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Reconstruction of Total Solar Irradiance and its implications for the last century

This presentation discusses the reconstruction of Total Solar Irradiance (TSI) from the last three solar cycles to 1915. It explores various proxy models and data sources, including the MgII index, sunspot index, and open field BR, to reconstruct TSI levels. The presentation highlights the short and long-term variability of TSI and compares the reconstructed TSI with observed data.

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Reconstruction of Total Solar Irradiance and its implications for the last century

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  1. Total Solar Irradiance during the last three cycles and what it means for the reconstruction back to 1915 Claus Fröhlich Physikalisch-Meteorologisches Observatorium Davos World Radiation Center CH 7260 Davos Dorf EGU 2011, Vienna, April 7, 2011

  2. Outline • Total Solar Irradiance during the last three solar cycles • Observations • 4-component proxy model • TSI reconstructed back to 1915 • Photometric sunspot index from RGO and SOON back to 1874 • MgII index reconstructed from CaK II observations from Mt.Wilson since 1915 • Solar open field BR from reconstructions since 1872 • Calibration of the proxy model with TSI 1975-2009 • Conclusions EGU 2011, Vienna, April 7, 2011

  3. TSI Database 1975 to Present EGU 2011, Vienna, April 7, 2011

  4. How can we explain the short and long-term Variability of TSI EGU 2011, Vienna, April 7, 2011

  5. 4-Component Model for the Period 1975-2010 EGU 2011, Vienna, April 7, 2011

  6. What is available for the last Century to reconstruct TSI with a 4-Component Model EGU 2011, Vienna, April 7, 2011

  7. MgII index back to 1915 from CaK Observations EGU 2011, Vienna, April 7, 2011

  8. PSI back to 1874 from RGO and SOON Data EGU 2011, Vienna, April 7, 2011

  9. Reconstruction of BR since 1880 EGU 2011, Vienna, April 7, 2011

  10. 4-Component Model 1915-20010 EGU 2011, Vienna, April 7, 2011

  11. Calibrate the 4-component model during 1975-2009 and apply it EGU 2011, Vienna, April 7, 2011

  12. Reconstruction of TSI back to 1915 EGU 2011, Vienna, April 7, 2011

  13. Comparison of Model and Observed EGU 2011, Vienna, April 7, 2011

  14. Conclusions • For the 4-component model back to 1915 the following components have been successfully used: • PSI from sunspot data from RGO and SOON • Open Field BR as reconstructions from the aa index • Decomposed MgII index from CaK observations at Mt.Wilson • There is no assumption about the long-term dependence; for TSI we use the correllation with BR, for UV radiation there is essentially no long-term trend observed • The reconstructed TSI is at about the same level during the minimum in 1924/25 as in 2008/09 • The change of TSI from the minimum in 1985/86 to the minimum in 1924 is 0.340 Wm-2 or 250 ppm. This presentation can be found on: ftp://ftp.pmodwrc.ch/pub/Claus/EGU_2011/EGU2011_TSI_cf.ppt EGU 2011, Vienna, April 7, 2011

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