Dependence of solar proton events on their associated activities: Coronal mass ejection parameters

Abstract

In this study we have examined the occurrence probability of solar proton events (SPEs) and their peak fluxes depending on coronal mass ejection (CME) parameters, linear speed (V), angular width (AW), and location (L). For this we used the NOAA SPE list and their associated CME data from 1997 to 2006. We found that the probability strongly depends on CME speed and angular width as follows. The highest association (36.1%) is found for the full halo CMEs with V ≥ 1500 kms−1 but the lowest association (0.9%) is found for the partial halo CMEs with 400 kms−1 ≤ V < 1000 kms−1. The SPE occurrence probabilities are different as much as 4.9 to 23 times according to CME speed and 1.6 to 6.5 times to angular width. The probabilities depending on CME speed and location increase from the eastern region to the western region and with speed. We have also examined the relationship between CME speed and SPE flux as well as its dependence on angular width (partial halo and full halo), longitude (east, center, and west) and direction parameter (<0.4 and ≥0.4). Our results show that the relationships strongly depend on longitude as well as direction parameter.