Proposed Solar Proton Event Classification System

Abstract

Considerable confusion exists on what is the’ size’ of a proton event. With the greatly improved sensitivity of detectors on satellites, it appears that almost every solar ‘hiccup’ is being reported as a solar proton event with the descriptive adjective ‘large’ being applied to some events that are very much smaller in particle flux and energy than some of the classic solar cosmic-ray events of the 19th solar cycle. Additional confusion arises when discussing specific events with respect to their detection by various ground-based sensors. For example the May 23, 1967 event which was extremely large to the radio astronomers was not detected by ground-based neutron monitors. Conversely, the large neutron monitor increase associated with the May 4, 1960 event was followed by only a ‘moderate’ riometer absorption.