Journal ArticleDOI
The secular variation of the earth's magnetic field
D. W. Allan,E. C. Bullard +1 more
- Vol. 62, Iss: 4, pp 783-809
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In this paper, the authors show that the magnitude of the geomagnetic secular variation cannot be explained on these lines without the presence of a subsurface toroidal magnetic field of some hundreds of gauss which is ‘convected through’ the surface of the core.Abstract:
The magnetic field observable outside a body of conducting fluid in which field is imbedded may be considerably altered by convection currents in the fluid. One possible explanation of the geomagnetic secular variation foci is that localized convection cells in the earth's core disturb the main field present. An analytic solution for such a process is readily obtained by assuming the form and dimensions for such a cell, and shows that the magnitude of the secular variation cannot easily be explained on these lines without the presence of a subsurface toroidal magnetic field of some hundreds of gauss which is ‘convected through’ the surface of the core.read more
Citations
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Journal ArticleDOI
Methods of Mathematical Physics. By Harold Jeffreys and Bertha Swirles Jeffreys. Pp. viii, 679. 63s. 1946. (Cambridge University Press)
TL;DR: In this paper, the real variable is replaced by a complex variable, and the factorial and related functions of the complex variable are used to solve linear differential equations of the second order.
Journal ArticleDOI
A three-dimensional convective dynamo solution with rotating and finitely conducting inner core and mantle
TL;DR: In this article, the authors presented the first 3D, time-dependent, self-consistent numerical solution of the magneto- hydrodynamic (MHD) equations that describe thermal convection and magnetic field generation in a rapidly rotating spherical fluid shell with a solid conducting inner core.
Journal ArticleDOI
The secular variation of Earth's magnetic field
TL;DR: In this paper, a model of the magnetic field at the core-mantle boundary at selected epochs from 1715.0 to 1980.0 reveal novel features in the field at core.
Journal ArticleDOI
Geomagnetic polarity transitions
Ronald T. Merrill,P. L. McFadden +1 more
TL;DR: The most recent geomagnetic polarity transition occurred at about 780 ka, so we have never observed a transition directly as discussed by the authors, but we have been able to obtain a reliable model for even the first few harmonic terms during a transition.
Journal ArticleDOI
Geographical distribution of transitional VGPs: Evidence for non-zonal equatorial symmetry during the Matuyama-Brunhes geomagnetic reversal
TL;DR: In this paper, the authors used a reversing axial dipole to explain the sense of equatorial symmetry exhibited by the Matuyama-Brunhes polarity reversal obtained recently from the northern, equatorial and southern latitudes of the Atlantic sector.
References
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Book
A Course of Modern Analysis
TL;DR: The volume now gives a somewhat exhaustive account of the various ramifications of the subject, which are set out in an attractive manner and should become indispensable, not only as a textbook for advanced students, but as a work of reference to those whose aim is to extend the knowledge of analysis.
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An Introduction to Fourier Analysis and Generalized Functions.
R. A. Kunze,M. J. Lighthill +1 more
TL;DR: The theory of generalised functions and their Fourier transforms is discussed in this paper. But the analysis of Fourier transform is limited to the case of generalized functions, and it is not suitable for generalised function analysis.
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Methods of Mathematical Physics
TL;DR: In this article, the authors present an account of those parts of mathematics that are most frequently needed in physics, including methods which have applications in at least two branches of physics and conditions under which theorems hold.
Journal ArticleDOI
Methods of Mathematical Physics. By Harold Jeffreys and Bertha Swirles Jeffreys. Pp. viii, 679. 63s. 1946. (Cambridge University Press)
TL;DR: In this paper, the real variable is replaced by a complex variable, and the factorial and related functions of the complex variable are used to solve linear differential equations of the second order.
Book
Homogeneous dynamos and terrestrial magnetism
E. C. Bullard,H. Gellman +1 more
TL;DR: The main object of as discussed by the authors is to discuss the possibility of a body of homogeneous fluid acting as a self-exciting dynamo, and the main focus of the discussion is for the most part confined to the solution of Maxwell's equations for a sphere of electrically conducting fluid in which there are specified velocities.