The dependence of solar energetic particle fluences on suprathermal seed-particle densities
- Creators
- Mewaldt, R. A.
- Mason, G. M.
- Cohen, C. M. S.
- Other:
- Hu, Qiang
Abstract
Measurements during solar cycle 23 showed that most solar energetic particles (SEPs) are accelerated from a seed-population of suprathermal ions (e.g., >10 keV/nuc) rather than from the bulk solar wind. In this case the SEP fluence should depend on the pre-existing density of suprathermal ions. Lacking near-Sun measurements of suprathermal ion densities we have used ACE/ULEIS daily-average densities of suprathermal Fe at 1 AU during 1998-2005 as a proxy. We find that the maximum Fe daily-average SEP fluences measured by ACE/SIS are apparently limited by the pre-existing suprathermal number density. Similarly, large fluences of Fe in solar energetic particle events only occurred when there was a pre-existing high density of suprathermal Fe. We conclude that in situ suprathermal ion data can play a key role in estimating the probability of large SEP events, or in forecasting all-clear periods.
Additional Information
© 2012 American Institute of Physics. NASA funded this work under grants NNX08AI11G and NNX11A075G at Caltech, and NNX10AT75G at JHU/APL; and subcontracts SA2715-26309 and SA4889-26309 from UC Berkeley under NASA contract NAS5-03131. We are grateful for the availability of SWEPAM data from the ACE Science Center.Attached Files
Published - Mewaldt_2012p128.pdf
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Additional details
- Eprint ID
- 36347
- Resolver ID
- CaltechAUTHORS:20130114-101755528
- NASA
- NNX08AI11G
- NASA
- NNX11A075G
- NASA
- NNX10AT75G
- NASA
- SA2715-26309
- NASA
- SA4889-26309
- NASA
- NAS5-03131
- Created
-
2013-01-14Created from EPrint's datestamp field
- Updated
-
2023-10-20Created from EPrint's last_modified field
- Caltech groups
- Space Radiation Laboratory
- Series Name
- AIP Conference Proceedings
- Series Volume or Issue Number
- 1500