Carriers and sources of magnetopause current: MMS case study

X. C. Dong, M. W. Dunlop, T. Y. Wang, J. B. Cao, K. J. Trattner, R. Bamford, C. T. Russell, R. Bingham, R. J. Strangeway, R. C. Fear, B. L. Giles, R. B. Torbert

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

We investigate the current carriers and current sources of an ion scale tangential magnetopause current layer using the Magnetospheric Multiscale four spacecraft data. Within this magnetopause current layer, ions and electrons equally contribute to the perpendicular current, while electrons carry nearly all the parallel current. The energy range of all these current carriers is predominantly from middle to high (>100 eV), where particles with higher energies are more efficient in producing the current. By comparing each term, two-fluid magnetohydrodynamic (MHD) theory is able to describe the current sources to a large degree because the sum of all the perpendicular currents from MHD theory could account for the currents observed. In addition, we find that the ion diamagnetic current is the main source of the total perpendicular current, while the curvature current can be neglected. Nevertheless, ions and electrons both carry comparable current due to the redistribution of the electric field and show features beyond the classic Chapman-Ferraro model, particularly on the front side of the boundary layer where the electric field reversal is most intense. We also show a second, comparative event in which ions do not satisfy MHD theory, while the electrons do. The small-scale, adiabatic parameter (square of curvature radius/gyroradius) supports our interpretation that this second event contains ion scale substructure. We suggest that comparing the predicted MHD current with plasma current can be a good method to judge whether the MHD theory is satisfied in each specific circumstance, especially for high-precision Magnetospheric Multiscale data.

LanguageEnglish
Pages5464-5475
Number of pages12
JournalJournal of Geophysical Research: Space Physics
Volume123
Issue number7
DOIs
Publication statusPublished - 17 Jul 2018

Fingerprint

Magnetopause
multimission modular spacecraft
magnetopause
Magnetohydrodynamics
Ions
ions
case studies
magnetohydrodynamics
electrons
ion
Electrons
electric field
electron
Electric fields
curvature
energy
Spacecraft
Boundary layers
Plasmas
Fluids

Keywords

  • current carriers
  • current sources
  • magnetopause current
  • two-fluid MHD

Cite this

Dong, X. C., Dunlop, M. W., Wang, T. Y., Cao, J. B., Trattner, K. J., Bamford, R., ... Torbert, R. B. (2018). Carriers and sources of magnetopause current: MMS case study. Journal of Geophysical Research: Space Physics, 123(7), 5464-5475. https://doi.org/10.1029/2018JA025292
Dong, X. C. ; Dunlop, M. W. ; Wang, T. Y. ; Cao, J. B. ; Trattner, K. J. ; Bamford, R. ; Russell, C. T. ; Bingham, R. ; Strangeway, R. J. ; Fear, R. C. ; Giles, B. L. ; Torbert, R. B. / Carriers and sources of magnetopause current : MMS case study. In: Journal of Geophysical Research: Space Physics. 2018 ; Vol. 123, No. 7. pp. 5464-5475.
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Dong, XC, Dunlop, MW, Wang, TY, Cao, JB, Trattner, KJ, Bamford, R, Russell, CT, Bingham, R, Strangeway, RJ, Fear, RC, Giles, BL & Torbert, RB 2018, 'Carriers and sources of magnetopause current: MMS case study' Journal of Geophysical Research: Space Physics, vol. 123, no. 7, pp. 5464-5475. https://doi.org/10.1029/2018JA025292

Carriers and sources of magnetopause current : MMS case study. / Dong, X. C.; Dunlop, M. W.; Wang, T. Y.; Cao, J. B.; Trattner, K. J.; Bamford, R.; Russell, C. T.; Bingham, R.; Strangeway, R. J.; Fear, R. C.; Giles, B. L.; Torbert, R. B.

In: Journal of Geophysical Research: Space Physics, Vol. 123, No. 7, 17.07.2018, p. 5464-5475.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Carriers and sources of magnetopause current

T2 - Journal of Geophysical Research: Space Physics

AU - Dong, X. C.

AU - Dunlop, M. W.

AU - Wang, T. Y.

AU - Cao, J. B.

AU - Trattner, K. J.

AU - Bamford, R.

AU - Russell, C. T.

AU - Bingham, R.

AU - Strangeway, R. J.

AU - Fear, R. C.

AU - Giles, B. L.

AU - Torbert, R. B.

PY - 2018/7/17

Y1 - 2018/7/17

N2 - We investigate the current carriers and current sources of an ion scale tangential magnetopause current layer using the Magnetospheric Multiscale four spacecraft data. Within this magnetopause current layer, ions and electrons equally contribute to the perpendicular current, while electrons carry nearly all the parallel current. The energy range of all these current carriers is predominantly from middle to high (>100 eV), where particles with higher energies are more efficient in producing the current. By comparing each term, two-fluid magnetohydrodynamic (MHD) theory is able to describe the current sources to a large degree because the sum of all the perpendicular currents from MHD theory could account for the currents observed. In addition, we find that the ion diamagnetic current is the main source of the total perpendicular current, while the curvature current can be neglected. Nevertheless, ions and electrons both carry comparable current due to the redistribution of the electric field and show features beyond the classic Chapman-Ferraro model, particularly on the front side of the boundary layer where the electric field reversal is most intense. We also show a second, comparative event in which ions do not satisfy MHD theory, while the electrons do. The small-scale, adiabatic parameter (square of curvature radius/gyroradius) supports our interpretation that this second event contains ion scale substructure. We suggest that comparing the predicted MHD current with plasma current can be a good method to judge whether the MHD theory is satisfied in each specific circumstance, especially for high-precision Magnetospheric Multiscale data.

AB - We investigate the current carriers and current sources of an ion scale tangential magnetopause current layer using the Magnetospheric Multiscale four spacecraft data. Within this magnetopause current layer, ions and electrons equally contribute to the perpendicular current, while electrons carry nearly all the parallel current. The energy range of all these current carriers is predominantly from middle to high (>100 eV), where particles with higher energies are more efficient in producing the current. By comparing each term, two-fluid magnetohydrodynamic (MHD) theory is able to describe the current sources to a large degree because the sum of all the perpendicular currents from MHD theory could account for the currents observed. In addition, we find that the ion diamagnetic current is the main source of the total perpendicular current, while the curvature current can be neglected. Nevertheless, ions and electrons both carry comparable current due to the redistribution of the electric field and show features beyond the classic Chapman-Ferraro model, particularly on the front side of the boundary layer where the electric field reversal is most intense. We also show a second, comparative event in which ions do not satisfy MHD theory, while the electrons do. The small-scale, adiabatic parameter (square of curvature radius/gyroradius) supports our interpretation that this second event contains ion scale substructure. We suggest that comparing the predicted MHD current with plasma current can be a good method to judge whether the MHD theory is satisfied in each specific circumstance, especially for high-precision Magnetospheric Multiscale data.

KW - current carriers

KW - current sources

KW - magnetopause current

KW - two-fluid MHD

U2 - 10.1029/2018JA025292

DO - 10.1029/2018JA025292

M3 - Article

VL - 123

SP - 5464

EP - 5475

JO - Journal of Geophysical Research: Space Physics

JF - Journal of Geophysical Research: Space Physics

SN - 2169-9402

IS - 7

ER -

Dong XC, Dunlop MW, Wang TY, Cao JB, Trattner KJ, Bamford R et al. Carriers and sources of magnetopause current: MMS case study. Journal of Geophysical Research: Space Physics. 2018 Jul 17;123(7):5464-5475. https://doi.org/10.1029/2018JA025292