Advertisement

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
Letter

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.

Key words

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

References

  1. Araki, T., Global structure of geomagnetic sudden commencements, Planet. Space Sci., 25, 373–384, 1977.CrossRefGoogle Scholar
  2. Araki, T., A physical model of geomagnetic sudden commencement, Geo-phys. Monogr., 81, AGU, 183–200, 1994.Google Scholar
  3. Araki, T., K. Keika, T. Kamei, H. Yang, and S. Alex, Nighttime enhancement of the amplitude of geomagnetic sudden commencement and its dependence on IMF-Bz, Earth Planets Space, 58, 45–50, 2006.CrossRefGoogle Scholar
  4. Ferraro, V. C. A. and H. W. Unthank, Sudden commencements and sudden impulses in geomagnetism: their diurnal variation in amplitude, Geofis. Pure Appl., 20, 2730, 1951.Google Scholar
  5. Fujita, S., T. Tanaka, T. Kikuchi, K. Fujimoto, K. Hosokawa, and M. Itonaga, A numerical simulation of the geomagnetic sudden commencement: 1. Generation of the field-aligned current associated with the preliminary impulse, J. Geophys. Res., 108(A12), 1416, doi:10. 1029/2002JA009407, 2003a.CrossRefGoogle Scholar
  6. Fujita, S., T. Tanaka, T. Kikuchi, K. Fujimoto, and M. Itonaga, A numerical simulation of the geomagnetic sudden commencement: 2. Plasma processes in the main impulse, J. Geophys. Res., 108(A12), 1417, doi:10. 1029/2002JA009763, 2003b.CrossRefGoogle Scholar
  7. Fujita, S., T. Tanaka, and T. Motoba, A numerical simulation of the geomagnetic sudden commencement: 3. A sudden commencement in the magnetosphere-ionosphere compound system, J. Geophys. Res., 110, doi:10.1029/2005JA011055, 2005.Google Scholar
  8. Kikuchi, T. and T. Araki, Horizontal transmission of the polar electric field, J. Atmos. Terr. Phys., 41, 927–936, 1979.CrossRefGoogle Scholar
  9. Kikuchi, T. and T. Araki, Preliminary positive impulse of geomagnetic sudden commencement observed at dayside middle and low latitudes, J. Geophys. Res., 90, 12195–12200, 1985.CrossRefGoogle Scholar
  10. Kikuchi, T., T. Araki, K. Maekawa, and H. Maeda, Transmission of polar electric field to the equator, Nature, 273, 650–651, 1978.CrossRefGoogle Scholar
  11. Kikuchi, T., S. Tsunomura, K. Hashimoto, and K. Nozaki, Field-alinged current effects on mid-latitude geomagnetic sudden commencements, J. Geophys. Res., 106, 15555–15565, 2001.CrossRefGoogle Scholar
  12. Kokubun, S., Characteristics of storm sudden commencement at geostationary orbit, J. Geophys. Res., 88, 10025–10033, 1983.CrossRefGoogle Scholar
  13. Kuwashima, M., S. Tsunomura, and H. Fukunishi, SSC associated magnetic variations at the geosynchronous altitude, J. Atmos. Terr. Phys., 47, 451–461, 1985.CrossRefGoogle Scholar
  14. Osada, S., Numerical calculation of the geomagnetic sudden commencement, Master’s Thesis, Faculty of Science, Kyoto University, 1992.Google Scholar
  15. Russell, C. T., M. Ginskey, S. Petrinec, and G. Le, The effects of solar wind dynamic pressure changes on low and mid-latitude magnetic records, Geophys. Res. Lett., 19, 1227–1230, 1992.CrossRefGoogle Scholar
  16. Russell, C. T., M. Ginskey, and S. Petrinec, Sudden impulses at low latitude stations: Steady state response for southward interplanetary magnetic field, J. Geophys. Res., 99, 13403–13408, 1994.CrossRefGoogle Scholar
  17. Shinbori, A., Y. Tsuji, T. Kikuchi, T. Araki, and S. Watari, Magnetic latitude and local time dependence of the amplitude of geomagnetic sudden commencement, J. Geophys. Res., 2009 (accepted).Google Scholar
  18. Tamao, T., Hydromagnetic interpretation of geomagnetic ssc*, Rep. Ionosp. Space Res. Japan, 18, 16–31, 1964.Google Scholar
  19. Tsunomura, S., Characteristics of geomagnetic sudden commencement observed in middle and low latitudes, Earth Planets Space, 50, 755–772, 1998.CrossRefGoogle Scholar
  20. Tsunomura, S., Numerical analysis of global ionospheric current system including the effect of equatorial enhancement, Ann. Geophys., 17, 692–706, 1999.CrossRefGoogle Scholar
  21. Tsunomura, S. and T. Araki, Numerical analysis of equatorial enhancement of geomagnetic sudden commencement, Planet. Space Sci., 32, 599–604, 1984.CrossRefGoogle Scholar

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

Personalised recommendations