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Space Science Reviews

, Volume 94, Issue 1–2, pp 145–152 | Cite as

Modelling solar irradiance variations: Comparison with observations, including line-ratio variations

  • Y.C. Unruh
  • S.K. Solanki
  • M. Fligge
Article

Abstract

Solar irradiance variations show a strong temporal and spectral dependence. The progression of the Sun through its activity cycle as well as solar rotation are mirrored in the irradiance variations. The spectral dependence is such that the variations are several magnitudes larger in the EUV than in the visible or infrared.

We present a simple 3-component model that is based on the assumption that changes in the solar flux are exclusively due to changes in spot and facular coverage. We compare our model to observations of the spectral solar irradiance variations.

Despite its simplicity, we find that the agreement between our model and the observations is surprisingly good. We also explore the reliability and the limitations of our approach by comparing observations of the solar facular contrast and of the changes in spectral line depths with our calculations.

Keywords

Spectral Line Solar Irradiance Activity Cycle Spectral Dependence Solar Rotation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • Y.C. Unruh
    • 1
  • S.K. Solanki
    • 2
  • M. Fligge
    • 3
  1. 1.Institute of AstronomyUniversity of ViennaWienAustria
  2. 2.Max-Planck-Institut für AeronomieKatlenburg-LindauGermany
  3. 3.Institute of AstronomyETH ZentrumZürichSwitzerland

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