Combining vertical and radial-horizontal point-source data via 4C rotation in isotropic media

2021 ◽  
Author(s):  
James Gaiser
Keyword(s):  
Point Source ◽  
Source Data ◽  
Isotropic Media

scholarly journals Spatial allocation of anthropogenic carbon dioxide emission statistics data fusing multi-source data based on Bayesian network

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jianbin Tao ◽  
XiangBing Kong
Keyword(s):  
Carbon Dioxide ◽  
Land Cover ◽  
Point Source ◽  
Bayesian Network ◽  
Prior Knowledge ◽  
Carbon Dioxide Emissions ◽  
Spatial Allocation ◽  
Source Data ◽  
Anthropogenic Carbon ◽  
Anthropogenic Carbon Dioxide

AbstractA gridded social-economic data is essential for geoscience analysis and multidisciplinary application. Spatial allocation of carbon dioxide statistics data is an important issue in the context of global climate change, which involves the carbon emissions accounting and decomposition of responsibility for carbon emission reductions. In this research a new spatial allocation method for non-point source anthropogenic carbon dioxide emissions (ACDE) fusing multi-source data using Bayesian Network (BN) was introduced. In addition to common-used DMSP (Defense Meteorological Satellite Program), PD (population density) and GDP (Gross Domestic Production) data, the land cover and vegetation data was imported into the model as prior knowledge to optimize the model fitting. The prior knowledge here was based on the understanding that ACDE was dominated by human activities and has strong correlations with land cover and vegetation conditions. A 1 km gridded ACDE map integrated emissions form point-source and non-point source was generated and validated. The model predicts ACDE with high accuracies and great improvement can be observed when fusing land cover and vegetation as prior knowledge. The model can achieve successful statistics data downscaling on national scale provided adequate sample data are available, offering a novel method for ACDE accounting in China.

scholarly journals A complex point-source solution of the acoustic eikonal equation for Gaussian beams in transversely isotropic media

Geophysics ◽  
2020 ◽  
Vol 85 (3) ◽  
pp. T191-T207
Author(s):  
Xingguo Huang ◽  
Hui Sun ◽  
Zhangqing Sun ◽  
Nuno Vieira da Silva
Keyword(s):  
Point Source ◽  
Eikonal Equation ◽  
Taylor Series Expansion ◽  
Transversely Isotropic ◽  
Complex Point ◽  
Transversely Isotropic Media ◽  
Isotropic Media ◽  
Anisotropy Parameters ◽  
Complex Point Source ◽  
Complex Eikonal

The complex traveltime solutions of the complex eikonal equation are the basis of inhomogeneous plane-wave seismic imaging methods, such as Gaussian beam migration and tomography. We have developed analytic approximations for the complex traveltime in transversely isotropic media with a titled symmetry axis, which is defined by a Taylor series expansion over the anisotropy parameters. The formulation for the complex traveltime is developed using perturbation theory and the complex point-source method. The real part of the complex traveltime describes the wavefront, and the imaginary part of the complex traveltime describes the decay of the amplitude of waves away from the central ray. We derive the linearized ordinary differential equations for the coefficients of the Taylor-series expansion using perturbation theory. The analytical solutions for the complex traveltimes are determined by applying the complex point-source method to the background traveltime formula and subsequently obtaining the coefficients from the linearized ordinary differential equations. We investigate the influence of the anisotropy parameters and of the initial width of the ray tube on the accuracy of the computed traveltimes. The analytical formulas, as outlined, are efficient methods for the computation of complex traveltimes from the complex eikonal equation. In addition, those formulas are also effective methods for benchmarking approximated solutions.

A slant‐stack procedure for point‐source data

Geophysics ◽  
1986 ◽  
Vol 51 (7) ◽  
pp. 1370-1386 ◽  
Author(s):  
Henry Brysk ◽  
Douglas W. McCowan
Keyword(s):  
Point Source ◽  
Computationally Efficient ◽  
West Florida Shelf ◽  
Florida Shelf ◽  
Lamb’S Problem ◽  
Amplitude Versus Offset ◽  
Surface Data ◽  
Source Data ◽  
Bessel Transforms ◽  
Slant Stacking

The proper implementation of the τ-p method for surface data excited by a point source requires a cylindrical slant stack. Usually the common (Cartesian) slant stack is computed instead as an approximation to the geometrically correct procedure. Here we describe a formulation of the cylindrical slant stack as a weighted sum of Cartesian slant stacks; our cylindrical slant stack is computationally efficient to perform. We show how, although the usefulness of the slant stack is most easily seen with Cartesian coordinates, it can also be used with Fourier‐Bessel transforms. An example of the method shows results computed from data recorded on the West Florida Shelf. Severe edge‐effect noise which overwhelms the Cartesian slant stack is attenuated by the cylindrical slant‐stacking. Applications of the cylindrical slant stack to other seismological calculations, such as Lamb’s problem, are also discussed. In particular, we prove that the plane‐wave reflection coefficients apply exactly in the τ-p domain; hence an amplitude‐versus‐offset analysis is unambiguous in that domain.

