Assessment of regional geomagnetic field modelling methods using a standard data set: spherical cap harmonic analysis |
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| Authors: | Z Düzgit & S R C Malin |
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| Institution: | ?stanbul University, Faculty of Engineering, Geophysics Department, 34850 Avc?lar, ?stanbul, Turkey,;Bogˇaziçi University, Kandilli Observatory and Earthquake Research Institute, 81220 Çengelköy, ?stanbul, Turkey. E-mail: |
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| Abstract: | Various methods that take account of the potential nature of the field have been proposed for modelling geomagnetic data on a regional scale. Several of these have been applied to a standard data set based on annual mean values from observatories in Europe. Here, we examine some of the properties of spherical cap harmonic analysis when applied to this data set, and compare the quality of fit with that of the other models. It is found that, for this data set, rectangular polynomial analysis provides a compact fit to main field data, but that in most other cases, for both main field and anomaly data, spherical cap harmonic analysis provides the better fit. Although relatively insensitive to chosen cap size, spherical cap harmonic analysis deteriorates more rapidly than the other methods when the number of coefficients is reduced. |
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| Keywords: | geomagnetism modelling regional field |
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