Special Issue: Modelling the Earth’s Magnetic Field: the 10th Generation IGRF
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New parameterization of external and induced fields in geomagnetic field modeling, and a candidate model for IGRF 2005
Earth, Planets and Space volume 57, pages 1141–1149 (2005)
When deriving spherical harmonic models of the Earth’s magnetic field, low-degree external field contributions are traditionally considered by assuming that their expansion coefficient q 01 varies linearly with the Dst-index, while induced contributions are considered assuming a constant ratio Q1 of induced to external coefficients. A value of Q1 = 0.27 was found from Magsat data and has been used by several authors when deriving recent field models from Èrsted and CHAMP data. We describe a new approach that considers external and induced field based on a separation of Dst = Est + Ist into external (Est) and induced (Ist) parts using a 1D model of mantle conductivity. The temporal behavior of q 01 and of the corresponding induced coefficient are parameterized by Est and Ist, respectively. In addition, we account for baseline-instabilities of Dst by estimating a value of q 01 for each of the 67 months of Èrsted and CHAMP data that have been used. We discuss the advantage of this new parameterization of external and induced field for geomagnetic field modeling, and describe the derivation of candidate models for IGRF 2005.
Holme, R., Modelling of attitude error in vector magnetic data: application to Èrsted data, Earth Planets Space, 52, 1187–1197, 2000.
Holme, R. and J. Bloxham, The treatment of attitude errors in satellite geomagnetic data, Phys. Earth Planet. Int., 98, 221–233, 1996.
Holme, R., N. Olsen, M. Rother, and H. Lühr, CO2: A CHAMP magnetic field model, in First CHAMP Mission results for Gravity, Magnetic and Atmospheric Studies, edited by C. Reigber, H. Lühr, and P. Schwintzer, pp. 220–225, Springer Verlag, 2003.
Kivelson, M. G. and C. T. Russell, Introduction to Space Physics, Cambridge University Press, 1995.
Langel, R. A. and R. H. Estes, Large-scale, near-Earth magnetic fields from external sources and the corresponding induced internal field, J. Geophys. Res., 90, 2487–2494, 1985a.
Langel, R. A. and R. H. Estes, The near-Earth magnetic field at 1980 determined from MAGSAT data, J. Geophys. Res., 90, 2495–2509, 1985b.
Langel, R. A. and W. J. Hinze, The Magnetic Field of the Earth’s Lithosphere: The Satellite Perspective, Cambridge University Press, 1998.
Langel, R. A., G. D. Mead, E. R. Lancaster, R. H. Estes, and E. B. Fabiano, Initial geomagnetic field model from Magsat vector data, Geophys. Res. Lett., 7, 793–796, 1980.
Lowes, F. J. and N. Olsen, A more realistic estimate of the variances and systematic errors in spherical harmonic geomagnetic field models, Geophys. J. Int., 157, 1027–1044, 2004.
Maus, S. and H. Lühr, Signature of the quiet-time magnetospheric magnetic field and its electromagnetic induction in the rotating Earth, Geophys. J. Int., 162, 755–763, 2005.
Maus, S. and P. Weidelt, Separating the magnetospheric disturbance magnetic field into external and transient internal contributions using a 1D conductivity model of the Earth, Geophys. Res. Lett., 31, L12,614, doi:10.1029/2004GL020,232, 2004.
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 Orbit, edited by C. Reigber, H. Lühr, P. Schwintzer, and J. Wickert, pp. 293–298, Springer Verlag, 2005a.
Maus, S., M. Rother, K. Hemant, H. Lühr, A. V. Kuvshinov, and N. Olsen, Earth’s crustal magnetic field determined to spherical harmonic degree 90 from CHAMP satellite measurements, Geophys. J. Int., 2005b (submitted).
Olsen, N., A model of the geomagnetic field and its secular variation for epoch 2000 estimated from Èrsted data, Geophys. J. Int., 149, 454–462, 2002.
Olsen, N., New parameterization of external and induced fields in geomagnetic field modeling, Geophysical Research Abstracts, 6, 02,454, 2004.
Olsen, N., T. J. Sabaka, and L. Tøffner-Clausen, Determination of the IGRF 2000 model, Earth Planets Space, 52, 1175–1182, 2000.
Olsen, N., F. Lowes, and T. J. Sabaka, Ionospheric and induced field leakage in geomagnetic field models, and derivation of candidate models for DGRF 1995 and DGRF 2000, Earth Planets Space, 57, this issue, 1191–1196, 2005.
Sabaka, T. J., N. Olsen, and M. Purucker, Extending comprehensive models of the Earth’s magnetic field with Èrsted and CHAMP data, Geophys. J. Int., 159, 521–547, doi: 10.1111/j.1365-246X.2004.02,421.x, 2004.
Schmucker, U., Magnetic and electric fields due to electromagnetic induction by external sources, in Landolt-Börnstein, New-Series, 5/2b, pp. 100–125, Springer-Verlag, Berlin-Heidelberg, 1985a.
Schmucker, U., Electrical properties of the Earth’s interior, in Landolt- Börnstein, New-Series, 5/2b, pp. 370–397, Springer-Verlag, Berlin- Heidelberg, 1985b.
Schmucker, U., Substitute conductors for electromagnetic response estimates, PAGEOPH, 125, 341–367, 1987.
Tsyganenko, N. A., Quantitative models of the magnetospheric magnetic field: methods and results, Space Sci. Rev., 54, 75–186, 1990.
Tsyganenko, N. A., A model of the near magnetosphere with a dawndusk asymmetry 1. Mathematical structure, J. Geophys. Res., 107, 12–1, 2002a.
Tsyganenko, N. A., A model of the near magnetosphere with a dawn-dusk asymmetry 2. Parameterization and fitting to observations, J. Geophys. Res., 107, 10–1, 2002b.
Utada, H., T. Koyama, H. Shimizu, and A. D. Chave, A semi-global reference model for electrical conductivity in the mid-mantle beneath the north Pacific region, Geophys. Res. Lett., 30, 43–1, DOI 10.1029/2002GL016,092, 2003.
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Olsen, N., Sabaka, T.J. & Lowes, F. New parameterization of external and induced fields in geomagnetic field modeling, and a candidate model for IGRF 2005. Earth Planet Sp 57, 1141–1149 (2005). https://doi.org/10.1186/BF03351897
- Geomagnetic Reference Model
- magnetospheric currents
- spherical harmonic analysis