Skip to main content

Quiet-day ionospheric currents and their application to upper mantle conductivity in Australia

Abstract

This study concerns the use of selected geomagnetic field records to establish the 1990 quiet-day current system (Sq) for Australia and to use the ionospheric current source of Sq for a determination of the Earth’s deep electrical conductivity. The primary data set came from a chain of eight, three-component magnetometer stations that was operated along a north-south line in central Australia. Additional records, necessary for boundary conditions, were added to the data set. A regional spherical harmonic analysis (SHA) allowed the separation of the internal and external field contributions to the Sq variations. Mapping of the equivalent ionospheric current from the external field showed that the Sq contour focus passed near the —30° geomagnetic latitude of central Australia with a 5° latitude variation between winter and summer and a corresponding change from about 80 to 200 kA in strength. A special transfer function allowed the computation of an equivalent conductivity-depth profile of central Australia from the paired external and internal coefficients of the SHA. A regression line through the conductivity estimates gives a profile that starts at 0.025 S/m for a depth of 130 km, rising gradually to about 0.045 S/m at 250 km, then steepens to 0.11 S/m at 360 km and rises moderately to 0.13 S/m at 470 km near the base of the upper mantle. No data were obtained through the mantle transition zone. Computations gave 0.18 S/m in the region of 800 km depth. Previous conductivity models for the upper mantle beneath central Australia, although less specific in values, are consistent with our profile. At depths greater than 500 km, the regression profile is in agreement with the conductivity distribution beneath the Tasman Sea determined from seafloor magnetotellurics, although both measurements lack high resolution at such depths.

References

  1. Arora, B. R., W. H. Campbell, and E. R. Schiffmacher, Upper mantle electrical conductivity in the Himalayan region, J. Geomag. Geoelectr., 47, 653–665, 1995.

    Article  Google Scholar 

  2. Bott, M. H. P., The Interior of the Earth: Its Structure, Constitution, and Evolution, 403 pp., Edward Arnold Company, London, 1982.

    Google Scholar 

  3. Campbell, W. H., The upper mantle conductivity analysis method using observatory records of the geomagnetic field, Pure and Appl. Geophys., 125, 427–457, 1987.

    Article  Google Scholar 

  4. Campbell, W. H., Differences in geomagnetic Sq field representations due to variations in spherical harmonic analysis techniques, J. Geophys. Res., 95, 20,923–20,936, 1990.

    Article  Google Scholar 

  5. Campbell, W. H., Introduction to Geomagnetic Fields, 304 pp., Cambridge University Press, New York, 1997.

    Google Scholar 

  6. Campbell, W. H. and R. S. Anderssen, Conductivity of the subcontinental upper mantle: an analysis using quiet-day records of North America, J. Geomag. Geoelectr., 35, 367–382, 1983.

    Article  Google Scholar 

  7. Campbell, W. H. and S. Matsushita, Sq Currents: A comparison of quiet and active year behavior, J. Geophys. Res., 87, 5305–5308, 1982.

    Article  Google Scholar 

  8. Campbell, W. H. and E. R. Schiffmacher, Quiet ionospheric currents of the Northern Hemisphere derived from geomagnetic field records, J. Geophys. Res., 90, 6475–6486, 1986.

    Article  Google Scholar 

  9. Campbell, W. H. and E. R. Schiffmacher, Quiet ionospheric currents and Earth conductivity profile computed from quiet-time geomagnetic field changes in the region of Australia, Aust. J. Phys., 40, 73–87, 1987.

    Article  Google Scholar 

  10. Campbell, W. H. and E. R. Schiffmacher, Quiet ionospheric currents of the Southern Hemisphere derived from geomagnetic records, J. Geophys. Res., 93, 933–944, 1988a.

    Article  Google Scholar 

  11. Campbell, W. H. and E. R. Schiffmacher, Upper mantle electrical conductivity for seven subcontinental regions of the Earth, J. Geomag. Geoelectr., 40, 1387–1406, 1988b.

    Article  Google Scholar 

  12. Campbell, W. H., E. R. Schiffmacher, and H. W. Kroehl, Global quiet day field variation model WDCA-SQ1, EOS, Trans. Amer. Geophys. Un., 70, 66 and 74, 1989.

