Dependence of Forbush-decrease characteristics on parameters of solar eruptions

We analyze relations between characteristics of an extended ensemble of Forbush decreases (FDs) caused by CMEs from the central zone of the solar disk during the 23rd solar cycle, on the one hand, and such solar eruption parameter as a summarized unsigned magnetic flux of CME-associated EUV dimmings and arcades, on the other hand. This eruption parameter is shown to have a pronounced direct correlation with the FD magnitude and a conspicuous reverse correlation with the ICME transit time from the Sun to the Earth. The revealed correlations indicate that main quantitative characteristics of major non-recurrent FDs (and geomagnetic storms as well) are largely determined by parameters of solar eruptions, in particular such as the summarized magnetic flux of dimmings and arcades.