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

Mewaldt, R. A. and Cohen, C. M. S. and Labrador, A. W. and Leske, R. A. and Mason, G. M. and Desai, M. I. and Looper, M. D. and Mazur, J. E. and Selesnick, R. S. and Haggerty, D. K. (2005) Proton, helium, and electron spectra during the large solar particle events of October-November 2003. Journal of Geophysical Research A, 110 (A9). Art. No. A09S18. ISSN 0148-0227. doi:10.1029/2005JA011038.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Mewaldt, R. A.0000-0003-2178-9111
Cohen, C. M. S.0000-0002-0978-8127
Labrador, A. W.0000-0001-9178-5349
Leske, R. A.0000-0002-0156-2414
Mason, G. M.0000-0003-2169-9618
Desai, M. I.0000-0002-7318-6008
Haggerty, D. K.0000-0001-6395-8943
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 Arthur Richmond thanks Gang Li and another reviewer for their assistance in evaluating this paper.
Group:Space Radiation Laboratory
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2005-04
Issue or Number:A9
Record Number:CaltechAUTHORS:20150323-154646214
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:55994
Deposited By: Deborah Miles
Deposited On:24 Mar 2015 16:55
Last Modified:10 Nov 2021 20:53

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