Skip to main content

Advertisement

We’d like to understand how you use our websites in order to improve them. Register your interest.

On long-term trends in European geomagnetic observatory biases

Abstract

We investigated the European geomagnetic observatory biases over 42 years, considered as contributions of the crustal field, and generally assumed to be constant in time. To estimate these biases, we compared observatory annual means to predictions given by the continuous CM4 model, and to four other core field models for different epochs. Solar-cycle related external fields are clearly present in the residuals. Although well-known, no suitable model to minimise them exists. We found that an empirical approach, taking advantage of the homogeneity of the external influences in the European region, can minimise these influences. Their reduction is better than when the external field description included in the comprehensive CM4 model is used. At several locations clear long-term trends remain after subtraction of the core field and minimisation of external fields. We investigated whether they are due to an insufficient description of the core field secular variation by the CM4 model, or to changes in induced lithospheric fields.

References

  1. Alldredge, L., Effects of solar activity on annual means of geomagnetic components, J. Geophys. Res., 81, 2990–2996, 1976.

    Article  Google Scholar 

  2. Cain, J. C., J. Frayser, L. Muth, and D. Schmitz, The use of Magsat data to determine secular variation, J. Geophys. Res., 88, 5903–5910, 1983.

    Article  Google Scholar 

  3. Cain, J. C., Z. Wang, C. Kluth, and D. R. Schmitz, Derivation of a geomagnetic model ton = 63, Geophys. J. Roy. Astr. Soc, 97, 431–441, 1989.

    Article  Google Scholar 

  4. Chambodut, A. and M. Mandea, Evidence for geomagnetic jerks in comprehensive model, Earth Planets Space, 57, 139–149, 2005.

    Article  Google Scholar 

  5. Courtillot, V. and J.-L. Le Mouël, On the long period variations of the Earth’s magnetic field from 2 months to 20 years, J. Geophys. Res., 81, 2941–2950, 1976.

    Article  Google Scholar 

  6. Gubbins, D. and J. Bloxham, Geomagnetic field ananlysis—III. Magnetic fields on the core-mantle boundary, Geophys. J. R. Astron. Soc, 80, 695–713,1985.

    Article  Google Scholar 

  7. Jankowski, J. and C. Sucksdorff, IAGA Guide for magnetic measurements and observatory practice, International Association for Geomagnetism and Aeronomy, 1996.

    Google Scholar 

  8. Langel, R. and W. Hinze, The magnetic field of the Earth’s lithosphere: The satellite perspective, Cambridge Univ. Press, 1998.

    Google Scholar 

  9. Langel, R. A., R. H. Estes, and G. D. Mead, Some new methods in geomagnetic field modeling applied to the 1960–1980 epoch, J. Geomag. Geoelectr., 34, 327–349, 1982.

    Article  Google Scholar 

  10. Langel, R. A., R. H. Estes, and T. J. Sabaka, Uncertainty estimates in geomagnetic field modelling, J. Geophys. Res., 94, 12,281–12,299, 1989.

    Article  Google Scholar 

  11. Lesur, V. and D. Gubbins, Using geomagnetic secular variation to separate remanent and induced sources of the crustal magnetic field, Geophys. J. Int., 142, 889–897, 2000.

    Article  Google Scholar 

  12. Macmillan, S., S. Maus, T. Bondar, A. Chambodut, V. Golovkov, R. Holme, B. Langlais, V. Lesur, F. Lowes, H. Lühr, W. Mai, M. Mandea, N. Olsen, M. Rother, T. Sabaka, A. Thomson, and I. Wardinski, The 9th-generation International Geomagnetic Reference Field, Geophys. J. Int., 155, 1051–1056, 2003.

    Article  Google Scholar 

  13. Macmillan, S. and A. Thomson, An examination of observatory biases during the Magsat and Ørsted missions, Phys. Earth Planet. Inter., 135, 97–105, 2003.

    Article  Google Scholar 

  14. Mandea, M. and B. Langlais, Observatory crustal magnetic biases during MAGSAT and Oersted satellite missions, Geophys. Res. Lett., 29, 11–15, 2002.

    Article  Google Scholar 

  15. Maus, S., A global lithospheric field model with reduced noise level polar regions, Geophys. Res. Let., 2006 (submitted).

    Google Scholar 

  16. Maus, S., H. Lühr, G. Balasis, M. Rother, and M. Mandea, Introducing POMME, The Potsdam Magnetic Model of the Earth, In Earth Observation with CHAMP, Results from Three Years in Space, edited by C. Reigber, H. Lühr, P. Schwintzer, and J. Wickert, 293-298, Springer, Berlin-Heidelberg, 2005.

    Google Scholar 

  17. Maus, S., M. Rother, K. Hemant, C. Stolle, H. Lühr, A. Kuvshinov, and N. Olsen, Earth’s lithospheric magnetic field determined to spherical harmonic degree 90 from CHAMP satellite measurements, Geophys. J. Int., 164, 319–330, 2006.

    Article  Google Scholar 

  18. Maus, S., M. Rother, C. Stolle, W. Mai, S. Choi, H. Lühr, D. Cooke, and C. Roth, Third generation of the Potsdam Magnetic Model of the Earth (POMME), Geochem. Geophys. Geosys., 7, Q07008, doi:10.1029/ 2006GC001269, 2006.

  19. Sabaka, T., N. Olsen, and R. Langel, A comprehensive model of the quiet-time, near Earth magnetic field: Phase3, Geophys. J. Int., 151, 32–68, 2002.

    Article  Google Scholar 

  20. Sabaka, T., N. Olsen, and M. Purucker, Extending comprehensive models of the Earth’s magnetic field with Ørsted and CHAMP data, Geophys. J. Int., 159, 521–547, 2004.

    Article  Google Scholar 

  21. Olsen, N., A model of the geomagnetic field and its secular variation for epoch 2000 estimated from Ørsted data, Geophys. J. Int., 149, 455–463, 2002.

    Google Scholar 

  22. Olsen, N., T. Sabaka, M. Mandea, M. Rother, L. T. Clausen, and S. Choi, CHAOS-a model of the Earth’s magnetic field derived from CHAMP, Ørsted, and SAC-C magnetic satellite data, Geophys. J. Int., 166, 67–75, 2006.

    Article  Google Scholar 

  23. Yukutake, T. and J. C. Cain, Solar Cycle Variations Annual Mean Values of the Geomagnetic Components of Observatory Data, J. Geomag. Geoelectr., 39, 19–46, 1987.

    Article  Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to Giuli Verbanac.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Verbanac, G., Korte, M. & Mandea, M. On long-term trends in European geomagnetic observatory biases. Earth Planet Sp 59, 685–695 (2007). https://doi.org/10.1186/BF03352731

Download citation

Key words

  • Geomagnetism
  • observatory data
  • annual means