Revising More Than 20 Years of EPHIN Ion Flux Data—A New Data Product for Space Weather Applications

Abstract

AbstractSolar energetic particle events and galactic cosmic rays are important aspects of space weather. Investigating them requires consistent measurements of electrons and ions over long time periods, that is, over more than a solar cycle. The Electron Proton Helium INstrument onboard the SOlar and Heliospheric Observatory is operational since 1995 and was designed to measure electrons in the energy range of 0.3 to 10 MeV as well as protons and helium ions in the energy range from 4 to 50 MeV per nucleon in four different coincidence channels with 1‐min resolution. Early in the mission and in 2017 two of six detectors became noisy and had to be switched of reducing the number of coincidence channels from 4 to 2, and thereby significantly reducing the energy resolution of the instrument. In order to restore the original count rate channels we present here a new data analysis applying the so called dE/dx − dE/dx method. A data set with different temporal resolutions from 1 min to a day has been generated for the whole ongoing SOlar and Heliospheric Observatory mission from 1995 to 2018. The resulting data sets are successfully validated against measurements from instruments close to Earth. Studies with regard to long‐term variation of the measured flux with special emphasis on the contribution of individual solar energetic particle events to the fluence observed over more than two solar cycles are presented here.