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Analysis of the potential radiation hazard of the 23 July 2012 SEP event observed by STEREO A using the EMMREM model and LRO/CRaTER

Joyce, C. J. and Schwadron, N. A. and Townsend, L. W. and Mewaldt, R. A. and Cohen, C. M. S. and von Rosenvinge, T. T. and Case, A. W. and Spence, H. E. and Wilson, J. K. and Gorby, M. and Quinn, M. and Zeitlin, C. J. (2015) Analysis of the potential radiation hazard of the 23 July 2012 SEP event observed by STEREO A using the EMMREM model and LRO/CRaTER. Space Weather, 13 (9). pp. 560-567. ISSN 1542-7390. doi:10.1002/2015SW001208.

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We present a study of the potential radiation hazard of the powerful, superfast interplanetary coronal mass ejection (ICME) observed by STEREO A on 23 July 2012. Using energetic proton flux data from the High Energy Telescope and Low Energy Telescope instruments aboard STEREO A together with the Earth-Moon-Mars Radiation Environment Module, we compute dose rates and accumulated doses during the event for both skin/eye and blood forming organs using four physically relevant levels of shielding. For spacesuit equivalent shielding, we compute a peak skin/eye dose rate of 1970 cGy-Eq/d, a value far greater than those of the 2003 Halloween storms or the January and March solar energetic particle events of 2012. However, due to the relative brevity of the event, the resulting accumulated dose was just 383 cGy-Eq, which is more aligned with the total doses of the 2003 Halloween and 2012 January/March events. Additionally, we use dose rates at STEREO B and Lunar Reconnaissance Orbiter/Cosmic Ray Telescope for the Effects of Radiation (LRO/CRaTER) during the event to show how the radiation impact is affected by the position of the ICME relative to the observer. Specifically, we find that the energetic particle event associated with the local shock and ICME passage at STEREO A caused greatly enhanced dose rates when compared to STEREO B and LRO/CRaTER, which were longitudinally distant from the ICME. The STEREO A/B dose rates used here will soon be made available to the community as a tool for studying the energetic particle radiation of solar events from different longitudes as a part of NASA's Heliophysics Virtual Observatories and on the Predictions of radiation from REleASE, EMMREM, and Data Incorporating CRaTER, COSTEP, and other SEP measurements (PREDICCS) and CRaTER websites.

Item Type:Article
Related URLs:
URLURL TypeDescription
Joyce, C. J.0000-0002-3841-5020
Schwadron, N. A.0000-0002-3737-9283
Mewaldt, R. A.0000-0003-2178-9111
Cohen, C. M. S.0000-0002-0978-8127
Additional Information:© 2015 American Geophysical Union. Received 22 APR 2015; Accepted 10 AUG 2015; Accepted article online 14 AUG 2015; Published online 11 SEP 2015. This work is supported by NASA LRO/CRaTER/PREDICCS Project (contract NNG11PA03C), the NSF/FESD Sun-to-Ice Project (grant AGS1135432), and the NASA/LWS/NSF EMMREM Project (grant NNX11AC06G). The work on the corrected STEREO A HET spectrum was performed at Caltech and was supported by NASA grants NNX11A075G and subcontract SA2715-26309 from UC Berkeley under NASA Contract NAS5-003131. We thank the STEREO HET and LET instrument teams for providing the STEREO data used here (available at: Simulation results have been provided by the Community Coordinated Modeling Center at Goddard Space Flight Center through their public Runs on Request system ( The CCMC is a multiagency partnership between NASA, AFMC, AFOSR, AFRL, AFWA, NOAA, NSF, and ONR. The ENLIL+Cone Model was developed by Dusan Odstrcil at the University of Colorado at Boulder. The CRaTER data used here are available on the CRaTER website:
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Issue or Number:9
Record Number:CaltechAUTHORS:20151119-133558925
Persistent URL:
Official Citation:Joyce, C. J., et al. (2015), Analysis of the potential radiation hazard of the 23 July 2012 SEP event observed by STEREO A using the EMMREM model and LRO/CRaTER, Space Weather, 13, 560–567, doi:10.1002/2015SW001208
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:62248
Deposited By: Tony Diaz
Deposited On:19 Nov 2015 21:47
Last Modified:10 Nov 2021 22:59

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