Effect of Coherent Structures on Energetic Particle Intensity in the Solar Wind at 1 AU

We present results from an analysis of ACE observations of energeticparticles in the 0.047-4.75 MeV range associated with shocks and discontinuities in the solar wind. Inour previous work, Tessein et al. 2013, we found a high correlation between discontinuities, identified using the PVI statistic (essentially a normalized vectorincrement) and the intensity of energetic particles measured by ACE/EPAM. Our previous study was primarily a superposed epoch analysis using 12 years worth of data. In this study we look more closely at what causesthis correlation by examining individual events to determine whatcauses the association between the intensity and the location of the discontinuity. We find that in many cases the discontinuity is located at the rising or trailingedge of an energetic particle peak which revealsthat the discontinuities may act as barriers which inhibit the motion ofenergetic particles across the boundaries, rather than as sources of particleacceleration. We also find that the energetic particle peak is often associatedwith strong interplanetary shocks that are not documented in the ACE shocklist. The distinction between weak shocks and other discontinuities, which can appearsimilar in the observations, is a further complication that we address in this study.