Solar mean magnetic field variability: A wavelet approach to Wilcox Solar Observatory and SOHO/Michelson Doppler Imager observations

Research output: Contribution to journalArticle


Solar mean magnetic field (SMMF) measurements from the Wilcox Solar Observatory and with the SOHO/MDI instrument are described and analyzed. Even though two completely different methods of observation are used, the two data sets obtained show a strong similarity. Using continuous wavelet transforms, SMMF variability is found at a number of temporal scales. Detected SMMF signals with a 1–2 year period are considered to be linked to variations in the internal rotation of the Sun. Intermediate SMMF oscillations with a period of 80–200 days are probably connected to the evolution of large active regions. We also find evidence for 90 min variations with coronal mass ejections as a suggested origin.


  • Fredrik Boberg
  • Henrik Lundstedt
  • J T Hoeksema
  • P H Scherrer
  • W Liu
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Astronomy, Astrophysics and Cosmology


  • coronal mass ejections, Solar magnetic field, active regions, wavelet analysis, internal rotation
Original languageEnglish
JournalJournal of Geophysical Research
Issue numberA10: 1318
Publication statusPublished - 2002
Publication categoryResearch

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Related research output

Boberg, F., 2003, Lund Observatory, Lund University. 76 p.

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