1850 2033 1861 2019 .00 AS BASE VALUE YEARLY TSI (W/M2) IN TIM SCALE 2033 1361.0400 2032 1361.0600 2031 1361.0800 2030 1361.1200 2029 1361.2000 2028 1361.3200 2027 1361.4000 2026 1361.4600 2025 1361.4400 2024 1361.3600 2023 1361.2000 2022 1361.1200 2021 1361.0600 2020 1361.0400 2019 1361.0400 2018 1361.2560 2017 1361.2147 2016 1361.3384 2015 1361.7017 2014 1361.5882 2013 1361.6117 2012 1361.5920 2011 1361.4640 2010 1361.2296 2009 1360.9856 2008 1360.9794 2007 1361.0004 2006 1361.1004 2005 1361.1431 2004 1361.2960 2003 1361.4971 2002 1361.9725 2001 1361.9009 2000 1361.9522 1999 1361.7339 1998 1361.4702 1997 1361.0787 1996 1360.9005 1995 1361.0200 1994 1361.1154 1993 1361.3081 1992 1361.5255 1991 1361.5875 1990 1361.6844 1989 1361.7357 1988 1361.2840 1987 1360.9677 1986 1360.8877 1985 1360.8359 1984 1360.9775 1983 1361.3923 1982 1361.4217 1981 1361.7126 1980 1361.6909 1979 1361.7566 1978 1361.2295 1977 1361.0500 1976 1360.9440 1975 1360.9566 1974 1360.9792 1973 1361.0660 1972 1361.1948 1971 1361.2392 1970 1361.4117 1969 1361.5281 1968 1361.4356 1967 1361.1374 1966 1360.9332 1965 1360.8301 1964 1360.8779 1963 1361.0138 1962 1361.1854 1961 1361.5795 1960 1361.9256 1959 1362.0576 1958 1362.3628 1957 1362.0982 1956 1361.4949 1955 1361.1123 1954 1360.9819 1953 1361.0253 1952 1361.1126 1951 1361.1933 1950 1361.6156 1949 1361.7306 1948 1361.9235 1947 1361.7197 1946 1361.2842 1945 1361.1456 1944 1360.9080 1943 1360.9052 1942 1361.0801 1941 1361.2455 1940 1361.3999 1939 1361.6299 1938 1361.6735 1937 1361.7170 1936 1361.4379 1935 1360.9766 1934 1360.8648 1933 1360.8356 1932 1360.8472 1931 1360.9547 1930 1361.1858 1929 1361.1000 1928 1361.2413 1927 1361.3065 1926 1361.0393 1925 1360.7004 1924 1360.6045 1923 1360.5976 1922 1360.7013 1921 1360.8915 1920 1361.1199 1919 1361.4560 1918 1361.7757 1917 1361.5701 1916 1361.4054 1915 1361.0964 1914 1360.7851 1913 1360.7110 1912 1360.6625 1911 1360.7133 1910 1360.9185 1909 1361.0208 1908 1361.1528 1907 1361.1264 1906 1361.2441 1905 1361.0005 1904 1361.0143 1903 1360.7228 1902 1360.6319 1901 1360.6394 1900 1360.7290 1899 1360.8152 1898 1360.8914 1897 1360.9385 1896 1361.2281 1895 1361.3363 1894 1361.4701 1893 1361.3458 1892 1361.1688 1891 1360.8840 1890 1360.7650 1889 1360.7764 1888 1360.8100 1887 1360.8577 1886 1361.0569 1885 1361.2171 1884 1361.3241 1883 1361.1109 1882 1361.1539 1881 1361.0932 1880 1360.7627 1879 1360.5930 1878 1360.6067 1877 1360.7192 1876 1360.7805 1875 1361.0057 1874 1361.3396 1873 1361.6337 1872 1361.7310 1871 1361.9733 1870 1361.6794 1869 1361.4661 1868 1361.1520 1867 1361.0301 1866 1361.1589 1865 1361.2800 1864 1361.2972 1863 1361.3489 1862 1361.4956 1861 1361.6242 1860 1361.6335 1859 1361.4779 1858 1361.1913 1857 1360.9499 1856 1360.8772 1855 1360.9770 1854 1361.0975 1853 1361.2921 1852 1361.4177 1851 1361.5037 1850 1361.7005 ******************************************************************* Data arrangement: 1st line: yr_start, yr_end, yr_cyc1, yr_cyc2, base_value (4i5,f8.2): yr_start, yr_end : starting and ending year of the table yr_cyc1, yr_cyc2 : marks for 1st and last cycles used for data beyond table range base_value : base value to be added 2nd line and so on: year, solcon in w/m2 (i4,f10.4) ---Huug Van den Dool (Dec 2019) The question was to update the annual solar constant Table for EMC’s models run by NCO, for 1850 to ‘present’ plus a forecast to about 2030. I have replied to a similar request in 2005 and 2011, the write up for 2011 is 1.5 pages down (still relevant). This time we rely on reconstructed TSI (Total Solar Irradiance or S) data produced elsewhere, downloaded from https://spot.colorado.edu/~koppg/TSI/ for 1750-2018 (2019 not yet available). Advantage: these are annual S numbers already, so