Mathematical Simulation of Convective Processes in the Liquid Core of the Earth and Implications for the Interpretation of Geomagnetic Field Variations in Polar Latitudes

In order to improve the representation of nutation, the effect of elasticity of the Earth on the nutation in space and diurnal nutation of the terrestrial rotation axis is considered and its amplitude is evaluated for the principal terms. The choice between several methods taking this effect into account is discussed. A comparison with the effect induced on nutation by the existence of a liquid core in the Earth's interior shows that the consideration of elasticity alone cannot give any amelioration in the representation of nutation.

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Eigenmode analysis of ballooning perturbations in the inner magnetosphere of the Earth

Annales Geophysicae ◽

10.5194/angeo-25-1391-2007 ◽

2007 ◽

Vol 25 (6) ◽

pp. 1391-1403 ◽

Cited By ~ 14

Author(s):

A. S. Parnowski

Keyword(s):

Stability Criterion ◽

Geomagnetic Field ◽

Finite Conductivity ◽

Nonlinear Structures ◽

Magnetic Hydrodynamics ◽

Longitudinal Displacement ◽

Inner Magnetosphere ◽

Transversal Displacement ◽

The Earth ◽

Eigenmode Analysis

Abstract. We analyze coupled Alfvén and slow magnetosonic eigenmodes in a dipole geomagnetic field with different ionospheric conductivities in the framework of ideal magnetic hydrodynamics (MHD) with finite pressure. We use numerical and, if possible, analytical methods to describe eigenmode frequencies, growth rates and eigenfunctions. The spectrum of Alfvén and slow magnetosonic modes is discrete and equidistant. The frequencies of the first Alfvén and slow magnetosonic eigenmodes are estimated as ~1 Hz and ~1 mHz, respectively. In the case of finite conductivity, periodic and aperiodic modes are separated and their interaction analyzed. It was shown that periodic and aperiodic perturbations can mutually transform into each other. A new flute stability criterion is derived (α~4.25), which is stricter than the Gold criterion (α=20/3). Here, as usual, α=−L/p dp/dL. For flute perturbations, the deviations of transversal displacement from a constant are calculated. An approximation for longitudinal displacement is derived. We determined the position of the main longitudinal peak, which can be responsible for nonlinear structures observed by Freja. An influence of nonlinear terms in pressure is estimated as well.

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Constraints on core composition from shock-waves data

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1982.0064 ◽

1982 ◽

Vol 306 (1492) ◽

pp. 37-47 ◽

Cited By ~ 61

Keyword(s):

Equations Of State ◽

Liquid Core ◽

Light Element ◽

Outer Core ◽

Atomic Ratio ◽

Core Material ◽

Solar Photosphere ◽

The Core ◽

The Earth ◽

Core Composition

Seismic data demonstrate that the density of the liquid core is some 8-10 % less than pure iron. Equations of state of Fe-Si, C, FeS 2 , FeS, KFeS 2 and FeO, over the pressure interval 133-364 GPa and a range of possible core temperatures (3500- 5000 K), can be used to place constraints on the cosmochemically plausible light element constituents of the core (Si, C, S, K and O ). The seismically derived density profile allows from 14 to 20 % Si (by mass) in the outer core. The inclusion of Si, or possibly G (up to 11 %), in the core is possible if the Earth accreted inhomogeneously within a region of the solar nebulae in which a C :0 (atomic) ratio of about 1 existed, compared with a G : O ratio of 0.6 for the present solar photosphere. In contrast, homogeneous accretion permits Si, but not C, to enter the core by means of reduction of silicates to metallic Fe-Si core material during the late stages of the accumulation of the Earth. The data from the equation of state for the iron sulphides allow up to 9-13 % S in the core. This composition would provide the entire Earth with a S:Si ratio in the range 0.14-0.3, comparable with meteoritic and cosmic abundances. Shock-wave data for KFeS 2 give little evidence for an electronic phase change from 4s to 3d orbitals, which has been suggested to occur in K, and allow the Earth to store a cosmic abundance of K in the metallic core.

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Correlation between Variations of the Geomagnetic Field and Precession of the Earth in the Quaternary

Nature Physical Science ◽

10.1038/physci244108a0 ◽

1973 ◽

Vol 244 (137) ◽

pp. 108-109 ◽

Cited By ~ 1

Author(s):

VÁCLAV BUCHA

Keyword(s):

Geomagnetic Field ◽

The Earth

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AN ANALYTICAL SOLUTION OF THE COSMIC RAYS TRANSPORT EQUATION IN THE PRESENCE OF THE GEOMAGNETIC FIELD

International Journal of Modern Physics A ◽

10.1142/s0217751x0201114x ◽

2002 ◽

Vol 17 (12n13) ◽

pp. 1645-1653

Author(s):

MARINA GIBILISCO

Keyword(s):

Magnetic Field ◽

Cosmic Rays ◽

Analytical Solution ◽

Transport Equation ◽

Geomagnetic Field ◽

The Earth ◽

Factorization Technique ◽

Diffusion Motion ◽

Geomagnetic Fields ◽

The Magnetic Field

In this work, I study the propagation of cosmic rays inside the magnetic field of the Earth, at distances d ≤ 500 Km from its surface; at these distances, the geomagnetic field deeply influences the diffusion motion of the particles. I compare the different effects of the interplanetary and of the geomagnetic fields, by also discussing their role inside the cosmic rays transport equation; finally, I present an analytical method to solve such an equation through a factorization technique.

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