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New Approach to Origin of Earth’s Magnetic Field

Citation

Ginzburg, Eric (2021), New Approach to Origin of Earth’s Magnetic Field, Dryad, Dataset, https://doi.org/10.5061/dryad.k98sf7m65

Abstract

The hypothesis of a “convective dynamo” is now a mainstream concept of geomagnetism origin. This concept is briefly described in [G. Glatzmaier at al, 2005]. The observations argue for a mechanism within the Earth’s interior that continually generates the geomagnetic field. It has long been speculated that this mechanism is a convective dynamo operating in the Earth's fluid outer core, which surrounds its solid inner core. There has been no detailed dynamically self-consistent model demonstrating that this mechanism could actually work or explaining why the geomagnetic field has the intensity it does. There has not been explained why the geomagnetic field has a strongly dipole-dominated structure with non dipolar field structure that varies on the time scale on ten to one hundred years and why the field occasionally undergoes dipole reversals. In order to test the convective dynamo hypothesis and attempt to answer these longstanding questions, the first self-consistent numerical model, the Glatzmaier-Roberts model has been developed [ibid].
Some of the above-listed questions were answered during the research run on parallel supercomputers at the Pittsburg Supercomputing Center and the Los Alamos National Laboratory in 2005 [ibid], but far not all of them. The reduced amount of published articles on the topic of “convective MGD-dynamo” during the last decade, points regarding
a dead end in this course of research about this topic.
These facts inspired us to explore and propose a different approach to the origin of the geomagnetic field. The concept of our approach is informed by the following issues:
- The earth’s magnetic field is maintained by loops with the electric current circulating in the core. Hence, the geomagnetic field has predominantly a dipole-dominated structure. However, the geomagnetic field observed at earth’s surface, has several world anomalies, and therefore, it would be reasonable to suggest that the core contains more than one exocentric dipoles.
- Digital simulation performed in this work, confirms that two elementary dipoles located at specific places within the core, can reproduce the map of magnetic field
intensity at earth’s surface. We denote this two dipoles scheme by a term “two dipoles model”.
- Digital simulation defined the unique location of the elementary dipoles in earth’s core and also determined the magnetic moment of each of them. The results of computations showed that the center of each elementary dipole is placed just on the boundary of earth’s inner and outer cores. In accordance with the conditions the elementary dipoles can be interpreted as a physical dipoles.
- Accordingly to our concept, the physical dipoles are capable to dissipate heat flux, which extends from earth’s depth to its surface. This heat flux, by sense, is a part of “solid earth’s heat flux” as was described in [J. H. Davies, et al, 2010].
- Beside, the dipoles within the core can accumulate and expend electromagnetic energy. A known analogy between the dipole and a flywheel, which can accumulate kinetic energy when it rolls up, is applicable here. When a dipole moves in a non-uniformed magnetic field, then an external magnetic field can induce the e.m.f.
in it.
- In order to understand the role of an external magnetic field, it is relevant to utilize electro-technical analogy. A small amount of power supplied by permanent magnets (or diverted in self-excited coils) in a generator of direct current allows to produce substantially more power. Similarly to this effect, a comparatively weak non-uniformed earth’s external magnetic field excites a powerful e.m.f. in the dipoles within earth’s core
- Because the dipoles in the core are located on the boundary between the inner and outer core, they are, probably, joined to the solid core with some mechanical ties. As a result, it occurs electrodynamic interactions which cause either a deceleration, or acceleration of earth’s rotation around earth’s axis. Presumably, the radial components of these interactions cause the Earth to move away the Sun, or to move the Earth toward the Sun.
- If we take into account calculations made by Krasinsky and Brumberg [Krasinsky, at al, 2004] regarding movement of the Earth away from the Sun an average distance 15 m per century, then over a period of a billion years the Earth would have moved away from the Sun approximately 150,000 km (about 100,000 miles) - that is about 0.1% of AU (Astronomical Unit). A known analogy between a dipole and flywheel , which can accumulate kinetic energy when it rolls up is applicable here.
- After our investigation we came to conclusion that our proposed self-sustained model of TDM-dynamo running on the customary principles of Faraday’s electromagnetic induction is quite competitive with traditional now MGD-dynamo.
- We also want to remark that the derivative dB/dt from the magnetic induction B may have two different signs. The e.m.f. induced in the dipole also may have different signs.
- Accordingly to [R. Feynman, at all, Ch. 17-7, 1977], one of these e.m.f. that coincides with the direction of the current e.m.f. in the dipole, is called a “direct
e.m.f.”, and another one (that is opposite to current e.m.f. in the dipole) called an “inverse e.m.f.” (or counter-e.m.f.).
- Because the “direct e.m.f.” increases the dipole’s energy, its running can be conditionally interpreted as the process of “dipole’s charge”, and running “inverse e.m.f.” can be conditionally interpreted as the process of “dipole’s discharge”. These effects are the key course of action for explanation of a phenomenon of earth’s magnetic poles reversal.