Harmonic Structure of Heliospheric Magnetic Field Polarity: Evidence for a Non-sinusoidal Hale Cycle

Harmonic Structure of Heliospheric Magnetic Field Polarity: Evidence for a Non-sinusoidal Hale Cycle | 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 Harmonic Structure of Heliospheric Magnetic Field Polarity: Evidence for a Non-sinusoidal Hale Cycle Jouni Juhani Takalo This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9265241/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract We investigate the temporal structure of heliospheric magnetic field (HMF) polarity using a monthly polarity index derived from IMF observations over 1963-2026. Spectral and time–frequency analyses, together with autocorrelation, consistently reveal a non-stationary signal dominated by the 22-year Hale cycle, accompanied by intermittent intermediate periodicities near 7.5 years and 3 years. We show that these timescales can be interpreted as arising from the harmonic structure of a non-sinusoidal Hale-cycle waveform. Using a synthetic quasi-square signal with Hale-cycle periodicity, we demonstrate that higher-order odd harmonics, particularly the third harmonic (about 7.45 years), naturally emerge from rapid polarity reversals. The variability of these harmonic components is consistent with observed cycle-to-cycle differences in polarity reversal structure. These results suggest that the heliospheric magnetic polarity exhibits a coherent but non-sinusoidal temporal structure. Heliospheric magnetic field Solar cycle Hale cycle Magnetic polarity Wavelet analysis Solar dynamo Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted 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. 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-9265241","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":618960056,"identity":"e7480636-f21c-4367-8c5d-c70473007b32","order_by":0,"name":"Jouni Juhani Takalo","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAuUlEQVRIiWNgGAWjYBACxgaGBCBlA2I2HiBeywGGNDCTOC1gcIDhMJQmBjC3NzyT/lBz3m5t+2GgLTU20YQd1nMgTeLAsdvJ284kArUcS8ttIKhlRgJQC9vtZLMDQC2MDYeJ1fLvXLLZ+YekaDnYdsDO7AbRtvQcSLY425ecYHYDaEsCMX4xbO9JvFHxzc7e7Hz6wwcfamyI0NLAkwCiE8EqEwgpBwF5BvYDINqeGMWjYBSMglEwQgEANilMe4xBQtEAAAAASUVORK5CYII=","orcid":"","institution":"","correspondingAuthor":true,"prefix":"","firstName":"Jouni","middleName":"Juhani","lastName":"Takalo","suffix":""}],"badges":[],"createdAt":"2026-03-30 10:08:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9265241/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9265241/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107303536,"identity":"2f97f95f-9924-44c8-8d94-2deb66ae5969","added_by":"auto","created_at":"2026-04-20 07:57:23","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":620085,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9265241/v1_covered_0f0c271a-9172-46cf-95d0-4d532a26e40f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Harmonic Structure of Heliospheric Magnetic Field Polarity: Evidence for a Non-sinusoidal Hale Cycle","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Heliospheric magnetic field, Solar cycle, Hale cycle, Magnetic polarity, Wavelet analysis, Solar dynamo","lastPublishedDoi":"10.21203/rs.3.rs-9265241/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9265241/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"We investigate the temporal structure of heliospheric magnetic field (HMF) polarity using a monthly polarity index derived from IMF observations over 1963-2026. 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