Intercomparison of Ocean Reanalyses for Interannual Ocean Temperature Variability in the Tropical Atlantic

Intercomparison of Ocean Reanalyses for Interannual Ocean Temperature Variability in the Tropical Atlantic | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Intercomparison of Ocean Reanalyses for Interannual Ocean Temperature Variability in the Tropical Atlantic Arthur Prigent, Ingo Richter, Andrea Storto, Riccardo Farneti, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5330579/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 28 Aug, 2025 Read the published version in Climate Dynamics → Version 1 posted 5 You are reading this latest preprint version Abstract Ocean reanalysis (ORA) products are widely used by the scientific community and are essential tools for monitoring and understanding tropical Atlantic inter-annual variability. However, large differences have been observed among these products in the tropical Atlantic Ocean. In that context, an ensemble of seven ORAs is examined and compared over the period ranging from January 1993 to December 2017. The analysis reveals a considerable spread (> 0.3º C) in tropical Atlantic Ocean temperature anomalies in the upper 150 m. Along the equatorial Atlantic and southwest African coast, which are regions of high interannual variability, most of the discrepancies among the ORAs are located around the depth of the thermocline. This spread is linked to the amount of in situ profiles assimilated by ORAs. The deployment of the PIRATA mooring array in early 1998 improved ORA consistency along the equatorial Atlantic, as well as down the path of equatorial Kelvin waves and subsequent coastal trapped waves. Despite a decreasing trend of -0.04º C·decade −1 of the ensemble spread averaged over the upper 150 m of the tropical Atlantic ocean, a few regions with limited in-situ observations present smaller improvements, such as in the Benguela upwelling system and around 15º W, 10º S. A comparison between ORAs and forced-ocean models indicates that ocean model biases contribute little to the total ensemble spread. Instead, it suggests that most of the spread can be attributed to discrepancies among the atmospheric fields used to force ORAs. The ensemble spread of the equatorial Atlantic zonal wind anomalies across four atmospheric reanalyses suggests that their consistency has not improved or even worsened. Tropical Atlantic Variability Ocean reanalysis intercomparison Tropical Atlantic Observing System PIRATA Argo floats Full Text Supplementary Files manuscriptclimatedynamicssupplementary24102024.pdf Cite Share Download PDF Status: Published Journal Publication published 28 Aug, 2025 Read the published version in Climate Dynamics → Version 1 posted Editorial decision: Major Revision 14 Jan, 2025 Reviewers agreed at journal 06 Nov, 2024 Reviewers invited by journal 05 Nov, 2024 Editor assigned by journal 29 Oct, 2024 First submitted to journal 25 Oct, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5330579","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":374556537,"identity":"bc2b421b-6ac6-4d0b-a1b6-31768fd46460","order_by":0,"name":"Arthur Prigent","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwElEQVRIiWNgGAWjYJCCAyCCnxnMliBei4RkMwNjA5AmUg9Ii8EBsBYirOGf3fvw4JeKO3XGx5mfPy5gsKgjbPqd4waHZc48kzA7zGbYPIMoh91IYzgs2XYYqIWHsZmHGC3yYC3/DksYNxOrxQCo5eDHhsMSBszEajG8c4zhMMOxw5IzgH6ZPcNAQrKBkBa5223MH3/UHObn7z/84HNBRR0/QVtA8cDMA2UzMxgQ1gDWwvgDrmUUjIJRMApGARYAAIJiOEhY8TinAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-0831-2696","institution":"Abdus Salam International Centre for Theoretical Physics","correspondingAuthor":true,"prefix":"","firstName":"Arthur","middleName":"","lastName":"Prigent","suffix":""},{"id":374556538,"identity":"7e323d03-3426-46f1-b1e6-ad2f4b8e7f9e","order_by":1,"name":"Ingo Richter","email":"","orcid":"","institution":"Japan Agency for Marine-Earth Science and Technology: Kaiyo Kenkyu Kaihatsu Kiko","correspondingAuthor":false,"prefix":"","firstName":"Ingo","middleName":"","lastName":"Richter","suffix":""},{"id":374556539,"identity":"2f748c78-478e-483f-af02-dcdd7471b88c","order_by":2,"name":"Andrea Storto","email":"","orcid":"","institution":"ISMAR - CNR: Istituto di scienze marine Consiglio Nazionale delle Ricerche","correspondingAuthor":false,"prefix":"","firstName":"Andrea","middleName":"","lastName":"Storto","suffix":""},{"id":374556540,"identity":"25d9fa2a-bc7f-4658-b3af-8dadc9c7041e","order_by":3,"name":"Riccardo Farneti","email":"","orcid":"","institution":"ICTP: Abdus Salam International Centre for Theoretical Physics","correspondingAuthor":false,"prefix":"","firstName":"Riccardo","middleName":"","lastName":"Farneti","suffix":""},{"id":374556541,"identity":"49ef2d11-7253-498d-8103-984545f27a86","order_by":4,"name":"Rodrigue Anicet Imbol Koungue","email":"","orcid":"","institution":"GEOMAR: Helmholtz-Zentrum fur Ozeanforschung Kiel","correspondingAuthor":false,"prefix":"","firstName":"Rodrigue","middleName":"Anicet Imbol","lastName":"Koungue","suffix":""},{"id":374556542,"identity":"20b88645-0d99-48af-ac9b-8c161e10e57a","order_by":5,"name":"Yuko Okumura","email":"","orcid":"","institution":"The University of Texas at Austin John A and Katherine G Jackson School of Geosciences","correspondingAuthor":false,"prefix":"","firstName":"Yuko","middleName":"","lastName":"Okumura","suffix":""},{"id":374556543,"identity":"3895b289-8648-40e4-8021-c4870f75b2d4","order_by":6,"name":"Ping Chang","email":"","orcid":"","institution":"Texas A\u0026M University","correspondingAuthor":false,"prefix":"","firstName":"Ping","middleName":"","lastName":"Chang","suffix":""}],"badges":[],"createdAt":"2024-10-25 08:07:57","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5330579/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5330579/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00382-025-07820-7","type":"published","date":"2025-08-28T15:56:55+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":90345534,"identity":"a469de8c-47ed-4c7b-8125-e39baa8066f8","added_by":"auto","created_at":"2025-09-01 16:10:31","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":49265882,"visible":true,"origin":"","legend":"","description":"","filename":"manuscriptclimatedynamics24102024.