ACE Observations of Energetic Particles Associated with Transient Interplanetary Shocks

We present preliminary results from a survey of the effects of interplanetary shocks on energetic >47 keV ions and >38 keV electrons as observed by the field (MAG), plasma (SWEPAM) and energetic particle (EPAM) experiments on the ACE spacecraft. From September 1997 to December 2001 ACE observed over 270 shocks, from which we have selected a total of 168 forward transient interplanetary shocks. Particle events associated with these shocks range from large particle intensity enhancements lasting several hours to small shock spikes lasting only a few minutes, as well as events where no intensity increases are observable. Our survey of the proton and electron intensity-time profiles has revealed the following: (1) intensity increases associated with a shock passage are more frequently observed in the low-energy ion fluxes; (2) electron shock events, which occur less frequently than ion shock events, are mainly spikes or step-like post-shock increases; and, (3) peak intensities are usually observed within ∼2 minutes of the shock passage with a clear trend towards occurrence in the downstream region of the shock