Skip to main content

A method for the interpretation of three-dimensional equatorial GDV fields

Abstract

The equatorial GDV fields have been widely measured in North-South magnetometer chains and the data so obtained interpreted by assuming that these variations are bi-dimensional. This hypothesis limits its application to the inference of the noon amplitude of the ionospheric current and to the case on which the suspected local Earth’s structure does not have discontinuities running along the direction normal to that of the electrojet current vector. In this work we develop a method to interpret three-dimensional GDV fields, based on the Riesz and in the Fourier integral transforms. This method consists in a numerical code that allows to separate, in real time, any threedimensional low frequency field, and a system equations to infer the ionospheric current system at daylight times and to predict the field induced from the external GDV field in a layered Earth’s model. We discuss the application of the method to data obtained in North-South magnetometer chains, and, by analyzing a particular case—data from the Indian geomagnetic observatories—we illustrate how the method increases the amount of information that may be obtained from these data.

References

  1. Agarwal, A. K. and J. T. Weaver, A theoretical study of induction by n electrojet over a coastline for Sq and substorm periods, Phys. Earth Planet. Inter., 61, 165, 1990.

    Article  Google Scholar 

  2. Arora, B. R., F. E. M. Lilley, M. N. Sloane, B. P. Singh, B. J. Srivastava, and S. M. Prasad, Geomagnetic induction and conductive structures in northwest India, Geophys. J. R. Astr. Soc., 69, 459, 1982.

    Article  Google Scholar 

  3. Beamish, D., R. C. Hewson-Browne, P. C. Kendal, S. R. Malin, and D. A. Quinney, Induction in arbitrary shaped oceans—VI. Oceans of variable depth, Geophys. J. R. Astr. Soc., 75, 387, 1983.

    Article  Google Scholar 

  4. Campbell, W. H., The upper mantle conductivity analysis method using observatory records of the geomagnetic data, PAGEOPH, 125, 427, 1987.

    Article  Google Scholar 

  5. Chamalaun, F. H., S. N. Prasad, F. E. M. Lilley, B. J. Srivastava, B. P. Singh, and B. R. Arora, On the interpretation of the distinctive pattern of geomagnetic induction observed in northwest India, Tectonophys., 140, 247, 1987.

    Article  Google Scholar 

  6. Chapman, S. and J. Bartels, Geomagnetism, Vol. 2, 3rd ed., Oxford University Press, 1940.

  7. Duhau, S. and A. Favetto, The conductosphere depth at equatorial latitudes as determined from geomagnetic daily variations, Pure Appl. Geophys., 134, 559, 1990.

    Article  Google Scholar 

  8. Duhau, S. and A. M. Osella, A correlation between measured E-region current and geomagnetic daily variation at equatorial latitudes, J. Geomag. Geoelectr., 34, 213, 1982.

    Article  Google Scholar 

  9. Duhau, S. and A. M. Osella, Evidences of mutual induction the ionosphere and the earth at equatorial latitudes, J. Geophys. Res., 90, A5, 4434, 1985.

    Article  Google Scholar 

  10. Duhau, S. and L. Romanelli, Electromagnetic induction at the South-American geomagnetic equator as determined from measured ionospheric currents, J. Geophys. Res., 84, 1849, 1979.

    Article  Google Scholar 

  11. Duhau, S., L. Romanelli, and F. Hirsh, Indication of anomalous conductivity at the Peruvian dip equator, Planet. Space Sci., 30, 97, 1982.

    Article  Google Scholar 

  12. Fambitakoye, O. and R. N. Mayaud, Equatorial electrojet and regular daily variations, i determination of equatorial electrojet parameters, J. Atmos. Terr. Phys., 38, 1, 1976.

    Article  Google Scholar 

  13. Favetto, A., A. M. Osella, and S. Duhau, Depth of the conductosphere under the Indian shield, Phys. Earth Planet. Int., 71, 180, 1992.

    Article  Google Scholar 

  14. Forbush, S. and M. Casaverde, Equatorial electrojet in Peru, Carnegie Inst. Washington Pub., 620, 1961.

  15. Hartmann, O., Behandlung lokaler erdmagnetischer felder als randwertaufgasbe der potential theorie abhandl, Akad. Wiss. Goettingen Math. Phys. Kl., Sonderhelt 3, 1963.

  16. Indian Institute of Geomagnetism, Indian Magnetic Data, 1982–1983, Colaba, Bombay, India, 1983.

  17. Kertz, W., Modelle fur erdmagnetisch induzierte elktrische Strome in Umtergrund, Nachr. Akad. Wiss. Gottingen, 2, Math-Physik. Kl., Na, 101, 1954.

  18. Matsushita, S., Physics of Geomagnetism Phenomena, Vol. 1, edited by B. Matsushita and C. Campbell, p. 301, Academic Press, New York, 1967.

  19. National Geographic Magazine, The Earth’s fractured surface, February, 1995.

  20. Onwumechilli, C. A., Physics of Geomagnetism Phenomena, Vol. 1, edited by B. Matsushita and C. Campbell, p. 462, Academic Press, New York, 1967.

  21. Osella, A. M. and S. Duhau, The effect of the depth of the non-conducting layer on the induced magnetic field at the Peruvian dip equator, J. Geomag. Geoelectr., 35, 245, 1983.

    Article  Google Scholar 

  22. Parkinson, W. D., Limitation in the use of spherical harmonic methods for deep conductivity determinations, PAGEOPH, 125, 459, 1987.

    Article  Google Scholar 

  23. Pecovä, J., Z. Marinec, and K. Pec, Appreciation of spherical symmetric models of electrical conductivity, Pure Appl. Geophys., 125, 1/2, 291, 1987.

    Article  Google Scholar 

  24. Press, W. H., S. A. Teukolsky, B. F. Flannery, and W. T. Vetterling, Numerical Recipes in FORTRAN, The Art of Scientific Computation, 2nd ed., Cambridge University Press, 1992.

  25. Price, A. T., Electromagnetic induction in a semi-infinite conductor with a plane boundary, Proc. London Math. Soc., 33, 233, 1950.

    Google Scholar 

  26. Ramaswamy, V., A. K. Agarwal, and B. P. Singh, A three-dimensional numerical model study of electromagnetic induction around the Indian peninsula and Sri Lanka Island, Phys. Earth Planet. Int., 39, 52, 1985.

    Article  Google Scholar 

  27. Riesz, M., Uses of magnetoteluric method for a better understanding of the west craton shield, J. Geophys. Res., 88, B12, 10625, 1983.

    Article  Google Scholar 

  28. Takeda, M., Note on the baseline for the geomagnetic daily variation, J. Geomag. Geoelectr., 43, 765, 1991.

    Article  Google Scholar 

  29. Weaver, J. T., On the separation of local geomagnetic fields into external and internal parts, Z. Geophys., 30, 29, 1963.

    Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to Silvia Duhau.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Duhau, S., Martínez, E.A. A method for the interpretation of three-dimensional equatorial GDV fields. Earth Planet Sp 50, 141–151 (1998). https://doi.org/10.1186/BF03352095

Download citation

Keywords

  • Tectonic Feature
  • Geomagnetic Variation
  • Equatorial Electrojet
  • Equatorial Latitude
  • Spherical Harmonic Analysis