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Time Variations in Elemental Abundances in Solar Energetic Particle Events

von Rosenvinge, T. T. and Cohen, C. M. S. and Christian, E. R. and Cummings, A. C. and Leske, R. A. and Mewaldt, R. A. and Slocum, P. L. and St. Cyr, O. C. and Stone, E. C. and Wiedenbeck, M. E. (2001) Time Variations in Elemental Abundances in Solar Energetic Particle Events. In: Solar and Galactic Composition. AIP Conference Proceedings. No.598. American Institute of Physics , Melville, N.Y., pp. 343-348. ISBN 0-7354-0042-3.

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The Solar Isotope Spectrometer (SIS) on-board the Advanced Composition Explorer has a large collection power and high telemetry rate, making it possible to study elemental abundances in large solar energetic particle (SEP) events as a function of time. Results have now been obtained for more than 25 such events. Understanding the causes of these variations is key to obtaining reliable solar elemental abundances and to understanding solar acceleration processes. Such variations have been previously attributed to two models: (1) a mixture of an initial impulsive phase having enhanced heavy element abundances with a longer gradual phase with coronal abundances and (2) rigidity dependent escape from CME-driven shocks through plasma waves generated by wave-particle interactions. In this second model the injected abundances are assumed to be coronal. Both these models can be expected to depend upon solar longitude since impulsive events are associated with flares at longitudes well-connected magnetically to the observer, and shock properties and connection of the observer to the shock are also longitude dependent. We present results on temporal variations from event to event and within events and show that they appear to have a longitude dependence. We show that the events which have been well-explained by model (2) tend to be near central meridian or the west limb. In addition, we show that there are events with little time variation and heavy element enhancements similar to those of impulsive events. These events seem to be better explained by model (1) with only an impulsive phase.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Cohen, C. M. S.0000-0002-0978-8127
Christian, E. R.0000-0003-2134-3937
Cummings, A. C.0000-0002-3840-7696
Leske, R. A.0000-0002-0156-2414
Mewaldt, R. A.0000-0003-2178-9111
St. Cyr, O. C.0000-0001-8906-6097
Stone, E. C.0000-0002-2010-5462
Wiedenbeck, M. E.0000-0002-2825-3128
Additional Information:© 2001 American Institute of Physics. Issue Date: 21 November 2001. This research was supported by the National Aeronautics and Space Administration at the Goddard Space Flight Center, the California Institute of Technology (under grant NAG5-6912), and the Jet Propulsion Laboratory. TvR acknowledges assistance from Hilary Cane with determining associated solar event locations.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:solar cosmic ray particles, element relative abundance, time series, acceleration, shock waves, solar corona, space telemetry
Series Name:AIP Conference Proceedings
Issue or Number:598
Classification Code:PACS: 96.60.Vg; 96.60.Fs; 95.75.Wx
Record Number:CaltechAUTHORS:20111118-134937338
Persistent URL:
Official Citation:Time variations in elemental abundances in solar energetic particle events T. T. von Rosenvinge, C. M. S. Cohen, E. R. Christian, A. C. Cummings, R. A. Leske, R. A. Mewaldt, P. L. Slocum, O. C. St. Cyr, E. C. Stone, and M. E. Wiedenbeck, AIP Conf. Proc. 598, 343 (2001), DOI:10.1063/1.1434022
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:27865
Deposited By: Ruth Sustaita
Deposited On:20 Nov 2011 23:58
Last Modified:11 Mar 2020 19:32

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