Open AccessThe separation of the geomagnetic field originated in the core, in the asthenosphere, and in the crust
Author(s) -
G. P. Gregori,
Wenyue Dong,
Xiang Gao,
Fabrizio Terenzio Gizzi
Publication year - 1999
Publication title -
annals of geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 60
eISSN - 2037-416X
pISSN - 1593-5213
DOI - 10.4401/ag-3713
Subject(s) - geophysics , geology , earth's magnetic field , asthenosphere , dynamo , core–mantle boundary , outer core , satellite , lithosphere , crust , field (mathematics) , ionospheric dynamo region , mantle (geology) , inner core , magnetic field , seismology , physics , tectonics , geomagnetic storm , astronomy , mathematics , quantum mechanics , pure mathematics
The separation of the field produced by different internal sources can be accomplished by means of the so-called spatial spectrum of the geomagnetic field of internal origin. It is shown how such a rationale, when suitably interpreted, allows to recognize the field that is originated by electric currents that flow either on the Inner-Core Boundary (ICB), or on the Core-Mantle Boundary (CMB), or on the Asthenosphere-Lithosphere Boundary (ALB). It appears crucial, however, to rely on satellite measurements alone, because ground-based and ship- and air-borne records are severely perturbed by the crustal field. Therefore, it is shown, on the basis of a critical reconsideration of a few key-papers in the literature, that the best approach is to avoid mixing together all kinds of measurements. Satellite data are best suited for recognizing the dynamo field, while ground-based, ship- and air-borne records, which are measured much closer to crustal sources, are best suited, after subtraction of the satellite-derived dynamo field, for inferring the geomagnetic anomalies that are to be associated with crustal sources alone