[Kallenrode 1992 a]

Influence of interplanetary shocks on approximately 10 MeV protons: A phenomenological classification

M.-B. Kallenrode and G. Wibberenz.
Influence of interplanetary shocks on approximately 10 MeV protons: A phenomenological classification
ESA, Study of the Solar-Terrestrial System (SEE N93-31674 12-90), 81-86. 1992a


Contents

In a statistical approach, the influence of interplanetary shocks on approximately 10 MeV protons for 357 interplanetary shocks observed by the solar wind and magnetic field instruments on Helios 1 and 2 during the time interval Dec. 1974 to Dec. 1983 was analyzed. Three basic reactions of energetic particles in a shock can be distinguished: no increase in particle intensity above quiet or increased background (42%); a slow and long lasting rise in intensity without evidence for particles accelerated previously, for example in a solar flare (22%); and an increase in particle intensity on a high background intensity (classical Energetic Storm Particle (ESP) event, 28%). From the first two reactions, it was concluded that a preaccelerated particle component is neither a necessary nor a sufficient condition for the occurrence of an ESP event. In addition, the shock 'strength' alone, as described for example by the Mach number or the compression ratio, does not order these events. However, there is evidence that with increasing shock strength the energetic particles react stronger (higher intensities and harder spectra) to the shock.


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