Effect of Interhemispheric Field-Aligned Currents on Region-1 Currents

Lyatskaya, Sonya; Lyatsky, W.; Khazanov, G. V.

doi:10.1002/2014gl060413

Cited by 10 publications

(16 citation statements)

References 45 publications

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“…Although there may be unbalanced currents [cf. Lyatskaya et al ., ], treating nonzero I Net as erroneous provides an estimate of the random uncertainty in I Total . Statistics of I Total and I Net for both events, denoted E1 and E2, are given in Table together with statistics for the period before each storm, indicated as Pre‐E1 and Pre‐E2.…”

Section: Storm Events Overviewmentioning

confidence: 99%

Comparison of predictive estimates of high‐latitude electrodynamics with observations of global‐scale Birkeland currents

et al. 2017

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Two of the geomagnetic storms for the Space Weather Prediction Center Geospace Environment Modeling challenge occurred after data were first acquired by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE). We compare Birkeland currents from AMPERE with predictions from four models for the 4–5 April 2010 and 5–6 August 2011 storms. The four models are the Weimer (2005b) field‐aligned current statistical model, the Lyon‐Fedder‐Mobarry magnetohydrodynamic (MHD) simulation, the Open Global Geospace Circulation Model MHD simulation, and the Space Weather Modeling Framework MHD simulation. The MHD simulations were run as described in Pulkkinen et al. (2013) and the results obtained from the Community Coordinated Modeling Center. The total radial Birkeland current, ITotal, and the distribution of radial current density, Jr, for all models are compared with AMPERE results. While the total currents are well correlated, the quantitative agreement varies considerably. The Jr distributions reveal discrepancies between the models and observations related to the latitude distribution, morphologies, and lack of nightside current systems in the models. The results motivate enhancing the simulations first by increasing the simulation resolution and then by examining the relative merits of implementing more sophisticated ionospheric conductance models, including ionospheric outflows or other omitted physical processes. Some aspects of the system, including substorm timing and location, may remain challenging to simulate, implying a continuing need for real‐time specification.

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Section: Storm Events Overviewmentioning

confidence: 99%

Comparison of predictive estimates of high‐latitude electrodynamics with observations of global‐scale Birkeland currents

et al. 2017

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“…In previous papers [ Lyatskaya et al ., , ], we showed that during summer/winter conditions, in addition to R1 and R2 currents, also significant IHCs could appear. These IHCs emerge at the gradients of ionospheric conductivity in any hemisphere; it is going along the magnetic field lines between conjugate regions in two hemispheres.…”

Section: Discussion and Main Resultsmentioning

confidence: 71%

“…[] and Lyatskaya et al . []. The Pedersen and Hall ionospheric conductivities due to solar luminosity are approximately equal in magnitude, but they may significantly differ in the case of precipitation of accelerated particles.…”

Section: Description Of the Modelmentioning

confidence: 99%

“…The main goal of this study is to compute the EICs in two ionospheres during the summer/winter conditions (when the IHCs are especially significant) with accounting the IHCs flowing between two conjugate ionospheres (i.e., located at the same field lines in ionospheres of two hemispheres) and compare the computed maps of the EICs with the available observation data. This study is an extension of our previous studies [ Lyatskaya et al ., , ]; it examines the effect of IHCs on EICs in two hemispheres, which was never investigated before.…”

Section: Introductionmentioning

confidence: 99%

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Effect of interhemispheric currents on equivalent ionospheric currents in two hemispheres: Simulation results

2016

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In this research, we used numerical simulation to study the effect of interhemispheric field‐aligned currents (IHCs), going between two conjugate ionospheres in two hemispheres, on the equivalent ionospheric currents (EICs). We computed the maps of these EICs in two hemispheres during summer‐winter conditions, when the effect of the IHCs is especially significant. The main results may be summarized as follows. (1) In winter hemisphere, the IHCs may significantly exceed and be a substitute for the local R1 currents, and they may strongly affect the magnitude, location, and direction of the EICs in the nightside winter auroral ionosphere. (2) While in summer polar cap the EICs tend to flow sunward, and in winter polar cap the EICs turn toward dawn due to the effect of the IHCs. (3) The well‐known reversal in the direction of the EICs in the vicinity of the midnight meridian, in winter hemisphere, is observed not at the polar caps boundary (as usually expected) but equatorward of this boundary in the region of the IHCs location. (4) The IHCs in winter hemisphere may be, in fact, not only a substitute for the R1 currents but also the major source of the Westward Auroral Electrojet, observed in both hemispheres during substorm activity.

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“…Near the neutral plane, field-aligned electron currents would flow along B y , i.e., j y current density can be considered as part of the field-aligned current system connecting to j x away from the neutral plane. Using our observations, we cannot determine what can trigger this electron current or where it can be closed (e.g., being connecting to ionosphere, this current system can become a part of interhemispheric field-aligned currents) [see Lyatskaya et al, 2014]. Because the initial magnetotail CS configuration does not contain such a field-aligned current system, this current may have been formed during the CS thinning.…”

Section: Discussionmentioning

confidence: 99%

Electron currents supporting the near‐Earth magnetotail during current sheet thinning

Artemyev

Angelopoulos

Liu

et al. 2017

Geophysical Research Letters

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Formation of intense, thin current sheets (i.e., current sheet thinning) is a critical process for magnetospheric substorms, but the kinetic physics of this process remains poorly understood. Using a triangular configuration of the three Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft at the end of 2015 we investigate field‐aligned and transverse currents in the magnetotail current sheet around 12 Earth radii downtail. Combining the curlometer technique with direct measurements of ion and electron velocities, we demonstrate that intense, thin current sheets supported by strong electron currents form in this region. Electron field‐aligned currents maximize near the neutral plane Bx∼0, attaining magnitudes of ∼20 nA/m2. Carried by hot (>1 keV) electrons, they generate strong magnetic shear, which contributes up to 20% of the vertical (along the normal direction to the equatorial plane) pressure balance. Electron transverse currents, on the other hand, are carried by the curvature drift of anisotropic, colder (<1 keV) electrons and gradually increase during the current sheet thinning. In the events under consideration the thinning process was abruptly terminated by earthward reconnection fronts which have been previously associated with tail reconnection further downtail. It is likely that the thin current sheet properties described herein are similar to conditions further downtail and are linked to the loss of stability and onset of reconnection there. Our findings are likely applicable to thin current sheets in other geophysical and astrophysical settings.

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Effect of Interhemispheric Field-Aligned Currents on Region-1 Currents

Cited by 10 publications

References 45 publications

Comparison of predictive estimates of high‐latitude electrodynamics with observations of global‐scale Birkeland currents

Comparison of predictive estimates of high‐latitude electrodynamics with observations of global‐scale Birkeland currents

Effect of interhemispheric currents on equivalent ionospheric currents in two hemispheres: Simulation results

Electron currents supporting the near‐Earth magnetotail during current sheet thinning

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