Effect of electrojet irregularities on DC current flow

Buchert, Stephan; Hagfors, T.; McKenzie, J. F.

doi:10.1029/2004ja010788

Cited by 8 publications

(34 citation statements)

References 28 publications

(31 reference statements)

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“…Plasma turbulence, however, can directly modify local ionospheric conductivities via a wave‐induced nonlinear current (NC) associated with plasma density irregularities [ Rogister and Jamin , 1975; Oppenheim , 1997; Buchert et al , 2006]. The physical nature of the NC is explained in Figure 1 for magnetized electrons and unmagnetized ions.…”

Section: Introductionmentioning

confidence: 99%

Magnetosphere-ionosphere coupling throughEregion turbulence: 1. Energy budget

Dimant

Oppenheim

2011

J. Geophys. Res.

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During periods of intense geomagnetic activity, strong electric fields and currents penetrate from the magnetosphere into the high‐latitude ionosphere, where they dissipate energy, form electrojets, and excite plasma instabilities in the E region ionosphere. These instabilities give rise to plasma turbulence which induces nonlinear currents and strong anomalous electron heating (AEH) as observed by radars. These two effects can increase the global ionospheric conductances. This paper analyzes the energy budget in the electrojet. Employing first principles, this paper proves for the general case an earlier conjecture that the source of energy for plasma turbulence and anomalous heating equals the work by external field on the nonlinear current. Using a two‐fluid model of an arbitrarily magnetized plasma and the quasi‐linear approximation, this paper describes the energy conversion process, calculates the partial sources of anomalous heating, and reconciles the apparent contradiction between the inherently 2‐D nonlinear current and the 3‐D nature of AEH.

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Section: Introductionmentioning

confidence: 99%

Magnetosphere-ionosphere coupling throughEregion turbulence: 1. Energy budget

Dimant

Oppenheim

2011

J. Geophys. Res.

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“…The dissipation and generation of electromagnetic power by fields and currents of the irregularities themselves do on average out to zeroe (Buchert et al, 2006). Because only the mean current and velocities are needed here, we omit from now on the brackets.…”

Section: Discussionmentioning

confidence: 99%

“…The heating is caused by dissipative Pedersen currents closing field-aligned current and so extracting and converting kinetic power from plasma convection in the near Earth space. While the ion Pedersen current is due to classical collisions between ions and neutrals, the electron current in the electrojet is affected by irregularities and plasma turbulence existing in the presence of high electric fields (Buchert et al, 2006). The effect can be parameterized by an anomalous collision frequency, that turns the mean electron velocity from the E ×B direction towards −E , exactly like ion-electron collisions.…”

Section: Discussionmentioning

confidence: 99%

“…j P closes field-aligned current, causing a divergence of the downward field-aligned Poynting flux, and it taps power from the free energy reservoir of plasma convection in the huge near Earth space. Buchert et al (2006) expected that this would have a much larger effect on the effective conductivities than the increase of T e . But how strongly the effective σ P and σ H would change in response to increasing |E ⊥ | and to the corresponding excitation of irregularities, remained unclear to some extent.…”

Section: Introductionmentioning

confidence: 99%

“…They also included an anomalous collision frequency, obtained from microphysical considerations (Sudan, 1983) and the heating formula by Robinson (1986), in the calculation of the effective conductivities. Buchert et al (2006) showed that electrojet irregularities affect directly the mean current (DC), j , which is averaged over spatial and temporal scales that are large compared to those of the irregularities. When warmer electrons collide (mainly inelastically) with neutral molecules, then power is converted into heat and transfered to the neutral gas.…”

Section: Introductionmentioning

confidence: 99%

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The Pedersen current carried by electrons: a non-linear response of the ionosphere to magnetospheric forcing

et al. 2008

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Abstract.Observations by the EISCAT Svalbard radar show that electron temperatures T e in the cusp electrojet reach up to about 4000 K. The heat is tapped and converted from plasma convection in the near Earth space by a Pedersen current that is carried by electrons due to the presence of irregularities and their demagnetising effect. The heat is transfered to the neutral gas by collisions. In order to enhance T e to such high temperatures the maximally possible dissipation at 50% demagnetisation must nearly be reached. The effective Pedersen conductances are found to be enhanced by up to 60% compared to classical values. Conductivities and conductances respond significantly to variations of the electric field strength E, and "Ohm's law" for the ionosphere becomes non-linear for large E.

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Effects of electrojet turbulence on a magnetosphere‐ionosphere simulation of a geomagnetic storm

et al. 2017

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Ionospheric conductance plays an important role in regulating the response of the magnetosphere‐ionosphere system to solar wind driving. Typically, models of magnetosphere‐ionosphere coupling include changes to ionospheric conductance driven by extreme ultraviolet ionization and electron precipitation. This paper shows that effects driven by the Farley‐Buneman instability can also create significant enhancements in the ionospheric conductance, with substantial impacts on geospace. We have implemented a method of including electrojet turbulence (ET) effects into the ionospheric conductance model utilized within geospace simulations. Our particular implementation is tested with simulations of the Lyon‐Fedder‐Mobarry global magnetosphere model coupled with the Rice Convection Model of the inner magnetosphere. We examine the impact of including ET‐modified conductances in a case study of the geomagnetic storm of 17 March 2013. Simulations with ET show a 13% reduction in the cross polar cap potential at the beginning of the storm and up to 20% increases in the Pedersen and Hall conductance. These simulation results show better agreement with Defense Meteorological Satellite Program observations, including capturing features of subauroral polarization streams. The field‐aligned current (FAC) patterns show little differences during the peak of storm and agree well with Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) reconstructions. Typically, the simulated FAC densities are stronger and at slightly higher latitudes than shown by AMPERE. The inner magnetospheric pressures derived from Tsyganenko‐Sitnov empirical magnetic field model show that the inclusion of the ET effects increases the peak pressure and brings the results into better agreement with the empirical model.

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Effect of electrojet irregularities on DC current flow

Cited by 8 publications

References 28 publications

Magnetosphere-ionosphere coupling throughEregion turbulence: 1. Energy budget

Magnetosphere-ionosphere coupling throughEregion turbulence: 1. Energy budget

The Pedersen current carried by electrons: a non-linear response of the ionosphere to magnetospheric forcing

Effects of electrojet turbulence on a magnetosphere‐ionosphere simulation of a geomagnetic storm

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