Total sunspot area as a solar activity index
Authors: Sarychev, A.; Roshchina, E.
Source: Solar System Research, Volume 40, Number 6, December 2006 , pp. 521-526(6)
Publisher: MAIK Nauka/Interperiodica
Abstract:Observational time series of the total sunspot area A in the visible solar hemisphere are analyzed. A technique that allows the instability of the scale of these series to be found and corrected has been developed. An internally homogeneous series of the index A on the Greenwich scale can be obtained from 1875 to the present. A method for the approximate calculation of the yearly mean A from the Wolf sunspot numbers known since 1700 is suggested to extend this series into the past. The resulting series of the index A characterizes the solar activity variations over a period of ∼300 years. These data are used to study processes in the Solar System related to the variability of the central star.
Document Type: Research Article
Publication date: December 1, 2006