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Spectra and Properties of Ground-Level Events During Solar Cycle 23

Mewaldt, R. A. and Looper, M. D. and Cohen, C. M. S. and Haggerty, D. K. and Labrador, A. W. and Leske, R. A. and Mason, G. M. and Masur, J. E. and von Rosenvinge, T. T. (2009) Spectra and Properties of Ground-Level Events During Solar Cycle 23. In: Proceedings of the 31st International Cosmic Ray Conference. , Lodz, Poland.

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We report spacecraft measurements of the energy spectra of solar protons and other solar particle properties during the 16 Ground Level Events (GLEs) of Solar Cycle 23. The measurements were made by seven instruments on the ACE, GOES, SAMPEX, and STEREO spacecraft and extend from »0.1 to »700 MeV. All of the proton spectra exhibit spectral breaks at energies ranging from »2.4 to »33 MeV and all are well fit by a double power-law shape. A comparison of GLE events with a sample of other SEP events shows that GLEs typically have harder spectra, with a mean slope of -3.17 at >40 MeV/nuc. On average, GLE events are enriched in species associated with impulsive _3He-rich SEP events, including enrichments in Ne/O, Fe/O, ^(22)Ne/^(20)Ne, and elevated mean charge states of Fe. This paper discusses these and other properties of particles measured in situ in GLE events.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Mewaldt, R. A.0000-0003-2178-9111
Cohen, C. M. S.0000-0002-0978-8127
Haggerty, D. K.0000-0001-6395-8943
Labrador, A. W.0000-0001-9178-5349
Leske, R. A.0000-0002-0156-2414
Mason, G. M.0000-0003-2169-9618
Additional Information:This work was supported by NASA at Caltech under grants NNX8AI11G and NNX06AC21G, and under subcontract SA2715-26309 from UC Berkeley under NASA contract NAS5-03131. We appreciate the availability of GOES data at the NOAA website and thank Allan Tylka for advice on HEPAD data. Finally, we thank Eileen Chollet for her assistance with this paper.
Group:Space Radiation Laboratory
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Space Radiation Laboratory2009-21
Record Number:CaltechAUTHORS:20150522-161943572
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57787
Deposited By: Deborah Miles
Deposited On:01 Jun 2015 23:43
Last Modified:09 Mar 2020 13:18

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