Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published August 2015 | Published
Book Section - Chapter Open

The Longitudinal Distribution of Solar Energetic Particles


Using observations from the High Energy Telescopes (HETs) on STEREO A and B and similar observations from SoHO, near-Earth, we have identified ~250 individual solar energetic particle events that include >14 MeV protons since the beginning of the STEREO mission [1]. Between the end of December 2009, when the STEREO A and B spacecraft were, respectively, ahead and behind Earth by ~ 65° in ecliptic longitude, and the end of December 2013, 43 different events were clearly detected at all three locations. The observed intensities of such an event are usually assumed to be Gaussian distributed as a function of the longitudes of the Parker Spiral footpoints at the Sun for each observer. This neglects the fact that the interplanetary magnetic field may have large deviations from Parker Spirals, e.g. due to coronal mass ejections from prior events. Nonetheless, we have fit Gaussians to the peak intensities observed simultaneously at three spacecraft for all 43 events. The Gaussian peak intensity is poorly correlated with the corresponding CME speed and the FWHM is uncorrelated with the CME speed. Surprisingly, however, there appear to be distinctly non-random variations of the FWHM values from event to event.

Additional Information

Copyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-ShareAlike.

Attached Files

Published - ICRC2015_104.pdf


Files (409.0 kB)
Name Size Download all
409.0 kB Preview Download

Additional details

August 20, 2023
January 14, 2024