Found 13 entries in the Bibliography.

Showing entries from 1 through 13


Variability of the Proton Radiation Belt

Significant steady but slow variability of radiation belt proton intensity, in the energy range \~19\textendash200 MeV and for L<2.4, has been observed in an empirical model derived from data taken by Van Allen Probes during 2013\textendash2019. It is compared to predictions of a theoretical model based on measured initial and boundary conditions. Two aspects of the variability are considered in detail and require adjustments to model parameters. Observed inward transport of proton intensity maxima near L=1.9 and associated ...

Selesnick, R.; Albert, J.;

YEAR: 2019     DOI: 10.1029/2019JA026754

protons; radial diffusion; Radiation belt; Van Allen Probes


A new ionospheric electron precipitation module coupled with RAM-SCB within the geospace general circulation model

Electron precipitation down to the atmosphere due to wave-particle scattering in the magnetosphere contributes significantly to the auroral ionospheric conductivity. In order to obtain the auroral conductivity in global MHD models that are incapable of capturing kinetic physics in the magnetosphere, MHD parameters are often used to estimate electron precipitation flux for the conductivity calculation. Such an MHD approach, however, lacks self-consistency in representing the magnetosphere-ionosphere coupling processes. In thi ...

Yu, Yiqun; Jordanova, Vania; Ridley, Aaron; Albert, Jay; Horne, Richard; Jeffery, Christopher;

YEAR: 2016     DOI: 10.1002/2016JA022585

Diffusion Coefficient; electron lifetime; electron precipitation; ionospheric conductivity; MI coupling; Van Allen Probes; wave-particle interactions


Electron lifetimes from narrowband wave-particle interactions within the plasmasphere

This paper is devoted to the systematic study of electron lifetimes from narrowband wave-particle interactions within the plasmasphere. It relies on a new formulation of the bounce-averaged quasi-linear pitch angle diffusion coefficients parameterized by a single frequency, ω, and wave normal angle, θ. We first show that the diffusion coefficients scale with ω/Ωce, where Ωce is the equatorial electron gyrofrequency, and that maximal pitch angle diffusion occurs along the line α0 = π/2\textendashθ, where α0 is the eq ...

Ripoll, J.-F.; Albert, J.; Cunningham, G.;

YEAR: 2014     DOI: 10.1002/2014JA020217

DSX; electron; narrowband; plasmasphere; wave-particle interactions

Radial diffusion simulations of the 20 September 2007 radiation belt dropout

This is a study of a dropout of radiation belt electrons, associated with an isolated solar wind density pulse on 20 September 2007, as seen by the solid-state telescopes (SST) detectors on THEMIS (Time History of Events and Macroscale Interactions during Substorms). Omnidirectional fluxes were converted to phase space density at constant invariants M = 700 MeV G-1 and K = 0.014 RE G1/2, with the assumption of local pitch angle α ≈ 80\textdegree and using the T04 magnetic field model. The last closed drift shell, which wa ...

Albert, J.;

YEAR: 2014     DOI: 10.5194/angeo-32-925-2014

radial diffusion

Three-dimensional stochastic modeling of radiation belts in adiabatic invariant coordinates

A 3-D model for solving the radiation belt diffusion equation in adiabatic invariant coordinates has been developed and tested. The model, named Radbelt Electron Model, obtains a probabilistic solution by solving a set of It\^o stochastic differential equations that are mathematically equivalent to the diffusion equation. This method is capable of solving diffusion equations with a full 3-D diffusion tensor, including the radial-local cross diffusion components. The correct form of the boundary condition at equatorial pitch ...

Zheng, Liheng; Chan, Anthony; Albert, Jay; Elkington, Scot; Koller, Josef; Horne, Richard; Glauert, Sarah; Meredith, Nigel;

YEAR: 2014     DOI: 10.1002/jgra.v119.910.1002/2014JA020127

adiabatic invariant coordinates; diffusion equation; fully 3-D model; Radiation belt; stochastic differential equation

Evidence of stronger pitch angle scattering loss caused by oblique whistler-mode waves as compared with quasi-parallel waves

Wave normal distributions of lower-band whistler-mode waves observed outside the plasmapause exhibit two peaks; one near the parallel direction and the other at very oblique angles. We analyze a number of conjunction events between the Van Allen Probes near the equatorial plane and POES satellites at conjugate low altitudes, where lower-band whistler-mode wave amplitudes were inferred from the two-directional POES electron measurements over 30\textendash100 keV, assuming that these waves were quasi-parallel. For conjunction ...

Li, W.; Mourenas, D.; Artemyev, A.; Agapitov, O.; Bortnik, J.; Albert, J.; Thorne, R.; Ni, B.; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

YEAR: 2014     DOI: 10.1002/2014GL061260

chorus waves; electron precipitation; oblique whistler; pitch angle scattering


The Electric Field and Waves (EFW) Instruments on the Radiation Belt Storm Probes Mission

The Electric Fields and Waves (EFW) Instruments on the two Radiation Belt Storm Probe (RBSP) spacecraft (recently renamed the Van Allen Probes) are designed to measure three dimensional quasi-static and low frequency electric fields and waves associated with the major mechanisms responsible for the acceleration of energetic charged particles in the inner magnetosphere of the Earth. For this measurement, the instrument uses two pairs of spherical double probe sensors at the ends of orthogonal centripetally deployed booms in t ...

