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Magnetohydrodynamic Fast Shocks and Their Relation to Solar Energetic Particle Event Intensities

Liou, Kan and Wu, Chin-Chun and Dryer, Murray and Wu, Shi-Tsan and Berdichevsky, Daniel B. and Plunkett, Simon and Mewaldt, Richard A. and Mason, Glenn M. (2013) Magnetohydrodynamic Fast Shocks and Their Relation to Solar Energetic Particle Event Intensities. Terrestrial Atmospheric and Oceanic Sciences, 24 (2). pp. 165-173. ISSN 1017-0839. doi:10.3319/TAO.2012.05.08.01(SEC).

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Gradual solar energetic particles (SEPs) are associated with interplanetary (IP) shock driven by coronal mass ejections. Testing theories/models that are built around shock acceleration mechanisms is difficult due to the complexity of SEP fluxes acquired by single-point measurements. To circumvent this, we correlate fast-forward shock Mach numbers derived from a 1.5D magnetohydrodynamics simulation with the intensity of solar energetic oxygen (O) and helium-4 (^4He) particles acquired by instruments aboard the ACE spacecraft during a series of coronal mass ejections in 2003 (October 28 - 31). A good correlation at the 5% significance level is found for O and ^4He with energy (E) > ~10 MeV n^(-1), with the peak correlation coefficient r = 0.82 for O (E = 63.8 - 89.8 MeV n^(-1)) and r = 0.77 for ^4He (E = 18.0 - 29.4 MeV n^(-1)), respectively, for hourly averaged data. This result not only bolsters the causal relationship between IP fast shocks and SEPs, but also suggests that the Mach number of IP shocks is one of the major controlling parameters for the intensity of SEPs measured in the near-Earth space.

Item Type:Article
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Mewaldt, Richard A.0000-0003-2178-9111
Mason, Glenn M.0000-0003-2169-9618
Additional Information:© 2013 TAO. Received 19 December 2011, accepted 8 May 2012. We would like to acknowledge E. Stone, who is the Principal Investigator of the ACE/SIS instrument team. We acknowledge the use of flare data from the NOAA Space Weather Prediction Center. The work of K. Liou was supported by NSF AGS-0964396 Grant. The work of C. C. Wu was supported by ONR. The work of S. Plunkett was supported by NRL 6.1 Program. The work of S. T. Wu is supported by AFOSR Grant FA9550-07-1-0468 and NSF Grant ATM0754278 to UAH. The work of G. M. Mason was supported by NASA grants NNX10AT75G and NNX07AP69G. The work at Caltech was sponsored by NASA grant NNX8AI11G.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Office of Naval Research (ONR)UNSPECIFIED
Naval Research LaboratoryUNSPECIFIED
Air Force Office of Scientific Research (AFOSR)FA9550-07-1-0468
Subject Keywords:Solar energetic particles, CME driven-shocks, MHD simulation, ACE
Issue or Number:2
Record Number:CaltechAUTHORS:20140214-101740451
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Official Citation:Liou, K., C. C. Wu, M. Dryer, S. T. Wu, D. B. Berdichevsky, S. Plunkett, R. A. Mewaldt, and G. M. Mason, 2013: Magnetohydrodynamic fast shocks and their relation to solar energetic particle event intensities. Terr. Atmos. Ocean. Sci., 24, 165-173, doi: 10.3319/TAO.2012.05.08.01(SEC)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43834
Deposited On:18 Feb 2014 15:48
Last Modified:10 Nov 2021 16:43

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