Quantifying the Impacts of Interplanetary Propagation and Transient Events on Solar Energetic Particle Intensity-Time Profiles

Abstract:

Gradual solar energetic particle events (SEPs) are produced in the solar corona and as these particle events propagate through the inner heliosphere and interplanetary space they might encounter intervening magnetic obstacles such as the heliospheric current sheet (HCS) or interplanetary coronal mass ejections (ICMEs). Intensity-time profiles of SEPs (E > 10 MeV) at 1 AU reflect the impacts of a number of physical processes both during acceleration and interplanetary transport. We investigate the extent to which propagation through these intervening structures in the inner heliosphere might be affecting later in-situ measurements of the peak intensity and rise phase of SEP intensity-time profiles at 1 AU. We use Advanced Composition Explorer (ACE) magnetometer observations and measurements of suprathermal electron pitch angle distributions from ACE's Solar Wind Electron, Proton & Alpha Monitor (SWEPAM) to indicate changes in magnetic polarity and magnetic topology. We use these along with potential field source surface models to validate potential HCS crossings. In a multi-year survey we use receiver operating characteristic (ROC) curves to quantitatively compare the correlations between potential ICME and HCS interactions with features of SEP intensity-time profiles.