Variations of aerosol optical properties during the extreme solar event in January 2005

Abstract

We present the results of analysis of the aerosol optical depth variations for January 2005 when an extreme solar energetic particle event occurred leading to a greatly enhanced flux of energetic particles penetrating into the atmosphere. An increase of the concentration of sulfate or nitrate aerosol was found on the second day after the solar energetic particle event in the south magnetic pole region with the maximum penetration of anisotropic solar cosmic rays. This suggests that an enhanced flux of solar energetic particles can lead to notable changes in the chemical and physical properties of the polar troposphere. A statistical test confirms that the observed change of the aerosol index is significant and is unlikely to be related to a spatial or temporal independent fluctuation of the aerosol content. Thus, the results of the present work provide evidence of a direct influence of cosmic rays on physical-chemical properties of the atmosphere. Copyright 2008 by the American Geophysical Union.