Differences in the Rising Protons of Relativistic Solar Protons and Solar Electrons at the Earth

Previous work on the onset times of ground-level events at the earth has shown that the onset time of relativistic electrons (i.e. electrons having energies of about 1 MeV) is equal to or later than the onset time of relativistic protons (i.e. protons having energies of 2 GeV). The onset profiles of these relativistic particle events are examined, and it is found that while the time-intensity curves are similar in shape on an event to event basis, the curves are offset from each other throughout the rising portion, with this offset approximately equal to the difference in onset time between the detection of the particles at the earth. These differences are indicative of either a delay in the release of the relativistic electrons into the interplanetary medium, or are indicative of different propagation characteristics while enroute to their detection point. Several examples of this curious behavior are illustrated. The analysis of events such as these illustrate the importance of small time interval data during the onset phase of ground-level cosmic ray events.