no hassle of ‘daily’ data as before. For the period 1979-2018 I assume these are actually measurements by satellite (calibrated and calibrated some more). For 1979-2018 we also downloaded annual sunspot numbers (N) derived from http://sidc.oma.be/silso/datafiles . For 1979-2018 we then find S=0.004*N +1361 as regression with a modest 0.83 correlation. This regression is applied to the predicted sunspot number (N) out of SWPC (their latest update of the forecast for solar cycle 25 made in Dec 2019). This yields estimates of the solar constant S for 2019-2033. (This is a little farther out than 11 years since SWPC expects a very long next cycle of 13 rather than 11 years. The next cycle is also expected to be weak.) The result is given in the Table immediately below +0 +1 +2 +3 +4 +5 +6 +7 +8 +9 1850 0.70 0.50 0.42 0.29 0.10 -0.02 -0.12 -0.05 0.19 0.48 1860 0.63 0.62 0.50 0.35 0.30 0.28 0.16 0.03 0.15 0.47 1870 0.68 0.97 0.73 0.63 0.34 0.01 -0.22 -0.28 -0.39 -0.41 1880 -0.24 0.09 0.15 0.11 0.32 0.22 0.06 -0.14 -0.19 -0.22 1890 -0.23 -0.12 0.17 0.35 0.47 0.34 0.23 -0.06 -0.11 -0.18 1900 -0.27 -0.36 -0.37 -0.28 0.01 0.00 0.24 0.13 0.15 0.02 1910 -0.08 -0.29 -0.34 -0.29 -0.21 0.10 0.41 0.57 0.78 0.46 1920 0.12 -0.11 -0.30 -0.40 -0.40 -0.30 0.04 0.31 0.24 0.10 1930 0.19 -0.05 -0.15 -0.16 -0.14 -0.02 0.44 0.72 0.67 0.63 1940 0.40 0.25 0.08 -0.09 -0.09 0.15 0.28 0.72 0.92 0.73 1950 0.62 0.19 0.11 0.03 -0.02 0.11 0.49 1.10 1.36 1.06 1960 0.93 0.58 0.19 0.01 -0.12 -0.17 -0.07 0.14 0.44 0.53 1970 0.41 0.24 0.19 0.07 -0.02 -0.04 -0.06 0.05 0.23 0.76 1980 0.69 0.71 0.42 0.39 -0.02 -0.16 -0.11 -0.03 0.28 0.74 1990 0.68 0.59 0.53 0.31 0.12 0.02 -0.10 0.08 0.47 0.73 2000 0.95 0.90 0.97 0.50 0.30 0.14 0.10 0.00 -0.02 -0.01 2010 0.23 0.46 0.59 0.61 0.59 0.70 0.34 0.21 0.26 0.04 2020 0.04 0.06 0.12 0.20 0.36 0.44 0.46 0.40 0.32 0.20 2030 0.12 0.08 0.06 0.04****************************************** Table: Annual solar constants with 1361W/m2 subtracted. Along each row we have 10 years. A few more comments: (Dec 2019) 1. We have done this exercise before in 2005 and 2011, and now in 2019. The status of the data (calibration) and availability (daily, annual etc) was very different at these three moments in time. Some basic uncertainties remain, both about N and TSI, for a casual user and different outlets exists. 2. The regression relating N to S has become weaker when adding the data for 2011-2018, which was a very weak solar cycle. One must acknowledge that data from 3 or 4 solar cycles is very little, and this situation will improve only slowly. While the regression is based mainly on the quasi 11 year cycle, longer term changes enter the calculation. The last few years appear ‘anomalous’ by having near zero N, but not very low S. 3. We are ‘lucky’ to deal with this question at this time. Normally SWPC does not make forecasts for the next solar cycle until we are IN it. But on this occasion they made a forecast for cycle 25 while cycle 24 may not yet have quite ended. It is difficult to know, in real time, the exact moment when cycle M ends and cycle M+1 starts. The forecast for cycle 25 (or what remains of it) will be updated in the coming years, but a forecast for any year >= 2033 may not be given until well after 2030. 4. The numbers in the above Table for 2019-2033 need to be replaced when the observations become available, one for each year at some point in the next year. The new solar cycle 25 may give us surprises, so we should not rely on outdated values for the next many years. When someone takes a serious look at the observations X years from now we also cannot rule out that more calibration has taken place and this would change the whole Table back to 1850 or 1750.