Citation: Usoskin, I. G., Kovaltsov, G. A., Mironova, I. A., Tylka, A. J., and Dietrich, W. F.: Ionization effect of solar particle GLE events in low and middle atmosphere, Atmos. Chem. Phys. Discuss., 10, 30381-30404, doi:10.5194/acpd-10-30381-2010, 2010. http://www.atmos-chem-phys-discuss.net/10/30381/2010/acpd-10-30381-2010.pdf Abstract: Using a new reconstruction of the solar proton energy spectra for Ground Level Enhancement (GLE) events, based on fits to measurements from ground-based and satellite-borne instruments covering a wide energy range, we quantitatively evaluate the possible ionization effects in the low and middle atmosphere for 58 out of the 66 GLE events recorded by the world-wide neutron monitor network since 1956. The ionization computations are based on the numerical 3-D CRAC:CRII model. A table of the ionization effect caused by the GLE events at different atmospheric heights is provided. It is shown that the direct ionization effect is negligible or even negative, due to the accomp