Biblio

Found 5 results
Filters: Author is Lyon, J. G.  [Clear All Filters]
2019
Authors: Eshetu W. W., Lyon J G, Hudson M K, and Wiltberger M. J.
Title: Simulations of Electron Energization and Injection by BBFs Using High-Resolution LFM MHD Fields
Abstract: We study electron injection and energization by bursty bulk flows (BBFs), by tracing electron trajectories using magnetohydrodynamic (MHD) field output from the Lyon‐Fedder‐Mobarry (LFM) code. The LFM MHD simulations were performed using idealized solar wind conditions to produce BBFs. We show that BBFs can inject energetic electrons of few to 100 keV from the magnetotatail beyond −24 RE to inward of geosynchronous, while accelerating them in the process. We also show the dependence of energization and injection on the initial relative position of the electrons to the magnetic field structure of the BBF, the initial pitch angle, and the initial energy. In addition, we have shown that the process can be nonadiabatic with violation of the first adiabatic invariant (μ). Further, we d. . .
Date: 02/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025789 Available at: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018JA025789
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2018
Authors: Eshetu W. W., Lyon J G, Hudson M K, and Wiltberger M. J.
Title: Pitch Angle Scattering of Energetic Electrons by BBFs
Abstract: Field line curvature scattering by the magnetic field structure associated with bursty bulk flows (BBFs) has been studied, using simulated output fields from the Lyon‐Fedder‐Mobarry global magnetohydrodynamic code for specified solar wind input. There are weak magnetic field strength (B) regions adjacent to BBFs observed in the simulations. We show that these regions can cause strong scattering where the first adiabatic invariant changes by several factors within one equatorial crossing of energetic electrons of a few kiloelectron volts when the BBFs are beyond 10RE geocentric in the tail. Scattering by BBFs decreases as they move toward the Earth or when the electron energy decreases. For radiation belt electrons near or inside geosynchronous orbit we demonstrate that the fields assoc. . .
Date: 10/2018 Publisher: Journal of Geophysical Research: Space Physics Pages: 9265 - 9274 DOI: 10.1029/2018JA025788 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025788
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2007
Authors: Kress B T, Hudson M K, Looper M D, Albert J, Lyon J G, et al.
Title: Global MHD test particle simulations of >10 MeV radiation belt electrons during storm sudden commencement
Abstract: [1] Prior to 2003, there are two known cases where ultrarelativistic (≳10 MeV) electrons appeared in the Earth's inner zone radiation belts in association with high speed interplanetary shocks: the 24 March 1991 and the less well studied 21 February 1994 storms. During the March 1991 event electrons were injected well into the inner zone on a timescale of minutes, producing a new stably trapped radiation belt population that persisted for ∼10 years. More recently, at the end of solar cycle 23, a number of violent geomagnetic disturbances resulted in large variations in ultrarelativistic electrons in the inner zone, indicating that these events are less rare than previously thought. Here we present results from a numerical study of shock-induced transport and energization of outer zone . . .
Date: 09/2007 Publisher: Journal of Geophysical Research DOI: 10.1029/2006JA012218 Available at: http://onlinelibrary.wiley.com/doi/10.1029/2006JA012218/abstract
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2002
Authors: ELKINGTON S, Hudson M K, Wiltberger M J, and Lyon J G
Title: MHD/particle simulations of radiation belt dynamics
Abstract: Particle fluxes in the outer radiation belts can show substantial variation in time, over scales ranging from a few minutes, such as during the sudden commencement phase of geomagnetic storms, to the years-long variations associated with the progression of the solar cycle. As the energetic particles comprising these belts can pose a hazard to human activity in space, considerable effort has gone into understanding both the source of these particles and the physics governing their dynamical behavior. Computationally tracking individual test particles in a model magnetosphere represents a very direct, physically-based approach to modeling storm-time radiation belt dynamics. Using global magnetohydrodynamic models of the Earth–Sun system coupled with test particle simulations of the radiati. . .
Date: 04/2002 Publisher: Journal of Atmospheric and Solar-Terrestrial Physics Pages: 607 - 615 DOI: 10.1016/S1364-6826(02)00018-4 Available at: http://www.sciencedirect.com/science/article/pii/S1364682602000184
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1999
Authors: Burch L, Carovillano L, Antiochos K, Hudson M K, Elkington S R, et al.
Title: Simulation of Radiation Belt Dynamics Driven by Solar Wind Variations
Abstract: The rapid rise of relativistic electron fluxes inside geosynchronous orbit during the January 10-11, 1997, CME-driven magnetic cloud event has been simulated using a relativistic guiding center test particle code driven by out-put from a 3D global MHD simulation of the event. A comparison can be made of this event class, characterized by a moderate solar wind speed (< 600 km/s), and those commonly observed at the last solar maximum with a higher solar wind speed and shock accelerated solar energetic proton component. Relativistic electron flux increase occurred over several hours for the January event, during a period of prolonged southward IMF Bz more rapidly than the 1-2 day delay typical of flux increases driven by solar wind high speed stream interactions. Simulations of th. . .
Date: Publisher: American Geophysical Union Pages: 171 - 182 DOI: 10.1029/GM10910.1029/GM109p0171 Available at: http://onlinelibrary.wiley.com/doi/10.1029/GM109p0171/summary
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