    Article  Google Scholar 

  13. Campbell, W. H., E. R. Schiffmacher, and B. R. Arora, Quiet geomagnetic field representation for all days and latitudes, J. Geomag. Geoelectr., 44, 459–480, 1992.

    Article  Google Scholar 

  14. Campbell, W. H., B. R. Arora, and E. R. Schiffmacher, External Sq currents in the India-Siberia region, J. Geophys. Res., 98, 3741–3752, 1993.

    Article  Google Scholar 

  15. Campbell, W. H., B. R. Arora, and E. R. Schiffmacher, Polar cap field response to IMF By sector changes on quiet days at a longitude line of observatories, J. Geomag. Geoelectr., 46, 735–746, 1994.

    Article  Google Scholar 

  16. Chamalaun, F. H. and C. E. Barton, The large-scale conductivity structure of Australia, J. Geomag. Geoelectr., 45, 1209–1212, 1993a.

    Article  Google Scholar 

  17. Chamalaun, F. H. and C. E. Barton, Electromagnetic induction in the Australian crust: results from the Australia-wide Array of Geomagnetic Stations, Explor. Geophys., 24, 179–186, 1993b.

    Article  Google Scholar 

  18. Chamalaun, F. H. and R. A. Walker, A microprocessor based digital fluxgate magnetometer for geomagnetic deep sounding studies, J. Geomag. Geoelectr., 34, 491–507, 1982.

    Article  Google Scholar 

  19. Chapman, S., The solar and lunar diurnal variation of the Earth’s magnetism, Phil. Trans. Roy. Soc. London, A218, 1–118, 1919.

    Article  Google Scholar 

  20. Chapman, S. and J. Bartels, Geomagnetism, 1049 pp., Oxford University Press, Oxford, 1940.

    Google Scholar 

  21. Cleveland, W. S., Robust locally weighted regression and smoothing scatter plots, J. Amer. Statistical Assn., 74, 828–833, 1979.

    Article  Google Scholar 

  22. Constable, S. and A. Duba, Electrical conductivity of olivine, a dunite, and the mantle, J. Geophys. Res., 95, 6967–6978, 1990.

    Article  Google Scholar 

  23. Constable, S., T. J. Shankland, and A. Duba, The electrical conductivity of an isotropic olivine mantle, J. Geophys. Res., 97, 3397–3403, 1992.

    Article  Google Scholar 

  24. Duba, A. and S. Constable, The electrical conductivity of Lherzolite, J. Geophys. Res., 98, 11885–11899, 1993.

    Article  Google Scholar 

  25. Ferguson, I. J., F. E. M. Lilley, and J. H. Filloux. Geomagnetic induction in the Tasman Sea and electrical conductivity structure beneath the Tasman seafloor, Geophys. J. Int., 102, 299–312, 1991.

    Article  Google Scholar 

  26. Gauss, C. F., Allgemeine Theorie des Erdmagnetismus, in Resultate aus den Beobachtungen des magnetischen Vereins im Yahr 1838, edited by C. F. Gauss and W. Weber, translated from the German by E. Sabine and R. Taylor, Sci. Mem. Select. Trans. Foreign Acad. Learned Soc. Foreign J., 2, 184-251, 1841.

  27. Heinson, G. S. and S. Constable, The electrical conductivity of the oceanic upper mantle, Geophys. J. Int., 110, 159–179, 1992.

    Article  Google Scholar 

  28. Heinson, G. S. and F. E. M. Lilley, An application of electromagnetic thin-sheet modelling to the Tasman Sea, Phys. Earth Planet. Int., 81, 231–251, 1993.

    Article  Google Scholar 

  29. Hoyt, D. V. and K. H. Schatten, The Role of the Sun in Climate Change, 279 pp., Oxford Press, Oxford, 1997.

    Google Scholar 

  30. Jackson, I. and S. Rigden, Composition and temperature of the Earth’s mantle: seismological models interpreted through experimental studies of mantle materials, in The Earth’s Mantle: Composition, Structure, and Evolution, edited by I. Jackson, Cambridge Univ. Press, 1997 (in press).

  31. Kennett, B. L. N., O. Gudmundsson, and C. Tong, The upper-mantle S and P velocity structure beneath northern Australia from broad-band observations, Phys. Earth Planet. Int., 86, 85–98, 1994.

