High-Performance Three-Dimensional Electromagnetic Modelling Using Modified Neumann Series. Anisotropic Earth

Pankratov, Oleg V.; Kuvshinov, A. V.; Avdeev, Dmitry B.

doi:10.5636/jgg.49.1541

Cited by 42 publications

(15 citation statements)

References 5 publications

(5 reference statements)

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“…For instance, with the IE approach, to get a wellpreconditioned matrix system A IE , the modified iterative-dissipative method (MIDM) has been successfully developed Pankratov et al, 1995Pankratov et al, , 1997Fainberg, 1995, 1997) and implemented (Avdeev et al, , 1998(Avdeev et al, , 2000(Avdeev et al, , 2002a(Avdeev et al, , 2002bZhdanov and Fang, 1997;Hursan and Zhdanov, 2002;Singer et al, 2003). It is remarkable that the MIDM-preconditioned system matrix A IE has such a small condition number,…”

Section: Techniques To Improve Solutions Using the Physics Of The Em mentioning

confidence: 97%

Three-Dimensional Electromagnetic Modelling and Inversion from Theory to Application

Avdeev

2005

Surv Geophys

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237

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The whole subject of three-dimensional (3-D) electromagnetic (EM) modelling and inversion has experienced a tremendous progress in the last decade. Accordingly there is an increased need for reviewing the recent, and not so recent, achievements in the field. In the first part of this review paper I consider the finite-difference, finite-element and integral equation approaches that are presently applied for the rigorous numerical solution of fully 3-D EM forward problems. I mention the merits and drawbacks of these approaches, and focus on the most essential aspects of numerical implementations, such as preconditioning and solving the resulting systems of linear equations. I refer to some of the most advanced, state-of-the-art, solvers that are today available for such important geophysical applications as induction logging, airborne and controlled-source EM, magnetotellurics, and global induction studies. Then, in the second part of the paper, I review some of the methods that are commonly used to solve 3-D EM inverse problems and analyse current implementations of the methods available. In particular, I also address the important aspects of nonlinear Newton-type optimisation techniques and computation of gradients and sensitivities associated with these problems.

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Section: Techniques To Improve Solutions Using the Physics Of The Em mentioning

confidence: 97%

Three-Dimensional Electromagnetic Modelling and Inversion from Theory to Application

Avdeev

2005

Surv Geophys

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237

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“…Pankratov et al, 1997). Here, j ext is the extraneous (impressed) current, time-harmonic dependency is e −iωt , μ o is the magnetic permeability of free space, i = √ −1, ω = 2π/T is the angular frequency, T is the period of the variations, σ (r, ϑ, ϕ) is the conductivity distribution in the model, and ϑ and ϕ are co-latitude and longitude respectively.…”

Section: Numerical Simulationmentioning

confidence: 99%

Can undersea voltage measurements detect tsunamis?

et al. 2010

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The movement of electrically conducting ocean water in the ambient geomagnetic eld induces secondary electric and magnetic elds in the oceans. Ocean water transport is now routinely inferred from undersea cable voltage data. We try to answer the question whether the method could also be useful to detect tsunami. A barotropic shallow water model along with a three-dimensional electromagnetic induction code was used to predict the electric elds induced by the Indian Ocean Tsunami occurred on December 26, 2004. We show that the ocean ow related to the Indian Ocean Tsunami must have induced electric voltages of the order of ±500 mV across the existing submarine cables in the Indian Ocean. The electric elds induced by the Tsunami ow have strength within the range of ±10 mV/km, with enhancements along the main ow region and near the coasts and islands. Thus, making use of the in-service or retired submarine cables to measure the electric potential across oceans, it may be possible to detect water movement related to tsunami.

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“…are reduced, in accordance with the MIDM, to a scattering equation of specific type (Pankratov et al, 1997) …”

Section: Forward Computation Of Ocean Magnetic Signalsmentioning

confidence: 99%

Ocean circulation generated magnetic signals

Manoj

Kuvshinov²,

Maus

et al. 2006

Earth Planet Sp

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Conducting ocean water, as it flows through the Earth's magnetic field, generates secondary electric and magnetic fields. An assessment of the ocean-generated magnetic fields and their detectability may be of importance for geomagnetism and oceanography. Motivated by the clear identification of ocean tidal signatures in the CHAMP magnetic field data we estimate the ocean magnetic signals of steady flow using a global 3-D EM numerical solution. The required velocity data are from the ECCO ocean circulation experiment and alternatively from the OCCAM model for higher resolution. We assume an Earth's conductivity model with a surface thin shell of variable conductance with a realistic 1D mantle underneath. Simulations using both models predict an amplitude range of ±2 nT at Swarm altitude (430 km). However at sea level, the higher resolution simulation predicts a higher strength of the magnetic field, as compared to the ECCO simulation. Besides the expected signatures of the global circulation patterns, we find significant seasonal variability of ocean magnetic signals in the Indian and Western Pacific Oceans. Compared to seasonal variation, interannual variations produce weaker signals.

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High-Performance Three-Dimensional Electromagnetic Modelling Using Modified Neumann Series. Anisotropic Earth

Cited by 42 publications

References 5 publications

Three-Dimensional Electromagnetic Modelling and Inversion from Theory to Application

Three-Dimensional Electromagnetic Modelling and Inversion from Theory to Application

Can undersea voltage measurements detect tsunamis?

Ocean circulation generated magnetic signals

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