Earth, Planets and Space

, Volume 54, Issue 2, pp 119–131 | Cite as

Local time features of geomagnetic jerks

  • Hiromichi Nagao
  • Toshihiko Iyemori
  • Tomoyuki Higuchi
  • Shin’ya Nakano
  • Tohru Araki
Open Access
Article

Abstract

The geomagnetic jerk amplitudes, which are defined as abruptness of changes in the trends of geomagnetic time series, are investigated with geomagnetic monthly means computed from hourly mean values at each local time. A statistical time series model in which the trend component is expressed by a second order spline function with variable knots is constructed for each time series. The optimum parameter values of the model including positions of knots are estimated by the maximum likelihood method, and the optimum number of parameters including the number of knots are determined based on the Akaike Information Criterion (AIC). The jerks are detected objectively and automatically by regarding the optimized positions of knots as the occurrence epochs. This analysis reveals that the spatial distributions of jerk amplitudes essentially do not depend on the local time, which indicates that the jerks cannot be explained by abrupt changes in intensities of latitudinally flowing external currents such as the field-aligned currents. Longitudinally flowing currents, on the other hand, such as the ring current could explain the distributions. The abrupt changes of the ring current intensity are estimated from the distributions of jerk amplitudes in the eastward component in 1969, 1978, and 1991 supposing that an abrupt change in the ring current intensity causes a jerk. However those estimated changes cannot consistently explain the distributions of the jerks in the northward and downward components. Therefore it is plausible that the jerks which occurred in 1969, 1978, and 1991 are not caused by external sources but internal ones. It is also confirmed that the occurrence epochs of jerks in the southern hemisphere are a few years after those of the 1969 and 1978 jerks in the northern hemisphere, and it is also found that the jerk in the southern hemisphere occurred a few years after the occurrence of the 1991 jerk in Europe. Taking these time lags in occurrence epochs into account, it can be said that the 1969, 1978, and 1991 jerks are global phenomena.

