Skip to main content
Log in

On the average rate of growth in sunspot number and the size of the sunspot cycle

  • Published:
Solar Physics Aims and scope Submit manuscript

Abstract

The average rate of growth during the ascending portion of the sunspot cycle, defined here as the difference in smoothed sunspot number values between elapsed time (in months) t and sunspot minimum divided by t, is shown to correlate (r ≥ 0.78) with the size of the sunspot cycle, especially for t ≥ 18 months. Also, the maximum value of the average rate of growth is shown to highly correlate (r = 0.98) with the size of the cycle. Based on the first 18 months of the cycle, cycle 22 is projected to have an R(M) = 186.0 ± 27.2 (at the ± 1σ level), and based on the first 24 months of the cycle, it is projected to have an R(M) = 201.0 ± 20.1 (at the ± 1σ level). Presently, the average rate of growth is continuing to rise, having a value of about 4.5 at 24 months into the cycle, a value second only to that of cycle 19 (4.8 at t = 24 and a maximum value of 5.26 at t = 27). Using 4.5 as the maximum value of the average rate of growth for cycle 22, a lower limit can be estimated for R(M); namely R(M) for cycle 22 is estimated to be ≳ 164.0 (at the 97.5% level of confidence). Thus, these findings are consistent with the previous single variate predictions that project R(M) for cycle 22 to be one of the greatest on record, probably larger than cycle 21 (164.5) and near that of cycle 19 (201.3).

This is a preview of subscription content, log in via an institution to check access.

Access this article

Subscribe and save

Springer+ Basic
EUR 32.99 /Month
  • Get 10 units per month
  • Download Article/Chapter or Ebook
  • 1 Unit = 1 Article or 1 Chapter
  • Cancel anytime
Subscribe now

Buy Now

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Similar content being viewed by others

References

  • Bracewell, R. N.: 1988, Monthly Notices Roy. Astron. Soc. 230, 535.

    Google Scholar 

  • de Jager, C.: 1959, in S. Flügge (ed.), Encyclopedia of Physics, Vol. LII, Astrophysics III: The Solar System, Springer-Verlag, Berlin, p. 51.

    Google Scholar 

  • Howard, R.: 1977, in A. Bruzek and C. J. Durrant (eds.), Illustrated Glossary for Solar and Solar-Terrestrial Physics, Vol. 69, Astrophysics and Space Science Library, D. Reidel Publ. Co., Dordrecht, Holland, p.17.

    Google Scholar 

  • McKinnon, J. A.: 1987, Sunspot Numbers: 1610–1985, Report UAG-95, World Data Center A for Solar-Terrestrial Physics, Boulder, Colorado.

    Google Scholar 

  • Waldmeier, M.: 1935, Astron. Mitt. Zürich 14, No. 133.

  • Waldmeier, M.: 1957, Z. Astrophys. 43, 29.

    Google Scholar 

  • Wilson, R. M. 1988a, J. Geophys. Res. 93, 10011.

    Google Scholar 

  • Wilson, R. M. 1988b, Solar Phys. 117, 179.

    Google Scholar 

  • Wilson, R. M. 1989, Solar Phys. 125, 143.

    Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Rights and permissions

Reprints and permissions

About this article

Cite this article

Wilson, R.M. On the average rate of growth in sunspot number and the size of the sunspot cycle. Sol Phys 125, 133–141 (1990). https://doi.org/10.1007/BF00154783

Download citation

  • Received:

  • Revised:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF00154783

Keywords

Navigation