Solar Irradiance Models and Measurements: A Comparison in the 220–240 nm wavelength band
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Solar irradiance models that assume solar irradiance variations to be due to changes in the solar surface magnetic flux have been successfully used to reconstruct total solar irradiance on rotational as well as cyclical and secular time scales. Modelling spectral solar irradiance is not yet as advanced, and also suffers from a lack of comparison data, in particular on solar cycle time scales. Here, we compare solar irradiance in the 220–240 nm band as modelled with SATIRE-S and measured by different instruments on the UARS and SORCE satellites. We find good agreement between the model and measurements on rotational time scales. The long-term trends, however, show significant differences. Both SORCE instruments, in particular, show a much steeper gradient over the decaying part of cycle 23 than the modelled irradiance or that measured by UARS/SUSIM.
KeywordsSun: activity Sun: irradiance Spectral And Total Irradiance REconstructions (SATIRE) SOlar Radiation and Climate Experiment (SORCE) Upper Atmosphere Research Satellite/Solar Ultraviolet Spectral Irradiance Monitor (UARS/SUSIM)
The authors would like to thank ISSI for the hospitality and lively meeting. The authors would also like to thank Jerry Harder for providing the SORCE/SIM data, as well as Linton Floyd for helpful discussions and information on SUSIM data and Marty Snow for information on the SORCE/SOLSTICE data. This work was supported by the Deutsche Forschungsgemeinschaft, DFG project number SO 711/1-3 and by the NERC SolCli consortium grant; we are indebted to Sami Solanki and Thomas Wenzler for many useful discussions.
- DeLand MT, Cebula RP (2008) Creation of a composite solar ultraviolet irradiance data set. Journal of Geophysical Research (Space Physics) 113:A11103Google Scholar
- Harder JW, Fontenla JM, Pilewskie P, Richard EC, Woods TN (2009) Trends in solar spectral irradiance variability in the visible and infrared. Geo Phys Res Lett 36:L07801Google Scholar
- Unruh YC, Solanki SK, Fligge M (1999) The spectral dependence of facular contrast and solar irradiance variations. Astron Astrophys 345:635–642Google Scholar