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Solar Mid-Term Periodicities
2003 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The investigations in this thesis are motivated by the discovery of a quasi- biennial fluctuation of the sunspot umbra-penumbra area ratio (U/P) in the Debrecen Photoheliographic Data (DPD), a detailed catalogue of sunspot activity. A summary of the phenomenon and the analyses of its periodic behaviour are followed by a presentation of some ideas of possible physical interpretations. The emphasis of the thesis lies in a wide survey of solar mid-term periodicities and their possible connections to the U/P fluctuation. When relevant data have been accessible, the periodic behaviours have been explored by filtering methods and spectral analyses. Several separate quantitative comparisons to the U/P fluctuation are given, illustrated by composite figures. No firm conclusion about the origin of the U/P fluctuation can be drawn at present, but several interesting similarities of the phenomenon and other mid-term periodicities are revealed. The research has been carried out at the Heliophysical Observatory in Debrecen, Hungary.

Place, publisher, year, edition, pages
Keyword [en]
Technology, sunspot, umbra, penumbra, photosphere, solar, solar, phenomena, solar activity, sunspot number, sunspot area, ratio, quasi-biennial, quasibiennial, Debrecen, heliophysical, DPD, DPR, QBO, solfläckar, solfysik, solobservatorium
Keyword [sv]
URN: urn:nbn:se:ltu:diva-52884ISRN: LTU-EX--03/170--SELocal ID: 9f74477b-35f7-4d96-a9e1-6e67144d9970OAI: diva2:1026256
Subject / course
Student thesis, at least 30 credits
Educational program
Space Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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