{"paper_id":"d610dcb9-e14f-4c7e-b7e7-39e264364b48","body_text":"Crying wolf with the 2023 El Niño: a predicted event that failed to materialize and an unexpected super-event by the second half of 2024? | 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 Article Crying wolf with the 2023 El Niño: a predicted event that failed to materialize and an unexpected super-event by the second half of 2024? Gian Luca Eusebi Borzelli, Sandro Carniel, Cosimo Enrico Carniel, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3816869/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The El Niño–Southern Oscillation (ENSO) is a phenomenon that involves the redistribution of heat in the tropical Pacific Ocean, resulting in irregular oscillations in the sea surface temperature (SST) between warm (El Niño) and cold (La Niña) phases. While ENSO originates in the tropical Pacific, its impacts are global. In July 2023, the World Meteorological Organization, formally responsible to declare the onset of El Niño, officially announced it to the media, urging governments to prepare for potential high impacts on health, ecosystems, and economies. However, our analysis of long-term meteorological and oceanographic data updated to the end of 2023 shows that while the eastern Pacific was warmer than normal in the second half of 2023, the overall configuration of the tropical Pacific climate system did not indicate a notable El Niño event. In fact, we found that the average SST over the global tropical ocean, excluding the eastern tropical Pacific, was significantly above normal during 2023. Therefore, the excess temperature in the eastern tropical Pacific during 2023 could be attributed to the overall warmth of the global tropical ocean itself. Our findings show that the 2023-24 El Niño event, initially predicted to be at least moderate and possibly strong, turned out to be weak and, de facto, the year is closing without the primary metrics, confirming it as a weaker event than the expectations. However, based on historical records, we hypothesize that the state of the Pacific climate system at the end of 2023, following the unusual 2023-24 El Niño, may lead to the development of a strong or very strong El Niño by mid-2024. Earth and environmental sciences/Ocean sciences Earth and environmental sciences/Climate sciences Earth and environmental sciences/Climate sciences/Ocean sciences Figures Figure 1 Figure 2 Figure 3 Figure 4 Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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. 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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-3816869\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":true,\"archivedVersions\":[],\"articleType\":\"Article\",\"associatedPublications\":[],\"authors\":[{\"id\":269750904,\"identity\":\"a312bc77-6394-42c4-b0d7-5938991c30ce\",\"order_by\":0,\"name\":\"Gian Luca Eusebi Borzelli\",\"email\":\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6klEQVRIiWNgGAWjYBACPhDB2AAimRsPJFQwMBiA2Al4tLAhtDA2HEg4A9OCRw+qFsY2qBZ81rBJJD/8wLjDJl++vbHhwMN5h+XN2ZsPMDz8gU9LmrEE45k0y8aegw0HErcdNtzZcywBv8MkchgkGNsOGzBLJIK1MG64kWNASAvzD5AWNvmHQC1zDtsTo4UNbAuPBND7iQ2HEwlr4XlmZgH0i4EED9BhCcfSkzecOZZwICENtxZ+9uTHN4AhZiDffvjgwx811rYbjjcDGTa4tYAA8x8EuxlMHsCvARXUkaJ4FIyCUTAKRggAADmYVgu0RwwUAAAAAElFTkSuQmCC\",\"orcid\":\"\",\"institution\":\"Center for Remote Sensing of the Earth (CERSE)\",\"correspondingAuthor\":true,\"prefix\":\"\",\"firstName\":\"Gian\",\"middleName\":\"Luca Eusebi\",\"lastName\":\"Borzelli\",\"suffix\":\"\"},{\"id\":269750905,\"identity\":\"3cc53870-73e2-497b-a79f-005e5ac9eb19\",\"order_by\":1,\"name\":\"Sandro Carniel\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"NATO STO-CMRE-Centre for Maritime Research and Experimentation\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Sandro\",\"middleName\":\"\",\"lastName\":\"Carniel\",\"suffix\":\"\"},{\"id\":269750906,\"identity\":\"40fe3a4e-4464-42f5-9401-4953ed520179\",\"order_by\":2,\"name\":\"Cosimo Enrico Carniel\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"ETH Zurich\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Cosimo\",\"middleName\":\"Enrico\",\"lastName\":\"Carniel\",\"suffix\":\"\"},{\"id\":269750907,\"identity\":\"e5d4b83a-481b-4347-ab79-fd6687ea8b08\",\"order_by\":3,\"name\":\"Aniello Russo\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"NATO STO-CMRE-Centre for Maritime Research and Experimentation\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Aniello\",\"middleName\":\"\",\"lastName\":\"Russo\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2023-12-28 13:29:14\",\"currentVersionCode\":1,\"declarations\":\"\",\"doi\":\"10.21203/rs.3.rs-3816869/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-3816869/v1\",\"draftVersion\":[],\"editorialEvents\":[],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":50304085,\"identity\":\"45c96df5-1e55-4ea0-b164-c979258a7964\",\"added_by\":\"auto\",\"created_at\":\"2024-01-29 12:51:55\",\"extension\":\"png\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":1173645,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003ea) 5-month median filtered average SST over the Niño 3.4 region (N34-blue line) and reference temperature, i.e. 5-month median filtered average SST over the global tropical ocean between 5\\u003csup\\u003eo\\u003c/sup\\u003eS and 5\\u003csup\\u003eo\\u003c/sup\\u003eN (black line). Red dots indicate months in which N34 exceeded 0.4\\u003csup\\u003eo\\u003c/sup\\u003eC. b) Difference between N34 and reference temperature. c) Longitude of the easterly/westerly winds convergence (blue line) and SOI (red line). Longitudes of the easterly/westerly winds convergence are reported on the left vertical axis while SOI values are reported on the right vertical axis with increasing values directed downward. In all panels, colored bullets on the top horizonatal axis represent El Niño events classified according to the following scheme: green, weak; blue, moderate; magenta: strong; red: very strong. Colored stars on the bottom horizonatal axis represent La Niña events classified according to the following scheme: green, weak; blue, moderate; magenta: strong. See https://ggweather.com/enso/oni.htm for the classification of El Niño/La Niña events. This figure was created using the MATLAB software package version 2018a (www.mathworks.com).