Cosmic ray decreases affect atmospheric aerosols and clouds
Article first published online: 1 AUG 2009
Copyright 2009 by the American Geophysical Union.
Geophysical Research Letters
Volume 36, Issue 15, 16 August 2009
How to Cite
2009), Cosmic ray decreases affect atmospheric aerosols and clouds, Geophys. Res. Lett., 36, L15101, doi:10.1029/2009GL038429., , and (
- Issue published online: 1 AUG 2009
- Article first published online: 1 AUG 2009
- Manuscript Accepted: 17 JUN 2009
- Manuscript Revised: 1 JUN 2009
- Manuscript Received: 31 MAR 2009
- Forbush decrease;
 Close passages of coronal mass ejections from the sun are signaled at the Earth's surface by Forbush decreases in cosmic ray counts. We find that low clouds contain less liquid water following Forbush decreases, and for the most influential events the liquid water in the oceanic atmosphere can diminish by as much as 7%. Cloud water content as gauged by the Special Sensor Microwave/Imager (SSM/I) reaches a minimum ≈7 days after the Forbush minimum in cosmic rays, and so does the fraction of low clouds seen by the Moderate Resolution Imaging Spectroradiometer (MODIS) and in the International Satellite Cloud Climate Project (ISCCP). Parallel observations by the aerosol robotic network AERONET reveal falls in the relative abundance of fine aerosol particles which, in normal circumstances, could have evolved into cloud condensation nuclei. Thus a link between the sun, cosmic rays, aerosols, and liquid-water clouds appears to exist on a global scale.