Deriving the geomagnetically induced electric field at the Earth's surface from the time derivative of the vertical magnetic field

Heikki Vanhamäki, Ari Viljanen, Risto Pirjola, Olaf Amm

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

We present a new method for estimating the geomagnetically induced electric field at the Earth's surface directly from the time derivative of the vertical magnetic field, without any need for additional information about the Earth's electric conductivity. This is a simplification compared to the presently used calculation methods, which require both the magnetic variation field and ground conductivity model as input data. The surface electric field is needed e.g. in modeling Geomagnetically Induced Currents (GIC) that flow in man-made conductor systems, such as gas and oil pipelines or high-voltage power grids. We solve the induced electric field directly from Faraday's law, by representing the magnetic variation field in terms of external equivalent current and taking time derivative of the associated vector potential. This gives an approximative solution, where the divergence- free part of the electric field is reproduced accurately (at least in principle), but the curl-free part related to lateral variations in ground conductivity is completely neglected. We test the new calculation method with several realistic models of typical ionospheric current systems, as well as actual data from the Baltic Electromagnetic Array Research (BEAR) network. We conclude that the principle of calculating the (divergence-free part of the) surface electric field from time derivative of the vertical magnetic field is sound, and the method works reasonably well also in practice. However, practical applications may be rather limited as the method seems to require data from a quite dense and spatially extended magnetometer network.

Original languageEnglish
Pages (from-to)997-1006
Number of pages10
Journalearth, planets and space
Volume65
Issue number9
DOIs
Publication statusPublished - 2013

Fingerprint

Earth surface
electric field
magnetic field
electric fields
magnetic variations
magnetic fields
conductivity
divergence
ionospheric currents
oil pipeline
gas pipeline
magnetometer
simplification
magnetometers
high voltages
estimating
conductors
oils
grids
electromagnetism

All Science Journal Classification (ASJC) codes

  • Geology
  • Space and Planetary Science

Cite this

Deriving the geomagnetically induced electric field at the Earth's surface from the time derivative of the vertical magnetic field. / Vanhamäki, Heikki; Viljanen, Ari; Pirjola, Risto; Amm, Olaf.

In: earth, planets and space, Vol. 65, No. 9, 2013, p. 997-1006.

Research output: Contribution to journalArticle

Vanhamäki, Heikki ; Viljanen, Ari ; Pirjola, Risto ; Amm, Olaf. / Deriving the geomagnetically induced electric field at the Earth's surface from the time derivative of the vertical magnetic field. In: earth, planets and space. 2013 ; Vol. 65, No. 9. pp. 997-1006.
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