Solar Physics

, Volume 267, Issue 2, pp 295-303

First online:

Periodicity of Total Solar Irradiance

  • K. J. LiAffiliated withNational Astronomical Observatories/Yunnan Observatory, CASKey Laboratory of Solar Activity, National Astronomical Observatories, CAS Email author 
  • , J. C. XuAffiliated withNational Astronomical Observatories/Yunnan Observatory, CASGraduate School of CAS
  • , X. H. LiuAffiliated withDepartment of Physics, Jiaozuo Advanced Normal College
  • , P. X. GaoAffiliated withNational Astronomical Observatories/Yunnan Observatory, CASGraduate School of CAS
  • , L. S. ZhanAffiliated withJingdezhen Ceramic Institute

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We investigate the periodicity in the PMOD composite of the daily total solar irradiance (TSI) from 21 September 1978 to 9 June 2009. Besides the Schwabe cycle period (10.32 years), the quasi-rotation period is found to be statistically significant in TSI, whose value is about 32 days, longer than that in sunspot activity (27 days), and it intermittently appears around the sunspot maximum times. The quasi-rotation period in TSI is inferred to be mainly caused by sunspot activity, but to be modulated by bright features as well. It was previously found that variations of TSI over a Schwabe solar cycle mainly come from the combination of the sunspots’ blocking and the intensification due to bright faculae, plages, and network elements, with a slight dominance of the bright-feature effect during the maximum of the Schwabe cycle. For the sunspot-blocking and the bright-feature effect to contribute to TSI over a Schwabe solar cycle, the former is inferred to lead the latter by 29 days at least.


Solar irradiance Solar cycle Observations