Proton Fluence Trends in Solar Cycles 23 and 24

This study presents the relationship between the typical parameters of the solar energetic protons (SEPs) and their solar origin—solar flares (SFs) and coronal mass ejections (CMEs) in solar cycles (SCs) 23 and 24 (1996–2019). In this study, the calculated onset-to-peak SEP and reported SF fluences are preferred over the peak SEP intensity and SF class, respectively. The energy dependence of the proton fluence is quantitatively assessed in terms of correlation analyses (Pearson and partial) with the parameters of the solar origin, i.e., SF fluence, CME speed and angular width. The energy trends of the results are investigated as a function of the SC (SC23 vs. SC24), helio-longitude (Eastern vs. Western), SEP magnitude (high vs. low) and SEP profile type (fast vs. slow-rising). The possible applications to space weather research are discussed.