Eccentric dipole approximation of the geomagnetic field: Application to cosmic ray computations |
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Authors: | J Nevalainen IG Usoskin A Mishev |
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Institution: | 1. Department of Physics, 90014 University of Oulu, P.O. Box 3000, Finland;2. Sodankylä Geophysical Observatory, Oulu unit, 90014 University of Oulu, Finland |
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Abstract: | A comparison of the full IGRF model of the geomagnetic field with two simplified models, the truncated IGRF and the eccentric dipole model, is performed. The simplified models were found to provide a reasonable approximation for the large scale geomagnetic field distribution. In the application of the simplified geomagnetic models to the shielding of cosmic rays in the magnetosphere as quantified via the geomagnetic cut-off rigidity, the eccentric dipole and the truncated IGRF provide a good large scale view. The use of the simplified model does not introduce any additional systematic errors at the global scale but may be a source of moderate uncertainty at the regional scale in the tropical Atlantic region. This study quantitatively validates the use of such simplified geomagnetic models when describing the shielding of cosmic rays in the magnetosphere. |
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Keywords: | Cosmic rays Geomagnetic field Paleomagnetism |
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