The interplanetary events of January-May, 1997 as inferred from energetic particle data, and their relationship with solar events

We use observations from the Goddard particle detectors on IMP 8 to investigate near-Earth interplanetary disturbances and the associated solar events in January-May 1997, We infer the presence of high-speed streams and ejecta (material in the solar wind associated with coronal mass ejections (CMEs) at the Sun) using depressions in the counting rate of >60 MeV/amu particles measured by the anti-coincidence guard. In addition to a sequence of high-speed streams, the guard detected four ejecta. A fifth ejecta (January 10-11), evident in solar wind observations, did not produce a particle decrease. During the study period there were five particle enhancements, indicating the occurrence of energetic CMEs at the Sun. All the particle enhancements were associated with halo CMEs observed by the SOHO LASCO coronagraphs. Five of the total of nine halo CMEs in this period impacted the Earth. None of the other similar to 120 CMEs detected by LASCO did so, Only the four CMEs associated with traditional flare signatures were also associated with >10 MeV particle increases.