Interdecadal change in triggering effect of subtropical Indian Ocean dipole on tropical Indian Ocean dipole and the role of Southern Annular Mode

Interdecadal change in triggering effect of subtropical Indian Ocean dipole on tropical Indian Ocean dipole and the role of Southern Annular Mode | 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 Interdecadal change in triggering effect of subtropical Indian Ocean dipole on tropical Indian Ocean dipole and the role of Southern Annular Mode Junqiao Feng, Linlin Zhang, Fujun Wang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8597166/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract Based on atmosphere reanalysis data from ERA5 and sea surface temperature (SST) from Hadley Center, this study investigates the triggering effect of the subtropical Indian Ocean Dipole (SIOD) on the following tropical Indian Ocean Dipole (IOD), as well as its interdecadal change, during the period 1960–2024. Results show that from 1960 to the late 1980s (WEAK period), the correlation between SIOD and IOD is not significant; whereas, from the late 1980s onward (STRONG period), a stable positive correlation appears between them. During the STRONG period, the positive SST anomalies (SSTA) in the southwestern Indian Ocean as well as the overlying anomalous anticyclonic circulation (AC), associated with the positive SIOD, are sustained and shift eastward under the positive wind–evaporation–SST (WES) feedback. This SSTA drives a vertical motion of the above atmosphere through diabatic heating, subsequently promoting the development of the low-level AC and its equatorward expansion by exciting Rossby wave trains and local meridional circulation. Ultimately, the development of IOD is triggered and enhanced through air–sea coupling processes, including the Bjerknes feedback, Walker circulation, and oceanic Rossby waves. In contrast, during the WEAK period, the responses of aforementioned physical processes are weak, preventing an effectively influence of the SIOD on the IOD. Further analysis indicates that the intensity variation of the Southern Annular Mode (SAM) plays a significant role in the interdecadal shift of the SIOD–to–IOD relationship: during the STRONG period, SAM intensity is generally stronger and predominantly in a negative phase, with its background circulation favoring an enhanced WES feedback and linkages between the subtropics and tropics; and vice versa during the WEAK period. This paper provides new insights for understanding cross-latitude air–sea interactions and improving seasonal IOD prediction. Indian Ocean Dipole Subtropical Indian Ocean dipole Southern Annular Mode Full Text Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Major Revision 15 Mar, 2026 Reviewers agreed at journal 01 Feb, 2026 Reviewers invited by journal 30 Jan, 2026 Editor assigned by journal 14 Jan, 2026 First submitted to journal 13 Jan, 2026 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-8597166","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":582900511,"identity":"934ab484-c778-49ea-96b5-9cfecb6cefb2","order_by":0,"name":"Junqiao Feng","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA9ElEQVRIie3RMWuDQBTA8SfC3XLF9UlI+hWEAzFTPosITm4FyRScbjP9AoV+jY7KQSZxD+1gFulwQ0qnbLkcgZZCz4wZ7g/ndD+f8gBcrjuMVvqB+hAAbwCC04Q1P8SPbifX9H1yw4cxWsvPpfiYb6ncrVWZLIDKAU5vFsL6PAnFyAXL8/1LjxxYHnl19z9ZYRFHoZCpgCJ+fxCYVlCA7wnLlEd1JYGKnwwJ1ARBxgdD9DjfEJyawooYsJdc4JiFl38hOEZtbSO0499Yyvnrc9YeVblZBEF2GE4WoiMzvT+vMi8As1NorEAv/ev4m7hcLpfrb2cPs0kzAuy5PQAAAABJRU5ErkJggg==","orcid":"","institution":"Institute of Oceanology Chinese Academy of Sciences","correspondingAuthor":true,"prefix":"","firstName":"Junqiao","middleName":"","lastName":"Feng","suffix":""},{"id":582900512,"identity":"b2c7c046-bb33-4d0a-a2a3-e073cdaad670","order_by":1,"name":"Linlin Zhang","email":"","orcid":"","institution":"Institute of Oceanology Chinese Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Linlin","middleName":"","lastName":"Zhang","suffix":""},{"id":582900513,"identity":"720ad8a2-09e0-4c45-b384-48ddf4b23d11","order_by":2,"name":"Fujun Wang","email":"","orcid":"","institution":"Institute of Oceanology Chinese Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Fujun","middleName":"","lastName":"Wang","suffix":""}],"badges":[],"createdAt":"2026-01-14 03:54:43","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8597166/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8597166/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":101753348,"identity":"ff1f9c28-382c-44c4-be36-2dc069029030","added_by":"auto","created_at":"2026-02-03 10:39:48","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3291214,"visible":true,"origin":"","legend":"","description":"","filename":"paper2allSIOD2IOD2026jan14eng.