Solar Physics

, Volume 76, Issue 2, pp 211–219 | Cite as

The effects of sunspots on solar irradiance

  • H. S. Hudson
  • S. Silva
  • M. Woodard
  • R. C. Willson


Sunspots have an obvious direct effect upon the visible radiant energy falling upon the Earth. We show how to estimate this effect and compare it quantitatively with recent observations of the solar total irradiance (Willson et al., 1981). The sunspots explain about half of the total observed variance of one-day averages. Since the sunspot effect on irradiance produces an asymmetry of the solar radiation, rather than (necessarily) a variation of the total luminosity, we have also estimated the sunspot population on the invisible hemisphere. This extrapolation allows us to estimate the true luminosity deficit produced by sunspots, in a manner that tends toward the correct long-term average value. We find no evidence for instantaneous global re-emission to compensate for the sunspot flux deficit.


Radiation Direct Effect Solar Radiation Radiant Energy Recent Observation 
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.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Albregtsen, F. and Maltby, P.: 1978, Nature 274, 41.Google Scholar
  2. Allen, C. W.: 1963, Astrophysical Quantities, London.Google Scholar
  3. Becker, U. and Kiepenheuer, K. J.: 1953, Z. Astrophys. 33, 132.Google Scholar
  4. Bray, R. J.: 1981, Solar Phys. 69, 3.Google Scholar
  5. Chapman, G. A.: 1980, Astrophys. J. Letters 242, L85.Google Scholar
  6. Dyson, F. E.: 1925, Monthly Notices Roy. Astron. Soc. 85, 553.Google Scholar
  7. Foukal, P. V. and Vernazza, J.: 1979, Astrophys. J. 234, 707.Google Scholar
  8. Foukal, P. V., Mack, P. E., and Vernazza, J. E.: 1977, Astrophys. J. 215, 952.Google Scholar
  9. Fröhlich, C.: 1977, in O. R. White (ed.), The Solar Output and its Variations, Boulder, Colo., p. 93.Google Scholar
  10. Gough, D. O.: 1977, in O. R. White (ed.), The Solar Output and its Variations, Boulder, Colorado, p. 451.Google Scholar
  11. Hoyt, D. V.: 1979a, Rev. Geophys. Space Phys. 17, 427.Google Scholar
  12. Hoyt, D. V.: 1979b, Climatic Change 2, 79.Google Scholar
  13. Mihalas, Dimitri: 1978, Stellar Atmospheres, second edition, Freeman.Google Scholar
  14. Ulrich, R. K.: 1975, Science 190, 619.Google Scholar
  15. Willson, R. C. and Hudson, H. S.: 1981a, Astrophys. J. Letters 244, L185.Google Scholar
  16. Willson, R. C. and Hudson, H. S.: 1981b, Adv. Space Res. 1, 285.Google Scholar
  17. Willson, R. C., Gulkis, S., Janssen, M., Hudson, H. S., and Chapman, G. A.: 1981, Science 211, 700.Google Scholar

Copyright information

© D. Reidel Publishing Co. 1982

Authors and Affiliations

  • H. S. Hudson
    • 1
  • S. Silva
    • 1
  • M. Woodard
    • 1
  • R. C. Willson
    • 2
  1. 1.Center for Astrophysics and Space Sciences, University of CaliforniaSan DiegoUSA
  2. 2.Jet Propulsion LaboratoryUSA

Personalised recommendations