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Total Solar Irradiance (TSI) Information


The time series of daily total solar irradiance (TSI) presented here for March 1, 2000 onwards is based primarily on Version-15 data from the Solar Radiation and Climate Experiment (SORCE). The time series is provided here. Steps outlined below are used to put together the above time series, extended beyond the period covered by SORCE data. The time series is updated every 2 months.

  1. SORCE data are used for the period 25Feb2003 to 30Jun2013. The SORCE data stream was interrupted in mid-July 2013 because of a battery problem on the instrument.

  2. TSI data for the period prior to 25Feb2003 came from Dr. Greg Kopp of LASP, University of Colorado, Boulder, who had extracted it from a composite dataset from the World Radiation Center (WRC), Davos. The file used, "composite_d41_62_0906.dat" was downloaded from the ftp site: ftp://ftp.pmodwrc.ch/pub/data/irradiance/composite. Dr. Kopp had offset WRC-Composite time series to match with the SORCE version available at the time (V-09). We offset the WRC-Composite time series further to match with SORCE V-15 data following the procedure suggested by Dr. Kopp. According to this procedure, the offset between the SORCE time series and another one is determined by comparing the two time series for the period 25Feb2003 to 31Dec2003.

  3. The period between 30Jun2013 and 31Oct2014 is covered using a composite dataset available from the Royal Meteorological Institute of Belgium (RMIB). This portion of the RMIB time series (01Jul2013 onwards) is also offset to match SORCE V-15 data. In this case, the offset is determined over a 5-year period (01Mar2003 - 29Feb2008) as:

    Mean of SORCE V15 - Mean of RMIB

  4. The period beyond 01Nov2014 is covered using SORCE V-17, which has been operating in hybrid mode beginning in March 5, 2014. This portion of the SORCE time series (01Nov2014 onwards) is also offset to match SORCE V-15 data. Similarly, the offset is determined over a 5-year period (01Mar2003 - 29Feb2008) as:

    Mean of SORCE V15 - Mean of SORCE V17

  5. Finally, the four portions described above are appended end-to-end to produce the entire time series.

Image: TSI Data Time Series Plot

SORCE References:

http://lasp.colorado.edu/home/sorce/instruments/tim/ link to external site

Kopp, G. and J. L. Lean (2011), "A new, lower value of total solar irradiance: Evidence and climate significance",
Geophysical Research Letters, 38, L01706, http://dx.doi.org/10.1029/2010GL045777 link to external site


RMIB References:

For the methodology of the RMIB composite construction:

Mekaoui, S., and S. Dewitte (2008),
Total Solar Irradiance measurement and modelling during cycle 23 link to external site
Solar Physics, 247, 203-216.

For the DIARAD/VIRGO dataset:

Dewitte, S., D. Crommelynck, and A. Joukoff (2004),
Total solar irradiance observations from DIARAD/VIRGO
Journal of Geophysical Research, 109, A02102, http://dx.doi.org/10.1029/2002JA009694 link to external site

For the absolute level:

Dewitte, S., E. Janssen, and S. Mekaoui (2013),
Science results from the Sova-Picard total solar irradiance instrument
AIP Conference Proceedings, 1531, 688-691, http://dx.doi.org/10.1063/1.4804863 link to external site

Janssen, E., S. Dewitte, C. Conscience, A. Chevalier, M. Meftah, A. Irbah, and D. Crommelynck (2013),
Efficiency revision for the DIARAD radiometers
submitted to Metrologia.


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