Impacts of Ocean–Land–Atmosphere Interactions on Bay of Bengal Summer Monsoon Onset Anomalies via Modulating the Monsoon-Triggering Intraseasonal Oscillations

Impacts of Ocean–Land–Atmosphere Interactions on Bay of Bengal Summer Monsoon Onset Anomalies via Modulating the Monsoon-Triggering Intraseasonal Oscillations | 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 Impacts of Ocean–Land–Atmosphere Interactions on Bay of Bengal Summer Monsoon Onset Anomalies via Modulating the Monsoon-Triggering Intraseasonal Oscillations Weihao Sun, Guoxiong Wu, Yimin Liu, Shaoyu Zhang, Xiaolin Liu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7523090/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 The onset of the summer monsoon marks an abrupt transition in the local annual hydrological cycle. As the earliest-established monsoon subsystem, the monsoon onset over the Bay of Bengal (BOB) not only influences early summer precipitation in the region but also plays a pivotal role in the subsequent progression of the Asian summer monsoon. Composite analysis in this study reveals that both the timing and northward propagation speed of monsoon-triggering intraseasonal oscillations (MTISOs) affect the reversal date of the upper-tropospheric meridional temperature gradient. Our results indicate that the occurrence of tropical deep convection is closely linked to Ocean–Land–Atmosphere interactions over the Indian Ocean, particularly modulated by the cross-equatorial flows (CEFs) over the BOB and the Somali region. Prior to monsoon onset, the springtime land-sea thermal contrast (LSTC) acts as a key driver, influencing the strength of the BOB-CEF and consequently the initiation of MTISO. When LSTC is anomalously stronger, the BOB-CEF can establish earlier and then promote the development of tropical convection. In Contrast, when LSTC is weaker, initiation of the MTISO is dominated by the Somali CEF. On a larger scale, diabatic-heating anomalies associated with Maritime Continent convection induce upper-tropospheric anticyclonic anomalies and further modify the vertical easterly shear over Southeast Asia, which can either promote or hinder the propagation of MTISO. In summary, anomalous monsoon onsets over the BOB are governed by a coupling process between lower-level Ocean–Land–Atmosphere interactions and upper-level circulation anomalies linked to Maritime Continent convection. This highlights the critical role of multi-scale interactions during the transitional season of the Asian summer monsoon. Asian summer monsoon onset Ocean–Land–Atmosphere interactions regional circulation monsoon-triggering intraseasonal oscillation (MTISO) Full Text Supplementary Files SupportingInformation.docx Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Major Revision 23 Nov, 2025 Reviewers agreed at journal 21 Sep, 2025 Reviewers invited by journal 21 Sep, 2025 Editor assigned by journal 11 Sep, 2025 First submitted to journal 09 Sep, 2025 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-7523090","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":518404741,"identity":"bfee3d53-2633-490e-952a-76405da27e08","order_by":0,"name":"Weihao Sun","email":"","orcid":"","institution":"Ministry of Natural Resources of the People's Republic of China","correspondingAuthor":false,"prefix":"","firstName":"Weihao","middleName":"","lastName":"Sun","suffix":""},{"id":518404742,"identity":"12fa1b6d-9103-4bfa-8dc6-165a4143a1e6","order_by":1,"name":"Guoxiong Wu","email":"","orcid":"","institution":"Institute of Atmospheric Physics Chinese Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Guoxiong","middleName":"","lastName":"Wu","suffix":""},{"id":518404743,"identity":"998f25ae-55ed-47ef-b0c0-3249e677dba5","order_by":2,"name":"Yimin Liu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0ElEQVRIiWNgGAWjYBACPgYGxgcPQCxmYrWwAdUaJJCqhU0igSSHsUlkp1Uk1NTZNbAzP3vAUGPHwD+7gZCW3G03Eo4dTm5gZjM3YDiWzCBx5wAxWtgOJAP9YibBwHaAwYCQO0FaChL+1QG1sH+TYPhHpBaGxDZmOwZmHjMJxjZitPC83SyR2Hc4gY2Zp9wgsS+ZR+IGAS387LkbP3z4VmfPz39824MP3+zk+GcQ0MIgAFGQ2AaKIyCbh4B6kDUHwJQ9AzhaR8EoGAWjYBRgAQDy7DiKhWMuFAAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0002-5050-1642","institution":"Institute of Atmospheric Physics","correspondingAuthor":true,"prefix":"","firstName":"Yimin","middleName":"","lastName":"Liu","suffix":""},{"id":518404744,"identity":"ad6e6caa-0079-4730-a469-99813a26a88c","order_by":3,"name":"Shaoyu Zhang","email":"","orcid":"","institution":"National Climate Center","correspondingAuthor":false,"prefix":"","firstName":"Shaoyu","middleName":"","lastName":"Zhang","suffix":""},{"id":518404745,"identity":"177967d8-fdff-442d-90ae-2f82e164b89d","order_by":4,"name":"Xiaolin Liu","email":"","orcid":"","institution":"Shanghai Maritime University","correspondingAuthor":false,"prefix":"","firstName":"Xiaolin","middleName":"","lastName":"Liu","suffix":""}],"badges":[],"createdAt":"2025-09-03 05:51:55","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7523090/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7523090/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":92748480,"identity":"0f6f4e5f-ebc5-4331-a450-8945167fa76a","added_by":"auto","created_at":"2025-10-03 