Statistical Trends (or Lack Thereof) in Solar Proton Events during the Last ThreeSolar Cycles

摘要

To study and analyze solar proton events over the past three solar cycles it isnecessary to assemble a consistent list of solar proton events. Using a criterion that each event have a proton flux of over 10 particles we have assembled a list of 218 solar proton events which have been recorded at the earth during the last three solar cycles. We have utilized this list to search for any recognizable pattern between the occurrence of solar proton events and the solar cycle. It is not possible to assemble a completely homogeneous list of solar proton events detected over the last three solar cycles, primarily because of different measurement techniques. However, we have assembled a list of solar proton events which is as homogeneous as possible using the criterion that each proton event must have a 10 MeV particle flux above 10 particles. We selected this flux criteria as the flux capable of producing a definitive effect in the polar ionosphere, and identified these events as significant solar proton events.