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5330579/v1_covered_30301491-0eab-4907-a932-29ac63625826.pdf"},{"id":69310857,"identity":"61d854a1-693e-4bea-90cc-5cfb16e8fc36","added_by":"auto","created_at":"2024-11-19 04:55:23","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":8106632,"visible":true,"origin":"","legend":"","description":"","filename":"manuscriptclimatedynamicssupplementary24102024.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5330579/v1/f8597fa4d51e611958bc5dbb.pdf"}],"financialInterests":"","formattedTitle":"Intercomparison of Ocean Reanalyses for Interannual Ocean Temperature Variability in the Tropical Atlantic","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"climate-dynamics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cldy","sideBox":"Learn more about [Climate Dynamics](https://www.springer.com/journal/382)","snPcode":"382","submissionUrl":"https://submission.nature.com/new-submission/382/3","title":"Climate Dynamics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Tropical Atlantic Variability, Ocean reanalysis intercomparison, Tropical Atlantic Observing System, PIRATA, Argo floats","lastPublishedDoi":"10.21203/rs.3.rs-5330579/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5330579/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eOcean reanalysis (ORA) products are widely used by the scientific community and are essential tools for monitoring and understanding tropical Atlantic inter-annual variability. However, large differences have been observed among these products in the tropical Atlantic Ocean. In that context, an ensemble of seven ORAs is examined and compared over the period ranging from January 1993 to December 2017. The analysis reveals a considerable spread (\u0026gt; 0.3º C) in tropical Atlantic Ocean temperature anomalies in the upper 150 m. Along the equatorial Atlantic and southwest African coast, which are regions of high interannual variability, most of the discrepancies among the ORAs are located around the depth of the thermocline. This spread is linked to the amount of in situ profiles assimilated by ORAs. The deployment of the PIRATA mooring array in early 1998 improved ORA consistency along the equatorial Atlantic, as well as down the path of equatorial Kelvin waves and subsequent coastal trapped waves. Despite a decreasing trend of -0.04º C·decade\u003csup\u003e−1\u003c/sup\u003e of the ensemble spread averaged over the upper 150 m of the tropical Atlantic ocean, a few regions with limited in-situ observations present smaller improvements, such as in the Benguela upwelling system and around 15º W, 10º S. A comparison between ORAs and forced-ocean models indicates that ocean model biases contribute little to the total ensemble spread. Instead, it suggests that most of the spread can be attributed to discrepancies among the atmospheric fields used to force ORAs. The ensemble spread of the equatorial Atlantic zonal wind anomalies across four atmospheric reanalyses suggests that their consistency has not improved or even worsened.\u003c/p\u003e","manuscriptTitle":"Intercomparison of Ocean Reanalyses for Interannual Ocean Temperature Variability in the Tropical Atlantic","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-11-19 04:55:18","doi":"10.21203/rs.3.rs-5330579/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major Revision","date":"2025-01-14T08:55:21+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2024-11-06T15:06:42+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-11-05T21:45:27+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-10-29T05:37:45+00:00","index":"","fulltext":""},{"type":"submitted","content":"Climate Dynamics","date":"2024-10-25T04:05:54+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"climate-dynamics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cldy","sideBox":"Learn more about [Climate Dynamics](https://www.springer.com/journal/382)","snPcode":"382","submissionUrl":"https://submission.nature.com/new-submission/382/3","title":"Climate Dynamics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"88a64179-d131-4cd3-9290-1cd40cce9e5f","owner":[],"postedDate":"November 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-09-01T16:03:47+00:00","versionOfRecord":{"articleIdentity":"rs-5330579","link":"https://doi.org/10.1007/s00382-025-07820-7","journal":{"identity":"climate-dynamics","isVorOnly":false,"title":"Climate Dynamics"},"publishedOn":"2025-08-28 15:56:55","publishedOnDateReadable":"August 28th, 2025"},"versionCreatedAt":"2024-11-19 04:55:18","video":"","vorDoi":"10.1007/s00382-025-07820-7","vorDoiUrl":"https://doi.org/10.1007/s00382-025-07820-7","workflowStages":[]},"version":"v1","identity":"rs-5330579","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5330579","identity":"rs-5330579","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}