20:15:39","extension":"xml","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":13183,"visible":true,"origin":"","legend":"","description":"","filename":"cldyCLDYD2500959.xml","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/c31e0923597ba49d11e19e5f.xml"},{"id":92747977,"identity":"f19eb928-556f-4da7-88b0-c30a4ba781ad","added_by":"auto","created_at":"2025-10-03 19:59:39","extension":"xml","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1578,"visible":true,"origin":"","legend":"","description":"","filename":"CLDYD250095921800.go.xml","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/5a2a86b53b56986f8be8547f.xml"},{"id":92747984,"identity":"7b420b1d-479d-4bbc-bd5c-0c80e5d3ee04","added_by":"auto","created_at":"2025-10-03 19:59:39","extension":"xml","order_by":21,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":926,"visible":true,"origin":"","legend":"","description":"","filename":"CLDYD2500959Import.xml","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/668d9928cf373d708b0b6058.xml"},{"id":92747989,"identity":"4d3b4c2b-5a74-4725-8ddb-6499d70c2684","added_by":"auto","created_at":"2025-10-03 19:59:39","extension":"xml","order_by":23,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":135157,"visible":true,"origin":"","legend":"","description":"","filename":"CLDYD25009590enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/506f6229d9d822d7349308d9.xml"},{"id":92747974,"identity":"518aa71e-000f-4763-8d2e-2730d2cebec1","added_by":"auto","created_at":"2025-10-03 19:59:39","extension":"eps","order_by":24,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2454290,"visible":true,"origin":"","legend":"","description":"","filename":"Figure1.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/93408adf5ef27572df1784fd.eps"},{"id":92747991,"identity":"390563e2-eeba-443c-beab-0739971259e0","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"eps","order_by":25,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":43583570,"visible":true,"origin":"","legend":"","description":"","filename":"Figure10.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/658f8b03c40d6da0d8016c8c.eps"},{"id":92747973,"identity":"1c34c454-a27b-4fcb-b11f-2341956fcbc3","added_by":"auto","created_at":"2025-10-03 19:59:39","extension":"eps","order_by":26,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":4641778,"visible":true,"origin":"","legend":"","description":"","filename":"Figure11.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/1742f60acd53bc0acb85b748.eps"},{"id":92748170,"identity":"cdb15a5d-4d9d-4e8a-823e-072103d53d36","added_by":"auto","created_at":"2025-10-03 20:07:39","extension":"eps","order_by":27,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":8795142,"visible":true,"origin":"","legend":"","description":"","filename":"Figure12.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/e35de64b9af0c29ce12fe50f.eps"},{"id":92747988,"identity":"f56fb861-6723-46d3-9d6f-063608f8383f","added_by":"auto","created_at":"2025-10-03 19:59:39","extension":"eps","order_by":28,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":4970342,"visible":true,"origin":"","legend":"","description":"","filename":"Figure2.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/4332a9692ceb1eb637ea1882.eps"},{"id":92748168,"identity":"821d7fa1-e9dd-4104-8385-d97531c615aa","added_by":"auto","created_at":"2025-10-03 20:07:39","extension":"eps","order_by":29,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":8678514,"visible":true,"origin":"","legend":"","description":"","filename":"Figure3.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/5e82d692223b37cd95f8076b.eps"},{"id":92747987,"identity":"2950060e-482f-443b-816c-138d3ad4bd21","added_by":"auto","created_at":"2025-10-03 19:59:39","extension":"eps","order_by":30,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":5439558,"visible":true,"origin":"","legend":"","description":"","filename":"Figure4.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/af8c84298c99400d8c7877cf.eps"},{"id":92747976,"identity":"5e9fb1aa-4ba9-4acd-a481-eb45c0f50262","added_by":"auto","created_at":"2025-10-03 19:59:39","extension":"eps","order_by":31,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2003106,"visible":true,"origin":"","legend":"","description":"","filename":"Figure5.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/0757262d39491ba5e2f2b4b7.eps"},{"id":92747992,"identity":"be3a49ef-ef6a-4bd7-814f-403559092ca3","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"eps","order_by":32,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1141226,"visible":true,"origin":"","legend":"","description":"","filename":"Figure6.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/3c140e7a196bdecf1b8ff424.eps"},{"id":92748007,"identity":"dc1e27a1-ceb9-4122-872e-0ce496dcb8d3","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"eps","order_by":33,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":30312894,"visible":true,"origin":"","legend":"","description":"","filename":"Figure7.