Table 1.
Previous studies of the relationship between sunspot and facular measurements.
| Study | Plage data | Sunspot data | Period | Relation |
||
|---|---|---|---|---|---|---|
| Annual | Monthly | Daily | ||||
| Ca II K plage areas and sunspot number series | ||||||
| Dorotović et al. (2010) | Co | ISNv1 | 1996–2006 | Quadratic (a) | ||
| Foukal (1996) | MW | ISNv1 | 1915–1984 | Linear | ||
| Fligge & Solanki (1998) | MW (b) | ISNv1 | 1944–1954 | Quadratic | ||
| Kuriyan et al. (1982) | Ko | ISNv1 | 1905–1977 | Linear | ||
| Bertello et al. (2016) | Ko (c) | ISNv2 | 1907–1999 | Linear | Linear | |
| Priyal et al. (2017) | Ko | ISNv2 | 1907–2007 | Linear | ||
| Singh et al. (2021) | Ko | ISNv2 | 1905–2007 | Linear | Linear | |
| Singh et al. (2022) | MW | ISNv2 | 1915–1985 | Linear | Linear | |
| Singh et al. (2022) | ML | ISNv2 | 1998–2015 | Linear | Linear | |
| Yeo et al. (2020) | SP (d) | ISNv1, ISNv2 | 1976–2017 | Power law (e) | ||
| Yeo et al. (2020) | SP (d) | CEA17, HoSc98 | 1976–2010 | Power law (e) | ||
| Ca II K plage areas and sunspot area series | ||||||
| Foukal & Vernazza (1979) | SGD | SGD | 1969–1974 | (∼0.5–685) (f) | ||
| Schatten et al. (1985) | SGD | SGD | 1969–1982 | (∼18–40) | ||
| Lawrence (1987b) | SGD | SGD | 1974–1985 | (∼5–30) | ||
| Foukal (1993) | SGD | RGO | 1954–1987 | Linear | ||
| Foukal (1996) | MW | RGO | 1915–1984 | Linear | ||
| Foukal (1998) | MW | RGO | 1915–1984 | Linear | Quadratic | |
| Tlatov et al. (2009) | MW | RGO | 1944–1963 | Quadratic | ||
| Tlatov et al. (2009) | Ko | RGO | 1944–1963 | Quadratic | ||
| Mandal et al. (2017) | Ko (g) | RGO | 1907–1965 | Linear | ||
| Singh et al. (2021) | Ko | RGO | 1905–2007 | Linear | Linear | |
| Singh et al. (2022) | MW | RGO | 1915–1985 | Linear | Linear | |
| Singh et al. (2022) | ML | RGO | 1998–2015 | Linear | Linear | |
| Chowdhury et al. (2022) | Ko (g) | RGO | 1907–1980 | Quadratic | ||
| Chapman et al. (1997) | SF1, SF2 | SF1, SF2 | 1988–1995 | Quadratic (h) | Quadratic | |
| Chapman et al. (2001) | SF1, SF2 | SF1, SF2 | 1988–1999 | (∼5–40) | ||
| Chapman et al. (2011) | SF1, SF2 | SF1, SF2 | 1988–2009 | Linear | Linear | |
| Steinegger et al. (1996) | SP | VTT (i) | 1980 | (∼3–30) | ||
| Yeo et al. (2020) | SP (d) | BEA09 (j) | 1976–2017 | power law (e) | ||
| Chatzistergos et al. (2020b) | SP | BEA09 (j) | 1960–2002 | (∼35–55) | ||
| Chatzistergos et al. (2020b) | Ky (k) | BEA09 (j) | 1928–1969 | (∼13–20) | ||
| Magnetogram facular areas and sunspot area/number series | ||||||
| Solanki & Unruh (2013) | KP (l) | KP areas | 1974–2002 | Quadratic | ||
| Shapiro et al. (2014) | KP (l) | KP areas | 1974–2002 | Quadratic | ||
| Borgniet et al. (2015) | MDI (m) | SOON (n) areas | 1996–2007 | (∼10–160) | ||
| Criscuoli (2016) | MDI (m) | ISNv2 | 1996–2011 | Linear | Quadratic | |
Notes. Columns are: Bibliography entry; Type of plage and sunspot data used; Period covered by the analysed data; Form of the derived relationship (considering sunspot data as a function of plage areas) for annual, monthly, and daily data (values in parentheses are reported values for the ratio of plage to sunspot area). The column corresponding to monthly values is for periods intermediate to annual and daily. Only Tlatov et al. (2009), Bertello et al. (2016), and Singh et al. (2021) used monthly values; Chapman et al. (1997, 2001) and Chapman et al. (2011) used 100-day bins, Shapiro et al. (2014) 58-day bins, and Criscuoli (2016) and Priyal et al. (2017) 6-month averages. See Tables 2 and 3, and the footnotes in this table for information on the abbreviations.
Not explicitly stated by the authors, but can be inferred from Fig. 6A in Dorotović et al. (2010).
The MW plage area series used in this study was produced by Foukal (1996).
The Ko plage area series used in this study was produced by Tlatov et al. (2009).
This is the Bertello et al. (2016) disc-integrated 1Å Ca II K composite index with SP and Synoptic Optical Long-term Investigations of the Sun Integrated Sunlight Spectrometer data. The SP data are not the full-disc spectroheliograms used in our study.
This was roughly estimated from Fig. 4 in Foukal & Vernazza (1979), who argued that there is large scatter in the data rendering sunspot areas poor indicators of plage areas.
The Ko plage area series used in this study was produced by Chatterjee et al. (2016).
The authors reported a quadratic relation for annual values; however, they also state that roughly 75% of the variance in the scatter plots is accounted for by the linear term.
Refers to the Balmaceda et al. (2009) sunspot area composite series.
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