Flapping current sheet with superposed waves seen in space and on the ground

G. Q. Wang, M. Volwerk, R. Nakamura, P. Boakes, T. L. Zhang, A. Yoshikawa, D. G. Baishev

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22 Citations (Scopus)


A wavy current sheet event observed on 15 October 2004 between 1235 and 1300 UT has been studied by using Cluster and ground-based magnetometer data. Waves propagating from the tail center to the duskside flank with a period ∼30 s and wavelength ∼1 RE are superimposed on a flapping current sheet, accompanied with a bursty bulk flow. Three Pi2 pulsations, with onset at ∼1236, ∼1251, and ∼1255 UT, respectively, are observed at the Tixie station located near the foot points of Cluster. The mechanism creating the Pi2 (period ∼40 s) onset at ∼1236 UT is unclear. The second Pi2 (period ∼90 s, onset at ∼1251 UT) is associated with a strong field-aligned current, which has a strong transverse component of the magnetic field, observed by Cluster with a time delay ∼60 s. We suggest that it is caused by bouncing Alfvén waves between the northern and southern ionosphere which transport the field-aligned current. For the third Pi2 (period ∼60 s) there is almost no damping at the first three periods. They occur in conjunction with periodic field-aligned currents one-on-one with 72 s delay. We suggest that it is generated by these periodic field-aligned currents. We conclude that the strong field-aligned currents generated in the plasma sheet during flapping with superimposed higher-frequency waves can drive Pi2 pulsations on the ground, and periodic field-aligned currents can even control the period of the Pi2s. Key Points Flapping superimposed on waves (∼30 s) are accompanied with BBF during substorm The waves propagate from the tail center to the duskside flank Field-aligned currents drive Pi2s on the ground, even control their period

Original languageEnglish
Pages (from-to)10,078-10,091
JournalJournal of Geophysical Research: Space Physics
Issue number12
Publication statusPublished - Dec 2014

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology


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