Earth, Planets and Space

, Volume 61, Issue 4, pp e13–e16 | Cite as

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

Open Access


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.

Key words

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


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Copyright information

© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB. 2009

Authors and Affiliations

  1. 1.SOA Key Laboratory for Polar SciencePolar Research Institute of ChinaShanghaiChina
  2. 2.Japan Meteorological AgencyTokyoJapan
  3. 3.Solar Terrestrial Environmental LaboratoryNagoya UniversityNagoyaJapan

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