Major solar-energetic particle fluxes: I. Comparison with the associated ground level enhancements of cosmic rays

We have identified 58 of extremely high solar energetic particle (SEP) events (with flux of over 10 protons (cm2 sec ster)−1 with energy ⩾60 MeV) that recorded at the Earth between January 1973 and May 2001. Each event had the potential of producing perturbations to the geophysical environment. Nearly 40% of these events shed ground level enhancements (GLEs) of cosmic rays. The March 1989–July 1991 period (29 months) of solar cycle 22 had the larger proton events (in magnitude and fluence) than those recorded in cycle 21. The 19 October 1989 event was the largest well-recorded particle event so far. The time-intensity profile of SEP fluxes showed that multiple particle injection or varying particles acceleration either at the solar source or in propagation to the Earth. Furthermore, high GLE was not a necessarily comes as a sequence of major SEP event and it was not a condition for creating major SEP fluxes. Some proposal factors are presented for production SEP and GLE together.