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Steady state toroidal magnetic field at earth's core-mantle boundaryMeasurements of the dc electrical potential near the top of earth's mantle have been extrapolated into the deep mantle in order to estimate the strength of the toroidal magnetic field component at the core-mantle interface. Recent measurements have been interpreted as indicating that at the core-mantle interface, the magnetic toroidal and poloidal field components are approximately equal in magnitude. A motivation for such measurements is to obtain an estimate of the strength of the toroidal magnetic field in the core, a quantity important to our understanding of the geomagnetic field's dynamo generation. Through the use of several simple and idealized calculation, this paper discusses the theoretical relationship between the amplitude of the toroidal magnetic field at the core-mantle boundary and the actual amplitude within the core. Even with a very low inferred value of the toroidal field amplitude at the core-mantle boundary, (a few gauss), the toroidal field amplitude within the core could be consistent with a magnetohydrodynamic dynamo dominated by nonuniform rotation and having a strong toroidal magnetic field.
Document ID
19910044073
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Levy, Eugene H.
(Arizona Univ. Tucson, AZ, United States)
Pearce, Steven J.
(Arizona, University Tucson, United States)
Date Acquired
August 14, 2013
Publication Date
March 10, 1991
Publication Information
Publication: Journal of Geophysical Research
Volume: 96
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
91A28696
Funding Number(s)
CONTRACT_GRANT: NSG-7419
Distribution Limits
Public
Copyright
Other

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