Conditions for arrival of solar energetic protons in Earth after strong solar flares

Abstract

We analyze the Sun-to-Earth transport of energetic protons accelerated in solar flares. We use a model which assumes that protons move earthward in the Parker electromagnetic field. In this model, protons are shown to be recorded on Earth when they, moving away from the solar flare region, reach the vicinity of the heliospheric current sheet, while Earth is at a distance smaller than the proton Larmor radius from the current sheet neutral line. We present the analysis of experimental data on solar flares in August–September 2011. This analysis shows that the absence of energetic protons recording in the vicinity of Earth for some major solar flares can be explained by the proposed model.