hangzhou 311115, China</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Atmospheric Research Division, Bangladesh Space Research and Remote Sensing Organization (SPARRSO), Dhaka, Bangladesh</addr-line>
</aff>
<pub-date pub-type="epub">
<day>11</day>
<month>09</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>57</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 S. M. Injamamul Haque Masum 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-2026-5300/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5300/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5300/egusphere-2026-5300.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5300/egusphere-2026-5300.pdf</self-uri>
<abstract>
<p>The Cyclone Global Navigation Satellite System (CYGNSS) provides extensive ocean-surface wind observations within tropical cyclones, yet its reference-relative mismatch can vary systematically with storm structure and the evolving sea state. This study develops a physics-guided diagnostic framework using 212,697 unique CYGNSS&amp;ndash;tropical-cyclone matchups from 147 storms during 2022&amp;ndash;2024 across the western North Pacific, Bay of Bengal, and North Atlantic. CYGNSS observations are combined with ERA5 atmospheric and wave fields and IBTrACS best-track information to construct six descriptors of derived wave-height departure, young-wave state, bulk wave steepness, transient wind forcing, transient sea-state response, and storm-relative proximity. A supervised Wind&amp;ndash;Wave Disequilibrium Index (WWDI&lt;sup&gt;&amp;lowast;&lt;/sup&gt;) is derived using training-only robust normalization and leave-one-component-out evidence weighting, with all parameters frozen before temporal and geographical evaluation.&lt;/p&gt;
&lt;p&gt;Across four storm-independent and observation-independent cross-basin transfers, WWDI&lt;sup&gt;&amp;lowast;&lt;/sup&gt; retains positive associations with absolute CYGNSS&amp;ndash;IBTrACS mismatch. Observation-level Spearman correlations range from 0.219 to 0.381, whereas 10-bin regime-scale &lt;em&gt;R&lt;/em&gt;&lt;sup&gt;2&lt;/sup&gt; values range from 0.639 to 0.753. Wave steepness receives the largest training-derived weight in both development basins, followed by young-wave state and transient significant-wave-height response. Permutation testing, storm-wise bootstrap resampling, and sensitivity experiments confirm the persistence of the regime-scale relationships. After controlling for ranked tropical-cyclone intensity, storm-relative radius, their quadratic terms, and their interaction, the residual association reverses sign in all four transfers, with residual Spearman coefficients from &amp;minus;0.645 to &amp;minus;0.543. This shows that the positive unconditional relationship is embedded within the joint storm-intensity&amp;ndash;radius structure rather than representing an independent monotonic effect.&lt;/p&gt;
&lt;p&gt;Independent comparison with 5,771 CMEMS significant-wave-height matchups gives an ERA5 RMSE of 0.631 m and Pearson correlation of 0.942. Diagnostic machine-learning experiments further show that local atmospheric wind provides substantial transferable information beyond tropical-cyclone intensity and radial position, with additional benefit from bulk wave-state variables in three of the four transfers. A training-derived WWDI&lt;sup&gt;&amp;lowast;&lt;/sup&gt;-conditioned adjustment reduces raw external RMSE by 29.8&amp;ndash;40.4 %; relative to a simpler global training-bias correction, the additional point-estimate improvement is 1.7&amp;ndash;13.0 %, with storm-wise bootstrap support for the reciprocal WP&amp;ndash;BOB transfers.&lt;/p&gt;
&lt;p&gt;These results identify transferable tropical-cyclone wind&amp;ndash;wave regimes associated with systematic changes in reference- relative CYGNSS mismatch. WWDI&lt;sup&gt;&amp;lowast;&lt;/sup&gt; is therefore interpreted as a supervised physical diagnostic of mismatch-prone storm environments rather than as a causal index or an operational wind-retrieval correction.</p>
</abstract>
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<funding-group>
<award-group id="gs1">
<funding-source>Beihang University</funding-source>
<award-id>KQ24016</award-id>
</award-group>
</funding-group>
</article-meta>
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