Variations of Heavy Ion Abundances Relative to Proton Abundances In Large Solar Energetic Particle Events
Technical Report,01 May 2017,21 Mar 2019
AIR FORCE INSTITUTE OF TECHNOLOGY WRIGHT-PATTERSON AFB OH WRIGHT-PATTERSON AFB United States
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Past studies of heavy ions Z2 in large E10 MeVnuc gradual solar energetic particle SEP events have focused on elemental abundances relative to those of a single element, such as Fe or O, and have often neglected ionized H the primary element used for space weather purposes. This work analyzes SEP abundances in a group of 15 large gradual SEP events from 2000 to 2015 across the energy range of 13.5-50.7 MeV. Hourly flux averages of He, C, O, Mg and Fe from the Advanced Composition ExplorerSolar Isotope Spectrometer ACESIS are compared to two-hour averages of H flux from the Solar and Heliospheric ObservatoryEnergetic and Relativistic Nuclei and Electron SOHOERNE experiment. Event-to-event comparisons reveal order of magnitude variances in all elements studied with Fe exhibiting variances spanning several orders of magnitude. A strong correlation is seen between abundance enhancement relative to the spectral coronal and linear coronal mass ejection CME speeds for He, C, O and Mg. Extreme Fe abundance events are determined to have energy loss rates equal to those of H the consequences of which are briefly discussed.