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

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

Solar 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 Helios...

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Bibliographic Details
Published in:Space weather 2019-01, Vol.17 (1), p.84-98
Main Authors: Kühl, P., Heber, B.
Format: Article
Language:eng
Subjects:
Channels
Cosmic rays
Data analysis
Electrons
Energetic particles
Energy measurement
Energy resolution
EPHIN
Fluence
Galactic cosmic rays
Helium
Helium ions
Ion flux
Ions
Observatories
SEP
SOHO
SOHO Mission
Solar cycle
Space
Space weather
Weather
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Summary:Solar 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. Key Points A new data product of SOHO/EPHIN with consistent data quality over more than two solar cycles is provided The fluence of protons and helium particles in the energy range from 5 to 50 MeV per nucleon is dominated by individual SEP events
ISSN:1542-7390
1539-4964
1542-7390