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Role of Flares and Shocks in Determining Solar Energetic Particle Abundances

Cane, H. V. and Mewaldt, R. A. and Cohen, C. M. S. and von Rosenvinge, T. T. (2006) Role of Flares and Shocks in Determining Solar Energetic Particle Abundances. Journal of Geophysical Research A, 111 (A6). Art. No. A06S90. ISSN 0148-0227. doi:10.1029/2005JA011071.

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We examine solar energetic particle (SEP) event-averaged abundances of Fe relative to O and intensity versus time profiles at energies above 25 MeV/nucleon using the SIS instrument on ACE. These data are compared with solar wind conditions during each event and with estimates of the strength of the associated shock based on average travel times to 1 AU. We find that the majority of events with an Fe to O abundance ratio greater than two times the average 5–12 MeV/nuc value for large SEP events (0.134) occur in the western hemisphere. Furthermore, in most of these Fe-rich events the profiles peak within 12 hours of the associated flare, suggesting that some of the observed interplanetary particles are accelerated in these flares. The vast majority of events with Fe/O below 0.134 are influenced by interplanetary shock acceleration. We suggest that variations in elemental composition in SEP events mainly arise from the combination of flare particles and shock acceleration of these particles and/or the ambient medium.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle Information
Mewaldt, R. A.0000-0003-2178-9111
Cohen, C. M. S.0000-0002-0978-8127
Additional Information:© 2006 by the American Geophysical Union. Received 13 February 2005; revised 6 February 2006; accepted 15 March 2006; published 23 June 2006. H.V.C. was supported at GSFC by a contract with USRA. The work at California Institute of Technology was supported by NASA under grant NAG5-12929. We thank the referees for constructive criticism. Shadia Rifai Habbal thanks Stephen Kahler and the other two referees for their assistance in evaluating this paper.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:flares; shocks; solar energy particles
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2006-07
Issue or Number:A6
Record Number:CaltechAUTHORS:20150324-102418436
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Official Citation:Cane, H. V., R. A. Mewaldt, C. M. S. Cohen, and T. T. von Rosenvinge (2006), Role of flares and shocks in determining solar energetic particle abundances, J. Geophys. Res., 111, A06S90, doi:10.1029/2005JA011071
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:56015
Deposited By: Deborah Miles
Deposited On:24 Mar 2015 19:29
Last Modified:10 Nov 2021 20:53

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