ERNE observations of energetic particle fluxes
J. Torsti, E. Valtonen, E. Riihonen, M. Teittinen, A. Anttila, R. Vainio, P. M\"akel\"a, T. Eronen, T. Laitinen, G. Schultz
The observations of the ERNE instrument on-board the SOHO spacecraft are analysed. The main period under study is from the beginning of May till mid-October 1996. Only very small energetic particle events were observed. A comparison of the ERNE measurements with energetic particle observations during the two previous solar minima indicates that the flux levels of protons during the first half of 1996 are exceptionally low. The daily counting rates of quiet-time protons and \^4He in the energy range 13-100 MeV/nucleon show statistically significant variations with time. Following two energetic particle events in July and August, anticorrelations were found between enhancements of low energy protons in the range 1.5-8 MeV, possibly accelerated in a corotating interaction region, and the modulation of high energy protons and helium above 13 MeV/nucleon. The period of the observed anticorrelations coincide with the solar rotation period.
Advances in Space Research, 20, 91-98, 1997