Centennial Total Solar Irradiance Variation

Steven Dewitte (1) , Jan Cornelis (2) , Mustapha Meftah (3)

1 ROB - Royal Observatory of Belgium [Brussels]
2 ETRO - Department of Electronics and Informatics [Vrije Univ Brussel]
3 STRATO - LATMOS

Total Solar Irradiance (TSI) quantifies the solar energy received by the Earth and therefore is of direct relevance for a possible solar influence on climate change on Earth. We analyse the TSI space measurements from 1991 to 2021, and we derive a regression model that reproduces the measured daily TSI variations with a Root Mean Square Error (RMSE) of 0.17 W/m2. The daily TSI regression model uses the MgII core to wing ratio as a facular brightening proxy and the Photometric Sunspot Index (PSI) as a measure of sunspot darkening. We reconstruct the annual mean TSI backwards to 1700 based on the Sunspot Number (SN), calibrated on the space measurements with an RMSE of 0.086 W/m2. The analysis of the 11 year running mean TSI reconstruction confirms the existence of a 105 year Gleissberg cycle. The TSI level of the current grand minimum is only about 0.15 W/m2 higher than the TSI level of the grand minimum in the beginning of the 18th century.

Keywords: total solar irradiance; sunspot number

Domains: Atmospheric and Oceanic Physics [physics.ao-ph]

Steven Dewitte, Jan Cornelis, Mustapha Meftah. Centennial Total Solar Irradiance Variation. Remote Sensing, 2022, 14 (5), pp.1072. ⟨10.3390/rs14051072⟩. ⟨insu-03584654⟩