WorldCat Identities

REEVES, G. D.

Overview
Works: 11 works in 12 publications in 1 language and 14 library holdings
Roles: Author
Publication Timeline
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Most widely held works by G. D REEVES
Association of substorm chorus events with drift echoes by G. A ABEL( )

1 edition published in 2006 in English and held by 2 WorldCat member libraries worldwide

Radial Diffusion as a Potential Source and Loss Mechanism of Relativistic Electrons in the Outer Radiation Belt( Book )

2 editions published in 2006 in English and held by 2 WorldCat member libraries worldwide

The loss mechanisms responsible for the sudden depletions of the outer electron radiation belt are examined based on observations and radial diffusion modeling. SAMPEX data for Oct-Dec 2003, indicates that depletions are correlated with increases in geomagnetic activity and are also correlated with sudden increases in the solar wind dynamic pressure. Multi-channel HEO observations show that depletions at higher L are seen at energies as low as a few hundred keV. For the same events, high-energy proton channels also show decrease in fluxes at higher L-values. These observations are consistent with outward radial diffusion driven by the loss to magnetopause at L>4. We further examine the viability of the outward radial diffusion loss by comparing CRRES observations with a radial diffusion model simulation. Model-data comparison shows that flux variation near geosynchronous orbit can be effectively propagated by the outward radial diffusion to L=4 and can account for the main phase storm depletions
Postmidnight VLF chorus events, a substorm signature observed at the ground near L = 4 by A. J Smith( )

1 edition published in 1996 in English and held by 2 WorldCat member libraries worldwide

The electric field response to the growth phase and expansion phase onset of a small isolated substorm by R. V LEWIS( )

1 edition published in 1997 in English and held by 2 WorldCat member libraries worldwide

EISCAT observations of unusual flows in the morning sector associated with weak substorm activity by N. J FOX( )

1 edition published in 1994 in English and held by 2 WorldCat member libraries worldwide

Nonlinear Electrostatic Steepening of Whistler Waves: The Guiding Factors and Dynamics in Inhomogeneous Systems( )

1 edition published in 2018 in English and held by 1 WorldCat member library worldwide

Abstract: Whistler mode chorus waves are particularly important in outer radiation belt dynamics due to their key role in controlling the acceleration and scattering of electrons over a very wide energy range. The efficiency of wave‐particle resonant interactions is defined by whistler wave properties which have been described by the approximation of plane linear waves propagating through the cold plasma of the inner magnetosphere. However, recent observations of extremely high‐amplitude whistlers suggest the importance of nonlinear wave‐particle interactions for the dynamics of the outer radiation belt. Oblique chorus waves observed in the inner magnetosphere often exhibit drastically nonsinusoidal (with significant power in the higher harmonics) waveforms of the parallel electric field, presumably due to the feedback from hot resonant electrons. We have considered the nature and properties of such nonlinear whistler waves observed by the Van Allen Probes and Time History of Events and Macroscale Interactions define during Substorms in the inner magnetosphere, and we show that the significant enhancement of the wave electrostatic component can result from whistler wave coupling with the beam‐driven electrostatic mode through the resonant interaction with hot electron beams. Being modulated by a whistler wave, the electron beam generates a driven electrostatic mode significantly enhancing the parallel electric field of the initial whistler wave. We confirm this mechanism using a self‐consistent particle‐in‐cell simulation. The nonlinear electrostatic component manifests properties of the beam‐driven electron acoustic mode and can be responsible for effective electron acceleration in the inhomogeneous magnetic field. Plain Language Summary: We consider the effects of induced scattering of the electromagnetic whistler wave to the electrostatic electron acoustic wave (observed as field‐aligned electric field bursts). The main discussed effect is based on the coupling of the slightly oblique whistler wave and a beam‐driven electron acoustic wave observed as "nonlinear whistler waves". The wave interaction as the result produces the whistler wave and the rapidly steepening acoustic electrostatic wave with the same phase (and the same k and frequency). Then, because the two different modes are the result of the interaction, the following dynamics of the waves in the inhomogeneous magnetic field is different: the whistler wave phase velocity depends on the background magnetic field magnitude but the acoustic mode propagate with the constant phase velocity. This dynamics leads to the waves phase differences and explains the fact that the observed in the experiment whistler and electrostatic bursts usually have actually random phase shift. To confirm this, we studied the dynamics of these waves in the inhomogeneous magnetic field system making use of the particle‐in‐cell simulation, reproduced all steps of the modes conversion, and confirmed that the dynamics in the inhomogeneous plasma system leads to the observed effects. Key Points: Nonlinear electrostatic steepening of whistler waves ‐ the induced scattering to electron acoustic waves Resonant electron beam is highly modulated by a weakly oblique whistler wave Modulated electron beam initiates the electron acoustic wave turned into the electrostatic nonlinear mode phase related to the whistler
Quantitative Evaluation of Radial Diffusion and Local Acceleration Processes During GEM Challenge Events( )

