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Uncertainties in the Sunspot Numbers: Estimation and Implications

  • Sunspot Number Recalibration
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Abstract

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.

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Notes

  1. In the following, “sunspot number” will designate the sunspot number in a generic way, whereas “Wolf number” will refer to the relative sunspot number \([N_{\mathrm{W}}]\) from specific stations, and “international Sunspot Number” will be used for the composite \(S_{\mathrm{N}}\) from SILSO.

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Acknowledgements

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

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Authors and Affiliations

  1. LPC2E, CNRS and University of Orléans, 3A avenue de la Recherche Scientifique, 45071, Orléans cedex 2, France

    Thierry Dudok de Wit

  2. Royal Observatory of Belgium, 3 avenue Circulaire, 1180, Brussels, Belgium

    Laure Lefèvre & Frédéric Clette

Authors
  1. Thierry Dudok de Wit
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  2. Laure Lefèvre
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  3. Frédéric Clette
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Correspondence to Thierry Dudok de Wit.

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Sunspot Number Recalibration

Guest Editors: F. Clette, E.W. Cliver, L. Lefèvre, J.M. Vaquero, and L. Svalgaard

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Dudok de Wit, T., Lefèvre, L. & Clette, F. Uncertainties in the Sunspot Numbers: Estimation and Implications. Sol Phys 291, 2709–2731 (2016). https://doi.org/10.1007/s11207-016-0970-6

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