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On long-term trends in European geomagnetic observatory biases
Earth, Planets and Space volume 59, pages685–695(2007)
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.
Alldredge, L., Effects of solar activity on annual means of geomagnetic components, J. Geophys. Res., 81, 2990–2996, 1976.
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.
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.
Chambodut, A. and M. Mandea, Evidence for geomagnetic jerks in comprehensive model, Earth Planets Space, 57, 139–149, 2005.
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.
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.
Jankowski, J. and C. Sucksdorff, IAGA Guide for magnetic measurements and observatory practice, International Association for Geomagnetism and Aeronomy, 1996.
Langel, R. and W. Hinze, The magnetic field of the Earth’s lithosphere: The satellite perspective, Cambridge Univ. Press, 1998.
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.
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.
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.
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.
Macmillan, S. and A. Thomson, An examination of observatory biases during the Magsat and Ørsted missions, Phys. Earth Planet. Inter., 135, 97–105, 2003.
Mandea, M. and B. Langlais, Observatory crustal magnetic biases during MAGSAT and Oersted satellite missions, Geophys. Res. Lett., 29, 11–15, 2002.
Maus, S., A global lithospheric field model with reduced noise level polar regions, Geophys. Res. Let., 2006 (submitted).
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.
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.
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.
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.
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.
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.
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.
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.
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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
- observatory data
- annual means