Chinese Science Bulletin

, Volume 45, Issue 14, pp 1287–1290 | Cite as

A method to predict amplitude and date of maximum sunspot number

  • Yanben Han


A method to predict the amplitude and date of the maximum sunspot number is introduced. The regression analysis of the relationship between the variation rate of monthly sunspot numbers in the initial stage of solar cycles and both of the maximum and the time-length of ascending period of the cycle showed that they are closely correlative. In general, the maximum will be larger and the ascending period will be shorter when the rate is larger. The rate of sunspot numbers in the initial 2 years of the 23rd cycle is thus analyzed based on these grounds and the maximum of the cycle is predicted. For the smoothed monthly sunspot numbers, the maximum will be about 139.2 ±18.8 and the time-length of ascending period will be about 3.31±0.42 years, that is to say, the maximum will appear around the spring of the year 2000. For the mean monthly ones, the maximum will be near 170.1±22.9 and the time-length of ascending period will be about 3.42 ±0.46 years, that is to say, the appearing date of the maximum will be later.


solar activity prediction sunspot number 23rd solar cycle 


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Copyright information

© Science in China Press 2000

Authors and Affiliations

  • Yanben Han
    • 1
  1. 1.Beijing Astronomical Observatory, Chinese Academy of Sciences, National Astronomical ObservatoriesChinese Academy of SciencesBeijingChina

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