A mechanism for driving the gross Birkeland current configuration in the auroral oval

Rostoker, G.; Boström, R.

doi:10.1029/ja081i001p00235

Cited by 140 publications

(37 citation statements)

References 37 publications

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“…3) The 0 + flow direction changes its sign, so that the computed E Z behaviour is in agreement with the magnetotail electric field configuration as modeled by Rostoker and Bostrom (1976). …”

Section: Discussionsupporting

confidence: 54%

The structure of the plasma sheet‐lobe boundary in the Earth's magnetotail

Orsini¹,

Candidi²,

Formisano³

et al. 1984

J. Geophys. Res.

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The structure of the magnetotail plasma sheet‐plasma lobe boundary is studied by observing the properties of tailward flowing O+ ion streams. These have been detected by the ISEE 2 plasma experiment and the ISEE 1 ion composition experiment inside the boundary during three time periods in April 1978; data from the ISEE 1 electron spectrometer are used to define the location of the boundary. The density of the O+ ion streams has a relative maximum, and their velocity has a relative minimum at the boundary. The xy drift velocity component across the local magnetic field reverses at the boundary, indicating a reversal of the Ez electric field component. These changes are consistent with the topology of the electric field lines in the tail as mapped from the ionosphere.

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Section: Discussionsupporting

confidence: 54%

The structure of the plasma sheet‐lobe boundary in the Earth's magnetotail

Orsini¹,

Candidi²,

Formisano³

et al. 1984

J. Geophys. Res.

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“…Mapping the ionospheric electric field into the tail region, they developed a projection of the magnetospheric electric field in the yz-plane. Specifically away from the nonmidnight meridian in the tail, Rostoker and Boström (1976) reported significant electric fields in the +z-or −z-direction. Note that the current system considered exists at large scales, possibly driven by a large scale MHD generator.…”

Section: Discussionmentioning

confidence: 99%

“…Rostoker and Boström (1976) investigated a MHD generator mechanism for driving the gross Birkeland current system. Mapping the ionospheric electric field into the tail region, they developed a projection of the magnetospheric electric field in the yz-plane.…”

Section: Discussionmentioning

confidence: 99%

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Occurrence and location of concentrated load and generator regions observed by Cluster in the plasma sheet

et al. 2009

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Abstract.Here, and in a companion paper by Hamrin et al. (2009) [Scale size and life time of energy conversion regions observed by Cluster in the plasma sheet], we investigate localized energy conversion regions (ECRs) in the Earth's plasma sheet. In total we have studied 151 ECRs within 660 h of plasma sheet data from the summer and fall of 2001 when Cluster was close to apogee at an altitude of about 15-20 R E . Cluster offers appropriate conditions for the investigation of energy conversion by the evaluation of the power density, E·J , where E is the electric field and J the current density. From the sign of the power density, we have identified more than three times as many Concentrated Load Regions (CLRs) as Concentrated Generator Regions (CGRs). We also note that the CLRs appear to be stronger. To our knowledge, these are the first in situ observations confirming the general notion of the plasma sheet, on the average, behaving as a load. At the same time the plasma sheet appears to be highly structured, with energy conversion occurring in both directions between the fields and the particles. From our data we also find that the CLRs appear to be located closer to the neutral sheet, while CGRs prefer locations towards the plasma sheet boundary layer (PSBL). For both CLRs and CGRs, E and J in the GSM y (cross-tail) direction dominate the total power density, even though the z contribution occasionally can be significant. The prevalence of the y-direction seems to be weaker for the CGRs, possibly related to a higher fluctuation level near the PSBL.

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“…33 Possible cause of the expansion phase as a result of the deflation of the magnetosphere after the magnetosphere is inflated during the growth phase have been published on this subjects (cf. Rostoker and Bostrom 1976;Shiokawa et al 1998;Nakamura et al 2001;Haerendel 2007Haerendel , 2008Haerendel , 2009Birth et al 2012). However, it is important to distinguish between the DD and UL currents in explaining the expansion phase.…”

Section: Possible Processesmentioning

confidence: 99%

Auroral Substorms: Search for Processes Causing the Expansion Phase in Terms of the Electric Current Approach

Akasofu

2017

Space Sci Rev

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Auroral substorms are mostly manifestations of dissipative processes of electromagnetic energy. Thus, we consider a sequence of processes consisting of the power supply (dynamo), transmission (currents/circuits) and dissipations (auroral substorms-the end product), namely the electric current line approach. This work confirms quantitatively that after accumulating magnetic energy during the growth phase, the magnetosphere unloads the stored magnetic energy impulsively in order to stabilize itself. This work is based on our result that substorms are caused by two current systems, the directly driven (DD) current system and the unloading system (UL). The most crucial finding in this work is the identification of the UL (unloading) current system which is responsible for the expansion phase. A very tentative sequence of the processes leading to the expansion phase (the generation of the UL current system) is suggested for future discussions.(1) The solar wind-magnetosphere dynamo enhances significantly the plasma sheet current when its power is increased above 10 18 erg/s (10 11 w). (2) The magnetosphere accumulates magnetic energy during the growth phase, because the ionosphere cannot dissipate the increasing power because of a low conductivity. As a result, the magnetosphere is inflated, accumulating magnetic energy. (3) When the power reaches 3-5 × 10 18 erg/s (3-5 × 10 11 w) for about one hour and the stored magnetic energy reaches 3-5 × 10 22 ergs (10 15 J), the magnetosphere begins to develop perturbations caused by current instabilities (the current density ≈3 × 10 −12 A/cm 2 and the total current ≈10 6 A at 6 Re). As a result, the plasma sheet current is reduced. (4) The magnetosphere is thus deflated. The current reduction causes ∂B/∂t > 0 in the main body of the magnetosphere, producing an earthward electric field. As it is transmitted to the ionosphere, it becomes equatorward-directed electric field which drives both Pedersen and Hall currents and thus generates the UL current system. (6) The substorm intensity depends on the location of the energy accumulation (between 4 Re and 10 Re), the closer the location to the earth, the more intense substorms becomes, because the capacity of holding the energy is higher at closer distances. The convective flow toward the earth brings both the ring current and the plasma sheet current closer when the dynamo power becomes higher.This proposed sequence is not necessarily new. Individual processes involved have been considered by many, but the electric current approach can bring them together systematically and provide some new quantitative insights.

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A mechanism for driving the gross Birkeland current configuration in the auroral oval

Cited by 140 publications

References 37 publications

The structure of the plasma sheet‐lobe boundary in the Earth's magnetotail

The structure of the plasma sheet‐lobe boundary in the Earth's magnetotail

Occurrence and location of concentrated load and generator regions observed by Cluster in the plasma sheet

Auroral Substorms: Search for Processes Causing the Expansion Phase in Terms of the Electric Current Approach

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