Different groups of ground level enhancements (GLEs). collective and recurrent GLEs due to solar energetic particles

This paper presents a classification of the ground level enhancements (GLEs) of solar energetic particles reaching the Earth's surface, based on the analysis of the ground-based observations of solar cosmic rays (SCRs) from February 28, 1942, when they were discovered, until today. We have detected new groups of quasi-GLEs, collective GLEs, recurrent GLEs, recurrent collective GLEs and collective-recurrent GLEs during the investigated period, which comprises the solar cycles 17÷24. Physical, methodical, and applied aspects, related to the SCRs and GLE events have been discussed as well. The obtained results have prognostic value and significance for the solar-terrestrial relationships and space weather, as well as for the space dosimetry. Key words: ground level enhancements (GLEs), solar cosmic rays (SCRs), solar energetic particles (SEPs), ionization effects, space weather and space climate