Marine cold-spells in the Philippines (1982–2021): a systematic characterization of metrics, trends, and asymmetries with marine heatwaves

Marine cold-spells in the Philippines (1982–2021): a systematic characterization of metrics, trends, and asymmetries with marine heatwaves | 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 Marine cold-spells in the Philippines (1982–2021): a systematic characterization of metrics, trends, and asymmetries with marine heatwaves Raven Quilestino-Olario, Dale Patrick D. Atup, Brenna Mei M. Concolis, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7801575/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract Marine cold-spells (MCSs)—discrete, multi-day cold anomalies—remain undocumented in the Philippines despite evidence of global weakening. We provide the first systematic assessment of MCSs across the Philippine Exclusive Economic Zone (PEEZ) for 1982–2021, using daily 0.05° CMEMS–OSTIA sea-surface temperatures and a percentile-based detection framework. Metrics of frequency, duration, intensity, cumulative intensity, and onset/decline rates show pervasive weakening: events have become fewer, shorter, and less intense, and MCS-free days increasingly dominate. Localized strengthening persists in some coastal and topographically influenced regions, consistent with upwelling, mixing, and other dynamic processes. A simple shape taxonomy indicates that Philippine MCSs typically intensify more rapidly than they decay. Comparisons with marine heatwaves (MHWs) reveal that although declines in several MCS metrics outpace increases in their warm counterparts, cumulative exposure from warming extremes is rising faster, indicating growing net thermal stress. Attribution analyses identify long-term mean ocean warming as the primary driver of MCS weakening, while internal variability explains the isolated areas of strengthening. By establishing a national baseline and a reproducible framework for Philippine MCSs, this study clarifies their asymmetry with MHWs and highlights implications for ecosystem vulnerability and management in a rapidly warming ocean. climate extremes coastal oceanography ocean warming Philippine Exclusive Economic Zone sea surface temperature trend attribution Full Text Additional Declarations No competing interests reported. Supplementary Files Supplementary1.pdf Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 25 Feb, 2026 Reviewers agreed at journal 17 Oct, 2025 Reviewers invited by journal 15 Oct, 2025 Editor assigned by journal 08 Oct, 2025 Submission checks completed at journal 08 Oct, 2025 First submitted to journal 07 Oct, 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. 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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-7801575","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":534925783,"identity":"14df3735-f985-435a-a7b7-fc1c5b00602c","order_by":0,"name":"Raven Quilestino-Olario","email":"data:image/png;base64,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","orcid":"","institution":"University of Cologne","correspondingAuthor":true,"prefix":"","firstName":"Raven","middleName":"","lastName":"Quilestino-Olario","suffix":""},{"id":534925784,"identity":"513c3fb3-e828-4d60-a12e-8ea248952f15","order_by":1,"name":"Dale Patrick D. 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