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A Pi2-associated dusk-to-dawn currents in the midnight sector as observed at L = 6.6 during multiple Pi2 onsets


We examined the magnetic fields and energetic particle data from geosynchronous satellites GOES 6 and S/C1984-129 during the multiple onset of Pi2. We found that the energetic particle injection in the midnight sector was associated with the consecutive Pi2 onset. The magnetometer on board GOES 6 at the midnight sector detected the increase of the field inclination as well as a decrease of the field magnitudes during the Pi2 events. We suggest that such a field reconfiguration could be provoked by the formation of the dusk-to-dawn currents in the vicinity of the geosynchronous altitudes. The present study supports the Pi2 model that the impulsive dusk-to-dawn current and field-aligned current diverted from it are a source of Pi2 pulsation in the midnight magnetosphere.


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Saka, O., Akaki, H. & Baker, D.N. A Pi2-associated dusk-to-dawn currents in the midnight sector as observed at L = 6.6 during multiple Pi2 onsets. Earth Planet Sp 56, 663–668 (2004).

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Key words

  • Magnetospheric substorm
  • Pi2 onset
  • plasma dynamics
  • geosynchronous altitudes