Skip to main content
Earth, Planets and Space
Download PDF

Volume 52 Supplement 12

Special Issue: Geomagnetic Field Modelling and IGRF 2000

  • Article
  • Published:

Unusual behaviour of the IGRF during the 1945–1955 period

Earth, Planets and Space volume 52, pages 1227–1233 (2000)Cite this article

Abstract

The International Geomagnetic Reference Field (IGRF) for 1900–2000 is testedin this paper. A peculiar behaviour is found in the time variations of higher-degree coefficients of the IGRF models. During the 1945–1955 period the spherical harmonic coefficients g mn and h mn with n > 7 show unusual jumps, while their variations before and after this period are quite smooth. These irregular variations have little effect on the main features of the surface magnetic pattern. However, when we extrapolate the field pattern downward through the insulating mantle to the core-mantle boundary (CMB), the contributions of the higher-degree coefficients become more important and are likely to affect the shape of the geomagnetic energy spectrum, distribution of magnetic flux, and magnetic determination of the conducting core radius. It seems necessary to re-examine and revise these coefficients in the IGRF models.

References

  • Baldwin, R. T. and R. A. Langel, Tables and maps of the DGRF 1985 and IGRF 1990, in IAGA Bulletin, 54, 183 pp., 1993.

  • Barraclough, D. R., International Geomagnetic Reference Field revision, Nature, 318, 316, 1985.

    Article  Google Scholar 

  • Barraclough, D. R., International Geomagnetic Reference Field: the fourth generation, Phys. Earth Planet. Int., 48, 279–292, 1987.

    Article  Google Scholar 

  • Barton, C. E., International Geomagnetic Reference Field: the seventh gen eration, J. Geomag. Geoelectr., 49, 123–148, 1997.

    Article  Google Scholar 

  • Benton, E. R., R. H. Estes, R. A. Langel, and L. A. Muth, Sensitivity of selected geomagnetic properties to truncation level of spherical harmonic expansions, Geophys. Res. Lett., 9, 254–257, 1982.

    Article  Google Scholar 

  • Bloxham, J. and D. Gubbins, The secular variation of Earth’s magnetic field, Nature, 317, 777–781, 1985.

    Article  Google Scholar 

  • Bloxham, J. and A. Jackson, Fluid flow near the surface of Earth’s outer core, Rev. Geophys., 29, 97–120, 1991.

    Article  Google Scholar 

  • Bloxham, J. and A. Jackson, Time-dependent mapping of the magnetic field at the core-mantle boundary, J. Geophys. Res., 97, 19537–19563, 1992.

    Article  Google Scholar 

  • Cain, J. C., Z. Wang, D. R. Schmitz, and J. Meyer, The geomagnetic spectrum for 1980 and core-crustal separation, Geophys. J., 97, 443–447, 1989.

    Article  Google Scholar 

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

    Google Scholar 

  • Ducruix, J., V. Courtillot, and J.L. LeMouel, The late 1960s secular impulse, the eleven year magnetic variation and the electrical conductivity of the deep mantle, Geophys. J. R. Astr. Soc., 61, 73–94, 1980.

    Article  Google Scholar 

  • Hide, R., How to locate the electrically conducting fluid core of a planet from external magnetic observations, Nature, 271, 640–641, 1978.

    Article  Google Scholar 

  • Hide, R. and S. R. C. Malin, On the determination of the size of the earth’s core from observations of the geomagnetic secular variation, Proc. R. Soc. Lond., A347, 15–33, 1981.

    Article  Google Scholar 

  • Hulot, G., J. L. Le Mouel, and J. Wahr, Taking into account truncation problems and geomagnetic model accuracy in assessing computed flows at the core-mantle boundary, Geophys. J. Int., 108, 224–246, 1992.

    Article  Google Scholar 

  • IAGA Commission 2 Working Group 4, International Geomagnetic Refer ence Field 1965.0, J. Geophys. Res., 74, 4407–4408, 1969.

    Article  Google Scholar 

  • IAGA Division 1 Study Group on Geomagnetic Reference Field, Interna tional Magnetic Reference Field 1975, J. Geomag. Geoelectr., 27, 437–439, 1975.

    Article  Google Scholar 

  • IAGA Division 1, Working Group 1, International geomagnetic reference field: DGRF1965, DGRF1970, DGRF 1975 and IGRF 1980, EOS Trans. Am. Geophys. Union, 62, 1169–1170, 1981.

    Article  Google Scholar 

  • IAGA Division 1, Working Group 1, International geomagnetic reference field revision 1985, J. Geomag. Geoelectr., 37, 1157–1163, 1985.

