Updated sunspot group number reconstruction for 1749–1996 using the active day fraction method

Tallbloke's Talkshop

Ilya Usoskin has kindly sent me the data for the new group sunspot number series he and his colleagues have published. I’ve done a rough and ready plot below. Excel file here in case you have problems wit the links below.

group-sunspot Group sunspot number average value. Missing values given as zero

T. Willamo1, I. G. Usoskin2,3 and G. A. Kovaltsov4

1 Department of Physics, University of Helsinki, 00014 Helsinki, Finland
2 Space Climate Research Unit, University of Oulu, 90014 Oulu, Finland
e-mail: Ilya.Usoskin@oulu.fi
3 Sodankylä Geophysical Observatory, University of Oulu, 90014 Oulu, Finland
4 Ioffe Physical-Technical Institute, 194021 St. Petersburg, Russia

Received: 4 October 2016
Accepted: 6 March 2017

View original post 261 more words

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