The New Sunspot Number: Assembling All Corrections
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Based on various diagnostics and corrections established in the framework of several Sunspot Number Workshops and described by Clette et al. (Space Sci. Rev. 186, 35, 2014), we now assembled all separately derived corrections to produce a new standard version of the reference sunspot-number time series. We explain here the three main corrections and the criteria used to choose a final optimal version of each correction factor or function, given the available information and published analyses. We then discuss the differences between the new corrected series and the original sunspot number, including the disappearance of any significant rising secular trend in the solar-cycle amplitudes after this recalibration. We also introduce the new version management scheme now implemented at the World Data Center Sunspot Index and Long-term Solar Observations (WDC-SILSO), which reflects a major conceptual transition: beyond the rescaled numbers, this first revision of the sunspot number also transforms the former static data archive into a living observational series open to future improvements.
KeywordsSunspots, statistics Solar cycle, observations
F. Clette and L. Lefèvre would like to acknowledge financial support from the Belgian Solar–Terrestrial Center of Excellence (STCE: www.stce.be ). Part of this work was developed in the framework of the SOLID project (EU 7th Framework Program, SPACE collaborative projects, projects.pmodwrc.ch/solid/ ) and of the TOSCA project (ESSEM COST action ES1005 of the European Union; lpcs2e.cnrs-orleans.fr/~ddwit/TOSCA/Home.html ).
Conflict of interest
The authors declare that they have no conflicts of interest.
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