The Influence of Large-scale Interplanetary Solar Wind Structures on the Peak Intensity of Solar Energetic Particle Events

The presence of large-scale solar wind structures in the interplanetary medium affects the transport of solar energetic particles (SEPs) in the heliosphere. In particular, counterparts of interplanetary coronal mass ejections (ICMEs) are able to modify the surrounding interplanetary medium by introducing changes in the direction and strength of the magnetic field as well as increasing the level of magnetic field turbulence. Understanding the transport of SEPs in the heliosphere can lead to the increased capability in forecasting and predicting future events. In this study, we classified paring SEP and ICME events from the 23rd solar cycle into six different categories based on when the peak of the SEP event occurred. For example, two different categories are: (1) the SEP peak occurred when an ICME is between the Sun and the Earth and (2) the SEP peak occurred after the ICME is beyond Earth. We performed a statistical analysis of the SEP peak intensities for each class of event and according to the characteristics of the associated solar event. For similar properties of the associated solar event we find that, on average, events observed after the passage of an ICME have larger peak intensities than those events observed with an ICME between the Sun and Earth. Strict analysis and understanding of the influence the dynamic interplanetary solar wind has on the peak intensity of SEPs can enable space weather operational forecasters to better predict solar energetic particle events based on the ICME or solar flare associated with the event. By forecasting solar energetic particle events spacecraft, satellites, and humans in space, can be better protected from the impact of space weather.