Astronomy Letters

, Volume 31, Issue 8, pp 557-562

To the description of long-term variations in the solar magnetic flux: The sunspot area index

  • Yu. A. NagovitsynAffiliated withPulkovo Astronomical Observatory, Russian Academy of Sciences

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We show that the Wolf sunspot numbers W and the group sunspot numbers GSN are physically different indices of solar activity and that it is improper to compare them. Based on the approach of the so-called “primary” indices from the observational series of W(t) and GSN(t), we suggest series of yearly mean sunspot areas beginning in 1610 and monthly mean sunspot areas beginning in 1749.

Key words

Sun solar activity