SH43B-4191:
25 MeV Solar Proton Events in Cycle 24 and Previous Cycles
Thursday, 18 December 2014
Ian G Richardson, NASA Goddard Space Flight Center, Greenbelt, MD, United States; University of Maryland College Park, CRESST and Department of Astronomy, College Park, MD, United States, Hilary V Cane, University of Tasmania, Hobart, TAS, Australia and Tycho T von Rosenvinge, NASA Goddard SFC, Greenbelt, MD, United States
Abstract:
We summarize observations of nearly 1000 solar energetic particle events that include 25 MeV protons made by Goddard instruments on various spacecraft (IMPs IV, V, 7, 8, ISEE-3) and by other instruments on SOHO, since 1967, encompassing solar cycles 20 to 24. We also include recent observations of such events from the STEREO spacecraft. These extended observations place studies focusing on Cycles 23 and 24 in a broader context. For example, the time distribution of 25 MeV proton events varies from cycle to cycle such that each cycle is unique. In the current cycle, ~25 MeV proton events were absent during the preceding solar minimum, whereas earlier minima showed occasional, often reasonably intense events, and there have been, so far, fewer exceptionally intense events compared to Cycles 22 and 23, though Cycle 21 also apparently lacked such events.
