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Heavy Ions in the Solar Wind and the Cosmic Radiation

Ivan Dorotovic
Observatório Astronómico, FCT UC, Coimbra / UNINOVA-CA3, FCT UNL, Caparica / IICT (Instituto de Investigação Científica Tropical), Lisboa / Slovak Central Observatory, Hurbanovo, Slovak Republic

Recently we have studied evolution of fluxes of heavy ions in the solar wind for the period of 1998 - 2006 and their eventual influence on the variations of the cosmic radiation as measured by neutron monitors. The analysis was focused mainly onto the events of sudden counts’ decreases (Forbush Decreases-FD). Basic input data were the fluxes of H, He, C, O, Ne, Mg, Si and Fe ions with a temporal resolution of 1 hour recorded by several instruments of the satellite ACE. The instruments of ACE measure degree of ionization as well as kinetic energy of ions originated from solar flares.
The FDs of cosmic radiation in the above mentioned period were identified already in our earlier paper (Dorotovic et al., 2009), where we investigated characteristics of these decreases in the solar cycle 23. The main result of that previous work was determination that besides the known disturbance in the magnetic field of the Earth is the FD in majority of events accompanied by an abrupt increase (up to 4 orders of magnitude) of the proton flux in the magnetosphere with energy of 0.4 – 4 MeV and by a contemporary decrease of the proton flux with energy of 165 – 500 MeV.

2010 January 20, 13:30

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