ULYSSES COSPIN observations of the energy and charge dependence of the propagation of solar energetic particles to the Sun's south polar regions
Kunow, H.; Heber, B.; McKibben, R. B.; Zhang, M.; Sanderson, T. R.; Marsden, R. G.; Tranquille, C.; Müller-Mellin, R.; Anglin, J. D.; Raviart, A.; Paizis, C.; Connell, J. J.; Lopate, C.; Balogh, A. Dalla, S.; COSPIN Collaboration
Abstract
We present a first report of energetic charged particle observations at latitudes above 70° S from the COSPIN instruments on Ulysses during Ulysses' recently completed pass over the Sun's south polar regions. Solar energetic particles dominated the particle flux during most of the pass, and for > 30 MeV protons there was a close correspondence between intensity increases at IMP-8 near Earth and at Ulysses. Intensities in the equator and polar regions were often comparable, especially in the late phases of large events, despite the large radial, longitudinal and latitudinal separations of the spacecraft. Enhancements attributable to events originating near the solar equator were observed at Ulysses down to the lowest energies measured (∼0.3 MeV). The clear conclusion is that even at solar maximum, latitudinal propagation is far more efficient than had been expected before Ulysses. At high energies (>∼100 MeV) two Forbush decrease-like events were observed, the highest latitude such events ever seen.