    Article  Google Scholar 

  32. Lilley, F. E. M., The analysis of daily variations recorded by magnetometer arrays, Geophys. J. Roy. Astr. Soc., 43, 1–16, 1975.

    Article  Google Scholar 

  33. Lilley, F. E. M., D. V. Woods, and M. M. Sloane, Electrical conductivity profiles and implications for the absence or presence of partial melting beneath central and south east Australia, Phys. Earth Planet. Int., 25, 419–428, 1981.

    Article  Google Scholar 

  34. Matsushita, S. and H. Maeda, On the geomagnetic quiet solar daily variation field during the IGY, J. Geophys. Res., 70, 2535–2558, 1965.

    Article  Google Scholar 

  35. Maxwell, J. C., Treatise on Electricity and Magnetism, 566 pp., Cambridge University Press, Cambridge, 1873.

    Google Scholar 

  36. Parker, R. L., The inverse problem of electrical conductivity in the mantle, Geophys. J. Roy. Astr. Soc., 22, 121–138, 1971.

    Article  Google Scholar 

  37. Parkinson, W. D., An analysis of the geomagnetic diurnal variation during the International Geophysical Year, BMR Bulletin No 173, Australian Geological Survey Organisation, Canberra, 196 pp., 1977.

    Google Scholar 

  38. Peyronneau, J. and J.-P. Poirier, Electrical conductivity of the Earth’s lower mantle, Nature, 343, 537–539, 1989.

    Article  Google Scholar 

  39. Poirier, J.-P. and J. Peyronneau, Experimental determination of the electrical conductivity of the material of the Earth’s lower mantle, in High Pressure Research: Application to Earth and Planetary Sciences, Geophysics Monograph No. 67, edited by Y. Syono and M. H. Manghani, pp. 77–87, American Geophysical Union, Washington, D.C., 1992.

    Google Scholar 

  40. Schmucker, U., An introduction to induction anomalies, J. Geomag. Geoelectr., 22, 9–33, 1970.

    Article  Google Scholar 

  41. Schuster, A., The diurnal variation of terrestrial magnetism, Philos. Trans. Roy. Soc. Lon., Ser. A, 180, 467–518, 1889.

    Article  Google Scholar 

  42. Schuster, A., The diurnal variation of terrestrial magnetism, Philos. Trans. Roy. Soc. Lon., Ser. A, 208, 163–204, 1908.

    Article  Google Scholar 

  43. Shearer, P. M., Constraints on upper mantle discontinuities from observations of long-period reflected and converted phases, J. Geophys. Res., 96, 18147–18182, 1991.

    Article  Google Scholar 

  44. Stacey, F. D., Physics of the Earth, 3rd edition, 513 pp., Brookfield Press, Brisbane, 1992.

    Google Scholar 

  45. Stening, R. J. and P. A. Hopgood, Geomagnetic quiet daily variations in the Australian region-information from a new station in Charters Towers, J. Atmos. Terr. Phys., 53, 959–964, 1991.

    Article  Google Scholar 

  46. Takeda, M., Electric currents in the ocean induced by the geomagnetic Sq field and their effects on the estimation of mantle conductivity, Geophys. J. Int., 104, 381–385, 1991.

    Article  Google Scholar 

  47. White, A. and G. Heinson, Two-dimensional conductivity structure across the southern coastline of Australia, J. Geomag. Geoelectr., 46, 1067–1081, 1994.

    Article  Google Scholar 

  48. White, A. and O. W. Polatayko, The coast effect in geomagnetic variations in South Australia, J. Geomag. Geoelectr., 30, 109–120, 1978.

    Article  Google Scholar 

  49. White, A. and O. W. Polatayko, Electrical conductivity anomalies and their relationship with tectonics of South Australia, Geophys. J. Roy. Astr. Soc., 80, 757–771, 1985.

    Article  Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to W. H. Campbell.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Campbell, W.H., Barton, C.E., Chamalaun, F.H. et al. Quiet-day ionospheric currents and their application to upper mantle conductivity in Australia. Earth Planet Sp 50, 347–360 (1998). https://doi.org/10.1186/BF03352121

Download citation

Keywords

  • Geomagnetic Latitude
  • Ionospheric Current
  • AWAGS Station
  • Conductivity Profile
  • Spherical Harmonic Analysis