Non-dipole and regional effects on the geomagnetic dipole moment estimation

Thumbnail Image
Full text at PDC
Publication Date
Advisors (or tutors)
Journal Title
Journal ISSN
Volume Title
Google Scholar
Research Projects
Organizational Units
Journal Issue
The study of the temporal evolution of the dipole moment variations is a forefront research topic in Earth sciences. It constrains geodynamo simulations and is used to correct cosmogenic isotope production, which is evidence of past solar activity, and it is used to study possible correlations between the geomagnetic field and the climate. In this work, we have analysed the main error sources in the geomagnetic dipole moment computation from palaeomagnetic data: the influence of the non-dipole terms in the average approach, the inhomogeneous distribution of the current palaeomagnetic database, and the averaging procedure used to obtain the evolution of the dipole moment. To evaluate and quantify these effects, we have used synthetic data from a global model based on instrumental and satellite data, the International Geomagnetic Reference Field: 11th generation. Results indicate that the non-dipole terms contribute on a global scale of < 6 % in the averaged dipole moment, whereas the regional non-dipole contribution can show deviations of up to 35 % in some regions such as Oceania, and different temporal trends with respect to the global dipole moment evolution in other ones, such as Europe and Asia. A regional weighting scheme seems the best option to mitigate these effects in the dipole moment average approach. But when directional and intensity palaeomagnetic information is available on a global scale, and in spite of the inhomogeneity of the database, global modelling presents more reliable values of the geomagnetic dipole moment.
© Springer International Publishing AG, Part of Springer Science + Business Media. The authors are grateful to the Spanish research project CGL2011-24790 of the Spanish Ministerio de Economia y Competitividad and the FPI grant BES-2012-052991, which has allowed to the author S.A. Campuzano a stay for 3 months at INGV in Rome. All algorithms have been developed in Matlab (R) codec (Matlab 7.11.0, R2010b) along with the figures. The authors also thank two anonymous reviewers for the constructive comments and suggestions which have helped to improve substantially this manuscript.
Unesco subjects
Christensen, U.R., Aubert, J., Hulot, G. (2010), Conditions for Earth-like geodynamo models. Earth Planet. Sci. Lett. 296 (3-4), 487-496. De Boor, C., A Practical Guide to Splines (Springer, New York 2001). Donadini, F., Korte, M., Constable, C. G. (2009), Geomagnetic field for 0-3 ka: 1. New data sets for global modeling. Geochem. Geophys. Geosyst. 10 (6), Q06007. Finlay, C. C., et al. (2010), International Geomagnetic Reference Field: the eleventh generation. Geophys. J. Int. 183, 1216–1230. Gallet, Y., Genevet, A., Fluteau, F. (2005), Are there connections between the Earth’s magnetic field and climate? Earth Planet. Sci. Lett. 236, 339-347. Gauss, C.F., Intensitas vis Magneticae Terrestris ad Mensuram Absolutam Revocata (Dieterich, Göttingen 1833). Genevey, A., Gallet, Y., Constable, C., Korte, M., Hulot, G. (2008), ArcheoInt: An upgraded compilation of geomagnetic field intensity data for the past ten millennia and its application to the recovery of the past dipole moment. Geochem. Geophys. Geosyst. 9 (4), Q04038. Genevey, A., Gallet, Y., Thébault, E., Jasset, S., Le Goff, M. (2013), Geomagnetic field intensity variations in Western Europe over the past 1100 years. Geochem. Geophys. Geosyst. 14 (8), 2858–2872. Glatzmaier, G.A., Roberts, P.H. (1995). A three-dimensional self-consistent computer simulation of a geomagnetic field reversal. Nature. 