Solar Physics

, Volume 166, Issue 1, pp 201–208 | Cite as

North-South asymmetry in the solar flare index

  • Tamer Ataç
  • Atila Özgüç


This paper reports the results of a study of the N-S asymmetry in the flare index using the results of Knoška (1985) combined with our results for the solar cycles 17 to the current cycle 22. By comparing the time-variation of the asymmetry curve with the solar activity variation of the 11-year cycle, we have found that the flare index asymmetry curve is not in phase with the solar cycle and that the asymmetry peaks during solar minimum. A periodic behaviour in the N-S asymmetry appears: the activity in one hemisphere is more important during the ascending part of the cycle whereas during the descending part the activity becomes more important in the other hemisphere. The dominance of flare activity in the southern hemisphere continues during cycle 22 and, according to our findings, this dominance will increase gradually during the following cycle 23.


Flare Solar Activity Southern Hemisphere Solar Cycle Solar Flare 
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  1. Ataç, T.: 1987, Astrophys. Space Sci. 135, 201.Google Scholar
  2. Ball, E.: 1955, Ann. Astrophys. 18(No. 2), 118.Google Scholar
  3. Carbonell, M., Oliver, R., and Ballester, J. L.: 1993, Astron. Astrophys. 274, 497.Google Scholar
  4. Garcia, H.: 1990, Solar Phys. 127, 185.Google Scholar
  5. Gleissberg, W.: 1947, Publ. Istanbul University Observatory, No. 31.Google Scholar
  6. Kleczek, J.: 1952, Publ. Inst. Centr. Astron., No. 22, Prague.Google Scholar
  7. Kleczek, J.: 1953, Publ Astrophys. Obs. Czech. Acad. Sci. No. 24, Prague.Google Scholar
  8. Knoška, S.: 1985, Contrib. Astron. Obs. Skalnaté Pleso 13, 217.Google Scholar
  9. Knoška, S. and Letfus, V.: Catalogue of Activity of Solar Flares 1950–1965 (unpublished).Google Scholar
  10. Knoška, S. and Petrásek, J.: 1984, Contr. Astron. Obs. Skalnaté Pleso 12, 165.Google Scholar
  11. Oliver, R. and Ballester, J. L.: 1994, Solar Phys. 152, 481.Google Scholar
  12. Roy, J. R.: 1977, Solar Phys. 52, 53.Google Scholar
  13. Swinson, D. B., Koyoma, H., and Saito, T.: 1986, Solar Phys. 106, 35.Google Scholar
  14. Verma, V. K.: 1987, Solar Phys. 114, 185.Google Scholar
  15. Verma, V. K.: 1993, Astrophys. J. 403, 797.Google Scholar
  16. Verma, V. K., Pande, M. C., and Uddin, W.: 1987, Solar Phys. 112, 341.Google Scholar
  17. Vizoso, G. and Ballester, J. L.: 1987, Solar Phys. 112, 317.Google Scholar
  18. Vizoso, G. and Ballester, J. L.: 1990, Astron. Astrophys. 229, 540.Google Scholar
  19. Waldmeier, M.: 1957, Z. Astrophys. 43, 149.Google Scholar
  20. Waldmeier, M.: 1971, Solar Phys. 29, 232.Google Scholar
  21. Yadav, R. S. and Badruddin, S. Kumar: 1980, Indian J. Radio Space Phys. 9, 155.Google Scholar

Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • Tamer Ataç
    • 1
  • Atila Özgüç
    • 1
  1. 1.Kandilli Observatory, Bogaziçi UniversityIstanbulTurkey

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