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/b7dca898ae9de26d6688fb48.eps"},{"id":92748173,"identity":"967ed73a-b560-4c10-93c0-dca2b10e4107","added_by":"auto","created_at":"2025-10-03 20:07:39","extension":"eps","order_by":34,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":3338974,"visible":true,"origin":"","legend":"","description":"","filename":"Figure8.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/208bfe8ac187112f539463e9.eps"},{"id":92748015,"identity":"6e143ac2-568e-4ecb-b630-9b140b80280a","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"eps","order_by":35,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":8062074,"visible":true,"origin":"","legend":"","description":"","filename":"Figure9.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/5f0b2767df2045452cbbdf06.eps"},{"id":92748003,"identity":"9df26e82-929e-42ec-a642-1c6126e8f32a","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"eps","order_by":36,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":808590,"visible":true,"origin":"","legend":"","description":"","filename":"Figures1.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/290d74aae0206245bf7ea0c4.eps"},{"id":92747986,"identity":"d5b3cb6b-3ce9-43a2-846e-01a70e9b2649","added_by":"auto","created_at":"2025-10-03 19:59:39","extension":"eps","order_by":37,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1921790,"visible":true,"origin":"","legend":"","description":"","filename":"Figures2.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/4ecca864ba7e9ee5a50730cf.eps"},{"id":92748182,"identity":"d42e2a08-af23-420c-92a5-55e7cc8ac3f2","added_by":"auto","created_at":"2025-10-03 20:07:40","extension":"eps","order_by":38,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":17107506,"visible":true,"origin":"","legend":"","description":"","filename":"Figures3.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/30ba293152d7556c971f0c5f.eps"},{"id":92747975,"identity":"ca0d2906-147f-4557-964c-cb4fa053a983","added_by":"auto","created_at":"2025-10-03 19:59:39","extension":"eps","order_by":39,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":4885050,"visible":true,"origin":"","legend":"","description":"","filename":"Figures4.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/db76c50e205f0cd3861439a2.eps"},{"id":92748178,"identity":"f75778ce-963d-4e72-a8f7-1353cf8a3c58","added_by":"auto","created_at":"2025-10-03 20:07:40","extension":"eps","order_by":40,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":3350650,"visible":true,"origin":"","legend":"","description":"","filename":"Figures5.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/21a2bde0f87915aa4468ac25.eps"},{"id":92748176,"identity":"5fda1979-27fd-4bbe-9a96-e97fc87a3fe6","added_by":"auto","created_at":"2025-10-03 20:07:40","extension":"eps","order_by":41,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":17465910,"visible":true,"origin":"","legend":"","description":"","filename":"Figures6.eps","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/ef2f91f9176e85a837aa60a3.eps"},{"id":92748177,"identity":"ed9e563a-879e-4db3-be2e-614164581f3e","added_by":"auto","created_at":"2025-10-03 20:07:40","extension":"png","order_by":42,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":284665,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/aa66522b562cf9ce51d394a2.png"},{"id":92748481,"identity":"e65f91b1-b515-4b93-b0cc-5ce3a1faa502","added_by":"auto","created_at":"2025-10-03 20:15:39","extension":"png","order_by":43,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":5805918,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/20410a60ab2c21877326a96e.png"},{"id":92748020,"identity":"4687a587-024e-4eee-85a3-7c3a6b03764f","added_by":"auto","created_at":"2025-10-03 19:59:41","extension":"png","order_by":44,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":313423,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/ce8aea8d11704f290333ba2c.png"},{"id":92748005,"identity":"7a012513-9263-4ff9-ac42-1d6ad3309b61","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"png","order_by":45,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":109875,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage12.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/f9b33d8189c2c72422766c76.png"},{"id":92747998,"identity":"71d47684-3fee-45fb-8ff3-e21b312ed2fc","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"png","order_by":46,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1679402,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/e20d0af27c6def5df18214ed.png"},{"id":92748014,"identity":"17624c19-cf6c-4453-8761-780dcbf15f44","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"png","order_by":47,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":933226,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/d7d5c23485a4b4bbb64428f2.png"},{"id":92747994,"identity":"0918bf96-33cf-4066-af23-418601428ed7","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