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Statistical characteristics of energetic storm particle events

  • Authors: Huttunen-Heikinmaa, K.; Valtonen, E.
  • Publication: 36th COSPAR Scientific Assembly. Held 16 - 23 July 2006, in Beijing, China., p.1565, 2006
  • Solar events between 1996 May and 2003 April
  • Statistical study
  • ADS link
  • Abstract: When a transient interplanetary IP shock arrives at a location far from the Sun an increase in energetic particle fluxes may be observed in the immediate vicinity of the shock due to particles trapped in the turbulent shock region. These particles are called energetic storm particles ESPs. We have initiated an extensive statistical study of high-energy ESP events using protons of 1-100 MeV observed by the ERNE particle telescope on-board the SOHO spacecraft. A central tool in the study is a comprehensive database of IP shock candidates gathered from several compiled shock lists available in the internet and literature. Currently our database includes a total of 606 entries from a seven-year period between May 1996 and April 2003 representing various structures seen in the solar wind data. Fast forward shocks constitute a major fraction 53 of the entries. Previously we have searched for the associated ESP signatures only for the most reliably identified fast forward shocks and mainly focused on the fact whether there are any ESPs or not. Considering only these reliable cases we concluded that 48 74 153 of the fast forward IP shocks produced ESPs protons at energies greater than 1 5 MeV. Our next step is to analyze the ESP events in more detail. We will determine e g 1 onset times and times of maximum intensities at different energies compared to the time of the IP shock passage 2 e-folding rise times of the intensities 3 energy spectra at the time of maximum and integrated over the event 4 maximum accelerated energy and 5 helium-to-proton.


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