Abstract
Because of the bimodal distribution of sunspot cycle periods, the Hale cycle (or double sunspot cycle) should show evidence of modulation between 20 and 24 yr, with the Hale cycle having an average length of about 22 yr. Indeed, such a modulation is observed. Comparison of consecutive pairs of cycles strongly suggests that even-numbered cycles are preferentially paired with odd-numbered following cycles. Systematic variations are hinted in both the Hale cycle period and R sum (the sum of monthly mean sunspot numbers over consecutively paired sunspot cycles). The preferred even-odd cycle pairing suggests that cycles 22 and 23 form a ‘new’ Hale cycle pair (Hale cycle 12), that cycle 23 will be larger than cycle 22 (in terms of R M, the maximum smoothed sunspot number, and of the individual cycle value of R sum), and that the length of Hale cycle 12 will be longer than 22 yr. Because of the strong correlation (r = 0.95) between individual sunspot cycle values of R sum and R M, having a good estimate of R Mfor the present sunspot cycle (22) allows one to predict its R sum, which further allows an estimation of both R Mand R sum for cycle 23 and an estimation of R sum for Hale cycle 12. Based on Wilson's bivariate fit (r = 0.98), sunspot cycle 22 should have an R Mequal to 144.4 ± 27.3 (at the 3-σ level), implying that its R sum should be about 8600 ± 2200; such values imply that sunspot cycle 23 should have an R sum of about 10500 ± 2000 and an R Mof about 175 ± 40, and that Hale cycle 12 should have an R sum of about 19100 ± 3000.
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References
De Jager, C: 1959, in S. Flügge (ed.), Encyclopedia of Physics, Vol. LII, Astrophysics III: The Solar System, Springer-Verlag, Berlin, p. 150.
Gnevyshev, M. N. and Ohl, A. I.: 1948, Astron. Zh. 25, 18.
Hale, G. E. and Nicholson, S. B.: 1938, Magnetic Observations of Sunspots, 1917–1924, No. 498, Carnegie Inst., Washington, D.C.
Howard, R.: 1977, in A. Bruzek and C. J. Durrant (eds.), Illustrated Glossary for Solar and Solar-Terrestrial Physics, Astrophysics and Space Science Library, Vol. 69, D. Reidel Publ. Co., Dordrecht, Holland, p. 7.
Kiepenheuer, K. O.: 1953, in G. P. Kuiper (ed.), The Sun, The Univ. of Chicago Press, Chicago, p. 322
Kopecký, M.: 1967, in Z. Kopal (ed.), Advancesin Astronomy and Astrophysics, Vol. 5, Academic Press, New York, p. 189.
Lapin, L.: 1978, Statistics for Modern Business Decisions, 2nd ed., Harcourt Brace Jovanovich, Inc., New York.
McKinnon, J. A.: 1987, Sunspot Numbers: 1610–1985, Report UAG-95, World Data Center A for Solar-Terrestrial Physics, Boulder, Colorado, 112pp.
Rabin, D., Wilson, R. M., and Moore, R. L.: 1986, Geophys. Res. Letters 13, 352.
Sargent, H. H., III: 1978, in Twenty-Eighth IEEE Vehicular Technology Conference, IEEE, Inc., New York, p. 490.
Vitinskii, Yu. I.: 1965, Solar Activity Forecasting, NASA TT F-289, NASA, Washington, D.C., 129 pp.
Waldmeier, M.: 1961, The Sunspot-Activity in the Years 1610–1960, Schulthess and Co., Zürich, Switzerland.
Wilson, R. M. 1987a, Solar Phys. 108, 195.
Wilson, R. M. 1987b, J. Geophys. Res. 92 (A9), 10101.
Wilson, R. M. 1987c, Solar Phys. 111, 255.
Wilson, R. M. 1988a, Solar Phys. 115, 397.
Wilson, R. M. 1988b, Geophys. Res. Letters 15, 125.
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Wilson, R.M. Bimodality and the Hale cycle. Sol Phys 117, 269–278 (1988). https://doi.org/10.1007/BF00147248
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DOI: https://doi.org/10.1007/BF00147248