Characteristics of High-Energy (90 MeV) SolarProton Events in the Rising Phase of Solar Cycle23 Observed by SOHO/ERNE

Characteristics of High-Energy (90 MeV) SolarProton Events in the Rising Phase of Solar Cycle23 Observed by SOHO/ERNE | 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 Characteristics of High-Energy (90 MeV) SolarProton Events in the Rising Phase of Solar Cycle23 Observed by SOHO/ERNE Firas Al-Hamadani, Amjad Al-Sawad This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8969970/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract This study aims to comprehend solar and interplanetary (IP) phenomena generating solar energetic particle (SEP) events with proton energies exceeding 90MeV and identify the locations and commencement times of proton acceleration during such events. Forty energetic proton events, with intensities surpassing 10 \((^{-3})\) cm \((^{-2})\) sr \((^{-1})\) MeV \((^{-1})\) at \(({\sim })\) 94MeV, were meticulously selected from observations by the {\it Energetic and Relativistic Nuclei and Electrons} (ERNE) instrument onboard the {\it Solar and Heliospheric Observatory} (SOHO) during solar cycle 23. Using the fixed path length method (1.2AU) and velocity dispersion analysis (VDA), we estimated particle injection times, cross validating results with the height of radio type II/IV burst emission and comparing them with flare and coronal mass ejection (CME) characteristics. All analyzed proton events were associated with CMEs and 27 of the proton events were associated with on-the-disk soft x--ray flares. Of the 13 other events, six did not have a GOES flare reported but in eleven events evidence exist of behind the limb flaring. Only two events were void of any flare signatures. Radio type II/IV burst emission association was also significant. Of the non associated two events, only one was completely void of radio emission and one showed metric continuum and tilted type III burst lane emission. Most of the first protons were injected when the CME leading edges were below 5R \((_{\odot})\) , and most of the protons reached their maximum intensity while the CMEs were above 10R \((_{\odot})\) . The maximum proton intensities were achieved much earlier than the possible passage of an interplanetary shock near Earth, suggesting that the majority of high energy protons at 90 MeV were accelerated as a result of earlier processes. In roughly half of the events the CME front was above the estimated type II burst location. We suggest that in these cases the type II bursts may be related to CME interaction processes and shocks at the CME flanks. Coronal mass ejections. Solar flares. Energetic particles Protons Propagation Radio bursts Meter-wavelengths and longer (m dkm hm km) Type II. Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 02 Apr, 2026 Reviewers agreed at journal 14 Mar, 2026 Reviewers agreed at journal 12 Mar, 2026 Reviewers invited by journal 26 Feb, 2026 Editor assigned by journal 26 Feb, 2026 Submission checks completed at journal 26 Feb, 2026 First submitted to journal 25 Feb, 2026 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-8969970","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":597519502,"identity":"bd2f294c-e29f-42e2-ab4d-9c2f1848da96","order_by":0,"name":"Firas Al-Hamadani","email":"data:image/png;base64,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","orcid":"","institution":"University of Basrah","correspondingAuthor":true,"prefix":"","firstName":"Firas","middleName":"","lastName":"Al-Hamadani","suffix":""},{"id":597519505,"identity":"bd581d43-f2bb-4e68-b217-04673b5a4159","order_by":1,"name":"Amjad Al-Sawad","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Amjad","middleName":"","lastName":"Al-Sawad","suffix":""}],"badges":[],"createdAt":"2026-02-25 16:53:19","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8969970/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8969970/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104401154,"identity":"e9fdbba7-8d67-4d46-b512-97f2a66b514c","added_by":"auto","created_at":"2026-03-11 12:11:59","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1149019,"visible":true,"origin":"","legend":"","description":"","filename":"CharacteristicsofHighEnergy.