Dependence of the large‐scale, inner magnetospheric electric field on geomagnetic activity

“…However, there are a few observations of the large-scale convection electric field with large amplitudes. Rowland and Wygant (1998) and Wygant et al (1998) showed measurements of the dawn-dusk component of the electric field in the inner magnetosphere ranging 590 N. Yu. Ganushkina et al: Substorm electric fields in storm ring current from 0.05 to 1.5 mV/m as K p increased from 0 to 9.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…Observations show that substorm-associated electric fields usually display a very complicated behavior (Maynard et al, 1996). Large, transient electric fields appear in the plasma sheet during the substorm expansion phase (Aggson et al, 1983;Cattell and Mozer, 1984;Rowland and Wygant, 1998; 580 N. Yu. Ganushkina et al: Substorm electric fields in storm ring current Wygant et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Role of substorm-associated impulsive electric fields in the ring current development during storms

2005

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Abstract.Particles with different energies produce varying contributions to the total ring current energy density as the storm progresses. Ring current energy densities and total ring current energies were obtained using particle data from the Polar CAMMICE/MICS instrument during several storms observed during the years 1996-1998. Four different energy ranges for particles are considered: total (1-200 keV), low (1-20 keV), medium (20-80 keV) and high (80-200 keV). Evolution of contributions from particles with different energy ranges to the total energy density of the ring current during all storm phases is followed. To model this evolution we trace protons with arbitrary pitch angles numerically in the drift approximation. Tracing is performed in the large-scale and small-scale stationary and time-dependent magnetic and electric field models. Small-scale time-dependent electric field is given by a Gaussian electric field pulse with an azimuthal field component propagating inward with a velocity dependent on radial distance. We model particle inward motion and energization by a series of electric field pulses representing substorm activations during storm events. We demonstrate that such fluctuating fields in the form of localized electromagnetic pulses can effectively energize the plasma sheet particles to higher energies (>80 keV) and transport them inward to closed drift shells. The contribution from these high energy particles dominates the total ring current energy during storm recovery phase. We analyse the model contributions from particles with different energy ranges to the total energy density of the ring current during all storm phases. By comparing these results with observations we show that the formation of the ring current is a combination of large-scale convection and pulsed inward shift and consequent energization of the ring current particles.

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“…This acts to suppress the convection strength in the near-Earth plasma sheet and enhance it in the region close to the Earth (midlatitudes). Such field configurations are seen in the magnetosphere (Rowland and Wygant, 1998;Burke et al, 1998) and in the ionosphere (Yeh et al, 1991;Anderson et al, 2001). Ring current calculations that self-consistently include this potential distribution show that it slightly rotates the asymmetric ring current eastward (Garner, 2000;Fok et al, 2001).…”

Section: Ring Current Inputmentioning

confidence: 99%

Ring Current Energy Input and Decay

Kozyra

Liemohn

2003

Space Science Reviews

122

104

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Abstract.A new view of the ring current as an active element in the geospace system has emerged in which the ring current responds not only to changing convection electric fields imposed by solar wind interactions but to internal dynamics of the magnetosphere-ionosphere-atmosphere (geospace) system. Variations in the plasma sheet density, temperature and composition, saturation of the polar cap potential drop (and presumably the cross-tail potential drop), modifications to the imposed convection potential in the inner magnetosphere due to ring current shielding effects, the presence of a pre-existing ring current population, storm-substorm coupling, and strong convection with and without accompanying substorm activity all have an impact on the ring current strength, formation and loss. All of these internal processes imply that the geoeffectiveness of a solar wind driver cannot be predicted on the basis of the characteristics of the driver alone but must reflect key aspects of the dynamically changing geospace environment, itself. This review gives a summary of new information on ring current input and decay processes focusing on implications for the global geospace response to solar wind drivers during magnetic storms and on open questions that can be addressed with new ENA imaging techniques.

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Dependence of the large‐scale, inner magnetospheric electric field on geomagnetic activity

Cited by 172 publications

References 18 publications

Combined Ionospheric Campaign 1: Ionospheric tomography and GPS total electron count (TEC) depletions

Combined Ionospheric Campaign 1: Ionospheric tomography and GPS total electron count (TEC) depletions

Role of substorm-associated impulsive electric fields in the ring current development during storms

Ring Current Energy Input and Decay

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