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Electromagnetic response of the mantle to long-period geomagnetic variations over the globe

Abstract

Long-period electromagnetic response must be estimated to derive information on the electrical conductivity distribution within the deep mantle of the Earth. For this, we estimated the electromagnetic response function for long-period geomagnetic variations, on the basis of the P1 approximation. The data used for analyses are geomagnetic daily mean values for 10 years (1965–1974) from 59 stations distributed over the globe and for about 20 years (1960–1980) from 9 stations. It turned out that the P1 approximation generally holds except for the periods corresponding to annual and semi-annual variations. We also found that accurate estimation is difficult for periods longer than a few years, probably because of contamination due to secular variations of core origin.

References

  • Achache, J., J. L. Le Mouël, and V. Courtillot, Long-period geomagnetic variations and mantle conductivity: An inversion using Bailey’s method, Geophys. J. R. Astr. Soc., 65, 579–601, 1981.

    Article  Google Scholar 

  • Banks, R. J., Geomagnetic variations and the electrical conductivity of the upper mantle, Geophys. J. R. Astr. Soc., 17, 457–487, 1969.

    Article  Google Scholar 

  • Banks, R. J., The overall conductivity distribution of the Earth, J. Geomag. Geoelectr., 24, 337–351, 1972.

    Article  Google Scholar 

  • Constable, S., Constraints on mantle electrical conductivity from field and laboratory measurements, J. Geomag. Geoelectr., 45, 707–728, 1993.

    Article  Google Scholar 

  • Currie, R. G., The geomagnetic spectrum–40 days to 5.5 years, J. Geophys. Res., 71, 4579–4598, 1966.

    Article  Google Scholar 

  • Ducruix, J., V. Courtillot, and J. L. Le Mouël, The late 1960’s secular variation impulse, the eleven year magnetic variation and the electrical conductivity of the deep mantle, Geophys. J. R. Astr. Soc., 61, 73–79, 1980.

    Article  Google Scholar 

  • Malin, S. R. C. and A. M. Işıkara, Annual variation of the geomagnetic field, Geophys. J. R. Astr. Soc., 47, 445–457, 1976.

    Article  Google Scholar 

  • Malin, S. R. C., D. E. Winch, and A. M. Işıkara, Semi-annual variation of the geomagnetic field, Abstracts of the 13th Workshop on Electromagnetic Induction in the Earth, Onuma, Hokkaido, Japan, 1996.

    Google Scholar 

  • McLeod, M. G., Signals and noise in magnetic observatory annual means: Mantle conductivity and jerks, J. Geophys. Res., 97, 17,261–17,290, 1992.

    Article  Google Scholar 

  • McLeod, M. G., Magnetospheric and ionospheric signals in magnetic observatory monthly means: Electrical conductivity of the deep mantle, J. Geophys. Res., 99, 13,577–13,590, 1994.

    Article  Google Scholar 

  • Nakagawa, T. and Y. Oyanagi, Analysis of Experimental Data by Least-Square Methods, 206 pp., Univ. Tokyo Press, 1982 (in Japanese).

  • Roberts, R. G., The long-period electromagnetic response of the Earth, Geophys. J. R. Astr. Soc., 78, 547–572, 1984.

    Article  Google Scholar 

  • Schultz, A. and L. C. Larsen, Analysis of zonal field morphology and data quality for a global set of magnetic observatory daily mean values, J. Geomag. Geoelectr., 35, 835–846, 1983.

    Article  Google Scholar 

  • Schultz, A. and L. C. Larsen, On the electrical conductivity of the midmantle—I. Calculation of equivalent scalar magnetotelluric response functions, Geophys. J. R. Astr. Soc., 88, 731–761, 1987.

    Article  Google Scholar 

  • Shankland, T. J., J. Peyronneau, and J.-P. Poirier, Electrical conductivity of the Earth’s lower mantle, Nature, 366, 453–455, 1993.

    Article  Google Scholar 

  • Tukey, J. W., Introduction to today’s data analysis, in Proceedings of the Conference on Critical Evaluation of Chemical and Physical Structural Information, edited by D. R. Lide, Jr. and M. A. Paul, pp. 3–14, National Academy of Sciences, Washington, 1974.

    Google Scholar 

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Correspondence to Yoshimori Honkura.

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Honkura, Y., Matsushima, M. Electromagnetic response of the mantle to long-period geomagnetic variations over the globe. Earth Planet Sp 50, 651–662 (1998). https://doi.org/10.1186/BF03352160

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  • DOI: https://doi.org/10.1186/BF03352160

Keywords

  • Response Function
  • Annual Variation
  • Secular Variation
  • Frequency Response Function
  • Lower Mantle