Slow mode structure in the nightside magnetosheath related to IMF draping

Тип публикации: статья из журнала

Год издания: 2014

Идентификатор DOI: 10.1002/2013JA019514

Ключевые слова: IMF draping, slow mode wave in distant tail

Аннотация: We apply a semianalytic magnetohydrodynamic approach to describe effects in the nightside magnetosheath related to accelerated magnetosheath flows caused by the draping of interplanetary magnetic field (IMF). Assuming a northward IMF direction, we show the development of slow mode fronts in the far tail (tailward of approximately -60 RmE). We find that accelerated flows north and south of the equator start to converge toward lower latitudes. The ensuing plasma compression gives rise to slow mode waves in the equatorial region which, further down the tail, evolve into slow mode shocks. These fronts propagating along the magnetic field lines are characterized by sharp increases of plasma density, pressure, and temperature and a decrease in the magnetic field strength. The magnetic pressure exhibits an anticorrelation with the plasma pressure, but the total pressure is fairly constant across the fronts. The field-aligned plasma velocity component anticorrelates with the plasma density, while the perpendicular velocity component does not have sharp variations at the fronts. For northward IMF, these fronts appear near the equatorial region and then propagate to higher latitudes. This effect is not very sensitive to the particular shape of the magnetopause. Lowering the upstream Alfven Mach number increases the strength of the slow mode waves, which also develop closer to Earth. We predict that this effect can be observed by space probes skimming the far tail. Key Points <list list-type="bulleted"><list-item id="jgra50856-li-0001">Magnetic field lines drape around the magnetosphere <list-item id="jgra50856-li-0002">The field line bend makes the flows converge in the far tail <list-item id="jgra50856-li-0003">We show that these give rise to slow mode waves</list-item></list-item></list-item></list>

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Издание

Журнал: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS

Выпуск журнала: Vol. 119, Is. 2

Номера страниц: 1121-1128

ISSN журнала: 21699380

Место издания: WASHINGTON

Издатель: AMER GEOPHYSICAL UNION

Авторы

  • Erkaev N.V. (Siberian Federal University)
  • Mezentsev A.V. (Siberian Federal University)
  • Farrugia C.J. (Space Science Center and Department of Physics, University of New Hampshire)
  • Torbert R.B. (Space Science Center and Department of Physics, University of New Hampshire)
  • Biernat H.K. (Institute of Physics, Karl-Franzens-University of Graz)

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