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.