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8969970/v1_covered_65cd8327-14a0-41ce-a218-2638bd02a58c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Characteristics of High-Energy (90 MeV) SolarProton Events in the Rising Phase of Solar Cycle23 Observed by SOHO/ERNE","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"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":"astrophysics-and-space-science","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"astr","sideBox":"Learn more about [Astrophysics and Space Science](https://www.springer.com/journal/10509)","snPcode":"10509","submissionUrl":"https://submission.nature.com/new-submission/10509/3","title":"Astrophysics and Space Science","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Coronal mass ejections. Solar flares. Energetic particles, Protons, Propagation, Radio bursts, Meter-wavelengths and longer (m, dkm, hm, km), Type II.","lastPublishedDoi":"10.21203/rs.3.rs-8969970/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8969970/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study aims to comprehend solar and interplanetary (IP) phenomena generating solar energetic particle (SEP) events with proton energies exceeding 90MeV and identify the locations and commencement times of proton acceleration during such events. Forty energetic proton events, with intensities surpassing 10\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\((^{-3})\\)\u003c/span\u003e\u003c/span\u003e cm\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\((^{-2})\\)\u003c/span\u003e\u003c/span\u003e sr\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\((^{-1})\\)\u003c/span\u003e\u003c/span\u003e MeV\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\((^{-1})\\)\u003c/span\u003e\u003c/span\u003e at \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(({\\sim })\\)\u003c/span\u003e\u003c/span\u003e 94MeV, were meticulously selected from observations by the {\\it Energetic and Relativistic Nuclei and Electrons} (ERNE) instrument onboard the {\\it Solar and Heliospheric Observatory} (SOHO) during solar cycle 23. Using the fixed path length method (1.2AU) and velocity dispersion analysis (VDA), we estimated particle injection times, cross validating results with the height of radio type II/IV burst emission and comparing them with flare and coronal mass ejection (CME) characteristics. All analyzed proton events were associated with CMEs and 27 of the proton events were associated with on-the-disk soft x--ray flares. Of the 13 other events, six did not have a GOES flare reported but in eleven events evidence exist of behind the limb flaring. Only two events were void of any flare signatures. Radio type II/IV burst emission association was also significant. Of the non associated two events, only one was completely void of radio emission and one showed metric continuum and tilted type III burst lane emission. Most of the first protons were injected when the CME leading edges were below 5R\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\((_{\\odot})\\)\u003c/span\u003e\u003c/span\u003e, and most of the protons reached their maximum intensity while the CMEs were above 10R\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\((_{\\odot})\\)\u003c/span\u003e\u003c/span\u003e. The maximum proton intensities were achieved much earlier than the possible passage of an interplanetary shock near Earth, suggesting that the majority of high energy protons at 90 MeV were accelerated as a result of earlier processes. In roughly half of the events the CME front was above the estimated type II burst location. We suggest that in these cases the type II bursts may be related to CME interaction processes and shocks at the CME flanks. \u003c/p\u003e","manuscriptTitle":"Characteristics of High-Energy (90 MeV) SolarProton Events in the Rising Phase of Solar Cycle23 Observed by SOHO/ERNE","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-03 18:10:02","doi":"10.21203/rs.3.rs-8969970/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-04-02T12:49:15+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"134737996685616830661205105640677029845","date":"2026-03-14T16:08:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"164628539770186346224826728265989504246","date":"2026-03-12T08:13:08+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-26T10:56:02+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-26T10:04:37+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-26T05:04:58+00:00","index":"","fulltext":""},{"type":"submitted","content":"Astrophysics and Space Science","date":"2026-02-25T16:40:53+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"astrophysics-and-space-science","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"astr","sideBox":"Learn more about [Astrophysics and Space Science](https://www.springer.com/journal/10509)","snPcode":"10509","submissionUrl":"https://submission.nature.com/new-submission/10509/3","title":"Astrophysics and Space Science","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"d78e0ae0-28d3-46cf-89ea-0ce369c8819f","owner":[],"postedDate":"March 3rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-03T18:10:03+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-03 18:10:02","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8969970","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8969970","identity":"rs-8969970","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}