Publication Date:
2021-03-18
Description:
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.
Description:
JCR Journal
Description:
open
Keywords:
dynamo
;
spatial spectrum
;
white spectrum
;
Lowes’law
;
Nevanlinna’s law
;
Hamilton’s principle
;
geomagnetic anomalies
;
inner core
;
outer core
;
asthenosphere
;
04. Solid Earth::04.05. Geomagnetism::04.05.01. Dynamo theory
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Format:
6517566 bytes
Format:
application/pdf
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