1 edition published in 2018 in English and held by 1 WorldCat member library worldwide

Abstract: We simulate the radiation belt electron flux enhancements during selected Geospace Environment Modeling (GEM) challenge events to quantitatively compare the major processes involved in relativistic electron acceleration under different conditions. Van Allen Probes observed significant electron flux enhancement during both the storm time of 17–18 March 2013 and non–storm time of 19–20 September 2013, but the distributions of plasma waves and energetic electrons for the two events were dramatically different. During 17–18 March 2013, the SYM ‐ H minimum reached −130 nT, intense chorus waves (peak B w ~140 pT) occurred at 3.5 <  L  < 5.5, and several hundred keV to several MeV electron fluxes increased by ~2 orders of magnitude mostly at 3.5 <  L  < 5.5. During 19–20 September 2013, the SYM ‐ H remained higher than −30 nT, modestly intense chorus waves (peak B w ~80 pT) occurred at L  > 5.5, and electron fluxes at energies up to 3 MeV increased by a factor of ~5 at L  > 5.5. The two electron flux enhancement events were simulated using the available wave distribution and diffusion coefficients from the GEM focus group Quantitative Assessment of Radiation Belt Modeling. By comparing the individual roles of local electron heating and radial transport, our simulation indicates that resonant interaction with chorus waves is the dominant process that accounts for the electron flux enhancement during the storm time event particularly near the flux peak locations, while radial diffusion by ultralow‐frequency waves plays a dominant role in the enhancement during the non–storm time event. Incorporation of both processes reasonably reproduces the observed location and magnitude of electron flux enhancement. Key Points: Energetic electron fluxes are enhanced during storm and non–storm time events, but wave and electron structures are dramatically different Local heating by whistler mode chorus wave is the major contributor to the flux enhancement near the peak during 17–18 March 2013 Radial diffusion by ultralow‐frequency wave is the major contributor to the observed flux enhancement during 19–20 September 2013
Radiation Belt "Dropouts" and Drift‐Bounce Resonances in Broadband Electromagnetic Waves( )

1 edition published in 2018 in English and held by 1 WorldCat member library worldwide

Abstract: Observations during the main phase of geomagnetic storms reveal an anticorrelation between the occurrence of broadband low‐frequency electromagnetic waves and outer radiation belt electron flux. We show that the drift‐bounce motion of electrons in the magnetic field of these waves leads to rapid electron transport. For observed spectral energy densities it is demonstrated that the wave magnetic field can drive radial diffusion via drift‐bounce resonance on time scales less than a drift orbit. This process may provide outward transport sufficient to account for electron "dropouts" during storm main phase and more generally modulate the outer radiation belt during geomagnetic storms. Key Points: Kinetic eigenmodes of the geomagnetic field may deplete the outer radiation belt during the main phase of geomagnetic storms Drift‐bounce resonances with the wave magnetic field can drive radial diffusion on time scales less than a drift period Broadband electromagnetic waves commonly observed in the inner magnetosphere during geomagnetic storms may be an important unrecognized driver of radiation belt dynamics
Electron acceleration in the heart of the Van Allen radiation belts by G. D Reeves( Book )

1 edition published in 2013 in English and held by 1 WorldCat member library worldwide

The relationship of HF backscatter to the accumulation of open magnetic flux prior to substorm onset by R. V LEWIS( )

1 edition published in 1998 in English and held by 0 WorldCat member libraries worldwide

A comparison of midlatitude Pi 2 pulsations and geostationary orbit particle injections as substorm indicators by T. K YEOMAN( )

1 edition published in 1994 in English and held by 0 WorldCat member libraries worldwide

 
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English (12)