How to distinguish between kink and sausage modes in flapping oscillations?

Тип публикации: статья из журнала

Год издания: 2014

Идентификатор DOI: 10.1002/2013JA019477

Ключевые слова: ,plasma sheet;,Flapping waves;,bnnmbm6

Аннотация: Flapping waves are most noticeable large-scale perturbations of the magnetotail current sheet, whose nature is still under discussion. They represent rather slow (an order of magnitude less than typical Alfven speed) waves propagating from the center of the sheet to its flanks with a typical speed of 20-60 km/s, amplitude of 1-2 R-e and quasiperiod of 2-10 min. The double-gradient MHD model, which was elaborated in Erkaev et al. (2007) predicts two (kink and sausage) modes of the flapping waves with differences in their geometry and propagation velocity, but the mode structure is hard to resolve observationally. We investigate the possibility of mode identification by observing the rotation of magnetic field and plasma velocity vectors from a single spacecraft. We test theoretical results by analyzing the flapping oscillations observed by Time History of Events and Macroscale Interactions during Substorms spacecraft and confirm that character of observed rotation is consistent with kink mode determination made by using multispacecraft methods. Also, we checked how the existence of some obstructive conditions, such as noise, combined modes, and multiple sources of the flapping oscillations, can affect on the possibility of the modes separation with suggested method.

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Издание

Журнал: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS

Выпуск журнала: Vol. 119, Is. 4

Номера страниц: 3002-3015

ISSN журнала: 21699380

Место издания: WASHINGTON

Издатель: AMER GEOPHYSICAL UNION

Авторы

  • Kubyshkina D.I. (St Petersburg State Univ, Earth Phys Dept, Fac Sci, St Petersburg 199034, Russia)
  • Sormakov D.A. (Arctic & Antarctic Res Inst, St Petersburg 199226, Russia)
  • Sergeev V.A. (St Petersburg State Univ, Earth Phys Dept, Fac Sci, St Petersburg 199034, Russia)
  • Semenov V.S. (St Petersburg State Univ, Earth Phys Dept, Fac Sci, St Petersburg 199034, Russia)
  • Erkaev N.V. (Inst Computat Modelling SB RAS, Krasnoyarsk, Russia; Siberian Fed Univ, Dept Appl Mech, Polytech Inst, Krasnoyarsk, Russia)
  • Kubyshkin I.V. (St Petersburg State Univ, Earth Phys Dept, Fac Sci, St Petersburg 199034, Russia)
  • Ganushkina N.Yu (Finnish Meteorol Inst, FIN-00101 Helsinki, Finland; Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA)
  • Dubyagin S.V. (Finnish Meteorol Inst, FIN-00101 Helsinki, Finland)

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