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8597166/v1_covered_28af427a-1587-4262-9233-5b639e5a56ec.pdf"}],"financialInterests":"","formattedTitle":"Interdecadal change in triggering effect of subtropical Indian Ocean dipole on tropical Indian Ocean dipole and the role of Southern Annular Mode","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"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":"Indian Ocean Dipole, Subtropical Indian Ocean dipole, Southern Annular Mode","lastPublishedDoi":"10.21203/rs.3.rs-8597166/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8597166/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eBased on atmosphere reanalysis data from ERA5 and sea surface temperature (SST) from Hadley Center, this study investigates the triggering effect of the subtropical Indian Ocean Dipole (SIOD) on the following tropical Indian Ocean Dipole (IOD), as well as its interdecadal change, during the period 1960\u0026ndash;2024. Results show that from 1960 to the late 1980s (WEAK period), the correlation between SIOD and IOD is not significant; whereas, from the late 1980s onward (STRONG period), a stable positive correlation appears between them. During the STRONG period, the positive SST anomalies (SSTA) in the southwestern Indian Ocean as well as the overlying anomalous anticyclonic circulation (AC), associated with the positive SIOD, are sustained and shift eastward under the positive wind\u0026ndash;evaporation\u0026ndash;SST (WES) feedback. This SSTA drives a vertical motion of the above atmosphere through diabatic heating, subsequently promoting the development of the low-level AC and its equatorward expansion by exciting Rossby wave trains and local meridional circulation. Ultimately, the development of IOD is triggered and enhanced through air\u0026ndash;sea coupling processes, including the Bjerknes feedback, Walker circulation, and oceanic Rossby waves. In contrast, during the WEAK period, the responses of aforementioned physical processes are weak, preventing an effectively influence of the SIOD on the IOD. Further analysis indicates that the intensity variation of the Southern Annular Mode (SAM) plays a significant role in the interdecadal shift of the SIOD\u0026ndash;to\u0026ndash;IOD relationship: during the STRONG period, SAM intensity is generally stronger and predominantly in a negative phase, with its background circulation favoring an enhanced WES feedback and linkages between the subtropics and tropics; and vice versa during the WEAK period. This paper provides new insights for understanding cross-latitude air\u0026ndash;sea interactions and improving seasonal IOD prediction.\u003c/p\u003e","manuscriptTitle":"Interdecadal change in triggering effect of subtropical Indian Ocean dipole on tropical Indian Ocean dipole and the role of Southern Annular Mode","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-02 12:07:58","doi":"10.21203/rs.3.rs-8597166/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major Revision","date":"2026-03-16T02:33:13+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2026-02-02T01:25:20+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-30T08:12:28+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-14T07:59:21+00:00","index":"","fulltext":""},{"type":"submitted","content":"Climate Dynamics","date":"2026-01-13T22:53:39+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":"5a9beb44-8ac4-49c5-b5de-64437f69dec0","owner":[],"postedDate":"February 2nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-16T12:46:59+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-02 12:07:58","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8597166","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8597166","identity":"rs-8597166","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}