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Solar energetic particle anisotropies and insights into particle transport

Leske, R. A. and Cummings, A. C. and Cohen, C. M. S. and Mewaldt, R. A. and Labrador, A. W. and Stone, E. C. and Wiedenbeck, M. E. and Christian, E. R. and von Rosenvinge, T. T. (2016) Solar energetic particle anisotropies and insights into particle transport. In: Solar Wind 14: Proceedings of the Fourteenth International Solar Wind Conference. AIP Conference Proceedings. No.1720. American Institute of Physics , Melville, NY, Art. No. 070004. ISBN 978-0-7354-1367-4. http://resolver.caltech.edu/CaltechAUTHORS:20160329-095104677

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Abstract

As solar energetic particles (SEPs) travel through interplanetary space, their pitch-angle distributions are shaped by the competing effects of magnetic focusing and scattering. Measurements of SEP anisotropies can therefore reveal information about interplanetary conditions such as magnetic field strength, topology, and turbulence levels at remote locations from the observer. Onboard each of the two STEREO spacecraft, the Low Energy Telescope (LET) measures pitch-angle distributions for protons and heavier ions up to iron at energies of about 2-12 MeV/nucleon. Anisotropies observed using LET include bidirectional flows within interplanetary coronal mass ejections, sunward-flowing particles when STEREO was magnetically connected to the back side of a shock, and loss-cone distributions in which particles with large pitch angles underwent magnetic mirroring at an interplanetary field enhancement that was too weak to reflect particles with the smallest pitch angles. Unusual oscillations in the width of a beamed distribution at the onset of the 23 July 2012 SEP event were also observed and remain puzzling. We report LET anisotropy observations at both STEREO spacecraft and discuss their implications for SEP transport, focusing exclusively on the extreme event of 23 July 2012 in which a large variety of anisotropies were present at various times during the event.


Item Type:Book Section
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1063/1.4943841DOIArticle
http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.4943841PublisherArticle
ORCID:
AuthorORCID
Cohen, C. M. S.0000-0002-0978-8127
Additional Information:© 2016 AIP Publishing LLC. This work was supported by the National Aeronautics and Space Administration (NASA) at the California Institute of Technology and the Jet Propulsion Laboratory under sub-contract SA2715-26309 from the University of California at Berkeley under NASA contract NAS5-03131, and by NASA award NNX08AK87G. We thank the STEREO/MAG team for making their data publicly available, and Lan Jian and Ying Liu for helpful discussions.
Group:Space Radiation Laboratory
Funders:
Funding AgencyGrant Number
NASASA2715-26309
NASANAS5-03131
NASANNX08AK87G
Record Number:CaltechAUTHORS:20160329-095104677
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160329-095104677
Official Citation:Solar energetic particle anisotropies and insights into particle transport Leske, R. A. and Cummings, A. C. and Cohen, C. M. S. and Mewaldt, R. A. and Labrador, A. W. and Stone, E. C. and Wiedenbeck, M. E. and Christian, E. R. and Rosenvinge, T. T. von, AIP Conference Proceedings, 1720, 070004 (2016), DOI:http://dx.doi.org/10.1063/1.4943841
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:65732
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:30 Mar 2016 19:30
Last Modified:08 Sep 2017 22:22

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