Differences in the solar cycle variability of simple and complex active regions during 1996-2018

dc.contributorAalto-yliopistofi
dc.contributorAalto Universityen
dc.contributor.authorNikbakhsh, Shabnam
dc.contributor.authorTanskanen, Eija
dc.contributor.authorKäpylä, Maarit
dc.contributor.authorHackman, T.
dc.contributor.departmentDepartment of Electronics and Nanoengineering
dc.contributor.departmentCentre of Excellence Research on Solar Long-Term Variability and Effects, ReSoLVE
dc.contributor.departmentUniversity of Helsinki
dc.contributor.departmentDepartment of Computer Scienceen
dc.date.accessioned2019-09-25T14:11:34Z
dc.date.available2019-09-25T14:11:34Z
dc.date.issued2019-09-04
dc.description.abstractAims. Our aim is to examine the solar cycle variability of magnetically simple and complex active region. Methods. We studied simple (alpha and beta) and complex (beta gamma and beta gamma delta) active regions based on the Mount Wilson magnetic classification by applying our newly developed daily approach. We analyzed the daily number of the simple active regions (SARs) and compared that to the abundance of the complex active regions (CARs) over the entire solar cycle 23 and cycle 24 until December 2018. Results. We show that CARs evolve differently over the solar cycle from SARs. The time evolution of SARs and CARs on different hemispheres also shows differences, even though on average their latitudinal distributions are shown to be similar. The time evolution of SARs closely follows that of the sunspot number, and their maximum abundance was observed to occur during the early maximum phase, while that of the CARs was seen roughly two years later. We furthermore found that the peak of CARs was reached before the latitudinal width of the activity band starts to decease. Conclusion. Our results suggest that the active region formation process is a competition between the large-scale dynamo (LSD) and the small-scale dynamo (SSD) near the surface, the former varying cyclically and the latter being independent of the solar cycle. During solar maximum, LSD is dominant, giving a preference to SARs, while during the declining phase the relative role of SSD increases. Therefore, a preference for CARs is seen due to the influence of the SSD on the emerging flux.en
dc.description.versionPeer revieweden
dc.format.extent9
dc.format.mimetypeapplication/pdf
dc.identifier.citationNikbakhsh , S , Tanskanen , E , Käpylä , M & Hackman , T 2019 , ' Differences in the solar cycle variability of simple and complex active regions during 1996-2018 ' , Astronomy & Astrophysics , vol. 629 , A45 . https://doi.org/10.1051/0004-6361/201935486en
dc.identifier.doi10.1051/0004-6361/201935486
dc.identifier.issn1432-0746
dc.identifier.otherPURE UUID: 0895a0b5-59e9-4459-883f-1c98a48130a0
dc.identifier.otherPURE ITEMURL: https://research.aalto.fi/en/publications/0895a0b5-59e9-4459-883f-1c98a48130a0
dc.identifier.otherPURE LINK: https://doi.org/10.1051/0004-6361/201935486
dc.identifier.otherPURE FILEURL: https://research.aalto.fi/files/37079955/ELEC_Nikbakhsh_Differences_in_the_solar_AaA.pdf
dc.identifier.urihttps://aaltodoc.aalto.fi/handle/123456789/40437
dc.identifier.urnURN:NBN:fi:aalto-201909255458
dc.language.isoenen
dc.publisherEDP SCIENCES S A
dc.relation.ispartofseriesAstronomy & Astrophysicsen
dc.relation.ispartofseriesVolume 629en
dc.rightsopenAccessen
dc.subject.keywordSun: magnetic fields
dc.subject.keywordSun: activity
dc.subject.keywordSun: photosphere
dc.subject.keywordsunspots
dc.subject.keywordMAGNETIC-STRUCTURE
dc.subject.keywordCLASSIFICATION
dc.subject.keywordFIELDS
dc.subject.keywordDEPENDENCE
dc.subject.keywordORIGIN
dc.subject.keywordISOON
dc.titleDifferences in the solar cycle variability of simple and complex active regions during 1996-2018en
dc.typeA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessäfi
dc.type.versionpublishedVersion
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