3 papers
astro-ph.SR2017
Assessment of the Failure of Active Days Fraction Method of Sunspot Group Number Reconstructions
Leif Svalgaard, Kenneth H. Schatten
We identify several pairs of 'equivalent' observers defined as observers with equal or nearly equal 'observational threshold' areas of sunspots on the solar disk as determined by t…
astro-ph.SR2017
Sunspot Group Numbers Since 1900 and Implications for the Long-term Record of Solar Activity
Leif Svalgaard, Kenneth H. Schatten
Recent work on improving and revising estimates of solar activity [Clette et al., 2014] has resulted in renewed interest in what has been called the longest running 'Science Experi…
astro-ph.SR2017
On the Sunspot Group Number Reconstruction: The Backbone Method Revisited
Leif Svalgaard, Kenneth H. Schatten
We discuss recent papers very critical of our Group Sunspot Number Series (Svalgaard & Schatten [2016]). Unfortunately, we cannot support any of the concerns they raise. We first s…