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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-2026-2277</article-id>
<title-group>
<article-title>LETKF-based Ocean Research Analysis version 2.0 for a quasi-global domain (LORA-QG): Validation and intercomparison with eddy-permitting global ocean reanalysis datasets</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Ohishi</surname>
<given-names>Shun</given-names>
<ext-link>https://orcid.org/0000-0003-4043-8886</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Miyoshi</surname>
<given-names>Takemasa</given-names>
<ext-link>https://orcid.org/0000-0003-3160-2525</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</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>Kachi</surname>
<given-names>Misako</given-names>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>RIKEN Center for Computational Science (R-CCS), Kobe, 650-0047, Japan</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), Kobe, 650-0047, Japan</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Japan Marine Science Foundation, Mutsu, Japan</addr-line>
</aff>
<aff id="aff5">
<label>5</label>
<addr-line>Earth Observation Research Center, Japan Aerospace Exploration Agency (JAXA), Tsukuba, Japan</addr-line>
</aff>
<pub-date pub-type="epub">
<day>23</day>
<month>04</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>42</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Shun Ohishi 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-2026-2277/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-2277/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-2277/egusphere-2026-2277.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-2277/egusphere-2026-2277.pdf</self-uri>
<abstract>
<p>We previously produced the local ensemble transform Kalman filter (LETKF)-based Ocean Research Analysis (LORA) version 1.0 datasets for the western North Pacific and Maritime Continent regions (LORA-WNP and LORA-MC, respectively) during the period from August 2015 to January 2024. However, these limited domains and periods constrain their applicability. Therefore, we developed a new eddy-permitting LETKF-based ocean data assimilation system and produced LORA version 2.0 for a quasi-global domain (LORA-QG) from June 2002, when the Advanced Microwave Scanning Radiometer (AMSR) series, a series of space-borne microwave imagers, began providing sea surface temperature observations and the Argo program substantially expanded in situ temperature and salinity measurements. We validated LORA-QG using observations from surface drifter buoys, tide gauges, and ocean climate stations, and compared the results with those of three eddy-permitting global ocean reanalysis datasets (GLORYS2V4, ORAS5, and C-GLORSv7). Although these observations are independent of LORA-QG, they may not be entirely independent of the other three reanalysis datasets. The validation results show that LORA-QG agrees well with the observations and has the second-highest accuracy among the four datasets in terms of overall root-mean-square deviations relative to the observations, thus achieving sufficient accuracy for geoscientific research and practical applications. LORA-QG provides features unavailable in conventional global reanalysis products, including ensemble-based uncertainty estimates and individual terms of the heat and salinity budget equations. These features make LORA-QG a valuable dataset for ensemble-based ocean forecasting and process-based studies. However, room for improvement remains, as LORA-QG exhibits significant warm biases in the tropics, particularly in the western tropical Pacific, and its sea surface salinity representation is likely limited due to relatively strong salinity nudging toward a climatological dataset in the mixed layer.</p>
</abstract>
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<funding-source>Japan Society for the Promotion of Science</funding-source>
<award-id>JP23K13174</award-id>
<award-id>JP24H00021</award-id>
<award-id>JP24H02227</award-id>
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<award-group id="gs2">
<funding-source>Japan Science and Technology Agency</funding-source>
<award-id>JPMJSA2109</award-id>
<award-id>JPMJCR24Q3</award-id>
</award-group>
<award-group id="gs3">
<funding-source>Japan Science and Technology Agency</funding-source>
<award-id>JPMJKP23D1</award-id>
</award-group>
<award-group id="gs4">
<funding-source>Japan Aerospace Exploration Agency</funding-source>
<award-id>RA3MAF001</award-id>
<award-id>ER4MAF004</award-id>
</award-group>
<award-group id="gs5">
<funding-source>Advanced Research and Invention Agency</funding-source>
<award-id>FPCW-PR01-P007</award-id>
</award-group>
</funding-group>
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