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A method for the interpretation of three-dimensional equatorial GDV fields
Earth, Planets and Space volume 50, pages141–151(1998)
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
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.
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.
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.
Campbell, W. H., The upper mantle conductivity analysis method using observatory records of the geomagnetic data, PAGEOPH, 125, 427, 1987.
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.
Chapman, S. and J. Bartels, Geomagnetism, Vol. 2, 3rd ed., Oxford University Press, 1940.
Duhau, S. and A. Favetto, The conductosphere depth at equatorial latitudes as determined from geomagnetic daily variations, Pure Appl. Geophys., 134, 559, 1990.
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.
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.
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.
Duhau, S., L. Romanelli, and F. Hirsh, Indication of anomalous conductivity at the Peruvian dip equator, Planet. Space Sci., 30, 97, 1982.
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.
Favetto, A., A. M. Osella, and S. Duhau, Depth of the conductosphere under the Indian shield, Phys. Earth Planet. Int., 71, 180, 1992.
Forbush, S. and M. Casaverde, Equatorial electrojet in Peru, Carnegie Inst. Washington Pub., 620, 1961.
Hartmann, O., Behandlung lokaler erdmagnetischer felder als randwertaufgasbe der potential theorie abhandl, Akad. Wiss. Goettingen Math. Phys. Kl., Sonderhelt 3, 1963.
Indian Institute of Geomagnetism, Indian Magnetic Data, 1982–1983, Colaba, Bombay, India, 1983.
Kertz, W., Modelle fur erdmagnetisch induzierte elktrische Strome in Umtergrund, Nachr. Akad. Wiss. Gottingen, 2, Math-Physik. Kl., Na, 101, 1954.
Matsushita, S., Physics of Geomagnetism Phenomena, Vol. 1, edited by B. Matsushita and C. Campbell, p. 301, Academic Press, New York, 1967.
National Geographic Magazine, The Earth’s fractured surface, February, 1995.
Onwumechilli, C. A., Physics of Geomagnetism Phenomena, Vol. 1, edited by B. Matsushita and C. Campbell, p. 462, Academic Press, New York, 1967.
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.
Parkinson, W. D., Limitation in the use of spherical harmonic methods for deep conductivity determinations, PAGEOPH, 125, 459, 1987.
Pecovä, J., Z. Marinec, and K. Pec, Appreciation of spherical symmetric models of electrical conductivity, Pure Appl. Geophys., 125, 1/2, 291, 1987.
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.
Price, A. T., Electromagnetic induction in a semi-infinite conductor with a plane boundary, Proc. London Math. Soc., 33, 233, 1950.
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.
Riesz, M., Uses of magnetoteluric method for a better understanding of the west craton shield, J. Geophys. Res., 88, B12, 10625, 1983.
Takeda, M., Note on the baseline for the geomagnetic daily variation, J. Geomag. Geoelectr., 43, 765, 1991.
Weaver, J. T., On the separation of local geomagnetic fields into external and internal parts, Z. Geophys., 30, 29, 1963.
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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
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Keywords
- Tectonic Feature
- Geomagnetic Variation
- Equatorial Electrojet
- Equatorial Latitude
- Spherical Harmonic Analysis