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure01.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-3816869/v1/ac061558aa0ec3806c723e87.png\"},{\"id\":50304088,\"identity\":\"5f3f93f7-a94e-4569-bc0a-63008e30122b\",\"added_by\":\"auto\",\"created_at\":\"2024-01-29 12:51:56\",\"extension\":\"png\",\"order_by\":2,\"title\":\"Figure 2\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":1479253,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eAnomaly of the 20oC isotherm depth (D20): a) Monthly D\\u003csub\\u003e20\\u003c/sub\\u003e anomalies from January 1986 to December 2023. b) 5-day D\\u003csub\\u003e20\\u003c/sub\\u003e anomalies from 2 January 2018 to 28 December 2023. In both panels, colored bullets/squares on the left/right vertical axis represent El Niño/La Niña events classified as discussed in the legend of Figure 1. This figure was created using the MATLAB software package version 2018a (www.mathworks.com).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure02.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-3816869/v1/4b329d317c62b2bfc63e2c12.png\"},{\"id\":50304087,\"identity\":\"d853942b-7ca6-4900-8aa4-660cd7a59957\",\"added_by\":\"auto\",\"created_at\":\"2024-01-29 12:51:56\",\"extension\":\"png\",\"order_by\":3,\"title\":\"Figure 3\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":458456,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eLongitude of the maximum heat content over the water column between 0 and 300 m. Colored bullets/stars on the top/bottom horizonatl axis represent El Niño/La Niña events classified as discussed in the legend of Figure 1. This figure was created using the MATLAB software package version 2018a (www.mathworks.com).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure03.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-3816869/v1/5ed5f9ae69ae47b947ecd703.png\"},{\"id\":50304086,\"identity\":\"72d83a84-10c0-4d50-b352-e8101863c48a\",\"added_by\":\"auto\",\"created_at\":\"2024-01-29 12:51:56\",\"extension\":\"png\",\"order_by\":4,\"title\":\"Figure 4\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":2324060,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003ea) Longitude of the maximum atmospheric convection (blue line) and SOI (red line). Left vertical axis refers to longitudes of the point of the maximum wind vertical advection; SOI values are reported on the right vertical axis with increasing values directed downward. Colored bullets/stars on top/bottom horizontal axis, represent El Niño/La Niña events classified as discussed in the legend of Figure 1. b) Longitude-time plot of the wind vertical component, the white line represents the longitude of the wind convergence. Colored bullets/squares on the left/right vertical axis represent El Niño/La Niña events classified as discussed in the legend of Figure 1. This figure was created using the MATLAB software package version 2018a (www.mathworks.com).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"Figure04.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-3816869/v1/8bf67c830a22a24f5f0c1d67.png\"},{\"id\":51853189,\"identity\":\"b539cea6-0233-4fc0-a0e3-061cfe120653\",\"added_by\":\"auto\",\"created_at\":\"2024-03-01 10:08:58\",\"extension\":\"pdf\",\"order_by\":1,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":779106,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"ManuscriptLineNumb.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-3816869/v1_covered_f4562185-1130-4394-ad87-ea5a5098233b.pdf\"}],\"financialInterests\":\"No competing interests reported.\",\"formattedTitle\":\"Crying wolf with the 2023 El Niño: a predicted event that failed to materialize and an unexpected super-event by the second half of 2024?\",\"fulltext\":[],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":false,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":true,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":false,\"isAuthorSuppliedPdf\":true,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":true,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true},\"keywords\":\"\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-3816869/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-3816869/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"The El Niño–Southern Oscillation (ENSO) is a phenomenon that involves the redistribution of heat in the tropical Pacific Ocean, resulting in irregular oscillations in the sea surface temperature (SST) between warm (El Niño) and cold (La Niña) phases. 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Our findings show that the 2023-24 El Niño event, initially predicted to be at least moderate and possibly strong, turned out to be weak and, de facto, the year is closing without the primary metrics, confirming it as a weaker event than the expectations. 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