Reply by the authors to Douglas W. McCowan

Geophysics ◽  
1990 ◽  
Vol 55 (3) ◽  
pp. 379-379 ◽  
Author(s):  
Rakesh Mithal ◽  
Emilio E. Vera
Keyword(s):  
Plane Wave ◽  
Point Source ◽  
Seismic Data ◽  
Wave Reflection ◽  
Suitable Alternative ◽  
Plane Wave Decomposition ◽  
Main Emphasis ◽  
Source Data ◽  
Wave Decomposition ◽  
Slant Stacking

In his discussion, McGowan directs his attention exclusively to which method should be used to produce a plane-wave decomposition of point-source seismic data. Although the choice of method is an important point, it was not the main emphasis of our paper which, as its title indicates, was the comparison between plane-wave decomposition (cylindrical slant stacking) and simple slant stacking. We demonstrated the differences between these two processes and clearly indicated the necessity of using cylindrical slant stacking in order to get the correct plane-wave reflection response of point-source data. McGowan criticizes our method because it makes use of the standard asymptotic approximation of the Bessel function [Formula: see text] and considers only outward traveling waves. In our paper we acknowledged that these simplifications do not produce accurate results for ray parameters near zero and explicitly mentioned the method of Brysk and McGowan (1986) as a suitable alternative to deal with this problem.

Wavenumber‐based filtering of marine point‐source data

Geophysics ◽  
1993 ◽  
Vol 58 (9) ◽  
pp. 1335-1348 ◽  
Author(s):  
Lasse Amundsen
Keyword(s):  
Plane Wave ◽  
Point Source ◽  
Line Source ◽  
Hankel Transform ◽  
Source Pressure ◽  
Function Type ◽  
Plane Wave Decomposition ◽  
Source Data ◽  
Processing Techniques ◽  
Wave Decomposition

In seismic processing, plane‐wave decomposition has played a fundamental role, serving as a basis for developing sophisticated processing techniques valid for depth‐dependent models. By comparing analytical expressions for the decomposed wavefields, we review several processing algorithms of interest for the geophysicist. The algorithms may be applied to marine point‐source data acquired over a horizontally layered viscoelastic and anisotropic medium. The plane‐wave decomposition is based on the Fourier transform integral for line‐source data and the Hankel transform integral for point‐source data. The involved wavenumber integrals of the cosine or Bessel‐function type are difficult to evaluate accurately and efficiently. However, a number of the processing techniques can easily be run as a filtering operation in the spatial domain without transforming to the wavenumber domain. The mathematical expressions for the spatial filters are derived using plane wave analysis. With numerical examples, we demonstrate the separation of upgoing and downgoing waves from the pressure, the removal of the source ghost from the pressure, and the transformation of point‐source pressure data to the corresponding line‐source data. The filters for these three processes work satisfactorily. Limited spatial aperture is discussed both for point‐source and line‐source data. The resolution kernels relating finite‐aperture decomposed data to infinite‐aperture decomposed data are given. The kernels are approximately equal in the asymptotic limit when the minimum offset is zero.

scholarly journals TheINTEGRALspectrometer SPI: performance of point-source data analysis

2005 ◽  
Vol 357 (2) ◽  
pp. 420-428 ◽  
Author(s):  
P. Dubath ◽  
J. Knödlseder ◽  
G. K. Skinner ◽  
P. Connell ◽  
I. Kreykenbohm ◽  
...  
Keyword(s):  
Data Analysis ◽  
Point Source ◽  
Source Data

Frequency-domain seismic data transformation from point-source to line-source for 2D viscoelastic anisotropic media

Geophysics ◽  
2021 ◽  
pp. 1-45
Author(s):  
Qingjie Yang ◽  
Bing Zhou ◽  
Mohamed Kamel Riahi ◽  
Mohammad Al-Khaleel
Keyword(s):  
Phase Shift ◽  
Point Source ◽  
Seismic Data ◽  
Line Source ◽  
Waveform Inversion ◽  
Full Waveform ◽  
Compensation Factor ◽  
Source Data ◽  
Amplitude Compensation ◽  
Homogeneous Media

We present a simple yet effective transform function to convert 3D point-source seismic data to equivalent 2D line-source data, which is required when applying efficient 2D migration and full-waveform inversion to field data collected along a line. By numerically comparing the 3D and corresponding 2D Green’s tensors in various media, the phase shift around 45° and the offset amplitude compensation factor, as well as small fluctuations of the amplitude ratios are observed in all nonzero components of the wave-equation solutions. Based on these observations, we derive a transform function comprised of (1) a simple filter for compensating amplitude and phase shift, and (2) stretching scalars for scaling amplitude differences for different components. We employ the 3D and 2D analytical wave solutions in various homogeneous media to demonstrate the accuracy of the proposed transform function, and then apply it to a heterogeneous, viscoelastic, anisotropic model and a modified Marmousi model. All of these results indicate that the proposed transform function is applicable for the conversion of point-source data to equivalent line-source data for imaging 2D subsurface structure.

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