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 March 25, 2010 | Published
Book Section - Chapter Open

STEREO and ACE Observations of Energetic Particles from Corotating Interaction Regions


Since early 2007, significant particle enhancements due to corotating interaction regions (CIRs) have regularly appeared at 1 AU without any appreciable contamination from solar energetic particles (SEPs). In 2009 the prevalence of CIRs diminished as the maximum speed of the high speed solar wind streams in the ecliptic decreased along with the tilt of the heliospheric current sheet. Observations of CIR time profiles at different longitudes from STEREO show delays between the Behind and Ahead spacecraft that are often roughly as expected from the corotation time lag, although small differences in the spacecraft latitudes introduce significant scatter in the time delays. In some cases different features seen at Ahead and Behind suggest that transient disturbances in the solar wind may alter connection to or transport from the shock, or that temporal changes occur in the CIR shock itself. H and He data from STEREO/LET at 1.8–6 MeV/nucleon show that 1) the CIR spectral index at these energies is ~−4, independent of intensity but with considerable variability, 2) the He/H ratio is ~0.03 for larger CIRs but varies systematically with energy and event intensity, and 3) although the correlation between the CIR MeV particle increases and solar wind speed is generally good, many times a high-speed stream is not associated with MeV particles, while at other times a recurring series of CIR particle increases appears only at higher energies and may be associated with current sheet crossings and low speed solar wind.

Additional Information

© 2010 American Institute of Physics. Issue Date: 25 March 2010. This work was supported by NASA at Caltech and JPL under sub-contract SA2715-26309 from UC Berkeley under NASA contract NAS5-03131. We thank STEREO/PLASTIC (NASA contract NAS5-00132), STEREO/MAG, and ACE/SWEPAM investigators for making their data publicly available.

Attached Files

Published - Leske2010p11409Aip_Conf_Proc.pdf


Files (767.6 kB)
Name Size Download all
767.6 kB Preview Download

Additional details

August 21, 2023
January 13, 2024