Information content and K-entropy of the present geomagnetic field
Author(s)De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia
Tozzi, R.; Università ''G. D'Annunzio'', Chieti, Italy
Gaya-Piqué, L.; Observatori de l'Ebre, Roquetes, Spain
04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals
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AbstractConcepts of information theory are applied to global models of the geomagnetic field B of the last century. The temporal behavior of information content suggests that B is in a chaotic state with characteristic times close to those of its westward drift and of the convective overturn in the outer core and the secular variation shows a comparable characteristic time of predictability. The main implication of these results is the suggestive hypothesis that a possible geomagnetic reversal or excursion is currently in progress.
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Improving total field geomagnetic secular variation modeling from a new set 3 of cross-over marine dataPavón-Carrasco, F. J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Torta, J. M.; Observatori de l'Ebre (Spain); Catalán, M.; Geophysical Dpt., Royal Spanish Naval Observatory (Spain); Talarn, A.; Observatori de l'Ebre; Ishihara, T.; Institute of Geology and Geoinformation, AIST (Japan) (Elsevier Science Limited, 2013-03)A new set of cross-over marine data has been used to generate a regional model for the secular variation of the total geomagnetic field, showing the potential of the suggested approach for gaining a better knowledge of the field over oceanic regions. The model, which is valid for the Northern Atlantic region during the temporal interval 1960–2000, was obtained using spherical cap harmonic analysis (SCHA) in space and penalized splines in time. The maximum spatial expansion is equivalent to degree 9 in ordinary spherical harmonic analysis. Annual mean intensity data from different geomagnetic observatories have been used to improve the spatial and temporal resolution of the original dataset. Results indicate that the regional model improves, in terms of the root mean square error, the prediction given by the 11th generation of IGRF and CM4 global models, especially for the geomagnetic observatories considered. We also provide the uncertainty of the model coefficients and the secular variation prediction given by a bootstrap algorithm. The model is available in the EarthRef. org Digital Archive at http://earthref.org/ERDA/1728/.
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