Climatic Change

, Volume 47, Issue 1–2, pp 7–15 | Cite as

Are Cosmic Rays Influencing Oceanic Cloud Coverage – Or Is It Only El Niño?

  • Paul D. Farrar


The monthly average (C2) cloudcoverage data produced by the International SatelliteCloud Climatology Project (ISCCP) for the period ofJuly 1986–June 1991 show strong global and regionalcloud coverage variations associated with the ElNiño of 1986–1987. The Pacific Ocean, inparticular, shows strong regional variations in cloudcoverage. These agree well with contemporaneoussatellite observations of broadband shortwave infraredcloud forcing measured by the Earth Radiation BudgetExperiment. Svensmark and Friis-Christensen (1997)noted a similarity between the shape of the timeseries curve of average cloud coverage fraction formid- to low-latitude ocean-areas and the time seriescurve of cosmic ray flux intensity. They proposed acausal relationship – a `missing link' for solarcycle influence on Earth climate. Further spatial andtemporal analysis of the same ISCCP C2 data in thispaper indicates that the cloud coverage variationpatterns are those to be expected for the atmosphericcirculation changes characteristic of El Niño,weakening the case for cosmic rays as a climaticforcing factor.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Fröhlich, C. and Lean, J.: 1998, 'The Sun's Total Irradiance: Cycles, Trends and Related Climate Change Uncertainties Since 1976', Geophys. Res. Lett. 25, 4377–4380.CrossRefGoogle Scholar
  2. Kernthaler, S. C., Toumi, R., and Haigh, J. D.: 1999, 'Some Doubts Concerning a Link between Cosmic Ray Fluxes and Global Cloudiness', Geophys. Res. Lett. 26, 863–865.Google Scholar
  3. Klein, S. A. and Hartmann, D. L.: 1993, 'Spurious Changes in the ISCCP Dataset', Geophys. Res. Lett. 20, 455–458.Google Scholar
  4. Kuang, Z., Jiang, Y., and Yung, Y. L.: 1998, 'Cloud Optical Thickness Variations during 1983–1991: Solar Cycle or ENSO?', Geophys. Res. Lett. 25, 1415–1417.Google Scholar
  5. Kyle, H. L., Weiss, M., and Ardanuy, P.: 1995, 'Cloud, Surface Temperature, and Outgoing Longwave Radiation for the Period from 1979 to 1990', J. Climate 8, 2644–2658.Google Scholar
  6. Peixoto, J. P. and Oort, A. H.: 1991, Physics of Climate, American Institute of Physics, New York.Google Scholar
  7. Ramanathan, V. and Collins, W.: 1991, 'Thermodynamic Regulation of Ocean Warming by Cirrus Clouds Deduced from Observations of the 1987 El Niño', Nature 351, 27–32.Google Scholar
  8. Ropelewski, C. F. and Halpert, M. S.: 1987, 'Global and Regional Scale Precipitation Patterns Associated with the El Niño/Southern Oscillation', Mon. Wea. Rev. 115, 1606–1626.Google Scholar
  9. Rossow, W. B. and Schiffer, R. A.: 1991, 'ISCCP Cloud Data Products', Bull. Amer. Meteorol. Soc. 72, 2–20.Google Scholar
  10. Sun, D.-Z. and Trenberth, K. E.: 1998, 'Coordinated Heat Removal from the Equatorial Pacific during the 1986–1987 El Niño', Geophys. Res. Lett. 25, 2659–2662.Google Scholar
  11. Svensmark, H.: 1998, 'Influence of Cosmic Rays on Earth's Climate', Phys. Rev. Lett. 81, 5027–5030.Google Scholar
  12. Svensmark, H. and Friis-Christensen, E.: 1997, 'Variation of Cosmic Ray Flux and Global Cloud Coverage-a Missing Link in Solar-Climate Relationships', J. Atmos. Solar-Terr. Phys. 59, 1225–1232.Google Scholar

Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • Paul D. Farrar
    • 1
  1. 1.Pass ChristianU.S.A.

Personalised recommendations