scholarly journals Problems of global geodynamics

2019 ◽  
pp. 180-198
Author(s):  
V. P. Trubitsyn
Keyword(s):  
Numerical Modeling ◽  
Phase Transformations ◽  
Thermal Convection ◽  
Seismic Data ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Mantle Structure ◽  
Convective Flows ◽  
The Earth ◽  
Global Geodynamics

Global geodynamics is determined by thermal convection in the mantle which manifests itself on the surface by movements, relief, heat flow, and volcanism. Thermal convection in the Earth is complicated by the fact that the lithosphere is broken into rigid plates, the crust is broken into six separate floating continents and a number of islands, on the mantle bottom there are two giant piles of heavy material, at high convection intensity the ascending convective flows acquire a plume shape, and phase transformations take place in the mantle. The impacts of many factors on the mantle structure have been thoroughly studied and fairly well understood. It is pertinent to reconcile the new data on phase transformations at depths of 650 to 700 km with the seismic data on the positions of these boundaries. The ultimate problem of global geodynamics has not yet been solved; the three-dimensional structure of the whole-mantle flows, consistent with the observations in geophysics, geochemistry, geology, and numerical modeling, is not known even on a semischematic level.

scholarly journals The Estimation of Surface Albedo from DSCOVR EPIC

2020 ◽  
Vol 12 (11) ◽  
pp. 1897
Author(s):  
Qiuyue Tian ◽  
Qiang Liu ◽  
Jie Guang ◽  
Leiku Yang ◽  
Hanwei Zhang ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Surface Albedo ◽  
Climate Models ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
High Temporal Resolution ◽  
Observation Data ◽  
Climate Change Research ◽  
Narrow Channels ◽  
The Earth

Surface albedo is an important parameter in climate models. The main way to obtain continuous surface albedo for large areas is satellite remote sensing. However, the existing albedo products rarely meet daily-scale requirements, which has a large impact on climate change research and rapid dynamic changes of surface analysis. The Earth Polychromatic Imaging Camera (EPIC) on the Deep Space Climate Observatory (DSCOVR) platform, which was launched into the Sun–Earth’s first Lagrange Point (L1) orbit, can provide spectral images of the entire sunlit face of Earth with 10 narrow channels (from 317 to 780 nm). As EPIC can provide high-temporal resolution data, it is beneficial to explore the feasibility of EPIC to estimate high-temporal resolution surface albedo. In this study, hourly surface albedo was calculated based on EPIC observation data. Then, the estimated albedo results were validated by ground-based observations of different land cover types. The results show that the EPIC albedo is basically consistent with the trend of the ground-based observations in the whole time series variation. The diurnal variation of the surface albedo from the hourly EPIC albedo exhibits a “U” shape curve, which has the same trend as the ground-based observations. Therefore, EPIC is helpful to enhance the temporal resolution of surface albedo to diurnal. Surfaces with a three-dimensional structure that casts shadows display the hotspot effect, producing a reflectance peak in the retro-solar direction and lower reflectance at viewing angles away from the solar direction. DSCOVR observes the entire sunlit face of the Earth, which is helpful to make up for the deficiency in the observations of traditional satellites in the hotspot direction in bidirectional reflectance distribution function (BRDF) research, and can help to improve the underestimation of albedo in the direction of hotspot observation.

Low-frequency seismology and the three-dimensional structure of the Earth

1989 ◽  
Vol 328 (1599) ◽  
pp. 329-349 ◽  
Keyword(s):  
Large Scale ◽  
Inner Core ◽  
Three Dimensional ◽  
Low Frequency ◽  
Quantitative Agreement ◽  
Phase Behaviour ◽  
Dimensional Structure ◽  
Order Structure ◽  
Three Dimensional Structure ◽  
The Earth

We attempt to catalogue those features of the three-dimensional structure of the Earth that are well-constrained by low-frequency data (i.e. periods longer than about 125 seconds). The dominant signals in such data are the surface-wave equivalent modes whose phase characteristics are mainly affected by a large scale structure of harmonic degree two in the upper mantle. Available aspherical models predict this phase behaviour quite well, but do not give an accurate prediction of the observed waveforms and we must appeal to higher-order structure an d /o r coupling effects to give the observed complexity of the data. Strong splitting of modes which sample the cores of the Earth is also observed and, though we do not yet have a model of aspherical structure which gives quantitative agreement with these data, anisotropy or large-scale aspherical structure in the inner core appears to be required to model the observed signal.

