Energetic Particle Observations Associated With the Workshop Events.
Ian Richardson
Abstract
This paper highlights some features of the energetic particle effects associated
with the workshop events, including data from the IMP 8, WIND and ACE spacecraft.
The workshop events show a remarkable variation in the maximum energetic
particle intensities detected at Earth, ranging over ~6 orders of magnitude
at energies of both ~2 MeV and ~20 MeV. The speeds of the associated
CMEs observed by LASCO order the intensities of the workshop events reasonably
well. This correlation between the proton intensity and CME speed, which
has also been found using Helios 1 and 2 and SOLWIND observations, suggests
that CME- driven shocks play a role in particle acceleration. For
the workshop events however, the correlation is helped by the fact that
a majority of the fastest CMEs happen to be associated with solar events
on the western-hemisphere, which are also magnetically well-connected to
the Earth. Thus, the east-west asymmetry in particle intensities
at Earth is not a major influence when comparing these particle enhancements.
Several events show interesting relationships between solar wind structures
and particle signatures such as intensity, compositional and anisotropy
variations, including bidirectional ion flows. These particle features
may help to confirm our understanding of the relationship between the solar
phenomena and interplanetary structures, but can also provide challenges
in particular events.
Authors: I. G. Richardson, H. V. Cane, O. C. St.
Cyr
Organization: Goddard Space Flight Center
Telephone: 301-286-3079/301-352-7856(H)
Fax: 301-286-1682
e-mail: richardson@lheavx.gsfc.nasa.gov
Address: Code 661,
Laboratory for High Energy Astrophysics,
Goddard Space Flight Center,
Greenbelt,
MD 20771