Table 1.
Studies that reconstructed solar irradiance by using Ca II K observations.
| Study | Ca II K data |
Years | Spectral range | |
|---|---|---|---|---|
| Type | Archive | [nm] | ||
| Empirical models | ||||
| Oster et al. (1982) | Disc-integrated plage area | MW | 1980 | TSI |
| Schatten et al. (1985) | Disc-integrated plage area | MW | 1978–1982 | TSI |
| Foukal & Lean (1986) | Disc-integrated plage area | MW | 1978–1982 | TSI |
| Foukal & Lean (1988) | Disc-integrated plage area | MW | 1978–1984 | TSI |
| Lean & Skumanich (1983) | Disc-integrated plage area | MW | 1969–1980 | 121.57 |
| Lean & Repoff (1987) | Disc-integrated plage area | MW | 1978–1982 | 205 |
| Pap et al. (1991) | Disc-integrated plage area | BB | 1986 | 125, TSI |
| Steinegger et al. (1996) | Disc-integrated plage area | SP | 1980 | TSI |
| Lean et al. (1998) | Disc-integrated plage area | BB | 1991–1995 | TSI, 120–420 |
| Solanki & Fligge (1998) | Disc-integrated plage area | MW (a) | 1915–1984 | TSI |
| Foukal (2002) | Disc-integrated plage area | MW, SP | 1915–1999 | TSI |
| Ambelu et al. (2011) | Disc-integrated index | MW, SP (b) | 1915–2009 | TSI |
| Foukal (2012) | Disc-integrated plage area | MW, SP | 1915–1999 | TSI, 130–240 |
| Morrill et al. (2011a) | Disc-integrated plage area | BB | 1991–1995 | 140–410 |
| Johannesson et al. (1995) | Disc-integrated intensity | BB | 1991–1994 | 125 |
| Chapman et al. (1996) | Disc-integrated intensity | SF | 1988–1992 | TSI |
| Johannesson et al. (1998) | Disc-integrated intensity | BB | 1987–1996 | 125 |
| Preminger et al. (2002) | Disc-integrated intensity | SF | 1988–1996 | TSI |
| Walton et al. (2003) | Disc-integrated intensity | SF | 1989–1996 | TSI |
| Vogler et al. (2005) | Disc-integrated intensity | ML | 1999 | TSI |
| Chapman et al. (2012) | Disc-integrated intensity | SF | 2003–2010 | TSI |
| Chapman et al. (2013) | Disc-integrated intensity | SF | 1988–2010 | TSI |
| Puiu (2019) | Disc-integrated intensity | RP | 2000–2019 | TSI |
| Choudhary et al. (2020) | Disc-integrated intensity | SF | 2003–2018 | TSI |
| Chatzistergos et al. (2020a) | Disc-integrated intensity | RP, SF | 1996–2020 | TSI |
| Worden et al. (2001) | Spatially resolved plage area | SP | 1991–1996 | 120–170 |
| Morrill (2005) | Spatially resolved plage area | BB | 1991–1995 | 276–288 |
| Morrill et al. (2011b) | Spatially resolved plage area | MW | 1961–1981 | 276–288 |
| Semi-empirical models | ||||
| Ermolli et al. (2003) | Spatially resolved plage area | RP | 1996–2001 | TSI |
| Penza et al. (2003) | Spatially resolved plage area | RP | 1996–2001 | TSI, 403, 501, 863 |
| Ermolli et al. (2011) | Spatially resolved plage area | RP | 1997–2010 | TSI |
| Criscuoli et al. (2018) | Disc-integrated plage area | SF, ML | 1988–2015 | 115–310 |
| Fontenla & Landi (2018) | Spatially resolved plage area | Co, MD1, RP | 2002–2016 | TSI,100–100 000 |
| This work | Spatially resolved filling factors | 13 archives | 1978–2019 | TSI, 115–160 000 |
Notes. Columns are: Bibliographic entry, type of input data and Ca II K archive(s) used, period and wavelength range of the reconstructed irradiance with Ca II K data. The studies are separated into four groups based on the method used for the irradiance reconstruction: empirical regression models using time series of plage areas or Ca II K index; empirical regression models using time series of disc-integrated intensities; empirical models using time series of plage areas and actual spectra; semi-empirical models using synthesised spectra from radiative transfer codes. See Table 2 for most of the archive abbreviations, while Co, ML, and SP refer to the Coimbra, Mauna Loa (centred at the core of the Ca II K line in contrast to the MLW data from the same observatory used here, which were centred at the wing of the line), and Sacramento Peak solar observatories, respectively.
Solanki & Fligge (1998) used the facular index compiled by Fligge & Solanki (1998), which included the MW plage areas by Foukal (1998).
Ambelu et al. (2011) used disc-integrated 1Å Ca II K index from SP and not the spectroheliograms.
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