Energetic Particles Measured in and out of the Ecliptic Plane During the Last Gnevyshev Gap
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We analyzed the temporal variation of energetic particles measured by the Low Energy Telescope (LET), the Kiel Electron Telescope (KET), and the High Energy Telescope (HET) instruments aboard Ulysses and the Electron Proton Helium Instrument (EPHIN) aboard SOHO during the last solar magnetic field polarity reversal in 2001. We have found two periods with anomalous low fluxes during that time that are present both at low and high heliolatitudes. We compared the energetic particle fluxes with solar energetic phenomena that traditionally have been associated with solar energetic particle (SEP) events at 1 AU. Our results show that these periods are related to relative minima in the number of X-ray flares and CMEs. Since Ulysses scanned the whole latitude range from 80 °S to 80 °N, we conclude that this process affects the inner three-dimensional heliosphere globally.
KeywordsSolar Cycle Coronal Mass Ejection Sunspot Number Energetic Particle Solar Energetic Particle
The authors acknowledge the use of the SOHO/LASCO CME catalog available at http://cdaw.gsfc.nasa.gov/CME list. This CME catalog is generated and maintained at the CDAW Data Center by NASA and The Catholic University of America in cooperation with the Naval Research Laboratory. We also thank the GOES team for providing the X-ray flare list used in this work and the International Space Science Institute for supporting the Energetic Particles in the Heliosphere team, to which some of the authors belong. We are grateful to COSPIN Principal Investigator R.B. McKibben of the University of New Hampshire, USA and M. Lancaster and C. Tranquille of the Ulysses Data System, ESA/ESTEC, NL for the use of their data. The SOHO EPHIN and Ulysses KET projects are supported under Grant 50 OC 0902 by the German Bundesministerium für Wirtschaft through the Deutsches Zentrum für Luft- und Raumfahrt (DLR). J. Rodríguez-Pacheco acknowledges financial support from the MICINN grants AYA2009-13478-C02-01 and AYA2011-29727-C02-01.
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