Survey and Comparison of Solar Activity and Energetic Particle Emission in 1970

Solar activity in 1970 was at a relatively high level with the number of major flares and important centers of activity reaching maximum numbers for all of cycle 20. Satellite data, primarily from Explorer 41, provided evidence for at least 152 distinct energetic particle enhancements during the year. These events have been compared with concurrent solar activity. All but one of the 13 particle events associated with Polar Cap Absorption in 1970 have been identified with specific solar flares. For the 50 proton events with energies 19-80 or 60 MEV, 72% have reasonably sure solar or geophysical sources. Of the 59 purely low energy particle events (1-10 MEV) only 39% could be assigned probable solar associations. For the numerous low-energy particle events without confident solar associations, there were assorted time coincidences with geomagnetic storms, sector boundary passages, the development of new regions on the disk, and the central meridian passage of significant centers of activity. At the present time, the significance of these solar and geophysical phenomena for particle enhancement is not known.