;Ca II K Plage area composite series ; ;Version/Date: 20231231 ; ;References: ;[1] "Chatzistergos et al., Analysis of full disc Ca II K ; spectroheliograms III. Plage area composite series covering 1892--2019". ; Astron. Astrophys. 639, A88 (2020). DOI: 10.1051/0004-6361/202037746 ;[2] Chatzistergos, T., Krivova N.A., Ermolli, I., ; "Understanding the secular variability of solar irradiance: ; the potential of Ca II K observations", ; JSWSC. (2024). DOI 10.1051/swsc/2024006 ; ;The archives included are those from the Arcetri (Ar), Baikal (Ba), ;Brussels (Br), Calern (CL), Catania (CT), Coimbra (Co), Kanzelhoehe (Ka), ;Kenwood (Ke), Kharkiv (Kh), Kislovodsk (Ki), Kodaikanal taken with the ;spectroheliograph (Ko), Kodaikanal taken with the Twin telescope (KT), ;Kodaikanal taken with the White-Light Active Region Monitor (WARM) ;telescope (KW), Kyoto (Ky), Manila (Ma), Mauna Loa (ML) taken with the ;Precision Solar Photometric Telescope (PSPT), McMath-Hulbert (MM), ;Mees (MS), Meudon taken with the spectroheliograph (MD1), Meudon ;taken with an interference filter (MD2), Mitaka taken with the ;spectroheliograph (Mi1), Mitaka taken with the Solar Flare ;Telescope with an interference filter (Mi2), Mt Wilson (MW), ;Pic du Midi (PM), SOlar Diameter Imager and Surface Mapper (SODISM) ;telescope on board the PICARD spacecraft (PS), Rome taken with the ;equatorial bar at Monte Mario (Ro), Rome taken with the PSPT (RP1), ;Rome taken with the PSPT with narrow bandwidth (RP2), ;Sacramento Peak (SP), San Fernando taken with the Cartesian ;Full-Disk Telescope (CFDT) 1 (SF1), San Fernando taken with the CFDT2 (SF2), Schauinsland (Sc), Teide (Te) taken with the ;Chromospheric Telescope (ChroTel), Upice (UP), Valasske Mezirici (VM), ;Wendelstein (WS), and Yerkes (YR) sites ; ;column 1: year, ;column 2: projected plage areas in disc fraction, ;column 3: corrected for foreshortening plage areas in microhemispheres ;-99 represents non-existent value ; 1892 0.0107 0.0124 1893 0.0177 0.0128 1894 0.0275 0.0197 1895 0.0218 0.0179 1896 -99.0000 -99.0000 1897 0.0104 0.0084 1898 0.0181 0.0145 1899 0.0047 0.0048 1900 0.0107 0.0081 1901 -99.0000 -99.0000 1902 0.0074 0.0061 1903 0.0158 0.0132 1904 0.0156 0.0144 1905 0.0143 0.0111 1906 0.0129 0.0101 1907 0.0168 0.0123 1908 0.0199 0.0150 1909 0.0172 0.0130 1910 0.0122 0.0094 1911 0.0069 0.0053 1912 0.0060 0.0047 1913 0.0054 0.0042 1914 0.0083 0.0066 1915 0.0183 0.0145 1916 0.0217 0.0171 1917 0.0313 0.0241 1918 0.0279 0.0214 1919 0.0254 0.0193 1920 0.0202 0.0152 1921 0.0163 0.0121 1922 0.0109 0.0085 1923 0.0084 0.0065 1924 0.0094 0.0079 1925 0.0180 0.0140 1926 0.0279 0.0222 1927 0.0286 0.0220 1928 0.0326 0.0245 1929 0.0284 0.0211 1930 0.0182 0.0135 1931 0.0120 0.0092 1932 0.0096 0.0072 1933 0.0079 0.0062 1934 0.0085 0.0069 1935 0.0171 0.0137 1936 0.0340 0.0260 1937 0.0403 0.0310 1938 0.0400 0.0306 1939 0.0351 0.0262 1940 0.0287 0.0213 1941 0.0222 0.0166 1942 0.0153 0.0119 1943 0.0114 0.0090 1944 0.0086 0.0068 1945 0.0157 0.0125 1946 0.0332 0.0266 1947 0.0449 0.0347 1948 0.0398 0.0304 1949 0.0447 0.0336 1950 0.0294 0.0223 1951 0.0243 0.0189 1952 0.0150 0.0114 1953 0.0095 0.0071 1954 0.0077 0.0059 1955 0.0150 0.0120 1956 0.0425 0.0338 1957 0.0517 0.0390 1958 0.0520 0.0392 1959 0.0479 0.0357 1960 0.0410 0.0306 1961 0.0252 0.0191 1962 0.0193 0.0146 1963 0.0152 0.0126 1964 0.0089 0.0070 1965 0.0101 0.0083 1966 0.0187 0.0152 1967 0.0326 0.0249 1968 0.0310 0.0238 1969 0.0315 0.0248 1970 0.0351 0.0271 1971 0.0223 0.0173 1972 0.0256 0.0198 1973 0.0161 0.0124 1974 0.0150 0.0118 1975 0.0099 0.0077 1976 0.0107 0.0080 1977 0.0151 0.0121 1978 0.0345 0.0273 1979 0.0459 0.0344 1980 0.0463 0.0339 1981 0.0487 0.0357 1982 0.0441 0.0321 1983 0.0292 0.0220 1984 0.0226 0.0173 1985 0.0108 0.0087 1986 0.0097 0.0077 1987 0.0131 0.0113 1988 0.0304 0.0240 1989 0.0484 0.0371 1990 0.0408 0.0317 1991 0.0434 0.0326 1992 0.0348 0.0255 1993 0.0206 0.0162 1994 0.0142 0.0112 1995 0.0105 0.0085 1996 0.0071 0.0057 1997 0.0102 0.0081 1998 0.0274 0.0222 1999 0.0388 0.0302 2000 0.0445 0.0333 2001 0.0431 0.0320 2002 0.0429 0.0314 2003 0.0272 0.0204 2004 0.0215 0.0163 2005 0.0161 0.0120 2006 0.0100 0.0074 2007 0.0046 0.0037 2008 0.0011 0.0010 2009 0.0013 0.0011 2010 0.0088 0.0068 2011 0.0228 0.0166 2012 0.0241 0.0180 2013 0.0263 0.0196 2014 0.0333 0.0250 2015 0.0238 0.0178 2016 0.0134 0.0097 2017 0.0073 0.0061 2018 0.0032 0.0030 2019 0.0017 0.0016 2020 0.0028 0.0025 2021 0.0100 0.0082 2022 0.0279 0.0208 2023 0.0372 0.0278