Relationships between energetic storm particle events and interplanetary shocks driven by full and partial halo coronal mass ejections

High-energy (>40 MeV) Proton Intensity Enhancements Associated with the Passage of Interplanetary Shocks at 1 au

“…However, this correlation becomes weaker at higher (90 MeV) proton energies (Figures 8(d) and (h)) because of the scarcity of events and the fact that the most intense events at these energies are class-12 events where the effects of intervening structures may have a larger effect on the production of higher particle intensities than just the V trans of the shock. Similar correlations between V trans and the peak intensity of the ESP events at lower energies were found by Ameri et al (2023), with correlation coefficients that diminish with proton energy within the range 5.0-31.6 MeV (see their Figure 4), although these authors did not distinguish whether intervening IP structures were present.…”

“…Similarly, in the multiparameter study of 62 ESP events with 0.5-2.0 MeV n −1 He, O, and Fe ion intensity enhancements, Dayeh et al (2018) found a moderate correlation (r P = 0.51) between the oxygen peak intensity and the shock speed, whereas for the density compression ratio r n and θ Bn no correlations were found (r p = 0.09 and r p = 0.07, respectively; see their Table 1). Ameri et al (2023) found that the highest correlation between I pk and shock parameters was found for the shock speed V SC (r P = 0.62 for 5.0-7.2 MeV protons and r P = 0.44 for 21.9-31.6 MeV protons) whereas the lowest correlation coefficients were found for the compression ratio (r P = 0.20 for 5.0-7.2 MeV protons and r P = 0.33 for 21.9-31.6 MeV protons) and θ Bn (r P = 0.05 for 5.0-7.2 MeV protons and r P = 0.10 for 21.9-31.6 MeV protons). All these studies indicate that, although moderate, the only correlation between the peak intensity or ESP size and the local shock parameters is found for the shock speed, though this is also only a poor predictor of the ESP intensity, especially at high energies.…”