The role of 3-D geomagnetic induction in the determination of the ionospheric currents from the ground geomagnetic data

Pulkkinen, A.; Engels, M.

doi:10.5194/angeo-23-909-2005

Cited by 17 publications

(18 citation statements)

References 21 publications

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“…three-dimensionalregion of sourthern Finland (Korja et al, 2002) and with a relatively short time series comprising only 8 days of data. Part of the validity of the 1D assumption results from the spectral characteristics of the GIC phenomenon; most of the power of GIC fluctuations are concentrated in frequencies which penetrate to depths where the ground is to a good approximation 1D (see also Pulkkinen and Engels, 2005). Furthermore, the random noise-like character of both GIC and the time derivative of the ground magnetic field (Pulkkinen et al, 2006a) renders signals both more stationary and spatially smooth on average.…”

Section: Discussionmentioning

confidence: 99%

Determination of ground conductivity and system parameters for optimal modeling of geomagnetically induced current flow in technological systems

2007

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In this work, methods to determine technological system parameters and the ground conductivity structure from different sets of geomagnetically induced current (GIC), magnetic field and geoelectric field observations are explored. The goal of the work is to enable optimal modeling of induced currents in any technological system experiencing GIC. As an additional product, the introduced methods can also be applied to utilize GIC observations in the imaging of the subsurface geological structures. Here a robust processing scheme and Occam's inversion technique familiar from magnetotelluric (MT) studies are applied to the determination of the ground conductivity structure. The application of the methods to GIC data from the Finnish pipeline for a storm period of October 24-November 1, 2003 demonstrate that optimal system parameters and ground conductivity structure can be obtained using time series comprising only 8 days worth of data. Importantly, the obtained ground model is in agreement with models obtained in earlier MT studies. Furthermore, it is shown that although in an ideal case the magnetic field data used should be obtained from the immediate vicinity of the GIC observation site, some spatial separation (200-300 km) between the sites can be tolerated.

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Section: Discussionmentioning

confidence: 99%

Determination of ground conductivity and system parameters for optimal modeling of geomagnetically induced current flow in technological systems

2007

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“…Amm, 2001;Sun and Egbert, 2012). Note that this approach was used by Pulkkinen and Engels (2005), who analysed the influence of 3-D induction effects on ionospheric currents during geomagnetic substorms.…”

Section: Estimates Of the Electric Field At Polar Latitudesmentioning

confidence: 99%

Towards quantitative assessment of the hazard from space weather. Global 3-D modellings of the electric field induced by a realistic geomagnetic storm

Püthe

Kuvshinov

2013

Earth Planet Sp

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In order to estimate the hazard to technological systems due to geomagnetically induced currents (GIC), it is crucial to understand the response of the geoelectric field to a geomagnetic disturbance and to provide quantitative estimates of this field. Most previous studies on GIC and the geoelectric field generated during a geomagnetic storm assume a 1-D conductivity structure of Earth. This assumption however is invalid in coastal regions, where the lateral conductivity contrast is large. In this paper, we investigate the global spatio-temporal pattern of the surface geoelectric field induced by a typical major geomagnetic storm in a conductivity model of Earth with realistic laterally-heterogeneous oceans and continents. Exploiting this model makes the problem fully 3-D. Data from worldwide distributed magnetic observatories are used to construct a realistic model of the magnetospheric source. The results of our numerical studies show large amplification of the geoelectric field in many coastal regions. Peak amplitudes obtained with 3-D modelling exceed the amplitudes obtained in a 1-D model by at least a factor 2, even if the latter makes use of the local vertical conductivity structure. Lithosphere resistivity is a critical parameter, which governs both amplitude and penetration width of the anomalous electric field inland.

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“…Pulkkinen et al 2003). Pulkkinen and Engels (2005) performed model studies for the Scandinavian region to study the effect of 3-D induction in the Earth on estimates of ionospheric equivalent currents of the substorm electrojet over Scandinavia.…”

Section: Polar Electrojetsmentioning

confidence: 99%

3-D Global Induction in the Oceans and Solid Earth: Recent Progress in Modeling Magnetic and Electric Fields from Sources of Magnetospheric, Ionospheric and Oceanic Origin

2008

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Electromagnetic induction in the Earth's interior is an important contributor to the near-Earth magnetic and electric fields. The oceans play a special role in this induction due to their relatively high conductivity which leads to large lateral variability in surface conductance. Electric currents that generate secondary fields are induced in the oceans by two different processes: (a) by time varying external magnetic fields, and (b) by the motion of the conducting ocean water through the Earth's main magnetic field. Significant progress in accurate and detailed predictions of the electric and magnetic fields induced by these sources has been achieved during the last few years, via realistic three-dimensional (3-D) conductivity models of the oceans, crust and mantle along with realistic source models. In this review a summary is given of the results of recent 3-D modeling studies in which estimates are obtained for the magnetic and electric signals at both the ground and satellite altitudes induced by a variety of natural current sources. 3-D induction effects due to magnetospheric currents (magnetic storms), ionospheric currents (Sq, polar and equatorial electrojets), ocean tides, global ocean circulation and tsunami are considered. These modeling studies demonstrate that the 3-D induction (ocean) effect and motionally-induced signals from the oceans contribute significantly (in the range from a few to tens nanotesla) to the near-Earth magnetic field. A 3-D numerical solution based on an integral equation approach is shown to predict these induction effects with the accuracy and spatial detail required to explain observations both on the ground and at satellite altitudes.

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The role of 3-D geomagnetic induction in the determination of the ionospheric currents from the ground geomagnetic data

Cited by 17 publications

References 21 publications

Determination of ground conductivity and system parameters for optimal modeling of geomagnetically induced current flow in technological systems

Determination of ground conductivity and system parameters for optimal modeling of geomagnetically induced current flow in technological systems

Towards quantitative assessment of the hazard from space weather. Global 3-D modellings of the electric field induced by a realistic geomagnetic storm

3-D Global Induction in the Oceans and Solid Earth: Recent Progress in Modeling Magnetic and Electric Fields from Sources of Magnetospheric, Ionospheric and Oceanic Origin

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