Results 301 to 310 of about 1,025,390 (347)

Magnetic Source Separation in Earth's Outer Core

Science, 2008
We present evidence that the source of Earth's axial dipole field is largely independent from the sources responsible for the rest of the geomagnetic field, the so-called nonaxial dipole (NAD) field. Support for this claim comes from correlations between the structure of the historic field and the behavior of the paleomagnetic field recorded in ...
Kenneth A, Hoffman, Brad S, Singer
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Outer-core compositional stratification from observed core wave speed profiles

Nature, 2010
Light elements must be present in the nearly pure iron core of the Earth to match the remotely observed properties of the outer and inner cores. Crystallization of the inner core excludes light elements from the solid, concentrating them in liquid near the inner-core boundary that potentially rises and collects at the top of the core, and this may have
Helffrich, GR, Kaneshima, S
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Outer-core— and valence—electron pseudopotential

Physical Review B, 1984
We describe an energy-independent, norm-conserving pseudopotential which is accurate for outer-core and valence electrons simultaneously and thus extremely useful in cases such as transition-metal dimers and Cs compounds, where the outer-core electrons play a part in the binding.
D. M. Bylander, Leonard Kleinman
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The velocities in the outer core

Bulletin of the Seismological Society of America, 1971
abstract Earlier studies of the velocity distribution in the outer core have been based on the travel times of SKS.SKS arrivals can only be observed satisfactorily for arc distances at the surface greater than 85°. This lower limit of observation of SKS corresponds to an arc distance of 40.2° within the core.
A. L. Hales, J. L. Roberts
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Stratification of the outer core at the core-mantle boundary

Physics of the Earth and Planetary Interiors, 1998
The thermal regime of the core is controlled by the heat flux taken by the mantle across the core-mantle boundary (CMB) and its ratio Nu, the Nusselt number, to the conductive heat flux along the core adiabat. If Nu > 1, then compositional convection from the inner-core boundary (ICB) will be augmented by thermal convection from the CMB, and the outer ...
John R. Lister, Bruce A. Buffett
openaire   +1 more source

Photoemission EXAFS on Outer Core Levels

1984
The first definitive measurements of EXAFS by monitoring the direct photoelectron emission as a function of photon energy have been made using the Mn 3p and F 2s core levels in evaporated films of MnF2 [1,2]. Good agreement is found with bulk transmission EXAFS obtained with the Mn Is level.
K. M. Choudhary, G. M. Rothberg, M. L. denBoer, G. P. Williams, M. H. Hecht, I. Lindau   +5 more
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Causes and consequences of outer core stratification

Physics of the Earth and Planetary Interiors, 2013
Abstract The Earth’s outer core appears to be compositionally layered. Exotic mechanisms such as an original chemically layered core preserved from the Earth’s accretionary period, or compositionally different core material delivered by a Moon-creating impactor are conceivable, but require a core whose outermost part has been stratified throughout ...
Helffrich, George R, Kaneshima, Satoshi
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Composition of the Earth's Outer Core

Nature, 1954
ATTENTION has lately been given to the following set of four postulates: (a) the Earth, Mars and Venus have a common primitive composition; (b) compressibility is essentially a smoothly varying function of pressure at pressures beyond 0.4 × 106 million atmospheres in all three planets; (c) the outer core of the Earth is a high-pressure modification of ...
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Viscosity of the Outer Core

2013
Estimates of outer core viscosity span 14 orders of magnitude. This wide range of values may be partially explained by the difference in type of viscosity, molecular viscosity (a rheological property of the material) vis-a-vis a modified or eddy viscosity (a property of the motion), inferred from the various observational and theoretical methods [24 ...
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Thermal regime of the Earth's outer core

pure and applied geophysics, 1980
First an introduction into the dynamo problem and the core paradox is given. A novel theory of the volume dependence of Gruneisen's parameter is used for calculating the adiabatic temperatures on the assumption that the melting temperature of the material is reached at the boundary between the inner and outer cores of the Earth (IOB). On this condition,
W. Ullmann, U. Walzer
openaire   +1 more source