377, 203-209. Gubbins, D. (1975), Can the Earth’s magnetic field be sustained by core oscillations? Geophys. Res. Lett. 2, 409-412. Gubbins, D. (1987), Mechanism for geomagnetic polarity reversals. Nature. 326, 167–169. Gubbins, D., and Bloxham, J. (1985), Geomagnetic field analysis. III. Magnetic fields on the core–mantle boundary. Geophys. J. R. Astron. Soc. 80, 695–713. Jackson, A., Jonkers, A.R.T., Walker, M.R. (2000), Four centuries of geomagnetic secular variation from historical records. Philos. Trans. R. Soc. Lond. A 358 (1768), 957-990. Jacobs, J. A., Geomagnetism (Vol. 1) (Academic Press 1991). Jonkers, A. R. T., Jackson, A., Murray, A. (2003), Four centuries of geomagnetic data from historical records, Rev. Geophys. 41(2), 1006. Korte, M., and Constable, C.G. (2003), Continuous geomagnetic field models for the past 3000 years. Phys. Earth Planet. Interiors. 140, 73-89. Korte, M., and Constable, C.G. (2005a), Continuous geomagnetic field models for the past 7 millennia: 2 CALS7K. Geochem. Geophys. Geosyst. 6, Q02H16. Korte, M., and Constable, C.G. (2005b), The geomagnetic dipole moment over the last 7000 years—new results from a global model. Earth Planet. Sci. Lett. 236, 348– 358. Korte, M., and Constable, C.G. (2011), Improving geomagnetic field reconstructions for 0-3 ka. Phys. Earth Planet. Interiors. 188, 247-259. Korte, M., Genevey, A., Constable, C.G., Frank, U., Schnepp, E. (2005), Continuous geomagnetic field models for the past 7 millennia: A new global data compilation. Geochem. Geophys. Geosyst. 6, Q02H15. Korte, M., Donadini, C., Constable, C.G. (2009), The geomagnetic field for 0-3 ka, part II: a new series of time-varying global models. Geochem. Geophys. Geosyst. 10, Q06008. Kovacheva, M., Boyadziev, Y., Kostadinova, M., Jordanova, N., Donadini, F. (2009), Updated archeomagnetic data set of the past 8 millennia from the Sofia laboratory, Bulgaria, Geochem. Geophys. Geosyst., 10, Q05002, doi:10.1029/2008GC002347. Licht, A., Hulot G., Gallet Y., Thébault E. (2013), Ensembles of low degree archeomagnetic field models for the past three millennia. Phys. Earth Planet. Interiors. 224, 38-67. Macouin, M., Valet, J.P., Besse, J. (2004), Long-term evolution of the geomagnetic dipole moment, Phys. Earth Planet. Interiors. 147, 239-246. Muscheler, R., Joos, F., Beer, J., Muller, S.A., Vonmoos, M., Snowball, I. (2007), Solar activity during the last 1000 yr inferred from radionuclide records. Quatern. Sci. Rev. 26, 82-97. Pavón-Carrasco, F.J., Osete, M.L., Torta, J.M., De Santis, A. (2014), A geomagnetic field model for the Holocene based on archaeomagnetic and lava flow data. Earth Planet. Sci. Lett. 388, 98-109. Roth, R., and Joos, F. (2013), A reconstruction of radiocarbon production and total solar irradiance from the Holocene 14C and CO2 records: implications of data and model uncertainties, Clim. Past Discuss. 9, 1165-1235. Tauxe, L. (1993), Sedimentary records of relative paleointensity of the geomagnetic field: theory and practice. Rev. Geophys. 31, 319–354. Usoskin, I., Korte, M., Kovaltsov, G.A. (2008), Role of centennial geomagnetic changes in local atmospheric ionization. Geophys. Res. Lett. 35, L05811. Vieira, L.E.A., Solanki, S.K., Krivova, N.A., Usoskin, I.G. (2011), Evolution of the solar irradiance during the Holocene. Astron. Astrophys. 531, A6. Whaler, K. A. & Gubbins, D. (1981), Spherical harmonic analysis of the geomagnetic field: an example of a linear inverse problem, Geophys. J. R. astr. SOC., 65, 645-693. Yang S., Odah, H., Shaw, J. (2000), Variations in the geomagnetic dipole moment over the last 12000 years. Geophys. J. Int. 140 (1), 158-162.