|Titre||Calculation methods of electric and magnetic fields at the Earth's surface produced by a line current|
|Auteur||Pirjola, R; Boteler, D|
|Source||Radio Science vol. 37, no. 3, 1042, 2002 p. 14.1-14.9, https://doi.org/10.1029/2001RS002576|
|Séries alt.||Secteur des sciences de la Terre, Contribution externe 20100341|
|Document||publication en série|
|Media||papier; en ligne; numérique|
|Sujets||géomagnétisme; champs géomagnétiques; variations géomagnétiques; paléomagnétisme; interprétations paléomagnétiques; champs électromagnétiques; géophysique|
|Programme||Targeted Hazard Assessments in Northern Canada, Géoscience pour la sécurité publique|
|Résumé||(disponible en anglais seulement)|
Space weather storms involve intense and rapidly varying electric currents in the ionosphere, which create electric and magnetic fields at the Earth's surface.
The electric fields drive geomagnetically induced currents (GIC) in technological networks and may have serious impacts. For assessing the hazards it is necessary to estimate GIC magnitudes, and this requires calculations of the electric and magnetic
fields produced at the Earth's surface by the ionospheric currents. The surface fields are also affected by currents induced within the ground and influenced by the conductivity of the Earth. This also has to be taken into account. The calculation
methods should be fast enough that they can be applied to forecasting the fields and GIC, for example, by using satellite observations of the solar wind. In this paper, we consider an infinitely long horizontal line current, which is the basic model
of an auroral electrojet and simple enough to give insight into the physics and calculation techniques. The Earth is assumed to be composed of horizontal layers. We consider the exact integral expressions of the fields at the Earth's surface. The
applicability of a series expansion technique (SER) and the complex image method (CIM), both of which were originally developed for other disciplines, are reviewed and summarized by giving the expressions of the electric and magnetic fields at the
Earth's surface and by considering the mathematical assumptions required. Numerical calculations and comparisons with exact solutions show that SER and CIM are very accurate.