Skip to main content
Article thumbnail
Location of Repository

Large Proton Anisotropies in the 18 August 2010 Solar Particle Event

By R. A. Leske, C. M. S. Cohen, R. A. Mewaldt, E. R. Christian, A. C. Cummings, A. W. Labrador, E. C. Stone, M. E. Wiedenbeck and T. T. von Rosenvinge


The solar particle event observed at STEREO Ahead on 18 August 2010 displayed a rich variety of behavior in the particle anisotropies. Sectored rates measured by the Low Energy Telescope (LET) on STEREO showed very large bidirectional anisotropies in 4 – 6 MeV protons for the first ∼ 17 hours of the event while inside a magnetic cloud, with intensities along the field direction several hundred to nearly 1000 times greater than those perpendicular to the field. At the trailing end of the cloud, the protons became isotropic and their spectrum hardened slightly, while the He/H abundance ratio plunged by a factor of approximately four for about four hours. Associated with the arrival of a shock on 20 August was a series of brief (< 10 minute duration) intensity increases (commonly called “shock spikes”) with relatively narrow angular distributions (∼ 45∘ FWHM), followed by an abrupt decrease in particle intensities at the shock itself and a reversal of the proton flow to a direction toward the Sun and away from the receding shock. We discuss the STEREO/LET observations of this interesting event in the context of other observations reported in the literature

Publisher: Springer
Year: 2012
OAI identifier:
Provided by: Caltech Authors
Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):
  • (external link)
  • (external link)
  • http://authors.library.caltech... (external link)
  • Suggested articles

    To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.