Method of auxiliary sources for calculating the magnetic and electric fields induced in a layered Earth

Shepherd, Simon; Shubitidze, Fridon

doi:10.1016/s1364-6826(03)00159-7

Cited by 17 publications

(11 citation statements)

References 18 publications

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“…52-53). In most cases CIM gives very good approximations to the exact solutions and we believe it to be completely adequate for our purposes (see Thomson and Weaver, 1975;Boteler and Pirjola, 1998;Pirjola and Viljanen, 1998;Shepherd and Shubitidze, 2003, for discussions of accuracy). The neglection of horizontal variations in the Earth's conductivity may not always be a valid approximation, as large horizontal conductivity gradients exists, for example, between well conducting oceans and more resistive inland areas.…”

Section: Introductionmentioning

confidence: 89%

“…The CIM technique of Thomson and Weaver (1975) can be directly applied to the divergence-free CECS, as j df has only a horizontal part. Equations (5-6) clearly represent the fields of a mirror system placed at a complex depth 2p+h below the surface, in accordance with having a perfect conductor at depth p.…”

Section: Appendix Amentioning

confidence: 99%

“…The inductive response of the Earth is calculated using the complex image method (CIM) introduced to geophysical applications by Thomson and Weaver (1975). In CIM the layered Earth is replaced by a perfect conductor at a complex depth, and the secondary electric and magnetic fields produced by the currents flowing in the Earth can be calculated by the standard image principle.…”

Section: Introductionmentioning

confidence: 99%

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Induction effects on ionospheric electric and magnetic fields

2005

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Abstract. Rapid changes in the ionospheric current system give rise to induction currents in the conducting ground that can significantly contribute to magnetic and especially electric fields at the Earth's surface. Previous studies have concentrated on the surface fields, as they are important in, for example, interpreting magnetometer measurements or in the studies of the Earth's conductivity structure. In this paper we investigate the effects of induction fields at the ionospheric altitudes for several realistic ionospheric current models (Westward Travelling Surge, -band, Giant Pulsation). Our main conclusions are: 1) The secondary electric field caused by the Earth's induction is relatively small at the ionospheric altitude, at most 0.4 mV/m or a few percent of the total electric field; 2) The primary induced field due to ionospheric self-induction is locally important, ∼ a few mV/m, in some "hot spots", where the ionospheric conductivity is high and the total electric field is low. However, our approximate calculation only gives an upper estimate for the primary induced electric field; 3) The secondary magnetic field caused by the Earth's induction may significantly affect the magnetic measurements of low orbiting satellites. The secondary contribution from the Earth's currents is largest in the vertical component of the magnetic field, where it may be around 50% of the field caused by ionospheric currents.

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Section: Introductionmentioning

confidence: 89%

Section: Appendix Amentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Induction effects on ionospheric electric and magnetic fields

2005

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“…Consequently, the ability of the resolved statistical pattern to predict a radar LOS velocity measurement in such a cell will be somewhat lower than it is over an area of lower variability. The presence of such variations in the observed velocities could be due to geophysical processes such as small‐scale variability [e.g., Codrescu et al , 1995] or motion of the large‐scale pattern resulting from dayside [e.g., Shepherd and Shubitidze , 2003] or nightside magnetospheric reconnection [e.g., Bristow and Jensen , 2007]. It is also possible that some variability is due to enhanced absorption, particularly on the nightside during more active periods, as was noted by RG96.…”

Section: Techniquementioning

confidence: 96%

Climatological patterns of high‐latitude convection in the Northern and Southern hemispheres: Dipole tilt dependencies and interhemispheric comparisons

2010

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Using line‐of‐sight measurements of horizontal plasma drift from the Super Dual Auroral Radar Network (SuperDARN) located in the Northern and Southern hemispheres over a period extending from 1998 to 2002, statistical models of the high‐latitude convection electric field are derived for various ranges of interplanetary magnetic field (IMF) magnitude and orientation and for several ranges of dipole tilt angle. Direct comparison of the corresponding convection patterns in each hemisphere shows that under neutral tilt conditions (dipole tilt angle magnitude <10°) the patterns are most similar. However, a strong dipole tilt angle dependence is observed under northward (Bz+) and By dominated IMF conditions. For IMF Bz+, reverse convection is observed to be much stronger during positive tilt than negative tilt. For IMF By dominated conditions (IMF Bz = 0), the round convection cell is more enhanced for positive tilt than for negative tilt, particularly for IMF By < 0 in both hemispheres. The presence of a lobe cell is a likely cause of this enhancement, although it is not entirely clear why it occurs preferentially under IMF By < 0. In addition, the crescent‐shaped cells are weakened as tilt angle progresses from negative to positive, most likely due to vastly different solar produced conductivities under different tilt angles. For IMF Bz−, asymmetric values of the cross‐polar cap potentials (ΦPC) are observed between hemispheres, with ΦPC in the south being systematically larger than ΦPC in the north. Although neutral tilt patterns are similar enough to be used interchangeably, convection has a strong dipole tilt dependence and a Northern Hemisphere convection model should not be applied to the Southern Hemisphere if dipole tilt angle is not taken into account. When dipole tilt is accounted for, ΦPC differs between hemispheres by less than 10% on average, but the strength of the convection in the individual cells differs by 15% to 20% on average.

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“…Neither of these methods solves the full/complete Maxwell's equations nor provides capabilities (2)-(4) from the above list. Another example, (Shepard and Shubitidze 2003), makes use of the method of auxiliary sources (MAS), which does permit some 2-D or 3-D geometrical inhomogeneities, but is limited by the size of the resulting matrix equations and also does not solve the complete Maxwell's equations (neglects displacement currents). Thus, FDTD modeling would yield a much more rigorous and realistic analyses of the dynamics involved in the interaction of a CME with the Earth-ionosphere environment.…”

Section: Space Weather Effectsmentioning

confidence: 99%

Current and Future Applications of 3-D Global Earth-Ionosphere Models Based on the Full-Vector Maxwell’s Equations FDTD Method

Simpson

2009

Surv Geophys

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Advances in computing technologies in recent decades have provided a means of generating and performing highly sophisticated computational simulations of electromagnetic phenomena. In particular, just after the turn of the twenty-first century, improvements to computing infrastructures provided for the first time the opportunity to conduct advanced, high-resolution three-dimensional full-vector Maxwell's equations investigations of electromagnetic propagation throughout the global Earth-ionosphere spherical volume. These models, based on the finite-difference time-domain (FDTD) method, are capable of including such details as the Earth's topography and bathymetry, as well as arbitrary horizontal/vertical geometrical and electrical inhomogeneities and anisotropies of the ionosphere, lithosphere, and oceans. Studies at this level of detail simply are not achievable using analytical methods. The goal of this paper is to provide an historical overview and future prospectus of global FDTD computational research for both natural and man-made electromagnetic phenomena around the world. Current and future applications of global FDTD models relating to lightning sources and radiation, Schumann resonances, hypothesized earthquake precursors, remote sensing, and space weather are discussed.

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Method of auxiliary sources for calculating the magnetic and electric fields induced in a layered Earth

Cited by 17 publications

References 18 publications

Induction effects on ionospheric electric and magnetic fields

Induction effects on ionospheric electric and magnetic fields

Climatological patterns of high‐latitude convection in the Northern and Southern hemispheres: Dipole tilt dependencies and interhemispheric comparisons

Current and Future Applications of 3-D Global Earth-Ionosphere Models Based on the Full-Vector Maxwell’s Equations FDTD Method

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