How well do we know the sunspot number?
- 1 October 2011
- journal article
- Published by Cambridge University Press (CUP) in Proceedings of the International Astronomical Union
- Vol. 7 (S286), 27-33
- https://doi.org/10.1017/s1743921312004590
Abstract
We show that only two adjustments are necessary to harmonize the Group Sunspot Number with the Zürich Sunspot Number. The latter has been increased from the 1940s on to the present by 20% due to weighting of sunspot counts according to size of the spots and can be corrected by increasing the earlier values as well. The Group Sunspot Number before ~1885 is too low by ~50%. With these adjustments a single sunspot number series results. Of note is that there is no longer a distinct Modern Grand Maximum.Keywords
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