"png","order_by":48,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":386233,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/181c3b14734c150b985185ad.png"},{"id":92747996,"identity":"09714b22-e0e1-4dc7-ab62-0b943e0682b1","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"png","order_by":49,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":172930,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/11cbeb5edf20519881ec3ba0.png"},{"id":92748010,"identity":"90986cbe-48a4-4170-9858-5cf3fc1a5fd2","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"png","order_by":50,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":235468,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/710f077fe242c629469f05c6.png"},{"id":92748171,"identity":"13581183-68a4-40f4-9b0f-aa809453ec8d","added_by":"auto","created_at":"2025-10-03 20:07:39","extension":"png","order_by":51,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2623684,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/6f500b5f4da471af7f5ba5a9.png"},{"id":92748016,"identity":"ceafed5d-8983-4b77-ad6f-e5b5ceaed363","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"png","order_by":52,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1276231,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/d345617e30e294509a448a5e.png"},{"id":92747979,"identity":"d667f867-0ac8-4ac1-b43d-d70cffa5f377","added_by":"auto","created_at":"2025-10-03 19:59:39","extension":"png","order_by":53,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":667992,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/037914d06b9908c0bcbc58ca.png"},{"id":92747995,"identity":"c72e5997-ed8f-4192-9524-31afd0c3f12e","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"png","order_by":54,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":30567,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/f3f436f94167b13747ad26fc.png"},{"id":92748006,"identity":"7cc2515e-99d8-4450-864c-626ba0505540","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"png","order_by":55,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1485540,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/bd52a16bb48660bbe7797ae6.png"},{"id":92748174,"identity":"f4a12cbe-edef-474e-b931-f6cb239fa4e9","added_by":"auto","created_at":"2025-10-03 20:07:40","extension":"png","order_by":56,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":45949,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/515170efbe941b9f202c39fc.png"},{"id":92748175,"identity":"cb374701-3e66-416e-b27c-ee899f14934c","added_by":"auto","created_at":"2025-10-03 20:07:40","extension":"png","order_by":57,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":39406,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage12.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/6c8a60459de78173d2bc0d52.png"},{"id":92748181,"identity":"8ad50b23-83e6-47ff-993a-7fdff6a4974c","added_by":"auto","created_at":"2025-10-03 20:07:40","extension":"png","order_by":58,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":637541,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/38f5d018ad5291dff03e42d1.png"},{"id":92748017,"identity":"8e53f0d1-bef5-4260-aa06-9c2fcc2a9c7a","added_by":"auto","created_at":"2025-10-03 19:59:41","extension":"png","order_by":59,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":210321,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/e12c93cca1de2a80424c4f6d.png"},{"id":92748011,"identity":"01478adb-45af-4c44-afde-a11f1e002991","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"png","order_by":60,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":63559,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/628ed18106c75f0cd1edb02b.png"},{"id":92747982,"identity":"c65b1f5a-4a70-4881-9eb1-3444d204d5d6","added_by":"auto","created_at":"2025-10-03 19:59:39","extension":"png","order_by":61,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":47554,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/4897a6bde2d6cd9b28a139be.png"},{"id":92748183,"identity":"146551df-408e-4298-ae9a-93588c114df6","added_by":"auto","created_at":"2025-10-03 20:07:41","extension":"png","order_by":62,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":42327,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/eece9c1adf25ffa8f4024ff9.png"},{"id":92748012,"identity":"237af088-3c83-4e92-93f7-116fdcc1a1a3","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"png","order_by":63,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":750665,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/15dd9fd3bc0ee5689b18bc61.png"},{"id":92748482,"identity":"e2ffaae7-fa69-435e-8770-9a804434e32a","added_by":"auto","created_at":"2025-10-03 20:15:40","extension":"png","order_by":64,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":509320,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/ac57fdca273f9eccb4f34fa1.png"},{"id":92748002,"identity":"e732320f-cf98-4067-b6fd-e51f6f963197","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"png","order_by":65,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":85464,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/ee196e393be2b98dfc5adb61.png"},{"id":92748180,"identity":"6beaab1c-7631-4766-b7e3-fec2cd24e649","added_by":"auto","created_at":"2025-10-03 