18 citations · 18 across the 4 of their papers we have counts for
6 papers
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…
The Effect of Sunspot Weighting
Leif Svalgaard, Marco Cagnotti, Sergio Cortesi
Waldmeier in 1947 introduced a weighting (on a scale from 1 to 5) of the sunspot count made at Zurich and its auxiliary station Locarno, whereby larger spots were counted more than…
Does Building a Relative Sunspot Number Make Sense? A Qualified 'Yes'
Leif Svalgaard
Recent research has demonstrated that the number of sunspots per group ('active region') has been decreasing over the last two or three solar cycles and that the classical Relative…
Solar Sector Structure
Hugh Hudson, Leif Svalgaard, Iain Hannah
The interplanetary magnetic field near has a characteristic "sector" structure that reflects its polarity relative to the solar direction. Typically we observe large-scale coherenc…