Solar Physics

, Volume 291, Issue 9–10, pp 2709–2731 | Cite as

Uncertainties in the Sunspot Numbers: Estimation and Implications

  • Thierry Dudok de WitEmail author
  • Laure Lefèvre
  • Frédéric Clette
Sunspot Number Recalibration


Sunspot number series are subject to various uncertainties that are still poorly known. The need to understand these better was recently highlighted by the major revision of the international Sunspot Number (Clette et al., in Space Sci. Rev. 186, 35, 2014). We present the first thorough estimation of these uncertainties, which behave as Poisson-like random variables with a multiplicative coefficient that is time- and observatory-dependent. We provide a simple expression for these uncertainties, and reveal how their evolution in time coincides with changes in the observations and processing of the data. Knowing their value is essential for properly building composites out of multiple observations, and for preserving the stability of the composites in time.


Sunspots Statistics 



We gratefully acknowledge funding from the European Community’s Seventh Framework Programme (FP7, 2012) under grant agreement no 313188 (SOLID, ). We sincerely thank the anonymous referee for carefully reviewing the manuscript, and for making pertinent comments.

Disclosure of Potential Conflicts of Interest

The authors declare that they have no conflicts of interest.


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Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  1. 1.LPC2ECNRS and University of OrléansOrléans cedex 2France
  2. 2.Royal Observatory of BelgiumBrusselsBelgium

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