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Regular Research Article 04 Dec 2013 formerly at: Department of Physics and Technology, Universtity of Tromsø, Norway Based on a simple harmonic model with these periods, we predict that the solar cycle length will in average be longer during the 21st century. Cycle 24 may be about 12 yr long, while cycles 25 and 26 are estimated to be about 9 and 11 yr long. The following cycle is estimated to be 14 yr long. In all periods during the last 1000 yr, when the solar cycle length has increased due to the 190 yr cycle, a deep minimum of solar activity has occurred. This is expected to re-occur in the first part of this century. The coherent modulation of the solar cycle length over a period of 400 yr is a strong argument for an external tidal forcing by the planets Venus, Earth, Jupiter and Saturn, as expressed in a spin-orbit coupling model. Citation: Solheim, J.-E.: The sunspot cycle length – modulated by planets?, Pattern Recogn. Phys., 1, 159-164, doi:10.5194/prp-1-159-2013, 2013. |
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