Wygant, J.; Bonnell, J; Goetz, K.; Ergun, R.E.; Mozer, F.; Bale, S.D.; Ludlam, M.; Turin, P.; Harvey, P.R.; Hochmann, R.; Harps, K.; Dalton, G.; McCauley, J.; Rachelson, W.; Gordon, D.; Donakowski, B.; Shultz, C.; Smith, C.; Diaz-Aguado, M.; Fischer, J.; Heavner, S.; Berg, P.; Malaspina, D.; Bolton, M.; Hudson, M.; Strangeway, R.; Baker, D.; Li, X.; Albert, J.; Foster, J.C.; Chaston, C.C.; Mann, I.; Donovan, E.; Cully, C.M.; Cattell, C.; Krasnoselskikh, V.; Kersten, K.; Brenneman, A; Tao, J.;

YEAR: 2013     DOI: 10.1007/s11214-013-0013-7

RBSP; Van Allen Probes


Relativistic electron precipitation by EMIC waves from self-consistent global simulations

[1] We study the effect of electromagnetic ion cyclotron (EMIC) wave scattering on radiation belt electrons during the large geomagnetic storm of 21 October 2001 with minimum Dst = -187 nT. We use our global physics-based model, which solves the kinetic equation for relativistic electrons and H+, O+, and He+ ions as a function of radial distance in the equatorial plane, magnetic local time, energy, and pitch angle. The model includes time-dependent convective transport and radial diffusion and all major loss processes and is ...

Jordanova, V.; Albert, J.; Miyoshi, Y.;

YEAR: 2008     DOI: 10.1029/2008JA013239


Global MHD test particle simulations of >10 MeV radiation belt electrons during storm sudden commencement

[1] Prior to 2003, there are two known cases where ultrarelativistic (≳10 MeV) electrons appeared in the Earth\textquoterights 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 vi ...

Kress, B.; Hudson, M.; Looper, M.; Albert, J.; Lyon, J.; Goodrich, C.;

YEAR: 2007     DOI: 10.1029/2006JA012218

Shock-Induced Transport. Slot Refilling and Formation of New Belts.


Energetic outer zone electron loss timescales during low geomagnetic activity

Following enhanced magnetic activity the fluxes of energetic electrons in the Earth\textquoterights outer radiation belt gradually decay to quiet-time levels. We use CRRES observations to estimate the energetic electron loss timescales and to identify the principal loss mechanisms. Gradual loss of energetic electrons in the region 3.0 <= L <= 5.0 occurs during quiet periods (Kp < 3-) following enhanced magnetic activity on timescales ranging from 1.5 to 3.5 days for 214 keV electrons to 5.5 to 6.5 days for 1.09 MeV electrons ...

Meredith, Nigel; Horne, Richard; Glauert, Sarah; Thorne, Richard; Summers, D.; Albert, Jay; Anderson, Roger;

YEAR: 2006     DOI: 10.1029/2005JA011516

Local Loss due to VLF/ELF/EMIC Waves


Evaluation of quasi-linear diffusion coefficients for whistler mode waves in a plasma with arbitrary density ratio

Techniques are presented for efficiently evaluating quasi-linear diffusion coefficients for whistler mode waves propagating according to the full cold plasma index of refraction. In particular, the density ratio ωpe/Ωe can be small, which favors energy diffusion. This generalizes an approach, previously used for high-density hiss and electromagnetic ion cyclotron waves, of identifying (and omitting) ranges of wavenormal angle θ that are incompatible with cyclotron resonant frequencies ω occurring between sharp cutoffs of ...

Albert, J.;

YEAR: 2005     DOI: 10.1029/2004JA010844

Local Acceleration due to Wave-Particle Interaction


Evaluation of quasi-linear diffusion coefficients for EMIC waves in a multispecies plasma

Quasi-linear velocity-space diffusion coefficients due to L-mode electromagnetic ion cyclotron (EMIC) waves are considered in a multispecies plasma. It is shown, with slight approximations to exact cold plasma theory, that within EMIC pass bands the index of refraction is a monotonically increasing function of frequency. Analytical criteria are then derived which identify ranges of latitude, wavenormal angle, and resonance number consistent with resonance in a prescribed wave population. This leads to computational technique ...

Albert, J.;

YEAR: 2003     DOI: 10.1029/2002JA009792

Local Loss due to VLF/ELF/EMIC Waves


Radial diffusion analysis of outer radiation belt electrons during the October 9, 1990, magnetic storm

The response of outer radiation belt relativistic electrons to the October 9, 1990, magnetic storm is analyzed in detail using a radial diffusion model and data from the Combined Release and Radiation Effects Satellite (CRRES) and the Los Alamos National Laboratory (LANL) geosynchronous satellite 1989-046. Electron measurements are expressed in terms of phase space density as a function of the three adiabatic invariants determined from CRRES magnetic field data and the Tsyganenko 1989 Kp-dependent magnetic field model. The r ...

Brautigam, D.; Albert, J.;

YEAR: 2000     DOI: 10.1029/1999JA900344

Radial Transport