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Toffoletto, F.; Sazykin, S.; Spiro, R. W.; Wolf, R. A.

doi:10.1023/a:1025532008047

Cited by 325 publications

(151 citation statements)

References 48 publications

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“…LFM is coupled with two other models which improve description of physical processes in the inner magnetosphere. The Rice Convection Model (RCM) provides a representation of ring current particle populations including drift physics (Toffoletto et al, 2003;Pembroke et al, 2012) and the Magnetosphere-Ionosphere Coupler/Solver (MIX) model provides an inner boundary at 2 R E (Merkin and Lyon, 2010).…”

Section: Mhd Modelmentioning

confidence: 99%

“…RCM assumes a Maxwellian distribution function for both electrons and ions decomposed in energy into 28 fluid channels for electrons and 62 channels for ions (Toffoletto et al, 2003). The flux tube averaged density, temperature and magnetic field are provided by LFM, while RCM provides the sound speed which is bled into LFM with a characteristic exchange time and a coupling ratio.…”

Section: Mhd Modelmentioning

confidence: 99%

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Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013

et al. 2015

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Abstract. Coronal mass ejection (CME)-shock compression of the dayside magnetopause has been observed to cause both prompt enhancement of radiation belt electron flux due to inward radial transport of electrons conserving their first adiabatic invariant and prompt losses which at times entirely eliminate the outer zone. Recent numerical studies suggest that enhanced ultra-low frequency (ULF) wave activity is necessary to explain electron losses deeper inside the magnetosphere than magnetopause incursion following CME-shock arrival. A combination of radial transport and magnetopause shadowing can account for losses observed at radial distances into L = 4.5, well within the computed magnetopause location. We compare ULF wave power from the Electric Field and Waves (EFW) electric field instrument on the Van Allen Probes for the 8 October 2013 storm with ULF wave power simulated using the Lyon-FedderMobarry (LFM) global magnetohydrodynamic (MHD) magnetospheric simulation code coupled to the Rice Convection Model (RCM). Two other storms with strong magnetopause compression, 8-9 October 2012 and 17-18 March 2013, are also examined. We show that the global MHD model captures the azimuthal magnetosonic impulse propagation speed and amplitude observed by the Van Allen Probes which is responsible for prompt acceleration at MeV energies reported for the 8 October 2013 storm. The simulation also captures the ULF wave power in the azimuthal component of the electric field, responsible for acceleration and radial transport of electrons, at frequencies comparable to the electron drift period. This electric field impulse has been shown to explain observations in related studies (Foster et al., 2015) of electron acceleration and drift phase bunching by the Energetic Particle, Composition, and Thermal Plasma Suite (ECT) instrument on the Van Allen Probes.

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Section: Mhd Modelmentioning

confidence: 99%

Section: Mhd Modelmentioning

confidence: 99%

Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013

et al. 2015

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“…The RCM [Harel et al, 1981a;Toffoletto et al, 2003] simulates the electric and magnetic drift of ions and electrons and their electrodynamic coupling to ionosphere. More specifically, it calculates the bounceaveraged electric drift and magnetic drift of a flux tube filled with an isotropic distribution of ions or electrons at specified kinetic energies inside the closed field line region of the magnetosphere.…”

Section: Plasma Transport and Distributionsmentioning

confidence: 99%

Formation of the Harang reversal and its dependence on plasma sheet conditions: Rice convection model simulations

et al. 2009

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[1] The goal of this paper is to understand the formation of the Harang reversal and its association with the region 2 field-aligned current (FAC) system, which couples the plasma sheet transport to the ionosphere. We have run simulations with the Rice convection model (RCM) using the Tsyganenko 96 magnetic field model and realistic plasma sheet particle boundary conditions on the basis of Geotail observations. Our results show that the existence of an overlap in magnetic local time (MLT) of the region 2 upward and downward FAC is necessary for the formation of the Harang reversal. In the overlap region the downward FAC, which is located at lower latitudes, is associated with low-energy ions that penetrate closer to Earth toward the dawn side, while the upward FAC, which is located at higher latitudes, is associated with high-energy ions. Under the same enhanced convection we compare the Harang reversal resulting from a hotter and more tenuous plasma sheet with the one resulting from a colder and denser plasma sheet. For the former case the shielding of the convection electric field is less efficient than for the latter case, allowing low-energy protons to penetrate further earthward, resulting in a Harang reversal that extends to lower latitudes, expands wider in MLT, and is located further equatorward than the upward FAC peak and the conductivity peak. The return flows of the Harang reversal in the hot and tenuous case are located in a low conductivity region. This leads to an enhancement of these westward flows, resulting in subauroral polarization streams (SAPS).

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“…The model uses the slow-flow approximation and assumes an isotropic pressure distribution along magnetic field lines. The RCM computes the adiabatic E × B and gradient/curvature drifts of plasma in the inner and middle magnetosphere and its coupling to the underlying ionosphere by using a multifluid representation of the plasma distribution (see review by Toffoletto et al [2003]). The potential electric field is calculated by solving the fundamental magnetosphere-ionosphere coupling equation [Vasyliunas, 1970].…”

Section: Introductionmentioning

confidence: 99%

On the contribution of plasma sheet bubbles to the storm time ring current

et al. 2015

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Particle injections occur frequently inside 10 Re during geomagnetic storms. They are commonly associated with bursty bulk flows or plasma sheet bubbles transported from the tail to the inner magnetosphere. Although observations and theoretical arguments have suggested that they may have an important role in storm time dynamics, this assertion has not been addressed quantitatively. In this paper, we investigate which process is dominant for the storm time ring current buildup: large‐scale enhanced convection or localized bubble injections. We use the Rice Convection Model‐Equilibrium (RCM‐E) to model a series of idealized storm main phases. The boundary conditions at 14–15 Re on the nightside are adjusted to randomly inject bubbles to a degree roughly consistent with observed statistical properties. A test particle tracing technique is then used to identify the source of the ring current plasma. We find that the contribution of plasma sheet bubbles to the ring current energy increases from ~20% for weak storms to ~50% for moderate storms and levels off at ~61% for intense storms, while the contribution of trapped particles decreases from ~60% for weak storms to ~30% for moderate and ~21% for intense storms. The contribution of nonbubble plasma sheet flux tubes remains ~20% on average regardless of the storm intensity. Consistent with previous RCM and RCM‐E simulations, our results show that the mechanisms for plasma sheet bubbles enhancing the ring current energy are (1) the deep penetration of bubbles and (2) the bulk plasma pushed ahead of bubbles. Both the bubbles and the plasma pushed ahead typically contain larger distribution functions than those in the inner magnetosphere at quiet times. An integrated effect of those individual bubble injections is the gradual enhancement of the storm time ring current. We also make two predictions testable against observations. First, fluctuations over a time scale of 5–20 min in the plasma distributions and electric field can be seen in the central ring current region for the storm main phase. We find that the plasma pressure and the electric field EY there vary over about 10%–30% and 50%–300% of the background values, respectively. Second, the maximum plasma pressure and magnetic field depression in the central ring current region during the main phase are well correlated with the Dst index.

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Cited by 325 publications

References 48 publications

Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013

Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013

Formation of the Harang reversal and its dependence on plasma sheet conditions: Rice convection model simulations

On the contribution of plasma sheet bubbles to the storm time ring current

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