Improvement of the Earth nutation theory by taking into account the atmosphere and viscosity of the liquid core

2002 ◽  
pp. 451-456
Author(s):  
V. E. Zharov ◽  
S. L. Pasynok
Keyword(s):  
Liquid Core ◽  
The Earth

Correlation between large-scale motions in the liquid core of the Earth and geomagnetic jerks, earthquakes, and variations in the Earth’s length of day

2016 ◽  
Vol 467 (1) ◽  
pp. 280-283 ◽  
Author(s):  
M. B. Gokhberg ◽  
E. V. Olshanskaya ◽  
O. G. Chkhetiani ◽  
S. L. Shalimov ◽  
O. M. Barsukov
Keyword(s):  
Large Scale ◽  
Liquid Core ◽  
Length Of Day ◽  
The Earth ◽  
Geomagnetic Jerks

scholarly journals Nutation in Space and Diurnal Nutation in the Case of an Elastic Earth

1979 ◽  
Vol 82 ◽  
pp. 169-174 ◽  
Author(s):  
Nicole Capitaine
Keyword(s):  
Rotation Axis ◽  
Liquid Core ◽  
Elastic Earth ◽  
The Earth ◽  
Earth’S Interior ◽  
Earth's Interior

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.

Constraints on core composition from shock-waves data

1982 ◽  
Vol 306 (1492) ◽  
pp. 37-47 ◽  
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.

scholarly journals Influence of the Solid Inner Core and Compressibility of the Fluid Core on the Earth Nutation

1991 ◽  
Vol 127 ◽  
pp. 250-253
Author(s):  
Sergei Diakonov
Keyword(s):  
Infinite System ◽  
Inner Core ◽  
Equations Of Motion ◽  
Liquid Core ◽  
Low Frequency ◽  
Approximate Solutions ◽  
Low Frequency Oscillations ◽  
The Earth ◽  
Fluid Core ◽  
Harmonic Representation

While calculating low frequency oscillations of the Earth liquid core spherical harmonic representation of the deformation field is usually used [1-3]:Substitution of (1) into the equations of motion gives an infinite system of differential equations for scalar functions Sɭm and Tɭm . Approximate solutions of such a system are obtained by truncating of the system. But results of [4] show that sometimes such method divergences.

Observation of the Earth Liquid Core Resonance by Extensometers

2017 ◽  
Vol 175 (5) ◽  
pp. 1631-1642 ◽  
Author(s):  
Dóra Bán ◽  
Gyula Mentes ◽  
Márta Kis ◽  
András Koppán
Keyword(s):  
Liquid Core ◽  
The Earth

scholarly journals Semidiurnal signal in UT1 due to the influence of tidal gravitation on the triaxial structure of the Earth

2009 ◽  
Vol 5 (H15) ◽  
pp. 217-217 ◽  
Author(s):  
Aleksander Brzeziński ◽  
Nicole Capitaine
Keyword(s):  
Polar Motion ◽  
Structural Model ◽  
Angular Displacement ◽  
Liquid Core ◽  
Ocean Tide ◽  
Axial Component ◽  
Truncation Level ◽  
The Earth ◽  
Recent Developments ◽  
Rigid Earth

AbstractThe axial component of Earth rotation, which is conventionally expressed by Universal Time (UT1), contains small physical signals with diurnal and subdiurnal periods. This part of the spectrum is dominated by the tidal effects which are regular and predictable. The largest components express the influence of the gravitationally forced ocean tides with diurnal and semidiurnal periods and amplitudes up to 0.02 milliseconds (ms) in UT1 corresponding to an angular displacement of 0.30 milliarcseconds (mas); see Table 8.3 of the IERS Conventions (IERS, 2003). There are also smaller subdiurnal components (amplitudes up to 0.03 mas), designated as “spin libration” by Chao et al. (1991), due to direct influence of the tidal gravitation on those features of the Earth's density distribution which are expressed by the non-zonal terms of the geopotential. These components are not included in the models recommended by the IERS Conventions, in contrast to the corresponding effect in polar motion (ibid., Table 5.1).Here we consider in detail the subdiurnal libration in UT1. We derive an analytical solution for the structural model of the Earth consisting of an elastic mantle and a liquid core which are not coupled to each other. The reference solution for the rigid Earth is computed by using the satellite-determined coefficients of geopotential and the recent developments of the tide generating potential (TGP). We arrived to the conclusion that the set of terms with amplitudes exceeding the truncation level of 0.005 mas consists of 11 semidiurnal harmonics due to the influence of the TGP term u22 on the equatorial flattening of the Earth expressed by the Stokes coefficients C22, S22. There is an excellent agreement between our estimates for the rigid Earth and the amplitudes derived by Wünsch (1991). The only important difference is the term with the tidal code ν2, which seems to be overlooked in the development of Wünsch. Our amplitudes computed for an elastic Earth with liquid core appear to be in reasonable agreement with those derived by Chao et al. (1991), but the latter model was not complete. The estimated effect is superimposed on the ocean tide influences having the same frequencies but 9 to 11 times larger amplitudes. Nevertheless, its maximum peak-to-peak size is about 0.105 mas, hence definitely above the current uncertainty of UT1 determinations. Comparison with the corresponding model of prograde diurnal polar motion associated with the Earth's triaxiality (IERS Conventions, Table 5.1) shows that: 1) the two effects are of similar size, 2) there is consistency between the underlying dynamical models, parameters employed, etc. In conclusion, we recommend adding the model developed here to the set of procedures provided by the IERS Conventions.

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