Solar Cycle Variation of 0.3–1.29 MeV Nucleon⁻¹ Heavy Ion Composition During Quiet Times Near 1 au in Solar Cycles 23 and 24

Abstract We report on the annual variation of quiet-time suprathermal ion composition for C through Fe using Advanced Composition Explorer (ACE)/Ultra-Low Energy Isotope Spectrometer data over energy range 0.3–1.28 MeV nuc −1 from 1998 2019, covering solar cycle 23's rising phase Solar Cycle 24's declining phase. Our findings are: (1) abundances resemble CIR-associated particles during minima; (2) suprathermals are M/Q fractionated in a manner that is consistent with fractionation large gradual energetic particle events (GSEP) maxima; and (3) variability within pool increases as function analogous GSEP events. From these observations, we infer ions remnants CIRs minima maxima. Coincident results, also unexpectedly show S behaves like low FIP regime, therefore drawn sources.