20:07:40","extension":"xml","order_by":66,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":133939,"visible":true,"origin":"","legend":"","description":"","filename":"CLDYD25009590structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/9617d7048884f91392cb3675.xml"},{"id":92748008,"identity":"feb9e77b-7d61-4785-aca1-418d46fc42ef","added_by":"auto","created_at":"2025-10-03 19:59:40","extension":"html","order_by":67,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":146307,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/6fb382b2b3ca189fbbbf6109.html"},{"id":92748808,"identity":"caba47b8-097c-4795-8001-bc5bc9215fcd","added_by":"auto","created_at":"2025-10-03 20:23:45","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2336354,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1_covered_4bbd6534-0f78-48c4-8a26-19c72b75e4e9.pdf"},{"id":92747972,"identity":"b69e30ce-cbaa-4833-bbc3-5b1726f10a1b","added_by":"auto","created_at":"2025-10-03 19:59:39","extension":"docx","order_by":22,"title":"","display":"","copyAsset":false,"role":"supplement","size":1027639,"visible":true,"origin":"","legend":"","description":"","filename":"SupportingInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-7523090/v1/854aac16e6e5c96f66d13692.docx"}],"financialInterests":"","formattedTitle":"Impacts of Ocean–Land–Atmosphere Interactions on Bay of Bengal Summer Monsoon Onset Anomalies via Modulating the Monsoon-Triggering Intraseasonal Oscillations","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":"Asian summer monsoon onset, Ocean–Land–Atmosphere interactions, regional circulation, monsoon-triggering intraseasonal oscillation (MTISO)","lastPublishedDoi":"10.21203/rs.3.rs-7523090/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7523090/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe onset of the summer monsoon marks an abrupt transition in the local annual hydrological cycle. As the earliest-established monsoon subsystem, the monsoon onset over the Bay of Bengal (BOB) not only influences early summer precipitation in the region but also plays a pivotal role in the subsequent progression of the Asian summer monsoon. Composite analysis in this study reveals that both the timing and northward propagation speed of monsoon-triggering intraseasonal oscillations (MTISOs) affect the reversal date of the upper-tropospheric meridional temperature gradient. Our results indicate that the occurrence of tropical deep convection is closely linked to Ocean\u0026ndash;Land\u0026ndash;Atmosphere interactions over the Indian Ocean, particularly modulated by the cross-equatorial flows (CEFs) over the BOB and the Somali region. Prior to monsoon onset, the springtime land-sea thermal contrast (LSTC) acts as a key driver, influencing the strength of the BOB-CEF and consequently the initiation of MTISO. When LSTC is anomalously stronger, the BOB-CEF can establish earlier and then promote the development of tropical convection. In Contrast, when LSTC is weaker, initiation of the MTISO is dominated by the Somali CEF. On a larger scale, diabatic-heating anomalies associated with Maritime Continent convection induce upper-tropospheric anticyclonic anomalies and further modify the vertical easterly shear over Southeast Asia, which can either promote or hinder the propagation of MTISO. In summary, anomalous monsoon onsets over the BOB are governed by a coupling process between lower-level Ocean\u0026ndash;Land\u0026ndash;Atmosphere interactions and upper-level circulation anomalies linked to Maritime Continent convection. This highlights the critical role of multi-scale interactions during the transitional season of the Asian summer monsoon.\u003c/p\u003e","manuscriptTitle":"Impacts of Ocean–Land–Atmosphere Interactions on Bay of Bengal Summer Monsoon Onset Anomalies via Modulating the Monsoon-Triggering Intraseasonal Oscillations","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-03 19:59:33","doi":"10.21203/rs.3.rs-7523090/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major Revision","date":"2025-11-23T21:46:21+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2025-09-22T02:33:39+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-22T02:07:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-11T07:57:51+00:00","index":"","fulltext":""},{"type":"submitted","content":"Climate Dynamics","date":"2025-09-10T02:08:51+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":"7afba9f4-c733-430e-88ce-188c3306aeb9","owner":[],"postedDate":"October 3rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-10T00:32:58+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-03 19:59:33","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7523090","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7523090","identity":"rs-7523090","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}