The area and absolute magnetic flux of sunspots over the past 400 years

Abstract

A new series of yearly-mean relative sunspot numbers SN₂ that has been extrapolated into the past (to 1610) is presented. The Kislovodsk series with the scale factor b = 1.0094 ± 0.0059 represents a reasonable continuation of the mean-monthly and mean-yearly total sunspot areas of the Greenwich series after 1976. The second maximum of the 24th solar-activity cycle was not anomalously low, and was no lower than 6 of the past 13 cycles. A series A₂ of values for the total sunspot area in 1610–2015 has been constructed, and is complementary to new versions of the series of the relative number of sunspots SN₂ and the number of sunspot groups GN₂. When needed, this series can be reduced to yield a quantity having a clear physical meaning—the spot absolute magnetic flux Φ_Σ(t)[Mx] = 2.16 × 10¹⁹A(t) [mvh]. The maximum sunspot area during the Maunder minimum is much higher in the new series compared to the previous version. This at least partially supports the validity of arguments that cast doubt on the anomalously low ampltude of the solar cycles during the Maunder minimum that has been assumed by many researchers earlier.