Beach-scale tidal variations observed from satellite-derived shoreline time series

Beach-scale tidal variations observed from satellite-derived shoreline time series | 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 Beach-scale tidal variations observed from satellite-derived shoreline time series Michael Hart-Davis, Thomas Monahan, Kilian Vos, Ole Andersen This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8967674/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Coastal tidal dynamics play a crucial role in a variety of biogeophysical processes, ranging from compound flooding to sediment transport. Satellite altimetry has revolutionized our understanding of ocean tides, but coastal regions remain challenging for satellite altimetry-based observations. In recent years, important efforts have been made to produce shoreline measurements from satellite optical imagery. These datasets raise the question of whether shoreline observations can resolve tidal dynamics at fine coastal scales. We show shoreline measurements provide fine-scale insights into tidal characteristics. Our results are contrasted with \emph{in situ} measurements and state-of-the-art models as well as with wide-swath satellite observations. We explore how both harmonic analysis and response-based methods can be applied to these data to study a range of tidal constituents, including the phase-locked solar constituent S$_2$. Based on the extended time series, trends and changes in the M$_2$ constituent are estimated using shoreline observations and a variational Bayesian harmonic estimator. Our results show statistically significant trends around New Zealand, which are consistent with those estimated from \emph{in situ} and altimetric observations. We demonstrate that satellite-derived shoreline measurements are a valuable resource for tidal research, particularly for model validation and the study of tidal constituent variability in the coastal zone. Earth and environmental sciences/Ocean sciences/Physical oceanography Earth and environmental sciences/Natural hazards Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Under Review 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. 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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-8967674","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":603125651,"identity":"10b64867-a71a-4262-89e2-658631cb488a","order_by":0,"name":"Michael Hart-Davis","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABCUlEQVRIiWNgGAWjYDACZgY2IGnBYADmsYEQ8wEQk7EBvxYJkBagIrAWtsQGvFoY0LUwMPAY4tWi28787MGPCgkGc/azzx8wlNkl9vGf+f6YN4dBth+HFrPDbOaGPWckGCx70oGGn0tObJPI3djMu43BeCYOa8wO87BJ8LYBHXYgjbH5bxuzMZAL1pK44QBuLZJ//wG1nH/G2MDYVm/Mxn/mIVjLfjxapHkbgFpupIG0HJZjY8hhhNiC2y9m0jLHJHgMbjxjnMFw7rgcm0Sa4cy52ySMZ+Cy5fzhZ5JvamzkDM6nMXxgKKvmke8//ODD2202sv04vA8DPOgCEvjVj4JRMApGwSjACwAAT1MgHVIF1AAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0001-9342-0335","institution":"Technical University of Munich","correspondingAuthor":true,"prefix":"","firstName":"Michael","middleName":"","lastName":"Hart-Davis","suffix":""},{"id":603125652,"identity":"85977820-b681-4031-a3b2-fc1b74e32aa6","order_by":1,"name":"Thomas Monahan","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Thomas","middleName":"","lastName":"Monahan","suffix":""},{"id":603125653,"identity":"ed0c81a4-908c-484d-ade8-0fc8c179b663","order_by":2,"name":"Kilian Vos","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Kilian","middleName":"","lastName":"Vos","suffix":""},{"id":603125654,"identity":"9b12d71a-5936-4463-a3b3-bff13ca9f6ec","order_by":3,"name":"Ole Andersen","email":"","orcid":"https://orcid.org/0000-0002-6685-3415","institution":"Technical University of Denmark","correspondingAuthor":false,"prefix":"","firstName":"Ole","middleName":"","lastName":"Andersen","suffix":""}],"badges":[],"createdAt":"2026-02-25 12:20:36","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8967674/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8967674/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104782814,"identity":"242cff9e-02ff-4809-b6af-5e1597d8417d","added_by":"auto","created_at":"2026-03-17 07:57:50","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":9341240,"visible":true,"origin":"","legend":"Article File","description":"","filename":"hartdavisetal2026cshorelinetides.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8967674/v1_covered_5dd3965b-5dd0-4216-9aa0-1fde13fc146f.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Beach-scale tidal variations observed from satellite-derived shoreline time series","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":true,"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":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8967674/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8967674/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Coastal tidal dynamics play a crucial role in a variety of biogeophysical processes, ranging from compound flooding to sediment transport. Satellite altimetry has revolutionized our understanding of ocean tides, but coastal regions remain challenging for satellite altimetry-based observations. In recent years, important efforts have been made to produce shoreline measurements from satellite optical imagery. These datasets raise the question of whether shoreline observations can resolve tidal dynamics at fine coastal scales. We show shoreline measurements provide fine-scale insights into tidal characteristics. Our results are contrasted with \\emph{in situ} measurements and state-of-the-art models as well as with wide-swath satellite observations. We explore how both harmonic analysis and response-based methods can be applied to these data to study a range of tidal constituents, including the phase-locked solar constituent S$_2$. Based on the extended time series, trends and changes in the M$_2$ constituent are estimated using shoreline observations and a variational Bayesian harmonic estimator. Our results show statistically significant trends around New Zealand, which are consistent with those estimated from \\emph{in situ} and altimetric observations. 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