Onsets of Solar Cycle 23 Ground Level Events as Probes of Solar Energetic Particle Injections at the Sun

Abstract : The inferred solar injection times of the first arriving particles of solar energetic particle ?SEP) events can be compared with solar eruptive events to provide information of how those particles were accelerated near the Sun. The injection times are best inferred from high- energy electrons and protons with long mean free paths in space. We use the neutron monitor counting rate profiles and space-based near-relativistic electron intensity profiles of the 10 ground level events (GLEs) of solar cycle 23 to determine the initial solar injection times of the SEP:s. Those times are compared with microwave, metric and decametric/hectometric (DH) radio burst and solar CME observations to determine the radiative signature% of early SEP injections. The space-borne solar observations of the current cycle 23 are far superior to those during GLEs of early cycles, allowing a more definitive description of solar events at the times of SEP injection.