Abstract
Proton measurements by two large area GM-counters (threshold energies E p > 12 MeV and E p > 30 MeV) on board the polar satellite GRSA/AZUR during the solar particle events of March 5–13,1970 are compared with similar measurements aboard Pioneer 8, HEOS Al, Explorer 41 and ATS 1. The solar proton event on March 7 and 8 is discussed in view of diffusion and convection transport theories. During the growth phase of the event a diffusion theory is applicable with a diffusion coefficient D = 2 × 10 20 to 8 × 10 20 cm 2/ sec . The decay phase is explained by a convective transport process and adiabatic deceleration in a spherically expanding solar wind. During the strong geomagnetic storm on March 8 ‘Energetic Storm Protons’ are observed followed by a large decrease of the flux of protons with energies E < 30 MeV. The transmission of protons with energies E < 30 MeV from interplanetary space into the magnetosphere varies between 60 and 90 per cent. Entry of protons into the magnetosphere is discussed using the interplanetary magnetic field and proton measurements of the HEOS Al satellite, together with the proton measurements of the other satellites. The results can best be explaine merging of interplanetary and Earth magnetic fieldlines. The protons appear to have direct access to the polar cap when the fields are antiparallel.
Published Version
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