Keywords

Local Time Occurrence Rate Secular Variation Trend Component Geomagnetic Jerk 

References

  1. Achache, J., V. Courtillot, J. Ducruix, and J.-L. Le Mouël, The late 1960s secular variation impulse: further constraints on deep mantle conductivity, Phys. Earth Planet. Int., 23, 72–75, 1980.CrossRefGoogle Scholar
  2. Alexandrescu, M., D. Gibert, G. Hulot, J.-L. Le Mouël, and G. Saracco, Detection of geomagnetic jerks using wavelet analysis, J. Geophys. Res., 100, 12557–12572, 1995.CrossRefGoogle Scholar
  3. Alexandrescu, M., D. Gibert, G. Hulot, J.-L. Le Mouël, and G. Saracco, Worldwide wavelet analysis of geomagnetic jerks, J. Geophys. Res., 101, 21975–21994, 1996.CrossRefGoogle Scholar
  4. Alldredge, L. R., A discussion of impulses and jerks in the geomagnetic field, J. Geophys. Res., 89, 4403–4412, 1984.CrossRefGoogle Scholar
  5. Alldredge, L. R., More on the alleged 1970 geomagnetic jerk, Phys. Earth Planet. Int., 39, 255–264, 1985.CrossRefGoogle Scholar
  6. Anderson, B. D. O. and J. B. Moore, Optimal Filtering, Prentice-Hall, 1979.Google Scholar
  7. Backus, G. E., Application of mantle filter theory to the magnetic jerk of 1969, Geophys. J. R. astr. Soc., 74, 713–746, 1983.Google Scholar
  8. Cafarella, L. and A. Meloni, Evidence for a geomagnetic jerk in 1990 across Europe, Annali di Geofisica, XXXVIII, 451–455, 1995.Google Scholar
  9. Courtillot, V., J. Ducruix, and J.-L. Le Mouël, Sur une accélération récente de la variation séculaire du champ magnétique terrestre, C. R. Acad. Série D, 1095–1098, 1978.Google Scholar
  10. Davis, R. G. and K. A. Whaler, The 1969 geomagnetic impulse and spin-up of the Earth’s liquid core, Phys. Earth Planet. Int., 103, 181–194, 1997.CrossRefGoogle Scholar
  11. De Michelis, P., L. Cafarella, and A. Meloni, Worldwide character of the 1991 geomagnetic jerk, Geophys. Res. Lett., 25, 377–380, 1998.CrossRefGoogle Scholar
  12. Ducruix, J., V. Courtillot, and J.-L. Le Mouël, The late 1960s secular variation impulse, the eleven year magnetic variation and the electrical conductivity of the deep mantle, Geophys. J. R. astr. Soc., 61, 73–94, 1980.CrossRefGoogle Scholar
  13. Gavoret, J., D. Gibert, M. Menvielle, and J.-L. LeMouël, Long-term variations of the external and internal components of the earth’s magnetic field, J. Geophys. Res., 91, 4787–4796, 1986.CrossRefGoogle Scholar
  14. Golovkov, V. P., T. I. Zvereva, and A. O. Simonyan, Common features and differences between “jerks” of 1947, 1958 and 1969, Geophys. Astrophys. Fluid Dyn., 49, 81–96, 1989.CrossRefGoogle Scholar
  15. Gubbins, D. and L. Tomlinson, Secular variation from monthly means from Apia and Amberley magnetic observatories, Geophys. J. R. astr. Soc., 86, 603–616, 1986.CrossRefGoogle Scholar
  16. Higuchi, T. and S. Ohtani, Automatic identification of large-scale field-aligned current structures, J. Geophys. Res., 105, 25305–25315, 2000.CrossRefGoogle Scholar
  17. Kerridge, D. J. and D. R. Barraclough, Evidence for geomagnetic jerks from 1931 to 1971, Phys. Earth Planet. Int., 39, 228–236, 1985.CrossRefGoogle Scholar
  18. Kitagawa, G. and W. Gersch, Smoothness priors analysis of time series, Lecture Notes in Statistics, 116, Springer-Verlag, New York, 1996.Google Scholar
  19. Le Huy, M., M. Alexandrescu, G. Hulot, and J.-L. Le Mouël, On the characteristics of successive geomagnetic jerks, Earth Planets Space, 50, 723–732, 1998.CrossRefGoogle Scholar
  20. Le Huy, M., M. Mandea, J.-L. Le Mouël, and A. Pais, Time evolution of the field flow at the top of the core. Geomagnetic jerks, Earth Planets Space, 52, 163–173, 2000.CrossRefGoogle Scholar
  21. Le Mouël, J.-L. and V. Courtillot, Core motions, electromagnetic core-mantle coupling and variations in the earth’s rotation: new constraints from geomagnetic secular variation impulses, Phys. Earth Planet. Int., 24, 236–241, 1981.CrossRefGoogle Scholar
  22. Le Mouël, J.-L., J. Ducruix, and C. H. Duyen, The worldwide character of the 1969–1970 impulse of the secular acceleration rate, Phys. Earth Planet. Int., 28, 337–350, 1982.CrossRefGoogle Scholar
  23. Macmillan, S., A geomagnetic jerk for the early 1990s, Earth Planet. Sci. Lett., 137, 189–192, 1996.CrossRefGoogle Scholar
  24. Malin, S. R. C. and B. M. Hodder, Was the 1970 geomagnetic jerk of internal or external origin?, Nature, 296, 726–728, 1982.CrossRefGoogle Scholar
  25. Mandea Alexandrescu, M., D. Gibert, J.-L. Le Mouël, G. Hulot, and G. Saracco, An estimate of average lower mantle conductivity by wavelet analysis of geomagnetic jerks, J. Geophys. Res., 104, 17735–17745, 1999.CrossRefGoogle Scholar
  26. Mandea, M., E. Bellanger, and J.-L. Le Mouël, A geomagnetic jerk for the end of the 20th century?, Earth Planet. Sci. Lett., 183, 369–373CrossRefGoogle Scholar
  27. McLeod, M. G., On the geomagnetic jerk of 1969, J. Geophys. Res., 90, 4597–4610, 1985.CrossRefGoogle Scholar
  28. McLeod, M. G., Signals and noise in magnetic observatory annual means: mantle conductivity and jerks, J. Geophys. Res., 97, 17261–17290, 1992.CrossRefGoogle Scholar
  29. Nevanlinna, H. and C. Sucksdorff, Impulse in global geomagnetic “secular variation”, 1977–1979, J. Geophys., 50, 68–69, 1981.Google Scholar
  30. Press, W. H., B. P. Flannery, S. A. Teukolsky, and W. T. Vetterling, Numerical Recipes: The Art of Scientific Computing, Cambridge University Press, 1986.Google Scholar
  31. Stewart, D. N. and K. A. Whaler, Optimal piecewise regression analysis and its application to geomagnetic time series, Geophys. J. Int., 121, 710–724, 1995.CrossRefGoogle Scholar
  32. Thompson, D. and J. C. Cain, The geomagnetic jerk of 1969 and the DGRFs, Phys. Earth Planet. Int., 48, 386–388, 1987.CrossRefGoogle Scholar
  33. Whaler, K. A., A new method for analysing geomagnetic impulses, Phys. Earth Planet. Int., 48, 221–240, 1987.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. 2002

Authors and Affiliations

  • Hiromichi Nagao
    • 1
  • Toshihiko Iyemori
    • 2
  • Tomoyuki Higuchi
    • 3
  • Shin’ya Nakano
    • 1
  • Tohru Araki
    • 1
  1. 1.Department of Geophysics, Graduate School of ScienceKyoto UniversityKyotoJapan
  2. 2.Data Analysis Center for Geomagnetism and Space Magnetism, Graduate School of ScienceKyoto UniversityKyotoJapan
  3. 3.The Institute of Statistical MathematicsTokyoJapan

Personalised recommendations