Three-dimensional structure of the Earth from splitting in free-oscillation spectra

Nature ◽  
1987 ◽  
Vol 325 (6103) ◽  
pp. 405-411 ◽  
Author(s):  
Domenico Giardini ◽  
Xiang-Dong Li ◽  
John H. Woodhouse
Keyword(s):  
Free Oscillation ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
The Earth

Computational Identification of a New Form of Li2MnSiO4 for Battery Applications

2017 ◽  
Vol 263 ◽  
pp. 160-164
Author(s):  
Maxim Arsentev ◽  
Marina Kalinina ◽  
Petr Tikhonov ◽  
Anastasia Shmigel ◽  
Nadezhda Kovalko ◽  
...  
Keyword(s):  
Phase Transformations ◽  
Three Dimensional ◽  
High Capacity ◽  
Dimensional Structure ◽  
Practical Application ◽  
Computational Identification ◽  
New Form ◽  
The Stability ◽  
Inorganic Framework ◽  
Computer Studies

The reversibility of phase transformations in Li2MnSiO4 and related materials during charge/discharge of the material is an important factor to enable the practical application of the cathode materials. However, the stability of this material is still unattainable. Here we report the computational identification of a new form of Li2MnSiO4 as a stable candidate with acceptable characteristics. The stability could arise due to the presence of the three-dimensional structure of the inorganic framework. The presence of a structure with a compact unit cell forms the basis for high capacity. Surprisingly it was found to have a stable analogue occurring in nature – Na2CaSiO4 with the same structure. Using this information the possible routes of obtaining such material are presented. The prediction of such material has been not found in the literature previously. Of course the problems such as phase transformations upon delithiation may exist, and to check the data the experimental and computer studies needed.

scholarly journals Visualization of three dimensional earth fissures in geological structure

2015 ◽  
Vol 372 ◽  
pp. 227-229
Author(s):  
L. Zhu ◽  
J. Yu ◽  
Y. Liu ◽  
H. Gong ◽  
Y. Chen ◽  
...  
Keyword(s):  
Seismic Data ◽  
Three Dimensional ◽  
Geological Structure ◽  
Triangular Prism ◽  
Structure Model ◽  
Geological Structures ◽  
Ground Fissures ◽  
Earth Fissures ◽  
The Earth ◽  
Cutting Operation

Abstract. This paper proposes a new method for visualizing the earth fissures of geological structure in three dimensional (3-D) domains on the basis of the seismic data and features information of earth fissures. The seismic data were interpreted for obtaining the stratagraphic data with various lithological information and the depth of the earth fissures. The spatial distribution of the ground fissures including the dip, strike and width were digitalized on an ArcGIS platform. Firstly, the 3-D geological structure was rebuilt using the Generalized Tri-Prism (GTP) method which is a real solid method for displaying geological structures. The GTP method can reflect the inner material of the strata and can simulate complicated geological structures such as faults and stratagraphic pinch outs. The upper and lower surfaces of each stratum consist of Triangle Irregular Networks (TIN). The inner solid between the two surfaces are a series of triangular prisms. Secondly, since the width of the ground fissure gradually decreases with depth, multiple edge lines of the earth fissures on the bottom stratum surface are deduced on the basis of the fissure characteristics. Then, the model of the earth fissures consisting of a series of triangular pyramids can be constructed using these points and the edge lines. A cutting operation was carried out on the 3-D geological structure using this ground fissures model. If the surfaces of the ground fissures model intersects with the GTPs in the geological structure model, new GTPs were generated within the local regions. During this process, the topological relations between TIN, triangular prism and lines were reconstructed so that the visualization of ground fissures in the geological structure model is realized. This method can facilitate the mechanism for studying fissures and avoid the gaps between the fissure solid and the geological structure to accurately reflect their 3-D characteristics.

Numerical simulations of three-dimensional thermal convection in a fluid with strongly temperature-dependent viscosity

1991 ◽  
Vol 233 ◽  
pp. 299-328 ◽  
Author(s):  
Masaki Ogawa ◽  
Gerald Schubert ◽  
Abdelfattah Zebib
Keyword(s):  
Thermal Convection ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Rectangular Pattern ◽  
Four Corners ◽  
Layer Mode ◽  
Constant Viscosity ◽  
Dependent Viscosity

Numerical calculations are presented for the steady three-dimensional structure of thermal convection of a fluid with strongly temperature-dependent viscosity in a bottom-heated rectangular box. Viscosity is assumed to depend on temperature T as exp (− ET), where E is a constant; viscosity variations across the box r (= exp (E)) as large as 105 are considered. A stagnant layer or lid of highly viscous fluid develops in the uppermost coldest part of the top cold thermal boundary layer when r > rc1, where r = rc1 ≡ 1.18 × 103Rt0.309 and Rt is the Rayleigh number based on the viscosity at the top boundary. Three-dimensional convection occurs in a rectangular pattern beneath this stagnant lid. The planform consists of hot upwelling plumes at or near the centre of a rectangle, sheets of cold sinking fluid on the four sides, and cold sinking plume concentrations immersed in the sheets. A stagnant lid does not develop, i.e. convection involves all of the fluid in the box when r < rc1. The whole-layer mode of convection occurs in a three-dimensional bimodal pattern when r > rc2 = 3.84 × 106Rt−1.35. The planform of the convection is rectangular with the coldest parts of the sinking fluid and the hottest part of the upwelling fluid occurring as plumes at the four corners and at the centre of the rectangle, respectively. Both hot uprising plumes and cold sinking plumes have sheet-like extensions, which become more well-developed as r increases. The whole-layer mode of convection occurs as two-dimensional rolls when r < min (rc1, rc2). The Nusselt number Nu depends on the viscosity at the top surface more strongly in the regime of whole-layer convection than in the regime of stagnant-lid convection. In the whole-layer convective regime, Nu depends more strongly on the viscosity at the top surface than on the viscosity at the bottom boundary.

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