697 citations · 1.6k across the 26 of their papers we have counts for
4 papers · 1 filter
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…
Gustav Spörer Was Not a Perfect Observer: Failure of the Active Day Fraction Reconstruction of Sunspot Group Numbers
Leif Svalgaard
We show that the Active-Day-Fraction calibration method (Willamo et al. [2017]) fails for Gustav Spörer's sunspot group observations. Spörer was labeled a 'perfect observer' on acc…
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…
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…