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<front>
<journal-meta>
<journal-id journal-id-type="publisher">ESSDD</journal-id>
<journal-title-group>
<journal-title>Earth System Science Data Discussions</journal-title>
<abbrev-journal-title abbrev-type="publisher">ESSDD</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">Earth Syst. Sci. Data Discuss.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1866-3591</issn>
<publisher><publisher-name></publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/essd-2026-433</article-id>
<title-group>
<article-title>Paleo-NorCPM: A framework toward fully coupled ocean-atmosphere paleoclimate reanalysis over the past centuries</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Dalaiden</surname>
<given-names>Quentin</given-names>
<ext-link>https://orcid.org/0000-0002-3885-3848</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>Counillon</surname>
<given-names>François</given-names>
<ext-link>https://orcid.org/0000-0002-6412-3806</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>Svendsen</surname>
<given-names>Lea</given-names>
<ext-link>https://orcid.org/0000-0002-0181-3332</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>Bethke</surname>
<given-names>Ingo</given-names>
<ext-link>https://orcid.org/0000-0002-6836-9838</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>Keenlyside</surname>
<given-names>Noel</given-names>
<ext-link>https://orcid.org/0000-0002-8708-6868</ext-link>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Nansen Environmental and Remote Sensing Center and Bjerknes Centre for Climate Research, Bergen, Norway</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Geophysical Institute, Bjerknes Centre for Climate Research, University of Bergen, Bergen, Norway</addr-line>
</aff>
<pub-date pub-type="epub">
<day>17</day>
<month>08</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>48</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Quentin Dalaiden 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://essd.copernicus.org/preprints/essd-2026-433/">This article is available from https://essd.copernicus.org/preprints/essd-2026-433/</self-uri>
<self-uri xlink:href="https://essd.copernicus.org/preprints/essd-2026-433/essd-2026-433.pdf">The full text article is available as a PDF file from https://essd.copernicus.org/preprints/essd-2026-433/essd-2026-433.pdf</self-uri>
<abstract>
<p>We present a new paleo reanalysis based on an adaptation of the Norwegian Climate Prediction Model (NorCPM), in which the Norwegian Earth System Model is equipped with an ensemble Kalman filter to assimilate hundreds of annually resolved proxy records, including tree rings, corals, and ice cores, over the last 500 years. First, an offline 30-member reanalysis is produced. This is followed by a dynamically coupled 10-member reanalysis obtained through atmospheric wind nudging from the offline reconstruction, allowing the ocean to respond to reconstructed atmospheric circulation variability. This approach enables an explicit representation of ocean dynamics and associated atmosphere-ocean feedback, which are typically indirectly represented in existing multi-century reanalyses. The offline reanalysis successfully reproduces large-scale atmospheric variability and hydroclimate variability over the 20th century across the tropics, mid-latitudes, and polar regions, and compares well with existing paleo reconstructions. The wind-nudged ensemble further captures ocean variability and exhibits more pronounced multi-decadal variability, highlighting the role of wind-driven ocean adjustment in shaping low-frequency climate variability. Challenges remain, particularly in the Southern Ocean where the wind-nudged ensemble shows strong sensitivity to wind variability. Nevertheless, these results demonstrate a promising pathway toward fully coupled ocean-atmosphere reanalyses spanning the past centuries, opening new opportunities to investigate the mechanisms underlying low-frequency variability and coupled feedback.</p>
</abstract>
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<funding-group>
<award-group id="gs1">
<funding-source>European Commission</funding-source>
<award-id>101149188</award-id>
</award-group>
</funding-group>
</article-meta>
</front>
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