Tracing the Solar Wind Cycle at 1 AU: Variability in the Delayed Response to Solar Activity

Tracing the Solar Wind Cycle at 1 AU: Variability in the Delayed Response to Solar Activity | 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 Tracing the Solar Wind Cycle at 1 AU: Variability in the Delayed Response to Solar Activity Raffaele Reda, Luca Giovannelli, Tommaso Alberti This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6882433/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 18 Feb, 2026 Read the published version in Solar Physics → Version 1 posted 7 You are reading this latest preprint version Abstract The continuous flux of energetic particles from the Sun, i.e., the solar wind, influences both planetary and circumplanetary environments. Although the precise origin of each type is still debated, the solar wind originates primarily from the expansion of the solar corona and is driven by the solar magnetic field. The cyclic 11-year variations observable in several solar activity proxies can also be traced in the average properties of the solar wind, though the relationship in terms of amplitude and phase synchronization with solar activity is not uniform. Focusing on the period 1965–2024, we investigate how the relationship between a chromospheric proxy, the Ca II K index, and 1AU solar wind properties, such as speed, temperature, and dynamic pressure, has evolved over the last five solar cycles. On the one hand, variations in their relationship are found in terms of time lag, correlation coefficient, and amplitude in a cycle-based analysis. In particular, we identify a linear relationship between the time lag (in years) and the slope of the fit characterizing the dependence of solar wind properties on the intensity of the solar magnetic cycle. On the other hand, continuous cross-correlation reveals distinct dynamical regimes in solar wind–Ca II K lag, with stable behavior at 2–4 years and instability emerging at both shorter and longer lag intervals, suggesting a nonlinear bifurcation mechanism.Finally, the cycle-to-cycle variations reported can help in understanding the space climate connection between solar activity and near-Earth solar wind properties. Space climate Solar wind Ca II K index Solar cycle Time lag Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 18 Feb, 2026 Read the published version in Solar Physics → Version 1 posted Editorial decision: Revision requested 08 Jul, 2025 Reviews received at journal 08 Jul, 2025 Reviewers agreed at journal 08 Jul, 2025 Reviewers invited by journal 08 Jul, 2025 Editor assigned by journal 14 Jun, 2025 Submission checks completed at journal 14 Jun, 2025 First submitted to journal 12 Jun, 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. 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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-6882433","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":482489705,"identity":"f24255b9-c8fb-46bc-b719-f8c1cad24791","order_by":0,"name":"Raffaele Reda","email":"data:image/png;base64,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","orcid":"","institution":"University of Rome Tor Vergata","correspondingAuthor":true,"prefix":"","firstName":"Raffaele","middleName":"","lastName":"Reda","suffix":""},{"id":482489706,"identity":"9306249e-651f-4563-854d-2c6b99236c57","order_by":1,"name":"Luca Giovannelli","email":"","orcid":"","institution":"University of Rome Tor Vergata","correspondingAuthor":false,"prefix":"","firstName":"Luca","middleName":"","lastName":"Giovannelli","suffix":""},{"id":482489707,"identity":"0fd3d043-987a-4951-a44a-d3bfa6afa9a3","order_by":2,"name":"Tommaso Alberti","email":"","orcid":"","institution":"Istituto Nazionale di Geofisica e Vulcanologia","correspondingAuthor":false,"prefix":"","firstName":"Tommaso","middleName":"","lastName":"Alberti","suffix":""}],"badges":[],"createdAt":"2025-06-12 17:23:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6882433/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6882433/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s11207-026-02616-2","type":"published","date":"2026-02-18T15:57:24+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":103251056,"identity":"bfb643ac-2e3b-4d63-9ab3-93b17848e87d","added_by":"auto","created_at":"2026-02-23 16:02:52","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1088179,"visible":true,"origin":"","legend":"","description":"","filename":"RedaetalSolarPhysics.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6882433/v1_covered_6fa4b443-0b8c-4dcb-a508-997b0f6d051c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Tracing the Solar Wind Cycle at 1 AU: Variability in the Delayed Response to Solar Activity","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":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"solar-physics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"sola","sideBox":"Learn more about [Solar Physics](http://link.springer.com/journal/11207)","snPcode":"11207","submissionUrl":"https://submission.nature.com/new-submission/11207/3","title":"Solar Physics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Space climate, Solar wind, Ca II K index, Solar cycle, Time lag","lastPublishedDoi":"10.21203/rs.3.rs-6882433/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6882433/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The continuous flux of energetic particles from the Sun, i.e., the solar wind, influences both planetary and circumplanetary environments. 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