Atmos. Chem. Phys. Discuss., 13, 5411-5428, 2013
www.atmos-chem-phys-discuss.net/13/5411/2013/
doi:10.5194/acpd-13-5411-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Possible effect of extreme solar energetic particle events of September–October 1989 on polar stratospheric aerosols: a case study
I. A. Mironova1 and I. G. Usoskin2
1Institute of Physics, St. Petersburg State University, St. Petersburg, Russia
2Sodankylä Geophysical Observatory (Oulu unit), University of Oulu, Oulu, Finland

Abstract. The main ionization source of the middle and low Earth atmosphere is related to energetic particles coming from outer space. Usually it is ionization from cosmic rays that is always present in the atmosphere. But in a case of a very strong solar eruption some solar energetic particles (SEP) can reach middle/low atmosphere increasing the ionization rate up to some orders of magnitude at polar latitudes. We continue investigating such a special class of solar events and their possible applications for natural variations of the aerosol content. After the case study of the extreme SEP event of January 2005 and its possible effect upon polar stratospheric aerosols, here we analyze atmospheric applications of the second sequence of several events that took place over the Autumn 1989. Using aerosol data obtained over polar regions from two satellites with space-borne optical instruments SAGE II and SAM II that were operating during September–October 1989, we found that an extreme major SEP event might have led to formation of new particles and/or growth of preexisting ultrafine particles in the polar stratospheric region. However, the effect of the additional ambient air ionization on the aerosol formation is minor, in comparison with temperature effect, and can take place only in the cold polar atmospheric conditions.

Citation: Mironova, I. A. and Usoskin, I. G.: Possible effect of extreme solar energetic particle events of September–October 1989 on polar stratospheric aerosols: a case study, Atmos. Chem. Phys. Discuss., 13, 5411-5428, doi:10.5194/acpd-13-5411-2013, 2013.
 
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