Duration and Fluence of Major Solar Energetic Particle (SEP) Events

摘要

To understand solar energetic particle (SEP) events and their acceleration processes, it is important to study the SEP properties, e.g. duration and fluence. In this work, we analyzed the temporal evolution of fluxes cm(-2) sr(-1) s(-1) of >10, >30, and >60 MeV protons and the temporal and spectral evolution of electromagnetic-radiation components for 34 major SEP events that include 13 ground-level enhancement (GLE)-SEP and 21 non-GLE-SEP events, and then determined their possible onset and end times UT, their duration hours, and fluence cm(-2) sr(-1). It is observed that the temporal fluxes of >30 MeV protons can sometimes be utilized for those of the fluxes of >10 MeV protons. Correspondence between SEP duration and fluence demonstrates the dependence of fluence on duration that helps distinguish the typical and atypical SEP events. For instance, for the >10 MeV protons, correspondence between the duration and fluence exhibited a weaker correlation (r approximate to 0.78; {-69pt} begin{document}$p$end{document}30 MeV protons exhibited a stronger correlation (r approximate to 0.82; p10 MeV protons, indicating that the temporal window of >30 MeV protons is sometimes more appropriate for obtaining a reasonable duration of SEPs. Accordingly, when the temporal window of flux of >30 MeV protons is utilized for that of the >10 MeV protons, the correlation increased significantly (r approximate to 0.86; p<0.0002) during the 13 GLE-SEPs.