Carriers and sources of magnetopause current : MMS case study

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Dong, X. C. and Dunlop, M. W. and Wang, T. Y. and Cao, J. B. and Trattner, K. J. and Bamford, R. and Russell, C. T. and Bingham, R. and Strangeway, R. J. and Fear, R. C. and Giles, B. L. and Torbert, R. B. (2018) Carriers and sources of magnetopause current : MMS case study. Journal of Geophysical Research: Space Physics, 123 (7). pp. 5464-5475. ISSN 2169-9380 (https://doi.org/10.1029/2018JA025292)

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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.

ORCID iDs

Dong, X. C., Dunlop, M. W., Wang, T. Y., Cao, J. B., Trattner, K. J., Bamford, R., Russell, C. T., Bingham, R. ORCID logoORCID: https://orcid.org/0000-0002-9843-7635, Strangeway, R. J., Fear, R. C., Giles, B. L. and Torbert, R. B.;
  • Item type:Article
    ID code:66009
    Dates:
    Date
    Event
    17 July 2018
    Published
    22 June 2018
    Accepted
    Subjects:Science > Physics
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:06 Nov 2018 14:07
    Last modified:27 Nov 2024 01:14
    URI:https://strathprints.strath.ac.uk/id/eprint/66009
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