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Large Scale ULF Waves and Energetic Particles in the Earth's Magnetosphere Open Access


Other title
Radiation Belt
Geomagnetic Storms
Energetic Particles
ULF Waves
Pc 5
Type of item
Degree grantor
University of Alberta
Author or creator
Lee, Eun Ah
Supervisor and department
Dr. Ian R. Mann (Physics)
Examining committee member and department
Dr. Ying Tsui (Electrical & Computer Engineering)
Dr. P.T. Jayachandran (Physics, University of New Brunswick, Canada)
Dr. Moritz Heimpel (Physics)
Dr. Frances Fenrich (Physics)
Department of Physics

Date accepted
Graduation date
Doctor of Philosophy
Degree level
In this thesis we examine the generation mechanisms of Pc 5 ULF waves during geomagnetic storms. Also, we study the interaction between Pc 5 ULF waves and energetic particles in the radiation belts and the observed energetic particle flux modulation by Pc 5 ULF waves is verified using particle simulations. Firstly, we present case studies of Pc 5 pulsations using ground-based magnetometer and satellite data during geomagnetic storm times, specifically we selecting three storm time events which show a brief increase in Dst in the main phase of the storms. By studying these events, we attempt to identify the generation mechanisms responsible for the geomagnetic pulsations. The observed pulsations exhibit the characteristic features of a Field Line Resonance. Our results also show evidence for the penetration of ULF wave power in the Pc 5 band to much lower L-shells than normal, suggesting significant reduction of the local Alfven eigenfrequency continuum as compared to non-storm times. This may have considerable significance for the interaction between ULF waves and MeV electrons in the outer radiation belt during storms. Secondly, based on the hypothesis that Pc 5 ULF waves may play an important role in energetic particle dynamics in the radiation belt and ring current, we investigated the relationship between Pc 5 pulsations and energetic particle flux oscillations. We observed very strong Pc 5 oscillations during the great magnetic storm of March 24, 1991 [Lee et al., 2007] and electron flux simultaneously oscillating with the same frequencies in the time domain. We also characterize two more events and present an examination of the relationship between the electron flux modulation and Pc 5 ULF pulsations. Based on our observations, the modulation of energetic particles might be associated with a drift-resonance interaction, or the advection of an energetic particle density gradient. Finally, we numerically calculate the trajectories and energy change of charged particles under the influence of model ULF wave electric fields. This modeling work is used to help to explain the observations and provides evidence which supports the modulation mechanisms such as advection of a flux gradient and drift resonance.
License granted by Eun Ah Lee ( on 2011-01-11T21:09:11Z (GMT): Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of the above terms. The author reserves all other publication and other rights in association with the copyright in the thesis, and except as herein provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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File title: Sun-Earth Connection
File title: Large Scale ULF Waves and Energetic Particles in the Earth's Magnetosphere
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