Millennium-Scale Sunspot Number Reconstruction: Evidence for an Unusually Active Sun since the 1940s

Ilya G. Usoskin, Sami K. Solanki, Manfred Schüssler, Kalevi Mursula, and Katja Alanko
Phys. Rev. Lett. 91, 211101 – Published 19 November 2003

Abstract

The extension of the sunspot number series backward in time is of considerable interest for dynamo theory, solar, stellar, and climate research. We have used records of the Be10 concentration in polar ice to reconstruct the average sunspot activity level for the period between the year 850 to the present. Our method uses physical models for processes connecting the Be10 concentration with the sunspot number. The reconstruction shows reliably that the period of high solar activity during the last 60 years is unique throughout the past 1150 years. This nearly triples the time interval for which such a statement could be made previously.

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  • Received 9 July 2003

DOI:https://doi.org/10.1103/PhysRevLett.91.211101

©2003 American Physical Society

Authors & Affiliations

Ilya G. Usoskin*

  • Sodankylä Geophysical Observatory (Oulu unit), University of Oulu, FIN-90014 Oulu, Finland

Sami K. Solanki and Manfred Schüssler

  • Max-Planck Institut für Aeronomie, Katlenburg-Lindau, Germany

Kalevi Mursula and Katja Alanko

  • Department of Physical Sciences, University of Oulu, FIN-90014 Oulu, Finland

  • *Electronic address: Ilya.Usoskin@oulu.fi
  • Electronic address: Solanki@linmpi.mpg.de

Comments & Replies

Comment on “Millennium Scale Sunspot Number Reconstruction: Evidence for an Unusually Active Sun Since the 1940s”

G. M. Raisbeck and F. Yiou
Phys. Rev. Lett. 92, 199001 (2004)

Usoskin et al. Reply:

Ilya G. Usoskin, Sami K. Solanki, Manfred Schüssler, and Kalevi Mursula
Phys. Rev. Lett. 92, 199002 (2004)

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Vol. 91, Iss. 21 — 21 November 2003

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