Astrophysics and Space Science

, 361:54

Mid-term quasi-periodicities in the CaII-K plage index of the Sun and their implications

  • Partha Chowdhury
  • M. H. Gokhale
  • Jagdev Singh
  • Y.-J. Moon
Original Article

DOI: 10.1007/s10509-015-2641-8

Cite this article as:
Chowdhury, P., Gokhale, M.H., Singh, J. et al. Astrophys Space Sci (2016) 361: 54. doi:10.1007/s10509-015-2641-8

Abstract

We present results of the fast Fourier transform (FFT), the MEM analysis, and the wavelet analysis (WA), of the temporal variation of the monthly disk integrated “CaII-K plage-area and enhanced network (EN) area” hereafter called ‘plage index’ derived by Tlatov et al. (2009), from spectro-heliograms taken in Ca II K line at Kodaikanal Observatory, from February 1907 to April, 1998, In the range \({>}3~\mbox{months}\) and < decade, the Fourier transform power spectra reveal solar cycle periodicity \({\sim}122~\mbox{months}\), its sub-harmonic \({\sim}61~\mbox{months}\), two short quasi-periodicities (\({>}2\) and \({<}4~\mbox{months}\)), and nine ‘intermediate-range’ quasi-periodicities (\({\gtrsim} 4~\mbox{mo}\) and \({<}11~\mbox{yr}\)), in the variation of the plage index. The quasi-periodicities include Rieger, Rieger type and quasi-biennial. The presence of quasi-periodicities and the mean values of the periods are confirmed by the maximum entropy method (MEM). The temporal spans of the quasi-periodicities during different solar cycles are determined from the complex Morlet-wavelet analyses. The Rieger quasi-periodicity (150–160 days) appeared during cycle 21 and cycle 22. Each of the quasi-periodicities in the studied range lies close to one or more planetary periodicities (orbital, or spring tidal, or heliocentric conjunction frequency). We discuss possible interpretations of our results, and those of similar results obtained earlier by other authors, towards understanding the mechanisms of excitation of various quasi-periodicities detected in solar variability parameters.

Keywords

Sun: activity Sun: chromosphere Sun: periodicities 

Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  • Partha Chowdhury
    • 1
  • M. H. Gokhale
    • 2
  • Jagdev Singh
    • 3
  • Y.-J. Moon
    • 1
  1. 1.School of Space ResearchKyung Hee UniversityYonginKorea
  2. 2.KothrudIndia
  3. 3.Indian Institute of AstrophysicsBangaloreIndia

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