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Local time variation of the amplitude of geomagnetic sudden commencements (SC) and SC-associated polar cap potential

Abstract

Local time (LT) variations of the averaged H-component amplitude of geomagnetic sudden commencements (SCs) observed at Memambetsu (geomagnetic latitude 35.4°) are derived separately for the summer and winter season. The amplitude was found to be higher at nighttime than daytime in both seasons, and the LT variations showed a good agreement with calculated LT variations of the resultant magnetic field due to a pair of fieldaligned currents (FACs) and ionospheric currents produced by the FACs. The DL- and DP-component of the disturbance field of SC can be separated based on a comparison of the observed and calculated LT variations. A method is introduced by which we can estimate the potential voltage difference associated with the FACs in the polar cap.

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Correspondence to T. Araki.

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Araki, T., Tsunomura, S. & Kikuchi, T. Local time variation of the amplitude of geomagnetic sudden commencements (SC) and SC-associated polar cap potential. Earth Planet Sp 61, e13–e16 (2009). https://doi.org/10.1186/BF03353154

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Key words

  • Geomagnetic sudden commencement (SC)
  • LT variation
  • field-aligned current
  • ionospheric current
  • interplanetary shock