    Article  Google Scholar 

  • IAGA Division 1, Working Group 1, International geomagnetic reference field revision 1987, J. Geomag. Geoelectr., 39, 773–779, 1987.

    Article  Google Scholar 

  • IAGA Division 5, Working Group 8, International Geomagnetic Reference Field, 1991 revision, J. Geomag. Geoelectr., 43, 1007–1012, 1991.

    Article  Google Scholar 

  • IAGA Division 5, Working Group 8, International Geomagnetic Reference Field, 1995 revision, Geophys. J. Int., 125, 318–321, 1996.

    Article  Google Scholar 

  • IAGA Division 5, Working Group 8, International Geomagnetic Reference Field 2000, Geophys. J. Int., 141, 259–262, 2000.

    Article  Google Scholar 

  • Langel, R. A., The main field, in Geomagnetism, edited by J. A. Jacobs, Vol. 1, pp. 249–512, Academic Press, London, 1987.

    Google Scholar 

  • Langel, R. A., International geomagnetic reference field: the sixth genera tion, J. Geomag. Geoelectr., 44, 679–707, 1992.

    Article  Google Scholar 

  • Langel, R. A. and R. H. Estes, A geomagnetic field spectrum, Geophys. Res. Lett., 9, 250–253, 1982.

    Article  Google Scholar 

  • Langel, R. A. and R. H. Estes, Derivation of proposed International Geomagnetic Reference Field models for 1945, 1950, 1955, and 1960, Phys. Earth Planet. Int., 48, 293–305, 1987.

    Article  Google Scholar 

  • Langel, R. A., D. R. Barraclough, D. J. Kerridge, V. P. Golovkov, T. J. Sabaka, and R. H. Estes, Definitive IGRF models for 1945, 1950, 1955, and 1960, J. Geomag. Geoelectr., 40, 645–702, 1988.

    Article  Google Scholar 

  • Lowes, F. J., Mean square values on sphere of spherical harmonic vector field, J. Geophys. Res., 71, 2179, 1966.

    Article  Google Scholar 

  • Lowes, F. J., Spatial power spectrum of the main geomagnetic field and extrapolation to the core, Geophys. J. R. Astr. Soc., 36, 717–730, 1974.

    Article  Google Scholar 

  • Macmillan, S. and C. E. Barton, Magnetic field maps for IGRF 1995, J. Geomag. Geoelectr., 49, 149–156, 1997.

    Article  Google Scholar 

  • Malin, S. R. C., B. M. Hodder, and D. R. Barraclough, Geomagnetic secular variation: A jerk in 1970. Publicado en volumen commemorativo 75 aniversario del observatorio del Ebro, (75th anniversary volume of Ebro observatory), edited by J. O. Cardus, pp. 239–256, Tarragona, 1983.

  • Olson, P. and J. Aurnou, A polar vortex in the Earth’s core, Nature, 402, 170–173, 1999.

    Article  Google Scholar 

  • Pais, A. and G. Hulot, Lengthof day decade variations, torsional oscillations and inner core superrotation: evidence from recovered core surface zonal flows, Phys. Earth Planet. Int., 118, 291–316, 2000.

    Article  Google Scholar 

  • Sabaka, T. J., R. A. Langel, R. T. Baldwin, and J. A. Conrad, The geo magnetic field 1900–1995, including the large-scale field from magnetospheric sources, and the NASA candidate models for the 1995 revision, J. Geomag. Geoelectr., 49, 157–206, 1997.

    Article  Google Scholar 

  • Verosub, K. L. and A. Cox, Changes in the total magnetic energy external to the earth’s core, J. Geomag. Geoelectr., 23, 235–242, 1971.

    Article  Google Scholar 

  • Voorhies, C. V. and E. R. Benton, Pole-strength of the Earth from MAGSAT and magnetic determination of the core radius, Geophys. Res. Lett., 9, 258–261, 1982.

    Article  Google Scholar 

  • Zmuda, A. J., The International Geomagnetic Reference Field, 1965.0, in IAGA Bulletin, 28, World Magnetic Survey, IUGG, Paris, 1971.

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Institute of Geophysics, Chinese Academy of Sciences, Beijing, 100101, China

    Wen-yao Xu

Authors
  1. Wen-yao Xu
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Wen-yao Xu.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Xu, Wy. Unusual behaviour of the IGRF during the 1945–1955 period. Earth Planet Sp 52, 1227–1233 (2000). https://doi.org/10.1186/BF03352355

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1186/BF03352355

Keywords