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Published September 2005 | Supplemental Material + Published
Journal Article Open

Proton, helium, and electron spectra during the large solar particle events of October-November 2003


The extraordinary period from late October through early November 2003 was marked by more than 40 coronal mass ejections (CME), eight X-class flares, and five large solar energetic particle (SEP) events. Using data from instruments on the ACE, SAMPEX, and GOES-11 spacecraft, the fluences of H, He, O, and electrons have been measured in these five events over the energy interval from ∼0.1 to >100 MeV/nucleon for the ions and ∼0.04 to 8 MeV for electrons. The H, He, and O spectra are found to resemble double power laws, with a break in the spectral index between ∼5 and ∼50 MeV/nucleon which appears to depend on the charge-to-mass ratio of the species. Possible interpretations of the relative location of the H and He breaks are discussed. The electron spectra can also be characterized by double power laws, but incomplete energy coverage prevents an exact determination of where and how the spectra steepen. The proton and electron fluences in the 28 October 2003 SEP event are comparable to the largest observed during the previous solar maximum, and within a factor of 2 or 3 of the largest SEP events observed during the last 50 years. The 2-week period covered by these observations accounted for ∼20% of the high-energy solar-particle fluence over the years from 1997 to 2003. By integrating over the energy spectra, the total energy content of energetic protons, He, and electrons in the interplanetary medium can be estimated. After correcting for the location of the events, it is found that the kinetic energy in energetic particles amounts to a significant fraction of the estimated CME kinetic energy, implying that shock acceleration must be relatively efficient in these events.

Additional Information

© 2005 American Geophysical Union. Received 1 February 2005; revised 1 June 2005; accepted 24 June 2005; published 30 September 2005. This work was supported by NASA under grants NNG04GB55G, NNG04088G, and NAG5-12929. We appreciate discussions with E. C. Stone, G. Li, R. Kallenbach, and G. P. Zank about particle transport and discussions with A. Vourlidas and N. Gopalswamy about CME kinetic energy estimates. We are also very grateful for the availability of GOES-11 data from NOAA's Space Environment Center at http://www.sec.noaa.gov/Data/index.html. Arthur Richmond thanks Gang Li and another reviewer for their assistance in evaluating this paper.

Attached Files

Published - 2005-04.pdf

Supplemental Material - jgra17892-sup-0001-t01.txt_v=003d1_s=003ddc5a08d4677d7c388c7ba410f33b1f64f8c37234

Supplemental Material - jgra17892-sup-0001-t01.txt_v=1_s=dc5a08d4677d7c388c7ba410f33b1f64f8c37234

Supplemental Material - jgra17892-sup-0002-t02.txt_v=003d1_s=003d935e858de51d4e946f548504c32f904610a3219a

Supplemental Material - jgra17892-sup-0002-t02.txt_v=1_s=935e858de51d4e946f548504c32f904610a3219a

Supplemental Material - jgra17892-sup-0003-t03.txt_v=003d1_s=003dd21b8d207339ce4fade3d6f2a639b1ca0fcea7cf

Supplemental Material - jgra17892-sup-0003-t03.txt_v=1_s=d21b8d207339ce4fade3d6f2a639b1ca0fcea7cf

Supplemental Material - jgra17892-sup-0004-t04.txt_v=003d1_s=003dcf733aba838dfbcde834c4679e6890d5cf9e8852

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Supplemental Material - jgra17892-sup-0006-t06.txt_v=003d1_s=003dc6f8d6db9a65871e0333e23d0de25979b05cbdaf

Supplemental Material - jgra17892-sup-0006-t06.txt_v=1_s=c6f8d6db9a65871e0333e23d0de25979b05cbdaf

Supplemental Material - jgra17892-sup-0007-t07.txt_v=003d1_s=003d5f9d0ed660f812c4489cd477b35d9d062eb5f223

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Supplemental Material - jgra17892-sup-0008-t08.txt_v=003d1_s=003d4569de7490120e992550a8ab6ba597b6425a5417

Supplemental Material - jgra17892-sup-0008-t08.txt_v=1_s=4569de7490120e992550a8ab6ba597b6425a5417

Supplemental Material - jgra17892-sup-0009-t09.txt_v=003d1_s=003dec8b8e20fb805d123282dcc618015453d7849bcd

Supplemental Material - jgra17892-sup-0009-t09.txt_v=1_s=ec8b8e20fb805d123282dcc618015453d7849bcd



Additional details

August 19, 2023
October 20, 2023